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Full text of "Practical Wireless 1973 August"

L 



WIRELESS 





MINI-COMM 
RECEIVER 



VHF BAND 
LOCATOR 



mm 



YOUR COMPLETE AUDIO-ELECTRONIC STORES 

More of everything at the right price. Ail your electronic requirements 
within 200 yards- call and see for yourself. 



-H 



BUILD 
THE 



TEXAN 



* FREE TEAK CABINET £&« 

FEATURES. New slim design with 6 - IC's. IC 
Sockets, 10 silicon transistors, 4 rectifier's, 2 zeners. 
Special Gardeners low field slim line transformer. 
Fibre glass PC panel. Complete chassis work. 
HIGH QUALITY & STABILITY ARE PREDOMINATE FEATURES 
—DEVELOPED BY TEXAS ENGINEERS FOR PERFORMANCE, 
RELIABILITY AND EASE OF CONSTRUCTION. 
FACILITIES. On/ off switch indicator, headphone socket, 
separate treble, bass, volume and balance controls, scratch and 
rumble filters, mono/stereo switch. Input selector; Mag. P.U 
Radio Tuner, Aux. Can be altered for Mic, Tape, Tape-head, etc 
(Pi res lite Ref. 20 on request). 
Constructional details Ref. No. 21 30p 



20 + 20 WATT INTEGRATED 
I.C. STEREO AMPLIFIER 

{As featured in "Practical Wittiest" 
May to August 1972) 




SPECIAL 
KIT 

PRICE 



£28-50 



P & P 45p 

COMPLETE WITH 



P.W. Tricolour 
as per April/May 
June 1973. Parts list 
on request (52A). 
FREE TEAK CABINET 



i x*4 : 



+ SLIM 
SN WITH 



Designer approved kits distributed by Henrys! 



J DESIGI 

SILVER TRIM 
Overall chassis size 
I4±" x 6" x 2" high 



LOW COST HI-FI SPEAKERS 

E.M.I. Size \3i" X 6£". Large Ceramic Magnet. 
TYPE 150 6 watt, 3, 8 or 15 

ohms 11 20. Post 22p. 
TYPE ISO TC Twin cone ver- 
sion £275. Pose 22p. 
TYPE 450 10 watt with twin 
tweeters and crossover. 3, 8 
or 15 ohms. £3-50. Post 25p. 
TYPE 350 20 watt with tweeter 
and crossover. 8 and 15 ohms. 
£750: Post 28p. 
POLISHED CABINETS 150, I50TC 450 £4 60. Post 30p. 
ASSEMBLED IN POLISHED CABINETS (8 ohms) 
SERIES 6 (Assembled 150 T/C) per pair £16-50. Post 70p 
SERIES 8 (Assembled 450) per pair £18-95. Post 70p 






ML-3 MW/LW 
TUNER to BUILD 



Uses Mullard Module. Slow 
motion tuning. Built in 
battery. Ferrite aerial. Overall 
size 7" x 2J" x Ji", TOTAL COST TO BUILD 
£4-85, Post I5p. All parts sold separately. Leaflet No. 6 



'BANDSPREAD" PORTABLE TO BUILD 

Printed circuit all transistor design 
using Mullard RF/IF Module. Medium 
and Long Wave bands plus Medium 
Wave Bandspread for extra selectivity. 
Also slow motion geared tuning, 600 
mW push-pull output, fibre glass PVC 
covered cabinet, car aerial. Attractive 
appearance and performance. 
TOTAL COST TO BUILD £7-98 
p.p. 32p. (Battery 22p). 





CATALOGUE 

Fully detailed and illus- 
trated covering every 
aspect of Electronics — 
plus data, circuits and 
information. 10,000 Stock 
lines at Special Low Prices 
and Fully Guaranteed. 

PRICE 55 P pajd 
(40p FOR CALLERS) 

PLUS! FIVE lOp 
VOUCHERS 

Send to this address — 
HENRY'S RADIO LTD. 
(Dept. PW) 3 ALBEMARLE 
WAY, LONDON, E.C.I. — 
for catalogue by post only. 
All other mail and callers 
to "303" see below. 




TEST EQUIPMENT Just a selection! 
SE2508 Pocket Pencil Signal Injector £1 -90 
5E500 Pocket Pencil Signal Tracer £1-50 
THL33D Robust 2K/Volt £4 '55 with case £4-95 
TEI5 Grid Dip Meter 440 KHz-280 mHz £13-45 
500 30 K/V Multimeter £9-25 

With leather case £10-50 
200H 20KJV Multimeter £4-20. With case £4-95 
AFI05 50K/V Multimeter £8-50. With case £9-50 
U434I ACJDC Multimeter with transistor tester with steel 

ease £10-50 
TE20D RF Generator l20KHz-500MHz £16-50. Carr. 35p 
TE22D Audio Generator 20Hz-200KHz £17-50. Carr. 35p 
CI-5 V Pulse Scope lOHz-IOmHi £39 00. Carr. 50p 

TE65 Valve Voltmeter 28 ranges £17-50. Carr. 40p 
ALL NOMBREX MODELS*iN STOCK 




PA-Di sco- Lighting 

UK's Largest Range — Write 

phone or call in. Details and 

demonstrations on request. 

DJ30L 3 Channel sound to light unitTTKW. £29-50 

DJ40L 3 channel Mic (built-in) to light., 3kW. £38-75 

DJ70S 70 watt Disco amp/ mixer. £49-75 

DISCOAMP 100 watt amp/mixer, £68-85 

DJI05S 30 watt Disco amp/ mixer, £32-25 

Anti-Feedback Quality Mic, £11 -50 

DJ500 50 watt PA Amplifier £43-95 

DJ700 70 watt £52-75 

DJ 1 000 1 00 watt £63 -00 

GROUP 300 150 watt rms "Group" Valve Amplifier £86-00 

FIBRE OPTICS LIGHTING. — MICS. EFFECTS. PROJECTORS, 

SPOTS. DIMMERS — STANDS. MIXERS. SPEAKERS. 

Everything for PA — Disco — Lighting. 

FREE Stock Lift Ref. No. IB 

• PORTABLE DfSCOS — DETAILS ON REQUEST 

• CREDIT TERMS FOR CALLERS 



BUILD THIS VHF FM TUNER 
5 TRANSISTORS 300 kc/s BAND- 
WIDTH, PRINTED CIRCUIT, HIGH 
FIDELITY REPRODUCTION. MONO 
AND STEREO 

A popular VHF FM Tuner for quality 
and reception of mono and stereo. 
There is no doubt about it — VHF FM 
gives the REAL sound. All parts sold 
separately. Free Leaflet No. 3 & 7. 
TOTAL £6-97, p.p. 20p. Mk. I Decoder Kit £5-97. 
Built IC Decoder £6-50, Tuning meter unit £1 -75. 
Mains unit for Tuner and/or Decoder PS6/I2 £3-25. Post 20p 




SINCLAIR PROJECT 60 MODULES 
—SAVE POUNDS! 



Z30 £3-57; Z50 £437 

STEREO 60 PZ5 £1-97 

£7-97; P28 £4-77 
PZ6 £6 37; 

Transformer for PZ8 £2-95 

Active Filter Unit £4 45 

Stereo FM Toner £16 95 

IC 12 £1 80; QI6's £15 pr. 

Post etc. 20p per item 



&#».## y 



PACKAGE DEALS 

Post 25p 
2xZ30, Stereo 60, PZ5 £15-95 
2xZ30, Stereo 60, PZ6 £18-00 
2xZ50, Stereo 60, PZ8 £20-25 
Transformer for PZ8 £2-95 
PROJECT 605 KIT £19-95 



VAT 



All prices are exclusive of 10% VAT 
which must be added to all orders inc. 
carr packing. (Note: Catalogue is not 
subject to VAT). 



See earlier page of this magazine for 
transistors, I.C.'s and Semi Conductor 
prices— latest list Ref. no. 36 on request. 

E. & O.E. 



ELECTRONIC KITS 

Henry's introduce new huge 
range of audio and electronic 
kits now in stock, everything 
supplied, tremendous value. 
Detailed list Ref. No. 14 on 
request. 



IC RECEIVER 

ZN4I4 Radio integrated 
circuit as featured in Practical 
Wireless, January 1973, 
Article Reprint Ref. No. 19 
I Op. Price £1 20. 



BATTERY TAPE DECK 

Garrard 9 volt Tape peek 
with heads, etc. As previously 
advertised. Limited quantity. 
£9 50, post 30p. 



LEARN A LANGUAGE 
Recorded Cassettes with step 
by step phrase books. 
French, German, Spanish 
Italian. £1-36 per course, 
£5-00 per set of four. 



DISCO SPOTBANK 

3 channel Disco Spotbank 
for use with any psychedelic 
lighting display. 
£12 75, p. & p. 35p. 



HI-FI EQUIPMENT 

Warehouse prices with 
BIG DISCOUNTS plus 
demonstrations (for call- 
ers) and GUARANTEES. 
FREE — 24 page detailed 
brochure (Ref. No. 17). 
You can see the savings! 



HIGH QUALITY 
CASSETTES 

The best UK low noise tapes 
but at a special price. 
'Living Sound* cassettes meet 
the highest international 
standard (IEC 94A). Fantastic 
price savings. 

,3 6 10 
for for for 



C60 1 1 -00 1-802-80 

C90 1-312-57 4-20 

CI20 I 62 3 15 5-00 

Full guarantee. Post paid 

Made by EMI especially for 

Henry'*, 



ULTRASONIC 
TRANSDUCERS 

Operate at 40kc/s up to 100 
yds. Ideal remote switching 
and signalling. Complete with 
data and new l.C. circuits. 
£5-90 per pair. Post I Op. 



MARRIOT TAPE HEADS 
4 TRACK MONO or 
2 TRACK STEREO 

'17' High Impedance £2-00 
'18' Med. Impedance £2 -00 
'36' Med,-Low Imp. £3-50 
Erase Heads for above 75p 
'63' 2 track mono- 
Hi Imp. £1-75 
'43' Erase Head for above 75p 



7 SEG «V NIXIE TUBES 
(Post I5p per I to 6) 

XN3, XNI3, GN6 0-9 ,jde 

view with data, 85p, 

GNP-7, GNP-8 0-9 side view 

with decimal points and data, 

95p. 

30I5F 7 seg £2 each. £7 per 

4 with data. 

12 and 24 hour clock circuits 

Ref, No. 31 I5p. 



Miniature Amplifier 
5 transistor. 300mW e/p. 
Fitted volume and sensitivity 
control, 9 volt operated. 
£1 -75 each P,'P 15p. 



Quality Slider Controls 

60mm stroke singles and 
ganged. Complete with knobs. 
5K, I OK, 25K, IO0K, 250K, 
500K. I meg, Log and Lin.4Qp 
each, I OK, 25K, 50K, I00K, 
250K, Log and Lin ganged, 
60p each. 



Henrys 



RADIO 
LIMITED 



404-406 Electronic Components and Equipment 01-4028381 I Open;-9am-6pr, 
354-356 High Fidelity and Tape Equipment 01-402 5854/4736 6 J?* s . a w V k 

.inflPll.niei-n.linhtmnUinhD C* I Al I'llEIICO I fWMWM** 



EDGWARE ROAD, W2 



309 PA- Disco-Lighting High Power Sound 01-723 6963 

303 Special offers and bargains store 

All mail to 303 Edgware Road, London W2 1BW 



Thursday) 
I Alt stores open 
all day Saturday 



PRACTICAL 

WIRELESS 



VOL 49 NO. 4 

ISSUE 708 

AUGUST 1973 



BRITAIN'S PREMIER MAflAZINE FOR THE DO-IT-YOURSELF RADIO AND ELECTRONICS CONSTRUCTOR 



EDITOR 



Morris A. Colweil 



ASSISTANT EDITOR 

Lionel E. Howes, G3AYA 




ART EDITOR 



Peter Metal II 



TECHNICAL EDITOR 

Eric Dowdeswell, G4AR 

PRODUCTION & NEWS 
EDITOR Colin R, Riches 

SECRETARIAL 

Jenny Maunder 
Jilt Afflatt 
Telephone 01-634 4292 

ADVT. MANAGER 

Roy Smith 
Telephone 01-634 4293 

CLASSIFIED ADVTS. 

Colin R, Brown 
Telephone 01-634 4301 



SUBSCRIPTIONS 

Subscription Rates for one year to any 
part of the world £265 including 
postage. Enquiries to Subscription 
Department, IPC Magazines Ltd., 
Carlton House, 68 Gt. Queen Street, 
London, WC2 5 DO. Phone 01-242 4477 
Binders (£1 -10) and Indexes (11p) can 
be supplied by the Binders Dept at the 
same address. 



BACK NUMBERS 

We regret that we are unable to supply 
back numbers of Practical Wireless. 
Readers are recommended to enquire 
at a public library to see copies. Re- 
quests for specific back numbers of 
Practical Wireless and Television only 
can be published in our CO Column. 



COPYRIGHT AND QUERIES 



NEWS & COMMENT 

312 THE SMALL PRINT— Leader article and September preview 

313 NEWS - . . NEWS . . . NEWS 
320 BOOK REVIEWS— New books reviewed 
322 TELEVISION— This month's attractions 

329 HOTLINES on recent developments— Ginsberg 

330 Looking at the London ELECTRONIC COMPONENTS SHOW 

—a visit to Otympia 
335 NEXT MONTH in Practical Wireless 
342 ON THE AIR— Reports on Broadcast Bands 
342 Short Wave — Malcolm Connah 
345 Medium Wave—Charles Molloy 

345 VHF/FM— Simon David 

346 Amateur Bands, Short Wave/ VH F— Da vid Gibson G3JDG 
366 PRODUCTION LINES— Products reviewed by Colin Riches 



• CONSTRUCTIONAL 

314 MINI COMM RECEIVER— F. G. Rayer 

325 LOW POWER CLASS A AMPLIFIER—/?. A. Pen 

326 CASSETTE RECORDER IN THE CAR— M. Vlietstra 

333 LIGHT OPERATED SWITCHES and alarms— ft. Penfold 
336 P.W. 'STUDENT OSCILLOSCOPE, Part 1—6. A. Cozens 

356 VHF BAND LOCATOR for 2 metres— A. Sydenham 

357 TAKE 20 No. 51 Touch Sensitive Switch— David Andrews 



+ OTHER FEATURES 

321 I.C. OF THE MONTH, LP10O0 Stored Energy Regulator— 

L A.J. Ireland 

349 CALIBRATING SHORT WAVE RECEIVERS— M. Connah 
353 GOING BACK Equipment of yesteryear— 

Colin Riches and Arthur Dow 

361 MAGNETIC AMPLIFIERS, Part 2—/. R. Sinclair 



Published by IPC Magazines Ltd., Fleetway House, Farrlngdon Street, London 
EC4A 4AD. Telephone: 01-634 4444. 




© IPC Magazines Limited 1973, Copyright in all drawings, photographs and articles published in "Practical Wireless tefutty protected and 
reproduction or Imitation In whole or in part Is expressly forbidden. All reasonable precautions are taken by "Practical Wireless to ensure 
that the advice and data given to readers are reliable. We cannot, however, guarantee it and we cannot accept legal responsibility for it. 

Prices are those current as we go to press. . . ,. _*»*«- 

We regret that we cannot answer technical queries by telephone nor can we provide information or advice on manufacturers products other 
than that given In the magazine. We will endeavour to assist readers who have queries relating to articles published but we cannot offer 
advice on modifications to our published designs. Alt correspondents expecting a reply should enclose a stamped addressed envelope. 

289 



PACKAGE PRICE 

FOR ILLUSTRATED UMTS 



ONLY 

£39-99 

Chit. £1 00 
Or deposit 18-06 
and 9 monthly 
payment* 14-22 
(Total 144 S3). 



R.S.C.STEREO PACKAGE OFFERS 



SAVE £30 approx. 




PACKAGE 
PRICE 



GARRARD 2025 



LINEAR 505 

Individual Hk, Ketatl Prices : 

LINEAR SOS 6 4- 5 Watt Amplifier £19 25 

OASKAKD 2025 Autochauger + KW0A Cartridge . . 118-4* 

Teak Veneer Plinth with. Transparent 1'lanlic Cover 15 -80 

Pair A55 LOUDNFEAKrIRS (Inc8" x 5" JO.00O faints) 1 10-82 

TOTAL {4841 



SEND S.A.E. FOR 

FREE COLOUR 

BROCHURE 




FANE 'MODE ONE' HIGH FIDELITY SPEAKER KIT 

Incorporating a model 801 8" 13,000 Gauss Bass Speaker 
with ultra low resonance. P.V.C. surround cone. 
Printed circuit cross-over assembly with Fertile 
cored coils. Model 303 Pressure Tweeter, Acoustic 
damping material, Screws, Panels etc., and in- 
structive diagrams, Frequency JTQ.OA P°st 
Response 25 Hz-20 kHz. *•' *° free 

Impedance 8-15 ohms. Or i> e p. £2 ft a inthty 



RSC G66 Mkll 6*6 WATT high quality STEREO AMPLIFIER 



Individual Ganged Controls: Buss. Treble, Volume and Balance. Printed 
circuit construction employing 10 Transistors plus Diodes, Output 
rating I. H.F.M. Frequency range 20-20,000 c.p.s. Bass Control ± 12db. 
Treble Control ± I3db, Selector switch for 
P.U. or Tape/Radio. For loudspeaker out- 
put impedances of 3 to 15 ohms. For 
standard 200-250v. A.C. mains operation. 
Attractive Black and Silver finished metal 
fascia plate and matching control knobs. 
COMPLETE KIT OF PARTS INCLUDING 
FULLY WISED PRINTED CIBCD1T and 
COMPREHENSIVE V7JRIKO DIAGRAMS * INSTRUCTIONS /n JCC Carr. 
Or FACTORY BUILT IK TEAK VEHEERED CABDTET K.IA'03 tn n 

as Illustrated £16 SO or dep. £8 and 9 monthly payment* 11-88 (Total £18-: 



'SUPER 30' AMP 



HIGH FIDELITY UNITS 



£1 08-25 Sft 

FOR ILLUSTRATED UNITS 

Or deposit IIS'OO and 

1 2 monthly payments 18 ft 
(Total 1120 36) 

iJOLDKING (1L72 Trans- 
cription Turntable +■ P. I ' . 

iSOLDRINO GB0O 
Magnetic Cartridge 

DE-LDXE PLINTH 

with Roll-over Cover 

J air R.3.C. MONARCH 

LOUDSPEAKERS 

it. B.C. SUPER SO 

ilk III AMPLIFIER 

Total value ol Individual items 

listed above £13814. 



SPIOI HIGH FIDELITY PLAYER UNIT 

Comprising Goldring GI01 hi-fi single player unit fitted high fidelity 
free field magnetic stereo cartridge with diamond stylus. Belt driven 
Attractive design super-slim plinth and 'roll-over' transparent tinted 
plastic cover. Or Deposit £4-95 and 9 Monthly flA.QC Post 
Payments of £3-75 (Total £38-70) Excellent value. *"" 7J paid 




asp 



AUDI0TRINE HIGH FIDELITY SPEAKERS 

Heavy construction. Latent high efficiency ceramic magnets. 
Piasticiserf Cone surround. "D" indicate* Tweeter Cone providing 
Ktcuded frriiueiicv range up to ] 5.000 c.p.s. Impedance 3 or 
8- 16 ohms. PLEASE STATE CHOICE. 

Exceptional oertonnence at low colt. 
HF808T 8* 10W 13 88 HflZOD 18" 16W I5i0 
HF102D 10* 10W £830 HF128 IS' 15W 18-S5 
HF120 12- I6W £4 85 HF128D 12' 1BW 19-85 



FANE 807T HIGH FIDELITY SPEAKER 



A full range Bin. 10 watt unit fur excellent eouuil quality, in suitable 
enclosure. Goal chassis Roll P.V.C- cone surround and long throw voice 
coil to achieve very low fundamental rcutmauce of 30 c.p.s. Tweeter 
cone is fitted to eiteud high note response. Frequency range 26 Hit to 
15 KHz. Gaum 10,000. Impedance 3 or 8-16 0. £~1 "7ft 

PLEASE STATE IMPEDANCE WHEN ORDERING *■■-* ,v 

MODEL 803T 8" 15w. with parasitic Tweeter. 
P.e-ponse 25 Hs to 15 KHz. Gaum 13.000 Imp 3 or 8-16. 




£4-95 




^ 



R.S.C. BATTERY/MAINS CONVERSION UNITS 



TYPE BMI. Ail all -dry battery eliminator. 8 lie E| 
approx. Completely replaces hattertee supplying l-6v 
to battery radio where A.C mains 200/ 260 v. 
50c/b is available. ASSEMBLED READY FOR USE 



£4-15 



HIGH FIDELITY LOUDSPEAKER UNITS 

Cabinet! lateit style Satin Teak veneer- Acoustically lined or filled 
aconjtic damping. Ported when appropriate. Credit terms available. 
DORCHESTER (Illustrated) Size 16x1 1 x9ln. appr. Range 45-15, 000 . 

e.p.j. Rating 8-10 watt*. Fitted High Bui 13 X Bin. /O.dC 
Dual Cone speaker. Imp. 3 or 15 ohms. ■»# ~ J Carr. 40p. 

MONARCH Size 10x101 x91n. approx. Rating 10 watte. Inc. 13 X Sin. apeaker' 
highly flexible P.V.C. cone surround, long throw voice coil and 10,000 Hue magnet 
High flux pressure tweeter. Handsome design cabinet. Range 33-20,000 c.p.s. Imp 
8 ohms. Gives smooth realistic sound output. £ I Q.TC 



I 

with 



See 'package oiler i' tor Illustration. 



Carr. 50p 



HI-FI SPEAKER ENCLOSURES MODERN DESIGN 

Teak veneer finish. Acouatically lined. Bizea approx. Can-. 35 p. per cur. 



JE8Size 16" x 11" x 9". 
Pressurised. Gives pleasing 
results with any / C , CA 
Sin. Ht-Fi speaker, w JW 

SE10 For outstanding results 
with lOin. Hi-Fi 
spkr.Size25ix!6 /A. 71 
x9in. P'td. tw * 3 



SE8 For optimum perform- 
ance with any Sin. M _-, 
Hi-Fi spkr. £6 " 50 

Size !9X lOixWn. 
SE12 For excellent 
performance with 1 2in. 
Hi-Fi speaker and tweeter 
Size fl*Vk 

25i k 16 x 9b. *•* Ta 





AUDIOTRINE HI-FI SPEAKER SYSTEMS 

Consisting of matched 12in. 11,000 line IS Watt IS ohm 
high quality speaker, cross-over unit and tweeter. Smooth 
response and extended frequency range £ f. , C A Carr. 
ensure surprisingly realistic reproduction. *"** JW 33p 
OR SENIOR 15 WATT INCLUDING IT 7. fJZ Carr. 
HFI26 15,000 LINE SPEAKER *-* •** 39p 



R.S.C. TA6 6 Watt HI-FI AMPLIFIER 

S00-25DT. AC mains operated. Frequency Response 30-20,000 c.p.s L G_© ©__ 
-2dB. Harmonic Distortion 3»; at 1,000 c.p.s. Separa-.e Bass and " -~2" *" —I 



2dB. Harmonic Distortion 3% at 1,000 c.p.s. Separav 
Treble 'lift and cut' controls. 3 input sockets for Mike, Gram, Radio 
or Tape. Input selector switch. Ontput tor 3-16 ohm eptu-s. Mai. sensitivity 6mV 
Output rating I.H.F.M. lully enclosed enamelled cf.se, 9^x2jx5iJn. Attractive 
tiruihed silver finish lacla plate lOixSfin. and matching knobs. 
Complete kit ol parti with fall wiring diagrams and inilructioni. £8*50 CuT ' 

OR FACTORY BUILT WITH 18 MOUTHS' GUARANTEE £I2'0S 



eOp. 



R.S.C. TRANSFORMERS, L.F. CHOKES & RECTIFIERS |l^KS'Zr d " (,1,nl,, ' dwb,,,D ' c ' ,, " r 



MIDGET CLAMPED TYPE 2i X 2| X 2,ln. 

260v., fiOmA, S3*. 2a 

260-0-25OT., 60mA 8-3v 2a 



1110 

11-16 



FULLY SHROUDED UPRIGHT MOUNTING 
2S0-O-250v. fiOmA, S3v. 2a., 0-5-6-3V. 2a. 11-5S 
260-0-260v. 100mA, «-3v. 4a., 0-B-6-31-, 3a, £2-46 
80O-O-3OOv. 100mA, 0-3v, 4a., 0-5-8 -3v. 3a. «2'46 
300-0-300v. 130!piA. 6 3v. 4a. c.t„ 6-3v. la. 

For Mullanl 610 Amplifier £2-06 

360-0-3SOT. 100mA, 6-3v. 4a., 6-6 -3v. 3a. 18.45 
350-0-3SDV. 150mA, ii3v. 4a., 0-5-6 -3v. 3a. 1Z-85 
426-0-425V. 200mA, 0-3v. 4a., c.t., 5 r. 3a. 15-46 
426kl.426v. 200mA, 6 -3v. 4a., 6 3v. 3*., Si 



:-:.i 



4S0.O-450v. '250IUA. 8- 



4a., c.t., Sv. 3a. 



■Ml 

18-00 



TOP SHROUDED DH0P-THK0' TYPE 

250-0-260v. 70mA, 6 3v. 2a., 0-5-6 3v. Sa. 1149 

260-0-250V. 100mA, 6-3v. 3 -5a. H-71 

350-0-360T. 100m A, 3 v. 2a., 6 3 v. la. . . SI -75 

36O-0-36O?. SOmA, fl-3v. 2a., 0-5-8 -3v. 2a. Jl-81 

260-0-260v. 100mA, 6-3v. 4a., 0-6-6 -3t. 3a, 1E'46 

300-0-300v. 100mA, fi-3r, 4a., 0-6-63v, 3a. 1£'45 
300-0-300v. 130mA, 6-3v. 4»., c.t. 6-3v. 1*. 

Suitable for Milliard 610 Amplifier «E-8S 

360-0-360v. 100mA, 6-3r. 4a., 0-6-6 -3v. 3a. l£-45 

36O-0-360v. 150mA. fi-3v, 4a., 0-6-6 -3v. 3a. £2-85 

FILAMENT or TRAKS1STOR POWER PACK 
Types 6 3v. 15a. 55p:63v. 2a- 80p; 6 3v. 3a. S5p; 
6-3v. Ga. 1146; 12v, la- Blp; 12v. 3a. or 24v. 
l-6atl60 9-iav Ha 11-25 jjg 10-* S; 2all-S5. 



CHAKGER TaANaFORMERS0-9-15v. Ha. £1-10, 
2 f a. £1 25; 3k. 11 40; 5a.ll 60; Call 85: e a. 12 20 
AUTO (Stsp UP/nep DOWN) TBANSFOBMEBS 
0-HO/120V. 200-230-260v. 60- B0 ivatta 11-25, 
ISO -watts, 12 10 250 watts £8 00; 600 watts £8 40 
OUTPUT TKANSEOEMEE8 

Standard PeDlode 6.0000 or 7,000 (1 to 31,1 55p 
Fush-Pull 8 watU ELS4 to 3 H or 15 Q. . 95p 
Push -Pull 10 watts 6V6, ECL86 to 3, 5, 8 or 

16 n 11-55 

Push-Pull EL34 to 3 or 16 O 10-12 watts. . 11-60 
Push-Puil Ultra Linear for Milliard 51 0, etc. £2-45 
Push-Pull 15- 18 watta, sectionally wound 

6L6, KT65. etc., for 3 or 16 17 £2 20 

Push-Pull 20 watt high quality sectionally 

wound EL34, 61*. KT66 etc. to 3 or 15 £365 



SELENIUM 

RECTIF1EES 

F. W. (Bridged) 

All 6;i2v. D.C. 

output. Max. A.C. 

input 18v. 

la, 28p. 2a. 39p. 

3a, 56p 4a, 72p. 

6a, EI8 p. 

SMOOTHING 

CHOKES 

150mA. 7-10H, 250 

n 77p; 100mA, 

10H, 200 CI 66p; 

80mA, I Oil, 350 Q 

55p; 60mA, I OH, 

400 Q 2Sp. 



For Magnetic or 
Ceramic Pick-Ups 
regardless of Price. 
Output (per chan- 
nel) 15 watts RMS 
into 8 SI. Fre- 
quency Response 
7 Hz to 70 KHz 
■A: li dB. 




R.S.C. Mklll SUPER 30 HIGH FIDELITY STEREO AMPLIFIER 

BUILD AN AMPLIFIER WORTH APPROXIMATELY 
DOUBLE THE KIT PRICE INCLUDING CABINET 
Only high grade components by leading manufacturers 

* Push Button Selector Switching 

* Jack Socket for Headphones 

* Neon Indicator 

* Satin Silver Finish Metal Fascia 

* Solid State Circuitry 

* Twenty Silicon Transistors 

* Four Diodes, Four Rectifiers 

Send S.A.E. for 

full descriptive leaflet. 

R.S.C. STEREO FM in TUNER. 

in cabinet 

Visually matches ^"S7."«A 

Super 30 Mk. Ill tJ * 3U 



COMPLETE KIT 

(less cabinet). 
Carr. 70p, 
Cabinet if req 
£5 extra. 



tvii 

£27" 



50 



FACTORY BUILT UNIT INC. 

CABINET with 12 months' guar- frfO-rtfl 
antee. Or Dep. £7 and 9 monthly TAu JU 
payments £4-54 (Total £47-86). 



'YORK' HIGH-FIDELITY 3 SPEAKER SYSTEM 

* Moderate size only 25 X 14 x \9ia. 

-a. r. aP T™ ™ nnn , „ ■ COMPLETE KIT 
ic Response 30-20,000 c.p.s. 

Impedance 15 ohms £25*25 

•k Performance comparable with 

units costing considerably more Carr. 65p 

Consists of (I) 12in. 15 watt Bass 

unit with cast chassis, Roll rubber cone surround 

for ultra low resonance, and ceramic magnet. 

(2) 3 -way quarter section series cross- over system. 

(3) 8x5in. high flux middle range speaker. 

(4) High efficiency tweeter. (5) Appropriate quantity acoustic 
damping material. (6) Handsome Teak veneered cabinet. 
(7) Circuit and full instructions. Terms: Dep. £4-60 and 
9 monthly payments £2-64 (Total £28-36). 




290 




/^GROUP/DISCO UNITS 

^-^fTlTc^^^ 100 WATT SO WATT 

s^akVrF*^ AMPL,F,ER SPiAKER 




PACKAGE OFFER 

Unit* listed below 
U) lOOw POWER AMPLIFIER 
(b)PAIR OF HI-FI HEAD- 
PHONES 
<c) MATCHING DYNAMIC 
•MIKE' (attached tort'rjhone> 
(d> PAIR SO WATT SPEAKERS 
Black Rexine covered 
Cabinets Sim appro*. 

(e)HSCTDI DISCO CONSOLE 



(a) (b) (e) td) » (c) 
Carr. £2-50 



jg^l 



Dl DISCO 
CONSOLE 



£145 



Terms Deposit £30 and 18 monthly 
payments of £8-00 (Total £17400). 



Incorporating twin Garrard SPS5 

ML. Ill turntablei and Sonotone or 

A co i CartridMi with diamond ityiil. 

Separate Vol. contrail lor each 

turntable. Alio KOHITOBIHO 

FACILITIES, plus Treble end Bui 

Contrail. Separata input tor 'mike' 

with tol. control iwltcb. Black 

Vrnide corared Cabinet with lid. 

it* it! nitration 

on left 

Or Dtp, 110 and 

B mthly pymts 18 80 

(Total 171 -20) Carr. 11-50 



£63-26 



HEADPHONES 
MICROPHONE 




R.S.C. COLUMN SPEAKERS StSSSS 

S&SSJSSSSx&SSSSWSm* m ELMmoHio <au> 

TYPE C31S 50 WATTS Lou JMillmit 
TYPE CI32 30-40 WATTS KItteil two tfasuijtoruau. pitted three Iff* x n" deep 
exceptionally efficient, low fi-filliiu-k howl char- L . llm . [.^j, mlst speakers with liljtli imwer 
..-tiriatli! tilKh flu* 13- i K* M watt /"> I ,95 voice coilH. fllz« appro*. 54" x 14" x 11". 
•ueakere. Terms: lirp.!8 mi'l » "*' ■*** u,.p. & * ninthly pymt«Sa-64 /TJ.71 
m/llily payment* 12-48 (Total 124-781 CeW. Bup. (TlI(a j £39 SB) Carr. BSp. *■"** * * 

TYP E C4 1 00 1 00 WATTS Inc. four If 60 watt ipnlim fur comer™- £7 I .Cft 
tiro ratine E*tr» heavy contraction. Bije appro*. 68x18X10- AmusUeallr " " ""* 
r»ej" 1 U r>""rhid Term.; hep, ill ai.d 19 imhly. »** 16-80 (Total J8Q-8Q1. Carr. 1150 




s 



Mt 



R.S.C. A 10 30 WATT ULTRA LINEAR 

mn AUDI I El CD MlKlJr iiiiiJtlye. Puib-Pull li It'll 
-PI RlTlrLiriCn output, Hiuh leyeJ-TOdH. Keiponte 
J-Sillt 30-'JO,000 eft. All hljli *rade component). Valfei EF8S 
BP*8 BOOSft KL34. BL84, UZS4. Separate Ban and Treble 
Control), Bemlllvlty 30 millivolts. Fur High Impedance micro- 
ohonet. For Club). School), Theatre). Sauce Halle, Outdoor Ponc- 
tioni. etc. For ElMtronio Oman, Ooitar, Btrinf Ban, ete. Uram, 
itadio m Tape. Two sepeiaie iiipule with vol, control) permit »ucb u "uiU»" "d Pill .OC 

pick-up etc. for uiSih.1 purpose. SfOO-aBOv. 60 oft A£. malne. For 8 wid 1 IS chut W f »| 

EL, Twln-bandled perforated ever 18 10. 18 HORTHS' QUABAMEE. t'arr. ,-ip * u 

DepOIlt 14 anil 8 monthly payment* ol 1 8 87 (ToUl 88* 48 1 ■ H*nd H.A.t,. (or leaflet 



F.A.L. DISCO PRE- AMPLIFIER M 0.Q7 

Designed for use with a pair of Player Units and Amplifier with Jl I U U I 
Bass and Treble Controls, Incorporates MONITORING 
FACILITIES and Mic. input. The 4 inputs are ind. controlled. Detector switch 
Gram (1), (2), and Tape. For operation on 200-250 v A.C, Mains 50Hz. Size approx 
161" x 3" x 4" deep. Brush Silver finished fascia. Fully enclosed but can be 
mo u me d in cabinet. 



FANE "CRESCENDO" SPEAKERS 

FULL RANGE AVAILABLE AT ALL BRANCHES 



FAL PHASE 50 Mk.lll AMPLIFIER 50 WATT, 

Bolld etate. 4 Heparately controlled Inpute PI in master rot, 
control. I nil. But and Treble Cuutriiln. Protective circuit In 
guard egalnit damage Irani accidental pboru. Output fin 
Speaker/i 3 to 80 ohine. Bl« 17* x 7' • 7(*- aOO-'JSOr, A.C 
malm. Output 80 weiti mnslc rating. PflTiftC 

Or depotit ITU ft montoli pa-- til/ HQ <: * r ' 

miBti MBS. Total I4£ 68. *"• Mu *Mp. 




RSC PHANTOM 




Combined SOW Amplifier 
and 1Iin. Loudepeaker, 

Pnr Lead titiltar, Ml«., drain, Radio, Tape (Kot for uie with fle"» 
Inetrumente). tnc, 3 Itiputi ami 2 veil, cnutrnln plu» Treble, Ban ami Preieuce. 
Output Jack lor additional 18 ohm Bpeaker. Attractively flalened In black with 
■llver.flnlnheil ta<ola tunl trlmmlnge. Umnpatt Mit. Fltteil carrying handle. 
Term*: ])rin«.it 18 85 ami VJ . immthly A ill V OCAifiC 

p.yn.ent. 14 SS(Tntal 18788). Carr.Frrr UNLT X3l1 DO 

8AE tnr leatlet trfc \r.mt..w1 



t'K Malnlainl 



RSC BASS-REGENT 
50 WATT AMPLIFIER 

A powerful blgu i.uiait.v all-purpinw unti 
for lead, rhythm, bann itultar, viwaltatn. 

Cam. rail In, tape. Peak Output rating, 
mdipeaker unit either hurlKotital m 
rertlcal tununtlng. 
if Two extra heavy duty lliln. BOw 

Loudipeakere. 
+ Fuiir Jack Input* ami i«" Vnlumr 
Controle (or litiUuii t)-e ut nu In tow 
plckupi or "inlke"", liaw and Trrhlr 
eontriiln, Beml H.A.K. i<ir lea net. 
Credit Ternn: DepoKlt US nnl Pft 
* 8 monthly payment* itf f / I fill 
17-81. (Tutil 17998. M^arr. fl ** ' ' " u 





RSC GP30 HI-FI 
AMPLIFIER 

For Guitar, Vocal or 
Inttrumental Group 



A 4 Input, ti vol. contrnl HI-FI 
30 wall null with Beparate Ma*e 
and Treble control*. Current 
valve-. Peak output rating. 
Strong Krjiue covered cabinet with 
handle!. Aliraidlve h[ai'k/«llvur P.V.U. tneola. Neon indifatur. 
For 2on-ssuv. A.t:. itiaiiiFi. Fur ;t iir 16 '■Ilih Artr nr 
■peakere. Send B.A.K. for leaBel. T^iik: I 'Jk'Uh l arT 
Depoelt 14 40 ami nmntbly paymruu of Jj£|-J |J|} '-? 



18-78 (Total 1'JU-IS). 



FANE ULTRAHIGH POWER LOUDSPEAKERS 

*lt power ratlngiare B.M.9. contluuoui. 2 YEARS' OOABAKTEH 
H I gh.nui ceramic magnet*. ALL CARRIAUG_FREE 



'POP' 100 'POP* 60 

8" lOOWatt 15" 60 Watt 

14,000 nun 14,000 ciuii 

8/15P B/ISO 

£25-95 £14-75 

Dep: IS and 9 
uithly payment! 
18-48 (Total 128-41) 
f OR BASS OTJITAB, ELECT. 0ROA5, ETC 



Pep. 18-80 ami 9 
monthly payments. 
U-60 (Total 116-80) 



'POP' 50 

12" 50 Watt 

13.000 Eiu» 
ISO £||.9t> 

Dep 18 and 1 
monthly pay- 
ment* 11-83 
(Total 118-87) 
PAIR BFITABLB 
ALL PCRPOSE3 



FANE SPEAKERS 'POP* 25/2 12 in. 25 WATT 

Dual Cone 15 a (for uses Pn.ftC 0I D * p ' * 

other than Bass Guitar or T. I J J 
Electronic Organ). Carr. free 



i ut lily pay me 
(Total 18 28). 



S9p 



DISCO PACKAGE OFFER £4 J 



Pair BSR MP60 T/tables GP91 PU Cartridges 
FAL Disco Pre-amp.Totel Rec. Ret. Price £50- 1 1 



Carr. £1 



6R0UP/DISGO EQUIPMENT PACKAGE OFFERS 



F.A.L. PHAIE 80 MEII1 AWLIfTEa 
PR. FARE POP 18 1 86W L.SPEAKERl 
Tirmi: Uipoilt 17-80 and 9 monthly 
paymenle of 16-88 (Total 165-74) 
P. AX. PHASE 80 HS.HI AMPLIFIER 
PR. FARE POP 80 L/ SPEAKERS 
Tumi: Uipoilt 110 and B monthly 
payment! ol 18-07 (Total 184-88) 
F.A.L. PHAIE 60 MK.in AMPLIF1IR 
PAIR LISilO 85 W L.i'l In eaelaete 
Tenni: Depodl 110 and 8 monthly 
payment) of 18-68 (Total 188-08) 
F.AX. PHAIE 100/8 AHPLinER 
4 PANE FOP 00 L/IPEAKXai 
Temu: Dipoill 180 and la monthly 
payment) ol 18-68 (Total 1123 -58 1 



117-95 
118 -90 



187-95 
183-98 



187-95 
188 'SO 



188 -Bl 

147-98 

1117 -81 



PACKAGE PRICE 

£49-50.- 

PACK A (IB PRICE 

£57-50-tt. 

PACKAOR PRICE 

£61 -Ts* 

FACKAdK PRICE 
ean, 



£110 



HIGH QUALITY LOUDSPEAKER UNITS 

ALL TWO TONE REXINE AND VYNAIR FINISH 
L125 50 WATT Fitted pair of 12" 50 POn.QC 
watt high flux speakers for conservative TQ f nil 
rating. Impedance 8-15 ohms. Carr. £1 50 •*** ' vw 

Or depotit 14 50 and 9 monthly payti. ol 14-87. Total 148 98 
L12/20 l'l"a0-M WATT 13,000 



lined 18 ohn 
Dep 1250 & B 
nithly pytnt* 11-48 
(Total U5'88) 



£13-15 

(Jarr. 5flp. 



LI2/I0 10-lfl "Watt veneer 
finish cabinet VI" unit 8-15 
obui. Hfie approx. 14" x 
14" x 0". Carr. 50p 



D 



£8-25 



CREDIT TERMS AVAILABLE ON PURCHASES OVER 
£8 (Kit. Exe.pt.d) INTEREST CHARGES REFUNDED 
ON CREDIT SALES Semlejd in i month! 



NOW FIVE NEW BRANCHES 

Rl*ll TflM 23 DEANSGATE 
BULIUN OPENS MID-JULY 

NOTTINGHAM "''^^SIeet 
SUNDERLAND i market square 

STOCKPORT 8UTTLB UNDERBANK 
COVENTRY I' SHELTON SQUARE 
NEW LARGER PREMISES AT HULL, 

DARLINGTON & NEWCASTLE ■« F 




HI-FI CENTRE! LTD. 
HAIL ORDERS * EXPORT EHQUIRIES TO: - 
AUDIO HOUSE. HEKCOEHER LAHE, LEED8, 18. 
Tel: Pulley (09788) 776S1. 

TERMS C.W.O, or 0.0. D. No C.O.D. under 11. 
POSTAOE 28p EXTRA UNDER 18. 8Sp EXTRA 
OVER IS OR AS QUOTED. TRADE SUPPLIED, 

B.A.E. PLEASE WITH ENQUIRIES. 
SUPPLIERS TO GOVT. DEPTS. S.M. FORCES. 
KDUCATIOS AUTHORITIES ft HOSPITALS. Etc. 
HAIL QBDEB8 MUST EOT BE 8EXT TO SHOPS 



R.S.C. BRANCHES OPERATE A 5-DAY WEEK 

OPEN ALL DAY SATURDAY 

BRADFORD 10 North Parade (Cloiad Wed). Tel. 15349 
BOLTON 23 Oeaneoate Tel: 33512 Openi Mid-July 
BIRMINGHAM 30/31 Oreel Weltern Arcedt. 

Til. 021-238 1279 (Cloied Wed.) . 
COVINTRY 17 Shelton Square, The Precinct 
OIRBV 28 Oemeiton PJd., The Spot ICIoeed W«d.). 

Tel. 41381 

DARLINGTON m 

19 Nerthgate"lClbied Wed) Tel 68048 
EDINBURGH 

101 Lothian Ed. (Cloaed Wed,), Tel, 889 1801 
OLABOOW 326 Arsyle St. (Cloied Tuee.). ( 

HULL 7 WhltefrlartjatB Tel. 20505 

Lf ICESTER 32 High Street (Cloeed Thun.), Tel . 58420 

L..D. 5-7 County <M.cc.) Arcade, Brlsg.1. ^ m 

LIVERPOOL 73 Dale St. (Cloaed Wed.). Tel. 238 3573 
LONDON 238 Edowere Road, W.2. (ClOlltl i-Thuri.). 

Tit . 7*3 i 629 

MANCHESTER 60 A Oldham Street, (Cloeed Wed.). 

Til. 238 2778 
MIDDLESBROUGH 108 Newport Rd. (Cloudy Wed.). 
NEWCASTLE UPON TYNE Tel .47098 

24 Newoate Shopping Centre (Cloeed Wed,). Tel 21489 
NOTTINGHAM 1B/18A Market Street (Cloeed ThureJ. 

Tel : sflOoo 

SHEFFIELD 13 Exchange Street tCaatle M«rkr* Bide) 

(Closed ThUft), Tel, 20718 

STOCKPORT 8 Little Underbank. Tel: 4B0-0777 

SUNDERLAND 8 Marset Sg. (Cloeed Wed.) Tel. 70573 



291 




KXJ CAN EARN £50 P .w 

Plus an exciting life and a secure future. 

HOW? 

Get into the fabulous Computer Industry now. On the ground 
floor. White industry, commerce, science and governments are 
desperately seeking trained personnel. Give us only four to 
six weeks and we can train you in any one of the three vital 
careers in computers: (1) Programming (men and girls). 
(2) Operating (men and girls). (3) Key Punching (girls 
exclusively). 



We are the only training organisation able to 
make this offer. And our teaching methods 
succeed because they combine specially pre- 
pared courses with equipment such as the 
unique Eduputer, exclusive to us. 

Thanks to our methods, people from all 
walks of life have exchanged boring, under- 
paid, insecure jobs for careers that have 
meaning, prestige and security. 



Past performance counts for nothing. Pro- 
vided you have the aptitude (which we can 
discover quite simply), there is no reason why 
you should not get out of the rut and into 
Tomorrow's World — the fascinating world 
of Computers. 



The moment you qualify — and we will help 
you do just that — one of our own exclusive 
appointments agencies will introduce you to 
opportunities galore. Worldwide. At no cost to 
you. All part of our continuing service. 



What have you to lose by enquiring? Information 
and advice are yours for the asking. 
Post the coupon TODAY for full details FREE and 
without obligation, 



London Computer Training Services 

R6S, Oxford House, 9-15 Oxford Street, W.l. Telephone: 01-437 99Q6 
127 The Piazza, Dcpt. R65, Piccadilly Plaza, Manchester 1. 061-236 2935 




Please send me your free illus- 
trated brochure on training for 
Computer Programming 

(men and girls) Q 

Computer Operating 
(men and girls) D 
Key Punching 
(girls exclusively □ 

(tick appropriate box) 



Name 

Address , . . 

Tel. 



B.H. COMPONENT FACTORS LIMITED 

SPECIAL RESISTOR KITS (iW S % or iW 5 % CARBON FILM) 

JOEIZ Kit: 10 of each Ell value. 10 ohm: — IM, a total of 610, £3 10 net 
25 EI3 Kit: 25 of each E I 2 value, 10 ohm s- IM, a total of 1,51 5 . £7 10 net 

POLYESTER CAPACITORS MULLARD C280 250V 
af: 001, 0015, 0032, 0033, 047, 3*p each; 0068, 01, 015, 4ip each; 
22, 5jp; 33, 3 p; 0-47, 9p; 66 , lip : 10. I5p: IS, 1 2p; 2 2, 25p. 

MULLARD POLYESTER CAPACITORS C296 SERIES 
160V: (uF) 0-01, 00(5, 022. 2+p: 0-047, 0068, 3ip; 01, 015, 4ip; 
22, Sp; 0-33, 6p; 0-47, 7+p; 0-68, lip: I 0, 12. p. 
400V: (ftF) 001, 0015, 0022, 0033, 01, 2ip; 0(5, 033, 3ip; 

068, 4*p. 

MINIATURE ELECTROLYTIC MULLARD C426 SERIES (6p each) 
C/iF/V) 1/63, 4i40. 8/40, 10/40. 10/64, 16/40, 20/64, 25/25, 32/10, 40/16, 64/10, 
80/16, 80/ 2S, 100/6-4, 125/16, 200/6-4, 200/10, 320/6 4, 125/10. 
MULLARD C437; (jzF/V) 64/64, I0p: I60/2S, lOp; 160/40, I2p; 640/6-4, 

1 Op; 160 0/6 4. I6p. 

" ELECTROLYTIC CAPACITORS. Tubular and largs can 
(liFIV) 2-5/50, 3p; 4/10, 10/25, 16/15, 20'25, 25/15, 25/25, 40/6, 64/10, 200/6. 
250/10. 5p: 10/6, 10/50, 25/50, 32/50, SO/ 10, 64/25, 100/25, 6p: 50/50, 64/40, 
250/ 15, 1 ,000/1, 7p: 1 00/50. 250/25, 400/ 1 0. 500/ 1 0. 500/12, 640/ 1 0. 1 ,000/6, 9p; 
500/25. lip; 500 50, I4p; 1,000/12, lip; 1,000/25, 2,000/12, 2,500/12, I7p; 
1,000/50, 39p; 2.000,75. 27p; 2.50O25. 33p; 2,500'SO, 62p; 3,000/50, 72p; 
5,000/50, 94p; 1,000 100, 66p; 8/350, 14 p; 16,350, Ivp; 32/350, 25p. 

MINJATURE CERAMIC PLATE CAPACITORS 
50V: <pF) 22, 27, 33, 39, 47. 56, 68. 82, 100, 120, 150, 180, 220. 270, 330. 390, 
470.560.680.820. IK, I K5, 2K2, 3K3. 4K7, 6K8. (tif) 01, 15,0 022,0 033, 

047. l jp; 0J. 30V, 4jp; 01, 100V, Sjp . 

CARBON FILM RESISTORS iW 5 %. 10 ohms— l"-2M, |W S%, 10 ohms— 

IM. Ip each or 100 for 62p; 1,000 (or £4-50. 

METAL FILM RESISTORS IW 5% ohms — I0M, lip each or 100 

f or £110. "ISEIl KIT (15 each valve lOf l— IM) t»" ____ 

Veroboard 01 15 IN400I 

IN4002 

1N4O03 

IN 4004 

IN9I4 



2+ X Sin 

2i x 3iin 

3j x 5in 

3} x 3|in 

l\ x I i n 7 

21 x Sin (plain) — 

2£x3iin (plain) — 



2Sp 
26p 
32p 

23p 
7p 



S x 3(in (plain) 
Insertion too) 
Track cutter 
Pins, pkt. 25 



59p 

44p 
I Op 



15 
28p 
I9p 
33p 
28p 
7p 
lip 
lip 
22p 
59p 
44p 
I Op 



^L914 
OC7I 
OC7S 
OC83 



S;P QUANTITY DISCOUNT 

7ip iSPECIAU BULK BUY PRICES 

*P ARE AVAILABLE BY 

9 *P QUOTATION FOR LARGE 
_ 7 P 'PROJECTS AND TRADE. 



35p 
Dp 
I7p 

20p 







S.C.R. 






SOV 


IA 


29p 


3A 


Up 


100 V 


IA 


J3p 


JA 


4Up 


400V 


IA 


50p 


iA 


60p 



Screened wire, m Sip 

Twin screened wire, m lOp 

Stereo s.c. wire, m lOp 

Connecting Wire, all colours ,,. — ..... 2Jp 

Neon bulb 90V wire ended 5 for 24p 

Preset skeleton pots IK- 1 M 6p 

ALL PRICES INCLUDE V.A.T. 

C.W.O. only. P. & P. (Op on orders below £5. 

Discount: £10^10%, £20—15%. 

Export Order enquirie s welcome (VAT free) 

Dipt, P.W.61, CHEDDINGTON ROAD, PITSTONE 
Near LEIGHTON BUZZARD, BEDS. LU7 9AQ 

Cheddington 668446 STD. (0296) GIRO No. 331 7056 

Inquiries — S.A.E. Catalogue FREE, Callers please phone first. 



2 pin DIN Plug. I2p; Skt., 
I Op, 3 pin DIN Plug, I3p; 
5kt., I Op. 5 pin DIN Plug, 
ISO", lip; Skt., I2p. Tran- 
sistor Equiv, Book, 40 p. 
Carbon pots 5K-2M log, & 
lin. single I6ip, single 
with switch 26p. dual 46p. 




BAKER 12 MAJOR £9-90 

30-14500 cps. Double cone woofer and 
tweeter combination. Baker ceramic magnet 
assembly flux density 1 4S000 gauss. 
Bass resonance 40 c.p.s. 20 watt RMS. 

MAJOR MODULE KIT ^IQ^fft 

30-17000 cps. witJi 
tweeter, crossover and baffle. 



Regent 12- ISW£8 80 
Major I2*20W £9-90 
Deluxe 12- ISW £11 



Baker Loudspeakers 

Superb 12' 20W£ 16-50 
Grp.2SI2-25W( r B 80 
Grp,35 l2'3SWi£9-90 



ALL PRICES 
INCLUDE VAT 



Baker Loudspeaker Co., Benshim Manor Passage 

-Thornton Heath, Surrey. Tel. 01-684 1665 
Loudspeakers Catalogue and Enclosure plan 5p 



ELECTROKIT 

12 Lauderdale Road, London, W.9 
Telephone 01-286 0011 

LIGHT DIMMER. Kit contains all parts including circuit 
and construction data, 480 watts;, futly suppressed. 

Price £2 10 

SCORPIO IGNITION SYSTEMS (P.E. Nov. 1971), £9 50. 

This kit includes all the parts For the assembly of this 
popular and reliable system. The hardware and the con- 
struction data are included. 

Send for details of kits available (pfease enclose S.A.E,). 
All kits sent POST FREE within the limits of the U.K. 

Please note, prices shown do not allow for V.A.T. Please 
add 10% to your order. 



292 



Antex X25 




The Japanese 
have a Yen 
for it. 




in case you are no t familiar 
th Japanese: 
Our distributors in Japan are telling 
their customers about the importance 
(when soldering I.C.'s and transistors) 
of the low leakage of our Model X.25 
soldering irons. 
Mode! X.25 -25 watt sells at £1-75+ P& P8p VATISp 
Model G -18 watt £ 1 -95 + P & P 5p VAT. 20p 
Model CCN -15 wait miniature iron £1-95 + P & P 5pVAT20p 



Ask your usual wholesaler or retailer for Antex irons or 
f you have any difficulty, send the coupon to us direct. 



From radio of electrical dealers. 

car accessory shops or in case of 

difficulty direct from: 

ANTEX LTD. FREEPOST 

PLYMOUTH PL1 1BH 

(no stamp required) Tel 0752 67377. 

^] Please lend the 
Please send the following: --■ AN TEX colour catalogue. 



Reg. No. 393594 



293 




AfroMerf 
wtmer 



Recommended 
retail price 



£9-96 



including V.A.T. 




TMODE 
ONE 



HIGH FIDELITY 
LOUDSPEAKER KIT 



Consisting of a Fane Model 803 ultra-tow 
resonance 8" speaker unit with PVC cone 
surround, and a Fane Model 303 high frequency 
pressure tweeter together with a printed 
circuit cross-over assembly with ferrite cored 
coils. 



SPECIFICATION OF UNITS 






Model 803 


Model 303 


Overall Diameter 


8" 


3" 


Natural resonance 


30Hi 





Main resonance 


- *35Hi 


I200Hi 


Magnet Pole Diameter 


1" 


i" 


Magnet Flux Density 


13,000 gauss 


10,000 gauss 


Frequency response 


30Hi-8kHz 


IOkHz-l7kHz 


Impedance 


8-15 ohms 


fl-fS ohms 


Power Handling 


•IS watts 


•15 watts 



Very easy to assemble, this boxed kit comes 
with acoustic foam damping material, panels, 
screws, wire, wiring diagrams and instruc- 
tions to provide a remarkable loudspeaker 
assembly — a pair is ideal for stereo. 



CABINETS for the 
veneer finish. SIZE 



'Mode One' 
15|" * to?" 



are available in Teak 
V. 



*VVfien used with above tobinet. 

holesafe Manufactured by 

FANE ACOUSTICS LTI 

Hick Lane. Batley. Yorkshire 
Tel Batlcy 6431 



Distributors to the 
and retail trade 

LINEAR PRODUCTS LTD 

Electron Works, Armley. Leeds 
LS 12 3SA Tel. 630126 



CAPACITOR 
DISCHARGE 
IGNITION KIT 




A comprehensive kit of parts with 
detailed constructional details, 
ready drilled diecast case, screws, 
leads, terminals etc. 
Available in both 6 and 12v ver- 
sions. State whether positive or 
negative earth. £9-62 incl. p. & p. 
U.K. only. 

De-coupling kit for impulse tacho- 
meter and interference suppres- 
sion. £1-10 incl. p, & p. U.K. only. 
AN our kits use guaranteed quality 
components and have been 
approved by the Author. 

MAGT0R LTD. 



68 DALE ST., 

Ml 2HS 



MANCHESTER 
061-236 3031 



EX COMPUTER PC PANELS 

2 x 4 in. packed with semiconductors and 

top quality resistors, capacitors, diodes etc. 

Guaranteed min. 35 transistors plus dat?„ 
10 boards 50p (9p) 

SPECIAL, BARGAIN PACK 

25 boards for £1 (25p), 

Panels with A Power transistors sim OC28 
50p (9p) 

ELECTRO LYTICS 

6B,0OOfi 16, 4i x 2 in. dia.. 25,OQ0> 2Sv 
20,000*1 30*, 5,000*s 90v. 35,000<u I5v 
8.000/4, 4{ x 3 dia. SOp (I5p) I5,000y (5v, 

10,000m 35v, 4} x 2 fan. dia. 30p (I Op), 
2.000,/ 25v wire ends ISp (5p). 12 for £1/50 

(I5p) 
20A DIODES 4 for £1 (7p) 

3A DIODES 4 for SOp (5p) 

8 BLACK TOGGLES dpit SOp <8p) 

250 MIXED CAPACITORS eOp (8p) 
250 MIXED RESISTORS 60p (3 P ; 

150 HI -STAB RESISTORS SOp (8p) 

200 SI PLANAR DIODES SOp (5p) 

SUB. MIN. CO-AX PLUGS & SKTS. 
4 pairs SOp (5p) 
REED RELAYS. MIXED 10 for SOp <5p) 
MICRO SWITCHES 8 for SOp (8p) 

ASSORTED RELAYS 8 for £1 (I2p) 
MIN. GLASS NEONS 12 for SOp (5p> 
10 WAY TERMINAL BLOCKS 

10 for 55p (5p) 
PAPST EXTRACTOR BLOWER FANS 
lOOcfm 4| x4|x2 in £3-50 (28p) 

Q-H BULBS I2v 55w 50p (Sp) 

Postage and package shown m brackets. 
Please add 10% VAT to prices. 

KEYTRONICS 

(Mail Order only) 

44 EARLS COURT ROAD 
LONDON W8. 01-478 8499 




GlilGER COUNTERS 
(FOR MAINS OR PORTABLE BATTERY USE) 
Latest Home Office 
release and probably the 
last, of thiB well known 
Contamination Meter No. I 
this very useful Instru- 
ment is used (or the 
measurement of Itadlo- 
Aetivlty. Indicated on an 
Internal Meter scaled 0-1 
to 10 milli Bontgene/Hour, 
a socket Is alee- provided 
for additional sound Moni- 
toring on Headphones. 
Thia Instrument is housed 
in a Strong light Alloy Case, 
placed in a carrying Haver- 
sack with Hhoui.dor strap. Containing Cable awl 
Hand held Probs. Instruction Card, plus the latest 
plug in Vibrator Power Unit, which uses ourrcnt 
small Transistor Radio Batteries (4 Mallory Look 
Life KM12 or 4 Ever Beady H.F.7 or equivalent 
makes). For mobile use anywhere. (Cost Gov, 
approx. £70 each). Supplied Brand New In Carton 
only £5-50 carr. SOp. An additional plug in Power 
Unit for Laboratory use, operating from 100-120 
volts or 200-260 volts A.C. Mains is available. 
Supplied Brand N'ew In Carton at only t& 50 
port SBp. 

TRANSCEIVERS 
11 ue to warehouse clear- 
ance we ha/ve for disposal, 
few only Transreceivers 
No. 62 Mk. 2, made by 
Pye lor tbe Navy and 
Army. Using a total ol 11 
valves. I RF and 2 I.F. 
stages. A.V.C., BFO, cover- 
ing 1-5 •He/is. to 10 Mfea. 
(approx. 200 to 30 metres) 
in t bo ,ii killed bandB. Can be used on ET ur C\V 
M.O. or Crystal, A very good internal ATU made 
of a rotating silver wire coil, tunable over the com- 
plete range, suitable for aerials 4ft. to 1 00ft., 
internal P.U. for 11! volt D.C. A meter is fitted for 
checking voltages, A.V.C. etc. Housed In a metal 
waterproof ease, approx. size 18* x 101* * 121*. 
Supplied in as tew new condition, being either 
rebuilt by Army Signals or store -soiled new »et, 
in cartons two s|iare valves, circuit, price 117-M, 
carriage £2. Sulubie band telephone witb. spring 
coil plus tnujsm.tur switch in handle, Modern. 
£1-50. 

JOHNS RADIO 

«4 BRADFORD ROAD, BATLEY, YORKS. 

Phone : Bailey 7732 




294 



Jl ) I.L.P. (Electronics) Ltd 



100 WATTS! 



* NO EXTERNAL COMPONENTS 

* MECHANICALLY & ELECTRICALLY 

ROBUST 

* INTEGRAL HEATSINK 

* HERMETICALLY SEALED UNIT 

* ATTRACTIVE APPEARANCE 

* LOW COST 

* BRITISH BUILT 

With the development of the HY200, I LP bring you the first COMPLETE Hybrid Power 

Amplifier, 

COMPLETE: because the HY200 uses no external components! 

COMPLETE: because the HY200 is its own heatsink! 

By the use of integrated circuit technique, using 27 transistors, the HY200 achieves total 

component integration. The use of specialty developed high thermally conductive alloy 

and encapsulant is responsible for its compact size and robust nature. 

The module is protected by the generous design of the output circuit, incorporating 

25amp transistors. A fuse in the speaker line completes protection. 

Only 5 connections are provided, input, output, power lines and earth. 

OUTPUT POWER : 100 watts RMS ; 200 watts peak music power. INPUT IMPEDANCE : 

10k«. INPUT SENSITIVITY: ODbm (0-775volt RMS). LOAD IMPEDANCE: 4-16". 

TOTAL HARMONIC DISTORTION: less than 0-1% at 100 watts, typically 005%. 

SIGNAL : NOISE: better than 75Db relative to 100 watts. FREQUENCY RESPONSE: 

10Hz-50KHz ±1Db. SUPPLY VOLTAGE: ±45volts. APPLICATIONS: P. A., Disco, 

Groups, Hi-Fi, Industrial. PRICE : £14-90 inc. VAT &. P&P. Trade applications welcomed. 




CROSSLAND HOUSE -NACKINGTON* CANTERBURY- KENT 
CANTERBURY 63218 

Please note we reserve the* right to substitute at our discretion updated versions of advertised designs 

where applicable. 



295 



\bu'U baldly 

be able to 

believe your 

ears! 



Can you really get 
sound quality like 
this FOR LESS 
THAN £(g? 
YES, YOU CAN!' 
WITH THE NEW 



Mahler 



Until now richly satisfying sound has always cost a richly satisfying price But not 
any more! For an almost unbelievable £17-95, you can have Stereo 2l-aud!o for the 
connoisseur! Whatever your taste in music, you can hear it on STEREO 21 
the way its composers heard it in their dreams! Beethoven or 
Ellington or Jell/roll Morton ... Das Nibelung 
or jesus Christ Superstar . . . Carols from King's 
College Chapel or the return of a Beatle . , . 
everything from a prettily fluting baroque 
organ to the newest pop group at full 
throttle— STEREO 21 does them 
all justice! 
And have you ever seen a handsomer 
audio installation? Compact enough 
to go in a university student's bedroom- 
study, elegant enough for the suavest 
penthouse pad in Town, STEREO 21 
offers you all the pride of possession as 
well as a thrilling musical experience! 
Top-quality amplifier, BSR turntable, match- 
ing speakers. Deck and speaker cabinets you 
simply wrap round and glue to build. Screw 
in the amplifier and connect up (all push 
fit no soldering whatsoever), so simple 
literally anyone can do it. Except for glue 
and panel pins all parts supplied in- 
cluding full instructions — ail for £17*95 
(plus the cost of post and packing if 
you buy by mail), and — to round 
it all off — a money-back 
Guarantee if your pleasure in 
STEREO 21 is not complete! 




Personal shoppers and mail order price 

*■■# 90 plus £1 -SO p 
Diamond stylii, if required, £1 -37 extra 




Just think — in only a few days 

you could be giving your ears 

the treat of a lifetime— AND 

introducing your envious friends 

to STEREO 21 ! 



RADIO AND TV COMPONENTS (ACTON) LTD 2IC HIGH STREET 
ACTON, LONDON W3 6NG ■ 323 EDGWARE ROAD, LONDON W2 

Mail orders to Man, Terms C.W.O. All enquires Stamped Addressed Envelope 
Goods not despatched outside U.K. 



296 







VISCOUNT III- 

a boost in the output, 



VISCOUNT 111 now gives you an imposing 20 watts per channel — and the price quoted is 
actually INCLUSIVE OF VAT! , 

The money's important, of course, but not nearly so important as value for money! And that s 
something you get in abundance with VISCOUNT III. We design it . . . we make it . . . we sell 
it direct to you— passing on all the economies that come from cutting out middle-men! That s 
the only way vou can get so much quality for so little money! 

The unique VISCOUNT 111 amplifier, plus the Garrard SP25 Mk III deck, plus the magnificent 
Duo Type III matched speakers (or Duo Type II for a small room) give you an audio installation 
that will prove unbeatable for listening pleasure! And the teak finish will harmonise and en- 
hance virtually any style of interior decor! On the brushed aluminium front panel of the ampli- 
fier you'll find all the facilities you need — volume, bass, treble and balance controls, plus 
switches for mono/stereo, on/off function and bass and treble filters. Plus headphone socket 

The' heart-stopping timbre of Tom Jones at his most virile . . . the last lingering harmonics of a 
solo performance by Heifetz or Memihin. . . , the pathos and the panache of Liza Minelli . . the 
majestic sonorities of the brass band and the elfin subtleties of the virtuoso elavi chord ist— 
hear every nuance with a fidelity that you have never experienced before! 
Come and hear VISCOUNT III! If it's inconvenient to travel, buy by post in the confidence 
that you won't be disappointed (and with a 24-carat Money-Back Guarantee to give you extra 
reassurance). Don't settle for second-best! .... „. ■ l. 

SPEAKERS: Duo Type II Size approx. I7in X lOJin X 6Jin. Drive unit I3in X 8tn with 
parasitic tweeter. Max, power 10 watts 8 ohms. Simulated Teak cabinet. £14*00 a pair + «-^u 
p & p Duo Type III Size approx. 23iin X I IJin x 9J!n. Drive unit approx 1 3 Jin X 8±in 
with HF speaker. Max. power 20 watts, 8 ohms. Freq. range 2QHz to 20kHz. Teak veneer 
cabinet. £3200 a pair + £3*30 p. & p. 

PRICES : SYSTEM I 
Viscount III Rl 02 

amplifier £24-20+ £lp&p 

2 Duo Type 1 1 speakers £14-00+ £2-20 p &p 
Garrard SP25 Mk 111 

with MAG. cartridge 

/plinth & cover £18-00 + £i-75p&p 

total £56 20 

Available complete fdQQCi + " 50 
for only * rtw *"* P & P 

PRICES : SYSTEM 2 

Viscount RI02 

amplifier £24*20 + £1 pip 

2 Duo Type III speakers £32-00 + £3*30p&p 
Garrard SP25Mk 111 with 

MAG cartridge 

plinth & cover £1800 + £1-75 p & p 

total £74*20 



Available complete //.C , flO + £4 
for ■""* ww P*P 



THE TOURIST PUSH- 
BUTTON CAR RADIO 

HIT £A. A.t% The Tourist PB is 

Ml tO OU suitable for 12 volt 
working on both negative and 
positive earth vehicles. It covers 
the full medium and long wave 
bands. It is permeability tuned and 
sturdily constructed, Output is a full 2-5 
watts into an 8 ohms speaker. But the Tourist 
PB will operate into any loud-speaker from 8 to IS ohms. 
Apart from the output stage, which is an integrated circuit, the only other 
electronic components that need soldering are some capacitors, resistors, 
etc. The kit includes a pre-built RF tuner unit, and fully modulised W 
stages which are pre-aligned before despatch. As well as electronic com- 
ponents this kit also contains 2 diamond-spun aluminium knobs, elegant 
matching front panel, dial, washers, screws and wire. 

The Tourist PB can be mounted in any standard size dash panel and it has an 
illuminated tuning scale. Chassis size is: 7in wide, 2in high and 4-ftin deep. 
Circuit diagram and comprehensive instructions 55p free with parts. 
Fully retractable and I ockable car aerial £1-37 post paid. 

CAR RADIO KIT £6-60 £gj £"£ ^g^'S ffg£»EH 

bought with the kit. Send stamped addressed envelope for leaflet. 

if you can solder on printed circuit board, you can build this push-button 

car radio kit. It's simple— just follow the step-by-«ep instructions. 

SOUND 50 45 WATT MONO AMPLIFIER. Ideal for Disco. 
Output Power: 45 watts R.M.S. (Sine Wave). Frequency Response 3dB 
points 30Hzand ISKHz. Total Distortion: less 

than 2% at rated output. Signal to noise 
ratio: better than 60dB. Bass Control Range: 
!3dB at 60Hz. Treble Control Range. l2dB at 
lOKHz. Inputs: 4 inputs at SmV into 470K. 
Each pair of inputs controlled by separate 
volume control, 2 inputs at 200mV into 470K. 
Size: IHxJOJx 8ms. Amplifier £$\ ?35 




RELIANT Mk IV 



♦5 Electrically Mixed inputs. 
"3 Individual Mixing controls. 
•Separate bass and treble 
controls common to all 5 
inputs. *Mixer employing F.E.T. 
(Field Effect Transistors). *Solid 
State Circuitry. * Attractive Styling. 
INPUTS I. Crystal Mic or Guitar 9mV. 2. Moving coil 
Mic. or Guitar BmV. Inputs 3, 4 & 5 are suitable for a wide 
range of medium output equipment (Gram, Tuner; Monitor, Organ, etc.) 
Al 1 2S0mV sensitivity. Output 20 watts into 8 ft JMT-^fl p. & p. 60p 
(suitable for 15 ft.) Size approx. 12Jx6x3| ins. ** ■ • *"* 

UNISOUND MODULES 

ONLY £7-64 + SSp. p &p 

For the man who wants to design his 
own stereo — here's your chance to 
start, with Unisound — pre-amp, power 
amplifier and control panel. No solder- 
ing — just simply screw together. 4 
watts per channel into 8 ohms. Inputs: 
!20mV (for ceramic cartridge). The 
heart of Unisound is high efficiency 
I.C. monolithic power chips which 
ensure very low distortion over the 
audio spectrum. 





,•«-»(, 




IN-CAR ENTERTAINMENT 
AT HOME 



output for 3. 8 and 15 ohm 
speakers. 



With this elegant stereo 8 track add on unit, 
audio enthusiasts now have the opportunity 
to extend their systems to include the play- 
ing of 8 track cartridges. Simply select your 
channel, by push button, four digital lamps 
indicate channel selected. The Viscount III. 
the fabulous Stereo 21 and the Unisound Modules £9 '90 plus p. & p. 



+ £1-65 p. & p. will accept this unit, simply connect up. 



297 



MAPLIN ELECTRONIC SUPPLIES 




3 



RD EDITION NOW AVAILABLE 

Send for your copy of this beautifully produced fully 

illustrated catalogue and we will forward it to you 

by return of post. Please send 9p in stamps. 

Everything guaranteed brand new marked by manufacturer 




•RETURN OF 
POST 

SERVICE 



MAF'LIN: Projected site of London' t 
third airport. 



RESISTORS 
Car b o n f i I m 5% f ro m 

in to iMfi, 10% 

from IMQ, I -2MQ 
co IQMQ. EI2 series. 
iW lp;+W I 2p. 
Metal Oxide 2% 
lOfl to IMfi. £24 
scries }W 4p. 
Also IW, 2±W, SW. 
I0W types stocked. 



7 SEGMENT 
DISPLAY 
Minitron 30ISF 

£1 98 each. 



POTENTIOMETERS 

Miniature carbon 

track with ^in. 

spindles. Skfi, lOkfi. 

25kfi, SOkfi, 100 

kfi, 250kfi, SOOkfi, 

IMQ, 2Mfi. 

Log or lin (and I kfi 

fin), tip. 

Log or lin with 

switch 13p. 

Dual gang less 

switch 38 p. 



THE OTHER DAY WE RECEIVED A WIRE 

It was too Ion g + Stop + so we cut it with a pair of our 
5 inch diagonal nippers + stop + fully insulated handles + 
stop + they make a clean cutatonly£I'40 a pair -f scop + 
then we had to strip to the bare copper without a nick 4 
stop -four fully adjustable strippers will strip cleanly any 
siie wire from 12 S.W.G. to 26 S.W.G. with no nicked 
wires even if its stranded + stop — real value at only 54p 
a pair + scop -finally the wire had to come to an end so 
we terminated it with our Sj" long nosed wiring pliers 4- 
stop+cheir slender jaws are gap free and the fully in- 
sulated handles are gently tensioned apart by leaf springs 
+ stop + irreiistable at only £!<9B a pair + stop 4 so the 
next -time you get a wire you'll know what to do, won't 
you? 



DIN PLUGS. 3 pin, 9p. S pin A (180°). 

S pin 8 (240°). I Op each. 

DIN SOCKETS. 3 pin, S pin A, 5 pin B, 

DIN LOUDSPEAKER. 2 pin plus. 8p. 

Socket ftp. 

JACK PLUGS standard +in plastic 

barrel, I3p, Stereo, 15p. 

Bright metal barrel, I7p. Stereo. 29p. 

tack sockets standard i-in open type 

I0p, Moulded 2 break I3p, Moulded 

stereo 3 break I8p 



ROTARY SWITCHES 
Adjustable stop. I pole 2-12 way, 

2 pole 2-6 way. 3 pole 2-4 way, 4 pole 
2-3 way. Only 24p each. 



SPECIAL IC. for organ builders. 
7 stage frequency divider in one 14 pin 
DIL package, £2-63 or special price 
for pack of 12, £25. 
Why not o«k us to ih'f> a data sheet in 
with your catalogue. 



NUDES! 

Clothe those naked projects with our 
superb instrument cases. We are sole 

distributors of the 

Centurion 

range, designed lor the provisional 
market, now available to you it 
•pedal low prices. S.A.E. pleat* for 
free illustrated leaflet 



8 pin Oil Op Amp 
741 C 36p, 
14 pin 74IC 4Sp. 
70V r.m.s. I -8A full 
wave bridge recti- 
fier. 

REC 4IA £1 06 
DIODES IN9I4 4p, 
BAXI3 Sp, IM400I 
6p, I N4002 & i p 
IN4O03 7p, IN4004 
7+p, I N400S 8p. 
IN4006 8Jp. 1N4007 
9p. 



SEMI- 
CONDUCTORS 
We stock a large 
range of transistors 
and I.C.s, for details 
please see our 
catalogue. LOOK! 
These popular de- 
vices at amazingly 
low prices. SCI 07/8.' 
9 I Op each. BCI69C 
I2p. BFY5I I6p. 
T1S43 (SS43) 28p. 
2N706 lOp. 2N2646 
4Sp. 2N3055 49p. 
IN 38 19 24p. 



HARDWARE 
Wide range of nuts and bolts, platted 
brass and nylon types plus solder tags, 
shakeproof washers, etc. 
SOLDER 10 metres of 22 gauge multi- 
core, 20 p. 
Insulating sleeving 3 sizes, 6 colours. 



MISCELLANEOUS 
LT700 eagle sub-miniature O/P trans- 
former I200/5Q 209mW max., 3Sp. 
Slide switch DPDT, 12p Miniature 
Push Co make non-locking switch Up. 
Silicon grease in special dispenser, 
20ml, 38p. 



SEE OUR CATALOGUE 

for details pf how you can 
obtain £1 worth of com- 
ponents. 

ABSOLUTELY FREE 



V.A.T. Please add 10% V.A.T. to final total. 

Orders and enquiries for catalogues co 
MAPLIN ELECTRONIC SUPPLIES, 
P.O. Box 1, Rayleigh, Es in 556 SLR 



Postage and packing FREE in U.K. But wi have to ask you to land a 
I Op handling charge with order under SOp. 







become 

a RADIO-AMATEUR ! 



free! 



learn how to become a radio-amateur 
In contact with the whole world. We give 
•killed preparation for the Q.P.O. licence 

Brochure, without obligation to: 



BRITISH NATIONAL RADIO & 
ELECTRONICS SCHOOL po. Box tse, jersey 

■ NAME: 

| ADDRESS ; 

I 



wwa 

.BLOCK CAPS please 



PLUGS & LEADS 

PlUgl 

Pack 107 S pin Dm Up 

Pack 108 3 pin Din 2 Op 

Pack 1 35 i" Jack 27p 

Pack 130 i" Jack Stereo SOp 
Pack 103 Loudspeaker Plug I7p 
Pack 100 Phono Plug 7p 

Pack 230 3 pin Socket 25p 
Pack 236 S pin Socket 33p 

Pack 234 Loudspeaker 

Socket 33p 

Read y-mad e Leads 
3 pin to 3 pin Din 70p 

3 pin co open end S5p 

5 pin to 5 pin Din 90p 

S pin to open end 70p 

5 pin to 4 phono plugs £1 00 
Speaker lead Din co spade 

12ft 40p 

Extension lead Din plug to 

socket 12ft. 70p 

All leads opprox. 6ft. in length 
DIAMOND STYLI 
'{Send SAE for complete lilt) 
8TA; 9TA: 9TAHC: GP9I; 
ST4; ST9; EV26; GC8.AII it 80p 
each, 

Double Diamond £1,25 
Diamond suitable for Orbit 
NM22: G800; M30 £2 2S etch 

cartridge* 

Goldring G800 to 00 

Orbit NM22 £4 00 

Shure 7S/6 £4-00 

Sonocone 9TAHC (Die) £2 00 

Sonotone 8T4A (Dig) £1 50 

Ronnette 105 (Oia) £1 25 

All pricei include VAT and 
postage 



RECORD CARE 

Cecil Watts Dust Bug £1 20 
Parastatie Disc Preener 45p 
Antistatic Fluid 20p 
Dust Bug Spares (Brush & 
Roll er) ISp 

CASSETTE TAPES 

Audio-Magnetic C60 
Qty 3 6 10 20 
Price £1-00 £1 90 £3 20 £6 30 
Cassette Caddy £1 20 
Cassette Head Cleaner 35p 

ZONAL1LFORDTAPE 
5" Standard 600ft 2Sp 

51" Standard 900ft 50p 

7" (Plain boxed) 1200ft 60p 
7" (Westminster Boxed) 

1800ft £1 25 

7" Reel of Leader Tape (Slue 

or green) 75p 



HEADPHONES 




Sennheisier HD4I4 


£1060 


AKG K50 


£6 50 


Beyer DT48S 


£35 00 



MICROPHONES 

AKG DI09 
AKG D 202 El 
AKG DI90C 
AKG D190E 
AKG D224 
Sennheitser MD2I IN 
Sennheisier MD4I3N 
Sennhelsser MD42IN 
Audio RMS7F Radio 



£11 50 

£39 50 
£1700 
£18 20 

£50 00 
£45 00 
£27 00 
£35 00 
Mike 
£210 00 



SPEAKERS 

E.M.I. 350 Kit Sohms 
E.M.I. 450 Kit Bohroi 



£8 20 
£4 50 



J. J. FrailCiS (Wood Green) Ltd 

MANWOOD HOUSE, MATCHING GREEN, HARLOW, 
ESSEX CM 1 7 ORS Telephone; Matching 476 



298 



Cool 



lighting for hot parties 



Velvet dim to full brightness at a 
touch of the finger. Off/on and 
infinitely variable. 

Beta light glow makes switch easy 
to find in the dark and consumes no 
current. 





Economical too! 

As the light is progressively 
dimmed, so the current consumption 
drops -think of it as an electric tap. 
300 watt capacity, straight 
replacementfor standard light 
switch. 



Complete kit of parts £2.80 or 
made up £2.90 




Hot Ignition for cold mornings. 



The Jermyn capacitor discharge 
ignition system. 

Instant starting in all weathers. 
Even with a near flat battery, the unit 
will produce a full sized spark. 

Just one of the many advantages 
of an electronic ignition system, the 
others are : 

High energy spark even at 
maximum revs. ■«§ 

"J 



Complete set of parts to build it 
yourself for only £7.75, as described 
in Practical Wireless and fully 
approved by the author. 




Smoother running 

Less strain on battery and starter. 

Lower petrol consumption. 

Long plug life with infrequent 
adjustment (typically 20,000 miles, 
gapped at .050"). 

No contact breaker arcing giving 
long life and less adjustment 
(typically 20,000 - 25,000 miles) 

STATE + or - earth 
when ordering. 






Save 55p 

Buy both for £10.00 



Reprints of ■ 

the two part feature are available at 

25p. 






To Jermyn Industries, 93 Vestry Estate, Sevonoaks, Kent. All Prices Exclusive of V.A.T. 

Please despatch return of post light dimmer kit light dimmer 

Ignition Kits ... . - or - earth £10 pair. Enclose cheque or postal order. ^^ 

BLOCK CAPITALS J ERIN/1 TT l\l 

NAME • — - " 

ADDRESS - : 






299 



NELSON-JONES FM TUNER KIT 






ins*- an urn 






as in 'W.W.' June 73 



Now available lor the first time to readers of 'Practical Wireless', The Nelson-Jones tuner was originally made available by this 
company In May 1971, and consequently all 'bugs' have been 'ironed out' of this highly successful kit 

A recent design addition has used variable capacitance diodes and a Push Button Unit with 6 positions;. AFC disable is incorpor- 
ated as well as a pointer for each button showing tuning position in the range 87-5-108MHz. 

Our complete metalwork system is supplied with nuts, bolts, board standoffs, push button mains on/off and stereo mute assembly, 
sockets, fuse and holder. Printed and Anodised Front Panel and Veneered Teak case. Power supply kits are supplied with complete 
kits of parts, or separately. 

Prices for complete kits start at £23-75 + 45p pp. + VAT for mono tuners, (phase locked decoders are also available to fit in 
the cabinet). Please send large SAE for complete details of special offers and our complete lists. 



TEXAN AMPLIFIER 



The Cabinet of the Nelson-Jones Tuner is specially designed to match the 
Texan amplifier cabiner, see photographs, so that owners of Texan's are 
assured of compatibility, both in superb performance and appearance. 

Texan amplifier kits are available at £28- 50 + 45 p pp. — Vat. 

Worried about tuner alignmenf? then let our alignment service take over. 



INTEGREX LIMITED, 




Dept. P.W., P.O. Box 45, Derby, DEI 1TW. Tel. Repton (028389) 3580 



A special 

ssage to the Fum 

■tigered Freds among u 



NEW STEPHENSPEAKERS 

A new range of loudspeaker kits and cabinets with a 
style and specification for every purpose. You'll be 
cheating a bit If you tell your friends "made it myself". 
We supply superb craftsmen built fully finished cabinets 
In beautiful stain and scuff resistant vinyl in white or 
teak. 

Just fit the speaker cloth {supplied) and screw in your 
speaker. 

HIGH QUALITY 
AT LOW COST 

Send for our free booklet 
" Choosing a Speaker " 



STEPHENSPEAKERS, 

WILMSLOW AUDIO, Dept. 'PW', Swan 
Works, Bank Square, Wilms low SKO 1HF 




ALL PRICES INCLUDE VAT 
BARGAIN PARCELS 141b at £1-60 plus 35p p.p.: 281b at £300 plus 
57ip p.p.; 561b at £4-95 plus £i -37£ p.p. Contain pots. Res. Valves, Diodes 
Taaboards, Chassis, Valveholders, etc. Good value save £££s. Lucky Dip 

Service. 

FANTASTIC BARGAIN. New 6 inch lubes. E4S0 4/B/I6 4VH. medium 
Persistence, green. Ideal scope tube. 

Also 7BP7. All unused as new. Price £1 '55 post paid. 

NEW HEAVY COAX CABLE dia. *" 70 ohms approx. 50ft. lengths £155. 

p. & p. 32£p. 100 ft. lengths £2-97, p. &. p. 55p. 

AERIALS, New Condition Whip Type, 4ft. 22p; II ft. 82] p. all collapsible 
type. P. & p. 4ft. lOp, lift. 15p. New bases on adjustable clamp for the 
above, 67£p. p. & p. 27 J p. 

CRYSTALS AS NEW. He 6u. 5.345; 5.030; 4,945; 4,875; 4.840; 4.795; 
4,580; 4,660; 4,520; 4,510; 2,295 Kc/s. 55p each plus 8p p.p. 

OUR SELECTION OF 6-Ex. Equ. METERS consisting of 3in., 2iin„ 2in. 
mill amps, volts, amps. Mixed at the bargain price of £220 P. &. P. 27£p, 
minimum order of six. 

ANY HEIGHT AERIAL TUBULAR SECTIONS |" dia. x 3ft, long. Brass 
screw in ends, copper coated and painted. Good condition. 22ip p. & p. 5p 
each. Minimum order 6, 

AS NEW AERIAL TUNER UNIT No. 6 RF. consisting of ii inch 500 mico' 
ampmeter 3 gang tuner 75 PF geared BNC type socket size Si* x 4i" x 
5". Price £1-65, p. &. p. 27 Jp. 

NEW AERIAL WIRE ON BOARDS 7/22 UNCOVERED 90ft SOp. 1 00ft. 
60p, p. & p. 22p. 

AERIAL POLES 4ft high 2" in diameter push-in type as new 7Sp each p. & p. 
25p each minimum four. 

AERIAL MAST POLES approx. 5ft high 2" dia. Interlocking ends. Mini- 
mum order three. New condition, £1-10 each section. Carriage 37|p each 
section, i" 75 ohms Coax in 50ft coils wich BNC plugs good condition. 
Price £110 + 32Jp p.p. 

AS NEW SOOua PENNY SIZE METERS complete with jack plug price 
£110 each, p. & p. I Op. 

COMMUNICATION RECEIVER PCRS price £10. post paid. 

C.W.O. CARRIAGE CHARGES MAINLAND ONLY 

WOULD CUSTOMERS PLEASE ENSURE THAT ALL ORDERS ARE 

PRINTED IN BLOCK CAPITALS AND INCLUDE YOUR ADDRESS. 

A. H. THACKER & SONS LTD. 

Radio Dept., High Street, Cheslyn Hay, Nr Walsall, 

Staffs. 



300 















Type 


Price p 




AC II 


7 


2-i 




AC113 


M 




ACHB 


H 




AC117K 


up 




ACl r 


"2 


u 



7H/S IS THE FIRST PAGE 
OF THE GREAT BI-PAK SECTION 



BRAND NEW FULLY GUARANTEED DEVICES 



AC12S 

AC126 

AC127 

AC128 

AC132 

AC134 

AC137 

AC141 

AC141K 

AC142 

AC142K 

AC1B1 

AC1B4 

AC165 

ACiea 

AC 157 

AC1B5 

AC168 

AC1B7 

AC188 

AC1B9 

AC178 

AC 177 

AC 17 8 

AC179 

AC1B0 

AC180K 

AC1S1 

AC1P1K 

AC187 

AC1S7K 

AC188 

AC188K 

ACT17 

ACY18 

ACT! 9 

ACY20 



19 
19 
19 

19 
18 
IS 

IS 
16 
19 

16 
19 
17 

n 

22 
99 
9? 

22 

n 
H 

87 

ia 

22 
2? 
SI 
SI 
19 
22 
19 

a 

94 



Type Ft tee p 
AD181 87 
AD 182 87 
AD181 4 
AD 182 (MP) 
SI 
ADT140 
AT114 



Type Prltt P 
BC14B BO 



Type Prire p 
DDiaa 72 



Type Price p 
BF182 44 



IlkJ 


ACY21 


22 




ACT22 


114 




ACY27 


SO 




ACT28 


21 




ACT29 


89 




AC130 


81 




ACT31 


ai 




ACTS4 


S3 




ACT35 


23 




ACT38 


31 




ACT40 


ID 




ACT41 


20 




ACY44 


39 




AD130 


49 


fwj 


AD140 


63 




AD142 


B3 


Pi 


42 




AD149 


66 



AF115 

AF118 

AF117 

AF118 

AF124 

AF12S 

AF126 

AF127 

AF139 

AF17S 

AT179 

API 80 

AF181 

AF1BS 

AF239 

AL102 

ALIOS 

A9Y26 

A8Y27 

AST28 

A8Y29 

ASY30 

ABY51 

A8Y52 

AST54 

A8YSS 

ABYB6 

A3T5T 

A SYS 8 

A 3221 

BC107 

BC10S 

EC109 

BC113 

BC114 

BC110 

BC116 

BC117 

BC11S 

BC119 

BCX20 

BC125 

BC129 

BC132 

BC1S4 

BC135 

BC138 

BC137 

BC139 

BC140 

BC141 

BC142 

BC143 



BC147 

BC148 

BC149 

BC100 

P.C151 

BC1B2 

BC1B3 

BC1B4 

BC157 

BC1SS 

BC169 

BC180 

BClfll 

BCW7 

BC188 

BC169 

BC170 

BC171 

BC172 

BC173 

BC174 

BC175 

BC177 

BC17H 

BC179 

BC180 

BC181 

BC182 

BC182L 

BC183 

BC1S3L 

BC184 

BC184L 

BC188 

BC187 

BC207 

BC208 

BC209 

BC212L 

BC213L 

BC214L 

BC22S 

BC228 

BCY30 

BCY8I 

BCY32 

BCY33 

BCY34 

BCY70 

BCY71 

BCY72 

BCZ10 

BCZ11 

BCX12 

BD121 

BD123 

BD124 

BD131 

BD132 



11 
11 
13 
20 
29 
19 
81 
38 
20 
18 
18 
50 
55 
18 
13 
IS 
13 

ia 

16 

IS 

16 

24 

21 

91 

£1 

27 

27 

11 

11 

11 

11 

13 
18 
81 
81 
12 
12 
13 
12 
12 
IS 
98 
89 
27 
29 
33 
24 
28 

ie 

20 
IB 
22 
£8 
28 
66 
72 
88 
66 
66 



44 
41 

50 

H 

81 
68 

M 



■72 
77 
77 
72 
72 
77 
77 
H3 
H!t 
94 

N 

M 

H 



BD135 

BD138 

BD1.37 

BD138 

BD139 

BD140 

BDlflO 

BD17B 

BD178 

BD177 

BD178 

80179 

BDlflO 

BD185 

BD1H8 

BD 137 

BD1B8 
BUI -9 
BD10O 
BD10D 
BD1W1 
BD1H7 
BD108 
BD199 106 
BD200 106 
BD20B 88 
BD209 88 
BD2D7 106 

nivjri.s 106 

BDY20 110 

BF113 27 

BF117 

BF118 

BF119 

BF121 

BV13S 

BF12B 

BF127 

BF152 

BFIM 

BF1B4 

BF166 

Bnss 

BF157 
BF138 
BF1B9 
BF180 
BF102 
BF103 
BF1B4 
BFI8S 
BF187 
BF173 
BF170 
BF177 
BF178 
BF179 
BF180 
BF181 



BF183 
BF184 
BF18B 
BF188 
BP1M 
BFlftS 
nvuHi 

BFIS17 
BF200 
BF222 
BF2B7 
BF2S8 
BFHB9 
BFSOl 
1! P383 
ntino 

BF271 

BF278 

BF273 

BK27* 

BFW10 

BPX.9S 

Br'XM 

BFX88 

BFX88 

BFX87 

BFX88 

BFYSO 

BFYB1 

BFYB2 

BFYB3 

BFX2B 

B9X19 

B9X20 

BBY26 

BBY20 

B9Y27 

B8Y28 

B8Y29 

BSY38 

B8Y39 

B8Y40 

BSY41 

BSYM 



44 

£8 
33 
44 
18 
13 
16 
IS 
SO 
106 
60 
SS 
94 
61 

ai 

89 
33 

88 
89 
39 
86 
30 
24 
33 
£4 
27 
24 
22 
22 
22 
19 
94 
17 
17 
17 
17 
17 
17 
17 
20 
20 
31 
31 
14 



Type P'le* P 

MAT120 £1 

M ATI 21 22 

MPF103 48 

STPF104 41 

Ml'FlOB 41 

oris 



B8Y9BA 14 
Buino 2-20 



5!> 
33 
28 
22 
SS 
39 
22 
3a 
33 
SV 
94 

MATlflO 21 
SIAT101 £3 



C111E 

C400 

C407 

C424 

C42B 

C426 

C+28 

C441 

C442 

C444 

C4S0 



OC20 
OC22 
OC23 
OC24 
OCB3 
OC28 
OC28 
OC2B 
OC3B 

ocnn 

OC41 
OC42 
OC44 
OC40 
OC70 
OC71 
OC72 
OC74 

or-ij 

Of78 

OC77 

CK781 

OC«lD 

OC82 

OCR2D 

OC«3 

OCA4 

onnn 

WHO 

oci no 

OC170 

OC171 

OC200 

OC201 

OC202 

OC203 

OC7204 

OC2<M 

OC309 

OCP71 

ORP12 

ORPr.O 

OBFfil 

P 34>1 A 

P3S7 

8T140 

8T141 

T1843 

t"T48 

20301 

2O302 

BGS03 

203114 

2CJ308 



70 

42 

4S 

62 

42 

23 

66 

65 

43 

66 

2£ 

£7 

16 

14 

11 

11 

16 

16 

17 

17 

28 

17 

17 

17 

17 

£2 

£2 



28 
28 

B 

:U 
31 
2S 

28 

M 

14 

43 
4S 
44 

44 
22 

If. 
14 

IS 

H 

30 
£1 
21 
21 
27 
44 



Type Prlre p 

«(:MS 39 ' 

2<':M19 

20330 

2 0339 A 

20:144 

20345 

20371 

2H371B 

20373 



20374 

20377 

20378 

20381 

S08M 

2O401 

W414 

2C417 

2N3H8 

2X388 A 

2N404 

2K404A 

| S 624 

2WSS7 

2NBB8 

2K9B9 

2K6M 

2S897 

2N898 

2J<fi99 

2S7(W 

2N708A 

2X708 

2N7U 

-N7I7 

2N718 

2X718A 

2X720 

2X727 

2X743 

2X744 

88914 

23913 

8R929 

2X1130 

2X1131 

2X1132 

asn» t 

2N1303 
2X1304 
2X1.105 
2X1308 
2X1307 
2X1308 
2X1309 
251613 
2N17U 
2X1889 
2B18N 
2X1893 
2X2147 



38 

22 

18 

£0 

18 

18 

18 

16 

19 

33 

18 

IS 

18 

33 

33 

28 

39 

SI 

22 

31 

46 

64 

48 

60 
14 
15 
87 
86 
9 

10 
13 
33 
39 
27 
55 
31 
31 
2£ 
22 
16 
33 
23 
28 
£2 
24 
18 
18 
19 
19 
23 
28 
28 
£6 
£2 
22 
36 
50 
U 
79 



Typr Price p 
2X2 148 
2S2100 
2N219S 

2H2194 

2S22I7 
2X2218 
2X2219 
BN2220 
2X2221 
ES2222 
2N23fl3 
S1T3349 
2X23IJ9A 18 
2X2411 27 
2X2412 27 
E342846 S2 
2X2711 83 
2X2712 £8 
2X2714 88 
2M2904 19 
2X2904 A £3 
2S29M 23 
2X2905 A 83 
2X2003 17 
2N290flA 20 
2X2907 22 
2N2907A 24 
2X2923 18 
2N2924 16 
2X2925 16 
2X2921HC) 14 
- . •.( Y) 12 
2<K0) 11 
■1(U)11 
2X29211(11)11 



2X3010 
2X3011 



AA119 
A A 120 
AA129 
AAY30 
AAZ13 
BAIOO 
BA116 
Ba 1S6 
BA149 
BA134 
BA155 
BA150 
BY100 
BY101 
BY' 105 
BY114 
BY128 
BT127 
BY 128 
BY 130 



Type Price p 

2X3053 19 

2X3054 51 

2X305S 66 

2X3391 18 

2X3301 A 18 

2X3392 18 

2X3393 

2X3394 

2N339S 

2X3402 

2X3403 

2X3404 

2X3405 

2X3414 

2X3410 

383416 

2X3417 

!SSS2fl 

2X3B4A 

UM";7i!2 

2X3703 

9K3704 

2X3703 
2X37011 
2X3707 
2X3708 
2X3709 
2X3710 
2X3711 
2X3819 
2X3820 
2X3*21 
2X3823 
2X3903 
2X3904 
8N8BW 
2X3906 
2X4033 



16 

16 
19 
83 
23 
81 
46 
17 
17 
31 
31 
S3 
10 
11 
11 
12 
11 
10 

10 
10 
10 
31 
65 
39 
31 
31 
83 
31 
30 
13 



Type Price i 

2X4059 11 

2X4090 

2X4061 

2X4062 

2X4284 

2X42B5 

2H4280 

2X4237 

2X42,18 

2X4289 

2X4290 

2X4291 

2X4292 

2X4293 

2X3172 

2Xr>457 

2X5438 

2X5439 

2B801 

2S302A 

29302 



2S303 

23304 

2830B 

28308 

28307 

2S321 

28322 

28322 A 

2S323 

28324 

28325 

2S326 

28327 

23701 

40301 

403fi2 



DIODES ASD EECTD7IEB8 
9 BY133 23 
B\ 164 56 
BTX.38/80 4S 



i 


10 

11 
11 

83 
24 
IS 
18 
IS 
15 
17 
13 
19 
13 
18 
17 
17 
18 



39 
S 

n 

H 

44 

N 

31 



BY-ZIO 

BVZI1 

BYZ12 

BYZ13 

BYZ18 

BYZI" 

BTZ18 

BYZ19 

CG62 

(OA91 EH-) 6 

CU651 

(OA70-OA79 

F.q.) 7 

0A5 39 

OAoSL. 23 
OAIO 39 

OA47 8 



OA70 
OA79 
OA81 

OA85 
OA90 

OA.il 

OA95 

OA200 

OA202 

SD10 

8D19 

1X34 

IX 34 A 

1X914 

1X910 

1X414B 

13021 

1S951 



48 
46 
62 
77 
77 
77 
77 
46 

M 

50 



8 
8 
8 
10 
7 
7 

a 

7 
8 
S 

8 

8 
8 
7 
7 
7 
11 
7 




NEW COMPONENT PAK BARGAINS 

Pa°k ~ -i u 

So Qtr. DewripUoti 

C 1* 2S0 BeBistori mixed Tallies apiirox. con^t by weight 
C 2 200 Capacitors mised values npproi. count by weight 



Precision Reslslors 1% mlied valuta 
4, ill W Resistors mixed preferred valoea 
Pieces assorted Ferrite Rods 
Timing Gangs, SHY/LW VHF 



Mm 
55 
65 
55 
063 
B5 
65 



1 Pack Wire 50 metres assorted colours J{»» 



:o 



06b 
56 
65 
55 
0-65 
55 
66 
55 
6b 
65 
68 
56 
65 



Beed Switches 

„ Micro Switches 
15 Assorted FoU 4 Pre-Set* . . . - -j ■ 

6 Jack Sockets 3 x Sfim 2 x Standard Switch Types . 
40 pap«r Condensers prelerred types mixed TiJne» 
20 Electfolvtics Trans, types .. ■■> • 

1 Pack assorted Hardware - Nuts /Bolts, Oroimnett etc.. 

4 Mains Switches, 2 Amp plus 

20 Assorted Tag Strips A- Panels 

10 Assorterl Control Knobs . . 

4 Hotar? Wave Chinne Switches 

3 Eelavs 8 — 24V Operating 

4 Sheets Copper Laminate spprox. 10' X 7* . ■ ■ 
Please add lOp post and packing on all component packs, plus a lurther lOp 
on pack Nos. CI, C2, C19 ft C20. 

Plus much more- 
send now for the 
BI-PAK "component 
catalogue" 

cover postage, etc. 



JUMBO C0HP05ENT PAKS 
Ml ZED ELECT ROXIC CO 11 POSES TS 
Resistors, capacitors, pots, eleetrolytlcs 
and colls plus many other usetul Items. 
Approximately Slbs In weight. Price Inch 
P. a P. £1 86 only. 

Exceptionally food rnliif 




BRAND NEW 
POST OFFICE 
TYPE TELE- 
PHONE DIALS 
ONLY 83 p each 



THE NEW S.G.S. EA 1000 AUDIO 
AMP MODULE * Guarantee 

3 Watts 

R.M.S. 
ONLY 

£2-89 eacli 

Module Tested and Guaranteed, 
Qt y , i_s (2-SB; 10—25 *2-50 Price Men. Laner 
ciuantltles nuoted on request. i*ull hook-up diagrams 
I and complete technical data supplied free with each 
I modal* or available separately at 10p each. 




5p to 



SYSTEM 12 STEREO 

Each Kit contains two Amplifier Mod- 
ules, 3 watts RMS, two loudspeakers, 
15 ohms, the pre-amplifler, trans- , 

former, power supply module, 
front panel and other acces- t 

sories, as well as an illus- I 

trated stage-by-stage instruc- -* kj ay 
tion booklet designed for the v-ri^i- ■ 

Further details available on JQ | Q " |)4 
request 




FREE 
P. & P. 



Ji 



miMJAhWjk kilMaM&l 



301 



The lamest selection 



HEW LOW PRICED TESTED S.C.R/s 

PIV1A 3A EA 5A 7A 10A 16A 30A 
TOB TO86T066TO64TO48T048T049T048 

eoo-ss o-28 0-39 039 052 055 o-so 1-27 

10OO'28 0-37 0-52 0-02 0-55 0-64 0-70 1-84 
200 0-39 0-41 0-54 0-54 63 0-67 0-83 170 
400 0-48 0-52 0-62 0-82 0-74 0-83 1-03 1-93 

6000-69 0-63 0-76 0-73 0-85 107 1-33 

800 0-70 0-77 0-88 0-88 0-99 1-32 1-05 4-40 



SIL RECTS. TESTED 

FIV 300mA 750mA 1A ISA 3 A 10A 30 A 

60 04 000 O-Ofi 008 0-1H 0-23 066 

100 004 0-07 0-06 015 018 0-26 0-83 

200 0-06 010 0-07 O-lfi 0-22 0-27 1-10 

400 07 016 0-08 0-22 0-30 0-41 1-38 

600 008 018 Oil 0-26 0-38 0-50 205 

8000-11 0-19 0-12 0-28 0-41 O-Bl 2-20 

10O0O-1-J 0-28 0-16 0-33 0-51 0-70 2-75 

1200 — 0-37 — 0-42 0-63 0-63 — 



TRIACS 

VBOM 2A 6A 10A 
TO-6 TO-88 TO-48 

£p £p £p 
100 83 6S 83 

200 65 68 9S 

400 77 82{ 1-21 



DIACB 

for mm with 

TRIACS 

BR 100 (D32) Up each 



FREE 



One GOp Pak ot your 
awn choice free with 
oiden valued £4 or over. 



BRAND NEW TEXAS 
GEEK. TRANSISTORS 
Coded nod Guaranteed 



Pat No. 



EQVT 



» 



8 2i;37l3 

8 D1374 

8 J.j I'.' IS 

8 2C381T 

8 2G382T 

8 2R344J1 
T7 8 20345B 
T8 8 2C37H 
T9 8 20399 A 2M302 
T10 8 20417 AF117 
All 55b each pa k 



OCT! 

OC76 

OC81D 

OC81 

OC82 

OC44 

OC45 

OC78 



D1699 NPN SILICON 
DUAL TRANSISTOR 
(Similar to 2N2000) 

1 26 100 + 

0-28 0-20 23 



ND 120 NIXIE DRIVER 

TRA5SIST0B. 
Suitable reiuacemf-nt for 
BSX 21. C 407, 2N~ 1893 
120veb, 

1 25 100 + 

019 017 018 



BU. trans, suitable for 
P.E. Ortran. Metal TO-18 
Eqvt. ZTX300 SJu each. 
Any Qty. 



GP 100 T03 METAL 
CASE GERMANIDM 
Vebo - 80V. Vceo ■ 60V. 
I.C. = 10 amps. Ptot = 
30W.hfe = 30-170, 
Replaces the majority of 
Germanium power tran- 
sistors fn the OC. AD 
and NKT range. 

1 26 100 + 

48 0-44 0-40 



GP 300 T03 METAL 
CASE SILICON 
Vebo - 100 V. Vcco - 60V 
I.C = lf> amps. Ptot = 
USTV. life =20. 100fT.= 
IMIlz. Suitable replace. 
ment for 2N 3055, 
BDY 11 or EDY 20, 

1 25 100 + 

0-55 53 51 



FULL RANGE OF 
ZENER DIODES 
VOLTAGE RANGE 

£-33 V. 4O0mV (DO-7 
Com) 15p ea. 1}W (Top- 
Hat) 20p ea. 10W (80-10 
Stud) 33p ea. 



in amo POTTED 
BRIDGE RECTIFIER 

on heat sink. 
I00PIV. 9?peach 



2 Amp. BRIDGE RECTS. 
50 v RMS 35p each 
100 v RMS 41p „ 
400 v RMS 61n „ 
Size 10 mm x 10 mm. 



TJT48 UNIJUNCTION 
TRANSISTORS 
Direct replacement for 
TIB 43rand BEN 3000 
also electrically equiva- 
lent to 2N2046 

1 25 100 + 

30 0-28 0-22 



CADMIUM CELLS 

ORP12 4Sn 
ORP60, ORrOl 41p each 



GENERAL PURPOSE 
NPN SILICON SWITCH- 
ING TRANS. T0-18 
SIM. TO 3N708f8. BSY- 
K7/28/B5A, All u»able 
devices no ooen or short 
circuit*. ALSO AVAIL- 
ABLE In PNP Sim. to 
2N2906. BCT70, When 
onlerlna; please state 
preference KPN or PN"P. 

to 
20 For 

60 For 

100 For 

600 For 

1000 For 



085 

110 
198 

8 25 
1430 



SIL. G.P, DIODES £p 

3nn m -w 30. .068 

40PIV(MIn.) 100 1-65 
Rub-Min. 600 5-50 

Full Tested 1,000 9 90 
Ideal for Organ Builder*. 



R 2400 T03 NPN 
SILICON HIGH 
VOLTAGE 

Vebo=250V. Vceo = 
100V. I.e. = 6 amp*. 
Ptot = 30W. hie - 1 vp.20 
IT = 5MHz. 

1 25 100 + 

0-55 0-50 0-44 



2N3055 

115 WATT SIL 
POWER KPN 
65p EACH 



KING OF THE PARS Unequalled Value and Quality 



SUPER PAKS 



NEW BI-PAK UNTESTED 
SEMICONDUCTORS 

Money back refund If not in til fled 



Pale No 



Deiorlpfclou 
120 Olass Bub-Mln. General Purpose Germanium Diode* 



Price 

SI' 
85 



C 2 60 Miieo Germanium Translators AF/RF 0-85 



U 3 75 Germanium (iold Bonded Snb-Min. like OA6, OA47 



U 4 40 Oermanlum Transistors like OC81, AC128 



U5 60 200mA Stib-Mtn. Bill con Diodes 0-65 



U 6 30 Bil. Planar Trans. NPN like BSY95A. 2N706 0-66 



(-■ 7 16 Bil. I J . arttflaia TOF-H at 780mA PT.T6. r..\ BOB apto 358 53 

S 50 Bil. Planar D i odes DO-7 Glass 2.10mA like OA'JOO/203 ■ . 55 
U9 20 MUed Voltages, 1 Watt Zen er Diodes 0-66 



UI0 20 BAT60 charge storage Diodes DO-7 Glass 0-56 



U U 25 PNF 811. Planar Trans, TO-5 like 2Klla2, 2S29Q4 . . . . 65 
U12 12 silicon Rectifiers Epoxy 600mA up to 800 FIV 0-68 



in 3 
in -i 



30 PJIP-NPN 811. Transistors OC200 A- 23 104 



65 



150 Mixed Silicon and Germanium Diodes 



(J13 25 NFS BU. Planar Trans, TO-6 like BFT51, 2S8S7 



DT8 10 3 Amp Silicon Rectifiers Stud Type up to lOOOPTV 



U17 30 Germanium PNP AF Transistors TO-5 like ACT 17-22 066 



I.'IB B 6 Amp Silicon Rectifiers HYZ13 Type up to fiOO PIV 



NPN Transistor* like BC108 



U20 12 1-5 Amp S ilic on Rcctlflcra Top Hat up to 1O00 PIV 0-55 

t"2J 30 AF. Cenn&nlum Alloy Transistors 36300 Scries A OC71 0-55 



1:23 30 MAJlT's like MHi Series PNP Transistors 0-66 



U25 



20 Germanium 1 Amp Rectifier* GJM Series up to 300 PIV 0-65 



25 300 MHz NPN Silicon Transistors 2N708, BSY27 



65 



Wt 38 Fast Switching Silicon Diodes like IN*914 Mlcro-Mln. 



U27 12 NPN Gem .an in in A K TrannlJitors TO-1 like AC127 



U20_ 

1'30 



10 1 A mn SCR 'a TO-6 can, up to SCO FIV CRSi;25-800 
16 Plastic Silicon Planar Trans. NPN 2H2S2A 



1 10 
"0 : 58 



U31 20 Silicon Planar Plastic NPN Trans. Lo w Noino Amp2N3707 0-66 
1:32^ 25 Zener~Dlode« 400mW DO-7 case 3-lfl volts mtetd 0-66 



ira.l 15 Plastic Case 1 Amp Silicon Rectifiers IM4000 Series 



0-65 



30 Silicon PNP Alloy Trans. TO-6 BCY26 28302/4 0-55 



25 Silieor. Planer Transl-tors PSP TO-18 2N2006 



U3H 25 Silicon Plan ar KPM Tnuuilstors TO-5 BFY50 ;51f52 
30 Silicon AUoy Translatora SO-2 PNP OC20Q, 28322. . 



U87 



0-66 
65 

55 



20 Fast Switching Sitkon Trans. NPN 400 MHz 2N3011 



U39 30 RF, Germ. PNP Transistor* 2N 13 03/5 TO-6 0-66 



VM 10 Dual Transistors lead TO-5 2X2060 0-58 



041 25 RF Germanium Transistors TO-1. OC45. NKT72 0-55 



U42 10 VHP Germanium PN1* Transistors TO-1 NKT6B7, AF117 0-65 



■ ! :-■ A.F, 1)0113/114 0-66 



U44 20 Sit. Trans. Plastic TO-5 HC116/116 



QUALITY TESTED SEMICONDUCTORS 

Pak No. Priea 

£ P 

Ql 20 lied spot transistors PSP .... 058 

Q2 16 White spot B.F. transistors PNP .0-56 

Q3 4 OC 77 type transistors 0-65 

Q4 6 Hatched transistors OC44/43/S1/S1D 0-66 

Q5 4 OC 75 transistors 0-88 

Q6 6 OC 72 translators ., 65 

<J7 4 AC 128 tranKlitiirs J'NPhlgb gain,. 0-56 

Q8 4 AC 12fi translators PNP 0-65 

Q9 7 CIC SI tyne transistors 55 

«30 7 OC 71 type transistors 0-55 

QH 2 AC 127/128 Complementary pairs 

PNP/NPN 085 

Q12 3 AF 116 type transistors 0-55 

(J13 3 AF 117 type transistors 0-56 

QI4 3 OC 171 U . 1\ type traneWora 65 

Q1E 7 2N2820 811. Epoxy transistors 

mixed coloors , . , , 0-55 

Q15 2 GET8S0 low noise Germaslura 

transistors 0-55 

Q17 6 NFN 2 x ST.141 Ux ST.140. . . . 0-65 
Q1B 4 MADT'S 2 x MAT 100 & 2 x MAT 

120 0-55 

Q19 3 MADT'S 2 X MAT 101 4 1 X MAT 

121 0-65 

Q20 4 OC 44 German I urn transistors A.F. 0-56 
Q21 4 AC 127 NPN Germanium transistors 0-65 
Q22 20 NKT transistors A.F. It. F, coded .. 0-65 

Q23 10 A 202 Silicon diodes aub-min 0-65 

«24 BOA 81 diodes 0-55 

Q2B IB 1N914 Silicon diodes 75 PIV 75mA 0-65 
Q2S 8 OAS5 Germanium diodes eub-min 

IM>9 055 

Q27 2 10 A PIV Silicon rectlflers IS425R . . 0-55 

Q28 2 Silicon power rectifiers BY2 13 0-55 

Q29 4 Silicon transistors 2 X 2X690, 

1 X 2N697, 1 x 2N098 0-56 

Q30 7 Sdlcon switch transistors 2N706 

NPN 0-55 

Q31 6 SJlcon switch transistors 2N708 

NPN , 0-55 

Q32 3 PNP Silicon transistors S X 2N1131, 

1 x 2N1I32 0-55 

Q33 3 Silicon Xl'X transistors 2N1711 0-55 

Q34 7 Silicon NPN transistor 2N2369, 

BOOMHi (code P397) 0-66 

Q35 3 Silicon PNP TO-5. 2 x 2N2604 A 

1 X 2X29(15 0-65 

Q36 7 2N3846 TO-18 plastic 300 MHi XPN 0-65 
Q37 3 2X3053 NPN Silicon transistors ..065 
Q38 7 NPN transistors 4 X 2X3703, J X 

2N3703 0-65 



TJ48 7 3A SCR. TOS6 up to 600FIV 



Code No's, mentioned above are given as a guide to Ibo type ot device In 
the pak. The devices themselves are normally unmarked- 



ELECTRONTC SLIDE-RULE 
The MfT Slide Rule, designed to simplify Elec- 
tronic calculations features the following scales:— - 
Conversion of Frequency and Wavelength. 
Calculation of L, C and fo of Tuned Circuits. 
Reactance and Self Inductance. Area ot Circles. 
Volume of Cylinders. Resistance of Conductors. 
Weight of Conductors. Decibel Calculations, 
Angle Functions. Natural Logs arid 'e' Functions. 
Multiplication and Division. Squaring, Cubing 
and Square Roots. Conversion of kW and Hp. 
A must for every electronic engineer and enthusi- 
ast. Size: 23 cm x 4cm. Complete with case and 
Instructions. Price each: £3-69 



SILICON PHOTO THAN- 
6ISTOR. TO-18 Lens end 
1\ PN Sim. to BP x 25 and P21. 
BRAND NEW. Fall data 
available. Fully guaranteed. 
Qty. 1-34 25-99 100 up 
Price each 49 p 4 1[> 88p 



2N3819 
2 X 3820 
2 N 3821 
2N3S23 



F.E.T.'S 

Sip 

55b 

Ml 

aip 



2X6458 
2N5459 
BKW10 
11PF103 



35p 
41p 
66p 
«1P 



NEW 6th EDtTtON 

TRANSISTOR EQUIVALENTS 
BOOK. A complete cross reference 
and equivalents book for Kuropran, 
American and Japanese Transis- 
tors. Exclusive to Bl-PAK 09p 



A LARGE RANGE OP TECHNICAL 
AND DATA BOORS ARE SOW 
AVAILABLE EX. STOCK. 
SEND FOR FREE LIST. 



AD 161 162 i-yp 

M/P COMP CERM TRANS. 
OUR LOWEST PRICb OF 
50p PEft PAIR 



B1P 19/20 T03 NPN PLASTIC SILICON 

Vebo=100V. Vceo = 50V I.C. = 10 amps. Ptot = 50W. 

hfe = typ. 100 IT " 3MHi B1P IB/SO Matched Pair. 

1 25 100+ I 25 100-h 

0-371 0-35 32 68 0-61 55 



Pak No. Contents Pries 



INTEGRATED CIRCUIT PAKS 

Manufacturers "Fall Outs" which Include Functional and Part-Functional TTntta, 
These are classed aa 'out-of-apec' from the maker's very rigid specifications, hut 
are Ideal for learning about I.C's and experimental work. 

Pak No. Contents Price Pak No. Content! Pries 

UJCO0-12x74OO 0-65 UIC46-KX7446 65 

UIC01 = 12x7401 0-66 IIIC47 = 5x7447 0-55 

OC02 = 12 X 7402 0-55 UIC48-6X744B 0-55 

UIC03 = 12x7403 0-66 U1C50 = 12 X7450 0-65 

UIC04 = 12x7404 55 TnC61-12x7451 0-65 

trlC05=- 12X7406 0-66 UIC53 = 12x7453 65 

UIC06 = 8x7406 65 tHC54 = 12x74S4 0-55 

TJICO7 = Bx7407 0-66 UIC60 = 12x7450 0-65 

UIC10 = 12x7410 65 t*IC70 = 8x 7470 0-65 

DIC13=Bx7413 55 UIC72 = Bx7472 0-56 

TJIC20 = 12x7420 66 UIC73 = Bx7473 0-65 

UIC30 = 12x7430 66 UIC74 = Bx7474 65 

UIC40 = 12x7440 56 UIC75 = 8x7475 66 

UIC41 = 5x7441 55 UIC78 = 8x747(5 55 

UIC42=5x7442 0-65 VIC80 = 5x7480 0-55 

I7IC43 = 5x7443 0-55 TJICS1-5 X7481 65 

UIC44 = 6x7444 0-56 UIC82 = 5 X74S2 0-55 

IJIC46 = 5x7445 0-55 UIC83-5X7483 0-56 

Packs cannot be split, but 2 S assorted pieces (our mil) is available as PAK UIC XI. 



65 

0-65 
65 
65 
65 
66 
0-66 
0-55 



lIIC88 = Ex7486 
tHC00 = 5x7490 
UIC91" 5x7401 
VIC93-6X7492 
UIC03 -6x7493 
LTC94-5X7494 
UIC95 =5x7495 
UICHS- 5x7498 
UlC100 = 5x74IOO 0-55 
UICl31 = 5x74121 0-55 
UIC141 = 6x 74141 0-65 
U1C151-5X 74151 0-65 
UIC154~6x74154 0-55 
1)16193 = 6x74193 0-55 
UIC199 = 5x 74199 0-65 

ricxi- 



61-PAKS NEW COMPONENT SHOP NOW OPEN WITH A WIDE RANGE OF 
ELECTRONIC COMPONENTS AND ACCESSORIES AT COMPETITIVE PRICES— 

18 BALDOCK STREET (AI0), WARE, HERTS. 
TEL. (STD 0920) 61593. 

OPEN MON.-SAT. 9. IS a.m. to « u.m.. FRIDAY UNTIL 8 p.m. 



Please add lOp postage and packing per order. Cash with order 

please. Orders to BI-PAK SEMICONDUCTORS, P.O. BOX 6. 

WARE, HERTS. 



302 



- the lowest prices ! 



74 Series T.T.L. I.C's 



BI-PAK BTILL 
GUARANTEED 

1 

17 
017 
017 
017 
017 
017 
0-30 
0-39 
020 
20 
017 
0-28 
0-39 
38 
48 
048 
017 
65 
66 
066 
0-50 
60 
0-77 
017 
50 



8N7-100 

SN7401 

BN7402 

6N7403 

SS7404 

BH7408 

9S740fl 

BN7407 

8S7408 

SN7409 

8N7410 

BN7411 

8N7412 

B>""413 

BK7410 

BS7JI7 

BN"4'J0 

8M74M 

SN7423 

8S7435 

8N742B 

8N7427 

8N7438 

8N7430 

8N7432 

8N7433 

BN7437 

6N7438 

BS7440 

BN7441 

BN7M2 

BN7443 £1-43 

8N7444 II 43 

8S7445 (1-98 

SS7448 £107 

8X7447 fl 10 

8S7448 sJl-10 



LOWEST IS PHICE. FULL 8PECTP1CAT10M 
ALL FAMOUS MANOFACTUEEES 

100+1 1 25 100+1 

013SN7460 017 0-lfl 

18i8N7461 0-17 

0-138N7463 17 

013SN7454 017 

13 SS7460 0-17 

13 8X7470 0-32 

31 3S7472 0-3B 

0-31JSS7473 0-41 

0-18 ! SX7474 0-41 

0-18 SN 7475 0-60 

1BSN7478 0-44 

88-SS7480 0-74 

-S18S7481 £1-33 

0-278N74B2 0'88 

0-48 8N7483 £1-81 

0-42 3X7484 £110 

013(8X7486 £3 OS 

0-60ISS7488 36 

O-603N7489 £9-05 

0-MSN7490 0-74 

0-44 3 N 7491 £1-10 

44SS7492 0-74 
68 8X7493 



0-71 
0-71 
17 
0-74 
0-74 



£6 
18 

o-ie 

0-18 
0-lfl 
018 

018 
034 

0-34 
18 
0-19 
0-16 
0-27 
0-34 
0-29 
0-44 
44 
0-lfl 
0-63 
0-53 
0-53 
0-43 
0-48 
0-72 
018 
0-46 
83 
0-88 
0-S8 
18 
0-71 
0-71 
£1-38 
£1-38 
£1-95 
£104 
£107 
£1 07 



%, 



0-18 
■ 44 
0-77 
68 
0-68 
0-13 
64 



0-74 

0-36 

0-86 

0-9B 



3X7494 
8 X 7 495 
3X7400 
8X74100 £1-82 
3X74104 £1-07 
8X74101) £1-07 
8X74107 0-44 
0-64'3N74nO 061 
£1-82 SN'741 11 £1-38 
£1-38 8X74 118 £1- 10 
£1-83 3X74 119 £1-49 
0-97 SX74121 0-44 
£1-05(8X74122 £1-64 
£1-06 3X74123 £308 



71 
71 

£'-i 
Si 
S3 
78 
04 
04 

a 

59 

£7 

05 

38 

0-41 

£1-48 

£2 97 



18;9N74141 0-74 
13 8X74145 £1-85 
13 8N74150£3 30 
13 3X74151 £110 
138X74153 £1 88 
B7ISS74 154 £108 
27i3X74155£l-54 



8X74 150 £1-64 

3X74157x2 09 

8X74160 81-98 

HN741-11 41-88 

BN74152£4-40 

21 3X741 03 £4 -40 

9418X741 64 £8 -43 

OS 3X741 65 £2 48 

S9lSX74186£3'S5 

74 8N74174£8-63 

33 3X74175 £1-78 

50 8X74176*2-76 

84 8X74177*2-75 

89SX7-i:-il£2 20 £1 



64S.VM:.-i£9-05 
84 3X74182*830 
78 8S74184 33-85 
75 3X74190 £215 





883X74191*8 OB 
£1-71 8X74192 £8-15 
0-97 8X74193 £2-20 
0-97 3X74194*8-97 
0-40 8X74195 £2-20 
0-66 8X74196*1-98 *1-B7 
£1-81 9X74107*1-98 £1-87 
89|BX7419S£e-05 £6-50 
*1-S1 , 8X74108£8O5 £5-50 

8818 Terminal Poi Volt Eeg. TO. 3 
Bl Plastic O/P l.S Amps. fiA7805 
IS-Bfl'SV. & fiA7812 12V. *l-76 each 



100 + 

64 
11-43 
£2 76 

O 99 
£1 05 
£1-78 
£1 38 
£1-38 
£1-37 
£1-76 
£1-78 
£3 85 
£3 85 
£2-31 
£2-37 
£3-30 
£2-81 
£1-54 
£2 53 
£2 53 
£1-64 
£5-83 
£1-76 
£3-80 
£8 04 
£1-98 
M 04 
£1-93 
£8-76 
£1-98 
£1-76 
£1-76 
£4-95 
£4 95 



LINEAR l.C's-FULL SPEC. 

Price 

Type No. 1-24 25-99 100 up 

BP 201C— 9L201C 70p 69b 60p 

BP701C— SL701C 70p 

BP 702C— 8I.702C 70p 

BP 702—72702 59P 

BP70B— 72709 40p 

BP 709P— HA709C 40u 

BP 710—72710 50p 

BP 711— <iA711 50p 



BP 741—72741 55p 

UA703C 31 p 

TAA 263 77n 

TAA 293 98p 

TAA 350 £1 • 87p £1 ■ 74~p II • fl5p 

B.O.B, EA1OO0 £S-90p 



55p 
55p 
60p 
3flD 
36p 
48p 
48c 
60p 
2Sp 
SAP 
83p 



50p 
50c 

m 

33; 
33p 
44p 
44p 

45p 
27p 

flip 
77p 



ROCK BOTTOM PRICES 
LOGIC DTL 930 Series l.C'a 



Tim 
No. 

BP930 

BP932 

BP933 

BP930 

BP936 

BP944 

BP945 

BP948 

BP948 

BPSB1 

BP962 

E Pill lis 

BP9094 

BP9097 

BP9099 



13p 
14p 

HP 
14p 
14P 

14p 
E8p 
ISP 

28p 
72p 
lap 

44p 
44p 
44p 
44p 



25 
18p 

13p 
13p 
ISp 



100+ 
Up 
12p 
12p 

lZp 



13p 18p 
13p 18p 



£7p 
ISp 
87p 
88p 
12p 
42p 
42p 
42p 
48p 



24p 
lip 
24p 
61p 
lie 

asp 
89p 
39p 
S9p 



Devices may be mixed to qualify lor 
quantity price. Larger Quantity price a 
on application. (DTL 930 Series only). 



NUMERICAL INDICATOR TUBES 



All indicator* 
0-9 + Decimal 
point. All side 
viewing. Poll 
data for all 
types available 
on request. 




MODEL 


CD88 


QB116 


3015F 
Mtnltroa 


Anode voltage (Vdc) 


lTOmln 


170mln 


B 


Cathode Current (niAi 


, 2-3 


14 


8 


Numerical Height (mm) 


IS 


13 


9 


Tube Height (mm) 


47 


32 


23 


Tube Diameter (ram) 


19 


13 


12 wide 


LC. Driver Beo. 


BF41 or 
141 


BF41 or 
141 


BP47 


PRICE EACH 


£1-87 


£1-70 


£1-50 



BTL MICROLOGIC CIRCTjrrS 

Price each 
Epoiy TO-5 case 1-24 26-99 100 up 
OL900 Buffer 38 p 86p S9p 

DL914 Dual Si/p 

gate 38p 36p SBp 

uL923 J- Kill p. Hop 65p 61 p 49p 

Data and Circuits Booklet far lO's 
PriotSp. 



DUAL-IfMJKE SOCKETS. 
14 & 16 Lead Sockets for use with 
DTJAIMJ.--LINE l.C'e. TWO Ranges 
PROFESSIONAL li NEW LOW COST. 

PROF. TYPE So. 1-24 25-99 lOOnp. 
TSO 14 pin tyre 83 p 3 Op 28 p 
T80 16 „ ,, 89p 35p 33p 



LOW C08T No. 
BF8 14 
BF8 10 



17P 
18p 



ISp 
ISp 



12p 
13p 




ONLY 
£3.58p each 

• Supply voltage 10-35 
Volts. 

■jV Overall size 63mm x 

105mm x 13mm. 



BI-PAK DO IT AGAIN! 

SOW Pk 25 w (RMS) 

0-1% DISTORTION! 
HI-FI AUDIO AMPLIFIER 

THE AL50 

-ft- Frequency Response 15Hz to 
100,000— 1dB. 

•k Load— 3, 4, 8 or 16 ohms. 

-jV Distortion — better than -1% at 
1KHz. 

•k Signal to noise ratio 80dB. 

Tailor made to the most stringent specifications using top quality components 
and incorporating the latest solid state circuitry and AL80 was conceived to All 
the need [or ail your A.F, amplification needs. 
FULLY BUHiT — TESTED — GUARANTEED. 

STABILISED POWER 

MODULE SPM80 

AF80 is especially designed to power 2 of the ALSO 
Amplifiers, up to 16 watt (r.m.s.) per channel simul- 
taneously. This modulo embodies the latest components 
and circuit techniques Incorporating complete short 
circuit protection. With the addition of the Mains Trans- 
former MT80, the unit will provide outputs of up to 1*0 
amps at 35 volts. Size: 63mm x 100mm x 30mm. 
These units enable you to build Audio Systems of the highest 
quality at a hitherto unobtainable price. Also ideal for many 
other applications including:— Disco Systems, Public Address, 
Intercom Units, etc Handbook available. lOp p R | Q £ £3 .25 

TRANSFORMER BMT80 £2-15 p. & p. 28p. 

STEREO PRE- AMPLIFIER TYPE PA100 

Built to a specification and NOT a price, and yet still the greatest value on the market, 
the PA100 stereo pre-amplifler has been conceived from the in test circuit techniques. 
Designed for use with the AL60 power amplifier system, this quality made unit incorporates 
no less than eight silicon planar transistors, two of theso arc specially selected low noise 
NPN devices for use In the Input stages. 

Three switched stereo Inputs, and rumble and scratch filters are features of the FA100, 
which also has a 8TERE0/M0XO switch, volume, balance and continuously variable 
baas and treble controls. 





SPECIFICATION 
Frequency Response 
Harmonic Distortion 
Inputs : 1. Tape Bead 

2. Radio, Tuner 

3. Magnetic P.TJ. 



20Hl - 2QKH-S ± ldB 
better than 1% 
1-28 mV into 60KQ 
36 in V Into 50K 11 
1-6 in V IntoSOKtl 



All Input voltages are for an output of 2B0mV, Tape and P.TJ. Inputs 
equalised to Hi A A carve within ± ldB. from BOHi to 20RHi. 
± lfidB at 20Hz 
± 16dB at 20EH2 
100 Hz 
SKHz 

better than - 65 dB 
+ 2-jiIB 

+ 36 volts at 20mA 
292mm x 6 2mm x 35mm 

ONLY £13 15 



Bass Control 
Treble Control 

F Uteri : Rumble (High Pass) 
Scratch (Low Pass) 
Signal/Noise Ratio 
Input overload 
Supply 
Dimensions 



SPECIAL COMPLETE KIT COMPRISING 2 ALSO's, 1 
SPM80, 1 BMT80 & 1 PA100 ONLY £2530 FREE p. & p. 



All prices quoted in new pence Giro Ha, 388-7086 

., warehouse and despatch depart. 




P.O. BOX 6, WARE HERTS 

Portage and packing add 100. Overiooi add extra far airmail. 
Minimum order JOp. Cash with order please. 

Guaranteed Satisfaction or Money Back 



tM 



m 









and it's 

FREE 

-The 
Book 



* kits 



See for yourself the range of wonderful new kits that 
Heath have presented in the latest catalogue. We now 
offer something for everyone, including stereo hi-fi 
equipment, radios, intercoms, calculators, automotive 
testers, shortwave and amateur radio, testers and instru- 
ments for technicians and hobbyists . . , all at money- 
saving prices. And payment is so easy — choose cash 
or our low deposit terms (starting at £2 per month for 
up to £40 credit). 

You can build a Hcathkit model using only a solder- 
ing .iron and a few simple hand tools. Foolproof 
assembly is guaranteed using the step-by-step construc- 
tion manual included with every kit. 

Add to this a technical consultant service both before 
and after purchase and you will see why kit building 
the H till !ik it way is so popular all over the world. 

Send now for your free copy of the Hcathkit elec- 
tronic kit catalogue — and if your friend is likely to 
borrow it, fill his name and address in below and we'll 
send him a copy too ! 

Please send a FREE Heathkit Catalogue to my 

friend 



NAME 



ADDRESS 



HEATH (GLOUCESTER) LTD., DEPT. PW .08/73 
BRISTOL ROAD. GI.Ol CESTER C.LI 6EE 



Please send me a FREE Heathkit Catalogue 
I want to know more about your Cash and Eow 
Deposit Terms, without obligation. 
N A M E 



ADDRESS 



E5-_i^_J HEATH (GLOUCESTER) LTD- DEPT. PW/08/73 
SyQ£|2£2i| RRISTOl. ROAD. GLOUCESTER CM 6EE 



Multicore Solder Cream 
for high quality joints in 
the Electronics Industry 



New -Munition* Solder Cream 
was designed for jobs where 
Bet mid best will jus! no! do. 
Like manufacturing diodes for 
instant e. Or making a tuner ' 
chassis, or spidering (hick-fiun 
circuits. Multicore Solder 
Cream, a finely graded snider 
alloy powder in a Ibixotropie 
organic vehicle, is easier 
quicker, more economic and 
more reliable than 
conventional techniques 

Muftieore Solder Cream is ■ 
different, fl doesn't gpil or 
need stirring. It can bf! applied 
by syringe, automata 
dispensers or screen printing- 
giving instant soldering with 



good spread, si rong joints with 
lovi contact .ingles. Suitable as 
a temporary adhesive during 

"assembly, the clear colour flux 
residue without solder \ 
globules makes inspection 
easier. There are three types 
of Multicore Solder Cream - 
ontr of them mav be just vvhal 

.you're looking for. 

For full information on this 
or my, other Multicore ■ 
products, please write, .on your 
company's 

letterhead 
direct to: 




>~^-^- 




Multicbre Solders Ud., \fa\ funds Avenue. I hum;] I leinpsiead 
f lei1s.ilR2 7EP. Tel: ! Icmcl Hempstead 3H3f). Telex: S236& 



PADGETTS RADIO STORE 

OLD TOWN HALL, LIVERSEDGE, 

YORKS WF15, 6PQ 

TEL HECKMQNDWi'KE 4285 
THE T.V. GRAVEYARD OF THE NORTH. AS SEEN ON T.V 
CLOSE TO THE MOTORWAY. PLENTY OF FREE PARKING 

SPACE. EST. 1935. 
SPECIAL OFFER 

1000 PYE 19' 13 Channel T.V. Sets. Brilliant Picture, Extra Slim 
Bench Tested. Sold with Money Back Guarantee. Hurry, have a 
second set at the price of £5-50. Plus carr. and ins. £1-80. 
FAMOUS R. & A. 7x4" Speakers ex T,V. 3 Ohm 2i Watt SO p. 
Post and Packing I2p, 

COMPLETE UNTESTED T.V, SETS. With back and all vatves , 
BBC I and ITV 17" 90° Tubes £110. 17" 110° Tube £2-20. I9t 
£3 30. Carr, and ins. on any set £1 -75. f 

Reclaimed T.V, Tubes. All with 12 Months Guarantee, AW43/8B h 
£1-45. MW43/69 £1 10, AW43/80, £145. Carr. and ins. on any 
tube £1 -75. 

i Cwt. of ex Government Scrap Resistors, Panels and Gears, etc. 
30p. Carr. 80p. 

SPEAKERS REMOVED FROM T.V. SETS, all 3 Ohm 2* Watts. 

7 x 4", 6 x 4", 8 x 2f . AH at 27p. Post and packing I2p. 

TOP QUALITY TAPE. Reel to Reel 5" ST. 44p 5" LP S5p. Si LP 

60p. 7" ST Up. 7" LP 80p. Cassette Types CM 3Sp. C90 45 p. 

CI 20 S5p, Post on any tape I2p. 

Jap Earpiece 8 Ohm Magnetic 3-5 I2p. 

Ex Equipment Vatves all tested on our Multard Valve Tester 

before despatch, 3 months guarantee on all valves. Single Valves 

Post 3p, over Post Free. 



ARPI2 

EB9I 

EF80 

E8F89 

ECC8I 

ECC82 

EF9I 

EYS6 

EFI83 

EFI84 



6p 
5p 

iop 

ISp 
I2 P 
12p 
5p 
22p 
20p 
20p 



PCF80 

PCCB4 

PCL82 

PCL83 

PCL84 

PL82 

PL63 

PL36 

PY8I 

PY80I 

PY800 



6p 
6p 
I4p 
"Sp 
ISp 
I Op 
lOp 
I7p 
I Op 
I7p 
I7p 



PY82 
PY33 
U)9I 

63V77 

6BW7 

6U4 

6F23 

20PI 

20 P3 

30F5 

30FLI 



lOp 
20p 
20p 
12p 
I2p 
lOp 
ISp 
I2p 
I2p 
20p 



ABOVE PRICES INCLUDE V.A.T. 



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305 



WEYRAD 

IMPORTANT ANNOUNCEMENT 

IT IS WITH GREAT REGRET THAT WE HAVE TO STATE THAT OWING TO 

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NOW CONVERT YOUR STEREO SYSTEM 



cs Catalogue 1973 



lill hi. -. hi * T ed ', ll °r ° f , Usk >' * famot " Audio-Tronics catalogue 
m!« ™ ■ '"» • T '* A r'- F REE on r ^ ue «- The 48 tabloid ful 
pages— many in full colour— have been reprinted with VAT price changes 
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Accessories. Send for your copy now and see for yourself that VAT can 
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imsi 



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Inclusion on our regular mailing list. 



NAME , 

ADDRESS, 



-I 



». I 

I 

.„ mmm PW14 I 

L. ^™'S* A f l °UMn_ED,3-1SCAyELL STREET, LONDON E.f. ' 

306 ' 



to 4 CHANNEL 



FOR 



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from all-around — NOT Jusl 
Irom two sides, 
Now yOU Cfln have ^channel 
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teak finished, size; 11- h, < *|- w. < 4" d. housing 
tuM.I, Speakers with a power handling of 7f waits 
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ible separately lor only CI 85 inc. pip. 



'<t. 



(Dgpt. PWI) 43, BARTHOLOMEW CLOSE. 
LONDON, EC1A THP. Tel: 01-SM 3211. 



LEARN RADIO 

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SEND FOR FREE 74 PAGE GUIDE TO RADIO/TY. 
ELECTRONICS, C A G, TELECOMMS ETC. 

Dept. BPWI8 Aldermwon Cgort, Reading RG7 4PF 
Name 




Aee ,CV I BPWIB I 



BRITISH INSTITUTE OF ENGINEERING TECHNOLOGY 



TRANNIES 

I DOCKYARD, STATION ROAD, OLD HARLOW, ESSEX 
Phone Harlow 37739 

P/P 10p. Price list S.A.E. (Saturday callers welcome) 
ALL PRICES INCLUDE VAT 



010,50 ELECTRONIC DIGITAL CLOCK 

ot# I *J (For complete kit of parts including case.) 




This 4 dixit 14 hour clock if available 
to readers at this special price. 
Parts would normally cost over £25, 
Kit of parts includes twelve IC's» 
indicators, and a smart white plastic 




8N74O0 
SN7401 
SN7402 

8 N 7403 
8N7404 
SN7405 

9 N 7406 
BN7407 
SN7408 
BN7409 
8N7410 
8N74U 
8N7412 
SN7413 
8N7416 
8N7417 
SN7420 
8X7422 



* Devices may 

* 100 Plus less 



8N7489 
SN749Q 
BK74S1 

8N7492 

SN7493 

8 N 7494 

8N7495 

SN7498 

8N7410Q 

BN74104 

BN74106 

SN74107 

8N74110 

SN7411I 

SN74118 

BN74119 

BN74121 

6 N 71 122 

to qualify for Price Breaks 
25 plus break 



1 25 

B 05p 6 S5p 

74p 72c 
11 Op 1-04P 

74p 72p 

74p 

86p 

85p 

bsp 



72p 
72p 
72p 
92p 



1-SOp 1-75B 

1-OSp 1-OBp 

1-09P 108p 

44p 42p 

Sip 59p 

l-37p l*B7p 

llOp 1-OSp 

l-47p l-87p 

44p Up 

i ■ Mb i ■ 48p 



Linear Integrated Circuits 



301 

301 

301 

301A 

301 A 

301A 

S07 

307 

307 

SOS 

MS a 

709c 

709c 



Ml, 
TOOT 

« ft n di l 

DIL 

T099 

8 PIN DIL 

DIL 

TOB9 

8 PIS DIL 

T099 

T099 

DIL 

T089 



60p I 

S5p 
48p 
BBp 
89p 
68p 
S9p 
69p 

esp 

5 45 p 

6 40p 
35p 
31p 



723c DIL 

723c TQ99 

741c 8 PIN DIL 

741c 14 PIN" DIL 

741c TOSS 

747c DIL 

748c DIL 

748c T099 

1437 DIL 

1458 T099 

3045 DIL 

7503 DIL 



Bto 

BSp 

3Bp 

39p 

Up 

4Bp 

39p 

41p 

1-27P 

l-27p 

84p 

l-B7o 




Electrolytic 
Capacitors 



4 VOLT 

47uF Hp 



IOOmF 
220jiF 
330mF 

iooo^f 

4700nF 



tip 
6ip 
6|p 
I3p 
29p 



4 3 VOLT 

33fiF *iP 



68^F 

ISO/jF 

470aiF 

680(iF 

ISOOfiF 

HQQ^F 

3300^ 



HP 
HP 
lip 
I3p 

lap 

I8p 
26> 



10 VOLT 

22**F eip 

47»iF 

IOOmF 

220nF 

330nF 

470jiF 

lOOOfiF 

ISOOfiF 

22CKVF 



6iP 

HP 

8p 

1 Op 
(Op 
Up 

2 Op 
24p 



16 VOLT 

IS^F 6ip 



33nF 

68fiF 

I50^F 

220 A F 

660/iF 

lOOOfiF 

ISOOfiF 

2000mF 



*4P 

*ip 
8p 
*P 

17p 
I7p 

2Sp 
43 P 



25 VOLT 
lO^F t>ip 



22^F 

47/iF 

lOO^F 

ISO^F 

220/if 

470,uF 

680ju.F 

iOOO^F 

2200nF 

SOOOjiF 



HP 
6ip 
8p 
8P 
I Op 
I3p 
20p 
22p 
3?P 
68p 



40 VOLT 
6-8WF HP 

I5^F *±p 

33mF HP 



40 VOLT 

47**F Hp 



lOOfxF 

ISO^F 

220^F 

470^F 

6S0»iF 

lOOOuF 

22CKVF 



9p 
I Op 
Up 

I9p 
25p 

25p 
44p 



BARGAIN 
PACKS 



A3 VOLT 


UF 


*ip 


2-2jiF 


HP 


4-7u-F 


6*p 


6-8*jF 


Hp 


IOjuF 


HP 


22mF 


Hp 


66VF 


lOp 


IOOmF 


1 lp 


I50fiF 


I3 P 


220nF 


I9p 


33Q(iF 


22p 


470fiF 


26p 


lOOO^F 


44 P 



Transistors 






AC107 lBp 

AC12S 14p 

AC127 18p 

AC 128 Hi j 

AC142K 22b 

AC141K 20 p 

AC170 16p 

AC187 13p 

AC187K 20p 

AC188 13p 

AC1KSK 20p 

ACY17 24p 

ACY18 Blp 

ACY19 B6p 

ACY20 28p 

ACY21 Mb 

AOY22 ISp 

ACY39 88 p 

A1U4II 40p 

AD142 44 p 

AD 143 80p 

AD149 SSp 

AD150 BOp 

AD1B1 £9p 

AD 162 89p 
AH 11/1' SOp 

AF114 Up 

AF11S 14p 

API 16 14p 

AF117 lip 

AF11S 8£p 

AF134 27p 

AF139 89p 

AF239 41p 

AL100 77p 

AL102 Sflp 

AL103 SSp 

ASY26 Sip 

ABY27 40b 

AU103 Mp 

Auiion-io 

AU1U 77p 

BC107 Sp 

BC108 Bp 

BC109 9p 

BC113 154P 

BCUB ISp 

BC12S lflp 

BC126 Up 

BC132 ISp 

BC1S4 Kp 

BC13S ISp 

BC137 ISp 



BC138 SSp 
BC142 83p 
BC143 SSp 
BC144 SOp 
BC145 26p 
BC147 Bn 
BC148 ftp 
BC149 Sp 
BC1H8 18p 
BC1S4 17p 
BC167 ISp 
1K.-158 12p 
BCHS9 14p 
BC1B7 ISp 
BC168 lip 
BC1B9 lip 
BC177 16p 
BC179 lBp 
BC182L 8p 
BC183L Bp 
BC1S4L Sp 
BC188 SSp 
BC212L lip 
BC213L Up 
BC214L lip 
BC2S8 Bp 
BC239 fip 
BC267 14p 
BC268 15p 
BC300 4 Op 
BC301 32p 
BC302 SOp 
BC303 SOp 
BC304 40p 
BCY70 17p 
BCY71 37p 
BCY72 17p 
BD123 86p 
BD130 SOp 
BD131 SSp 
BD132 BOp 
BD13B 4£p 
RD136 SOp 
BD141 £1-87 
BD142 SOp 
BF159 SSp 
BF173 B»P 
BF177 SSp 
BF178 B9p 
BF17B SSp 
BF194 lBp 
BF19S 17p 
BF244 87p 



BF260 BBp 
BP32B 180 
BF330 18b 
BF390 87p 
BFX84 E8p 
BFX85 SSp 
BFX86 E2p 
BFX87 28pi 
BFX88 26p 
BFY50 Elp 
BFY61 17p 
BFYS2 17p 
BFY64 SSp 
BFY90 72p 
BSX20 19p 
C407 B8p 
C42B SSp 
C428 Sip 
C450 17p 
MP8111 SSp 
MPS 112 4Bp 
HP8113 SSp 
MP8121 SSp 
UFS122 44p 
MP8133 SOp 
NKT211 BSp 
NKT212 BSp 
NKT214 BSp 
NKT217 SSp 
NKT261 £3p 
NKT271B0P 
NKT274 BOp 
NKT275 B6p 
NKT403 71p 
KKT405 88p 
NKY603F 

SSp 
NKT6I3G 

SSp 
SKT67428p 
NKT677G 

£4p 
NKT713 3Bp 
NKT77387P 
OC19 S5p 



OC44 
OC45 
OC70 
OC71 
OC72 
OC81 
OC83 
OC84 



1*P 

Up 

14p 
14p 
14p 
BBp 
BSp 



OC20 
0C23 

ocas 

OC38 
OC29 
OC35 
OC38 
OC41 



55? 
S6- 
SSp 
S3; 
3f" 
SSp 
38p 
Up 



TIP29A 68p 
TIF30A 84p 
TIF31A S4p 
TIF32,A 73p 
TIP33 £l-BS 
TIP34A 

£154 
TIF 35 A 

fBSS 
TIP3BA 

ISIS 
TIP41A 7Bp 
TIP42A Blp 
2N706 18p 
2N930 BSp 
2S1131 BBp 
2N1132 BSp 
2N1913 BBp 
2N1711 BSp 
2N2904 lOp 
2N2904A 

44p 
2N3905 46p 
2N2S24 ISp 
2N2926 lOp 
2S3053 BSp 
2N30S4 SSp 
2N3055 52p 
2S3485 tip 
2N3663 57p 
2N3702 SB 
2N3703 
■JN;i704 
2N3705 
2N3706 
2N3707 
2N3708 
2N3709 
2 N 37 10 
2N3711 
2N3794 17p 
2N3S19 BSp 
40381 SOp 
40362 SOp 
40636 SOp 



Diodes 


& 


R«tifi«r» 


1X914 


Sp 


1N91S 


to 


1N4148 


s fl 


1844 


Ml 


1N4007 


asiT> 


18113 


17p 


18120 


17p 


IS 121 


ISp 


1S130 


to 


1S131 


lip 


18132 


I3 r 


IS 920 


Kp 


1B922 


Sp 


18923 


13p 


13940 


8p 


AA119 


lid 


AA129 


Up 


AA213 


lip 


AAZ15 


Up 


AAZ17 


Up 


BA100 


Ititl 


BA102 


25u 


BA115 


»v 


BA144 


14b 


BA14S 


22? 


BA154 


Up 


BAX13 


14 5 


BAX16 


Up 


BAY18 


19p 


BAY31 


M 


BY! 00 


lfcp 


BY128 


Uj 


BY127 


19? 


BYX10 


24p 


OA5 


19 F 


OAS 


Up 


OA10 


24? 


OA47 


9P 


OA70 


8p 


OA73 


lip 


OA79 


Sp 


OAS1 


9p 


OA8S 


Up 


OA90 


Sp 


OA91 


Bj 


OA9S 


Sp 


OA200 


Ul 



MULLARD POLYESTER'S 



mullARD POLYESTER CAPACITORS C280 SERIES 

01SjjF.0-22^F. Stp. 033^F,7p.0'47nF, 9)p.08SMt.lBB-10^F.14p.l5tit.Kgp.-^r,«/P 

mullARD POLYESTER CAPACITORS C296 SERIES 

*m"- 001 uF frOOI MB t Too'" F. O'OOSSmF. 0-OO47)J, S|p. 006*^F, 0-01uF. O-OlBfA 

lflOV °0 4 OiSf"'6i5uF, 0Sa«F, O-OSS^F, 0.047^F. 0068MF SB. 0-l^F Sip. 0-lBjJ? , iip. 
22kF, Hi. 6.3811 Ah». »iW. 8tB- 0-SBU. IBB- l-OttP. Ufa- . 



VOLUME CONTROLS 

Potentiometer* _ _ 

Carbon track 800 CI to 2-211 Q 

Log or Linear 

Single 13b- Dual K»nK (otereo) «p 

Sliifle type with D.P. switch 1 3B eitra. 



RECTIFIERS 

P.I.V. 1 AMP 



SLIDE POTENTIOMETERS 

58mm, TRACK 

BINOLE GANGED, LOG or LIN Ik to 1M. 

TWIN°GANGED, LOO or LIN lie to 500k. 
08p each. 



SD 

1 00 

-(Xi 
400 
fiOO 
800 
1000 



CARBON SKELETON PRESETS 

Small high quality type (linear only). 

All Talves 100-6 meg ohma. 

• 1 wi SiP each 

-2-5 watt Otpeach 



VEROBOARO 

2+1 n x 31 In 
Sim x Sin 
3} in x 31 Id 
3}in x Bui. 
51n x 17fn (plain) 



18 

Matrli 

lOp 

2Sp 

BSp 

SSp 

B4p 



0*1 

Matrlr 

26p 

BSp 

2SP 

SSp 



Vera Pln» (bae of 38), 22p 

Vero cotter, SOp; Flu insertion Tools (0-1 and 

15 matrix) at flip. 



SLIDE SWITCH 

8PS.T 11b each. D.P.D.T. I3p each. 



MINIATURE NEON LAMPS 

240V or 110V 1-4 Sp. 5 plus itp each. 



MIN1TRON DIGITAL 
INDICATOR TYPE 30I5F 

Reads 0-9 and decimals 
(Data Sheet on request) 
ONLY £1 50 

16 DIL Socket 8Sp 

Driven by 7447 fl'05 



IN4001 4iP 
IN 4002 4tp 
1N4003 5JB 
IN 4004 SiP 
IN40O5 8p 
IN4008 Bp 
IN 4 007 lOp 



1-5 AMP 

PL4001 Sp 
PL4002 Bp 
PL4D03 lOp 
PL4004 10b 
PL4005 13b 
PL4006 16 b 
PL4007 BOp 



BRIDGE RECTIFIERS 

P.I.V, 1 AMP 2 AMP 5 AMP 10 AMP 

*1-76B £B-20b 



33b 
SSb 
37b 

40p 

44p 
49p 



53p 

57p 

eop 

64p 
BSp 



fl-BSp 
*215B 
£2-42p 



£2-31p' 
£2 42p 
£275p 



THYRISTORS 

prv so loo 

1 Amp 2 S 25 
3 Amps 4* SO 
7 Ampa — B6 



300 
44 



RESISTORS 

i watt 5% carbon lp each 
i watt 10% carbon lp each 
1 watt 10% carbon BiB each 
Range 10 ohms to 4-7 meg. 
j watt m/o 2 % 3b each 
Range 10-1 meg ohms 



Unmarked 
Packs 

Pack or 26 

IN-1148 

SSp 



Pack a 1 10 

BC108 SSp 

BC107 SSp 

(i'laitlc can) 



Pack ol 10 

Plastic BC109 

SSp 



Pack or 10 

BC189 SSB 

(unmarked) 
but teated 



smut 

(unmarked) 
33 p each 



Pack ol 10 

•N2926G SSp 

unbranded hut 

tented 



Unmarked but fully 

teated 

2N3055 

1-9 SSp 

10 plus 27p 



FULLY 

MARKED 
TYPES 

ADiai. ADiaa 

M/P 
1-9 SOp 

10 plus SSp 



BC107-BC108 
BC109 



10-99 
100 plus 


8p 

8iP 


BC 182L 
1-9 
10 plus 


■3-4-212-4 
BP 
Sp 


AC127 or AC128 
1-9 13b 
10 plus 12b 
100 plua Up 



ZENER 

DIODES 

400 M/W S%" 
Miniature 
BZY 88 Range 

All voltages 

S-3-38 Volt 

flp each 



All voltages 
6-8-200 Volts 
14p each 



All Voltagea 
7-5-100 Volts 
Sip each 



307 



discount warehouses 



Rec. Retail 

Price 

STEREO AMPLIFIERS £ p 

AKAI AA520O 87-45 

AKA1 AA5500 109-45 

AKAI AA58O0 164-45 

AKAI SSI Quadraphonic Decoder 54-45 

ALBA UA 700 41-72 

AMSTRAD BOOO MK, II 30-75 

AMSTRAD IC 2000 50 68 

AMSTRAD Integra 4000 39-05 

FERRQGRAPH F307 Mk, II (cased) 74 80 
GLJXOR MW3000, 19 watts RMS 

per channel 54 45 

GOODWIN RH 25 25 65 95 

JVC Nlvlco VN 300 69-85 

VN 700 SEA 140-25 

VN900SEA 169-40 

MCA 1042 93-50 

4DD5 Demodulator lor CD4 67-10 

MCA V5E/VN550 Quadraphonic 104-50 

MCA V9E/VN880 Quadraphonic 170 50 136-95 

VN 990 Quadraphonic 236 50 189-95 

KELETRON KSA 700 Mk. II 34 -10 

KELETRON KSA 1500 Mk. II 45 10 

LEAK Delta 30 (cased) 76 89 

LEAK Delta 70 (cased) 94-49 

METROSOUND ST20 Mk. II 4620 

METROSOUND ST40 59-40 

METROSOUND ST60 7700 

PHILIPS RH 520 8500 

RH 521 119-90 

PIONEER SA500A 55-96 

SA600 113-43 

SAS0O 150 34 

SA1000 185 12 

SA6200 1(4-40 

SA7100 , 144-10 

SA8100 20240 139-95 

SA9100 248 60 17195 

QL600A Quadraphonic 

Converter 141-32 

OD210 Quadraphonic 

decoder 50 91 

QAS00A Quadraphonic 249 92 172 95 
OC8 00 A Pre- amp Quad- 
raphonic 178 31 122 95 

QMSOOA Pow. amp. 

Quadraphonic 2)2 14 

Reverberalion 202w 65-25 

RANK ROTEL 310 57-20 

RANK ROTEL 610 86-35 

RANK ROTEL RA 610 11605 

RANK ROTEL RA 1210 141-90 

ROGERS Ravensbrook Mk. Ill 

(cased) 63 25 

ROGERS Ravenabou/ne 77-00 

Ravensbourne (cased) B2 50 

SINCLAIR 2000 38-50 



■4 15 

80 95 
121 95 
42 !)b 
27 95 
16 SO 
IB 25 
23 95 
49 95 

25 95 
49 95 

55 95 
112 95 
135 95 
74 95 
52 95 
83-95 



21-95 
29-50 
50-95 
63 20 
32 95 
42 95 
50-95 
66 95 
49 95 
38 95 
73 95 
103 95 
121 95 
79 95 
99-95 



96 95 
33 95 



146 95 
44 95 
37 B 5 
56 75 
71-95 
96 50 



3000 



49 50 



49 95 
59 50 
64 95 
26 95 
34 95 



SOLARVOX 20. 10 watts RMS per 

channel 4395 26 95 

SOLARVOX 30. 15 watts RMS per 

Channel 5165 35 95 

SOLARVOX MA801 2 i 8 waits 

RMS plus MATRIX 4 channel .. 42-30 29 75 
SOLARVOX MA613 2 x 18 watts 

RMS plus MATRIX 4 channel .. 56-52 

TANDBERG TA300 (Teak) 86-32 

TANDBERG TA300M (Teak) 96-24 

WHARFEOALE Linton amplifier .. 71-50 
All take both ceramic and magnetic cartridges 
TUNERS 

AKAI AT550 AM/FM/MPX/FET. . . . 84-10 

AT580 AM/FM^MPX/MOS FET . . 131 -09 

AMSTRAD Multiplex 3000 FM .... 37-90 

JVC Nlvlco MCT V5E/FT500 AM/FM 82-50 

VT700 , 126-50 

MCT V7E AM/FM .... 115-25 

LEAK Delta FM 74-43 

Delta AM/FM 83-79 

METROSOUND FMS 20 MKk II.... 54 45 

FMS 40 58-10 

PHILIPS RH 690 45 66 

RH 621 10306 

PIONEER TX 500 A AM/FM 79-72 

TXG00 AM/FM 110-39 

TX6200 94 63 

TX7100 111-10 

TX8100 150-70 

TX9100 204-60 

RANK ROTEL 320 , 55 91 

620 67-86 

ROGERS Ravensbourne Series II 

(cased) 61-05 47 50 

Ravensbrook Series It 

(cased) 46 75 

SINCLAIR2000 42-44 

3000 42-44 

All the above Tuners are complete with MPX Stereo 

Decoder 
TUNER/AMPLIFIERS 

AKAI AA8030 130 54 

AKAI AA6080 176-07 

AKAI AS8100S Quadraphonic... 243-85 

AKAI 6300 129-21 

AUTOMATIC RADIO CHX 9912 
AM/FM: MPX stereo tuner/ampli- 
fler with built-in stereo cassette 

recorder 107 25 49 95 



42 95 
67 95 
79 95 
51 95 



64 95 

102 95 
23 95 

65 95 
101 SO 

94 95 
52 95 
62 25 

39 95 

40 52 
33 SO 
78 80 
54-95 

75 95 
65 50 

76 95 
103-95 
139 95 

36 20 
59-95 



36 95 
26 95 
28 95 



99 95 

128 50 
1S9 95 
69 95 




All prices quoted In this 
advertisement Include VAT 



Rec. Retail Comet 

Price Price 

TUNER 'AMPLIFIERS— cortt Inued £ p £ p 

GOODMANS Module 80, 3Sw. RMS 87-55 60-25 

Module 80 Compact 158-16 112 50 

Module 90 112-04 7S-7S 

Module 110 FM/MW/LW/SW/ 

lOOw. RMS 130-86 68 50 

GOODMANS Module 110. Compact 230-65 169 95 

JVC Nlvlco 4MM 1000 Quadraphonic 161-15 128 95 
4VR 1006 Quadraphonic with 

CD4 demodulator 229-35 113 M 

VR 5501 AM'FM 108-35 85-95 

VR 5521 L AM/FM and SEA .... 172-70 138-95 

4VR 5414 Quadraphonic SEA.... 229-35 163-50 

4VR 5445 Quadraphonic SEA 30800 246-56 

KYOTO 1000 AM/FM Tuner/ Ampli- 
fier with built in Stereo Cassette 
Recorder. Complete with two 

speakers and two microphones 79-90 57 95 

LEAK Delta 75 AM/FM MPX 163-83 112-85 

PHILIPS RH 702 ,, 90-38 87-95 

PHILIPS RH 720 , 202-41 152-95 

PIONEER SX 424 AM/FMjMPX 116-70 78-50 

PIONEER SX52S AM/FM/MPX .... 148-36 10195 

PIONEER SX626 AM/FM'MPX .... 203-21 13895 

PIONEER SX727 AM/FM/MPX .... 244-53 188-95 

PIONEER SX828 AM/FM/MPX .... 313-74 216-95 
PIONEER QX 4000 Ouadraphonic 

AM/FM/MPX 238-50 164 95 

PIONEER QX 8OQ0A Quadraphonic 

AM/FMIMPX 339-23 233 95 

PIONEER OX 9900 Ouadraphonic 

AM/FM/MPX 473-26 327-50 

ROTEL RX 150A 65-68 45-95 

ROTEL RX2O0A 84-10 60 95 

ROTEL RX 40OA 10101 69-95 

ROTEL RX 600 A 14001 68 95 

ROTEL RX 800A 17807 126-25 

ROTEL RX 154A Quadraphonic .. 121 68 18-95 
SOLARVOX TAM 1105 2 x 5 watts 
RMS AM/FM Multiple! camp. 
with 2 speakers and leaturlno 

Matrix 4 channel 3706 29 75 

TANDBERG TR200 MPX (Teak) .. 112-20 93-95 

TANDBERG TR1000FM MPX (Teak) 163-71 138 95 
TANDBERG TR1010 AM/FM MPX 

(Teak) 177-33 146-95 

TELETON CR55 116-63 64 95 

WHARFEDALE LINTON WE40 

AM/FM MPX 107-66 79-95 

All the above lake magnetic cartridges except 
Kyoto (000 and Automatic Radio CHX 9S12 which 
take ceramic only. All Include MPX Stereo Decoder. 

TURNTABLES 

CONNOISSEUR BD1 Kit Chassis 12-65 10 59 

CONNOISSEUR 6D2 Chassis .... 31-02 24 95 

CONNOISSEUR BD2 P/C/SAU2 .. 39-16 32-25 

GARRARD SP25 Mk. Ill Chassis .. 15-25 80S 

GARRARD 40B Chassis. 12-85 9-50 

GARRARD SL65B Chassis 18-78 12-95 

GARRARD SL95B Chassis 46-40 30 60 

GARRARD 401 Chassis 40-43 25-95 

GARRARD SL72B Chassis 30-73 20 25 

GARRARD AP76 Chassis , 26-82 16-95 

GARRARD Zero tOOA Chassis,... 51-57 33-25 

GARRARD Zero 100S Chassis ., 47-44 30-70 

GOLDRING G101P/C 31-35 21-50 

GOLDRING GL72 Chassis 34-65 23 95 

GOLDRING GL72P , 45-87 31-50 



The following Turntables are complete with 
base, plinth, cover and cartridge. Fully 
wired and ready for use. 

Mcdonald mpso with 

G800 Sp. Price 15-95 

Mcdonald ht?o with 

G800 Sp. Price 20-95 

GARRARD 2025 TC with 

Sonotone9TAHC ceramic Sp. Price 12-10 
GARRARD SP25Mk.UI 

with GSM . . Sp. Price 15 95 

GARRARD AP76 with GBOO Sp. Price 25 95 
GOLDRING GL72 with G800E Sp. Price 33 95 
GOLDRING GL75 with G800E Sp. Price 41-95 
GOODMANS TD100 with 

G800E cartridge 77-29 52 95 

JVC Nivico SRP 473 with Nivica 

magnetic cartridge 71-50 5695 

LEAK Delta deck with 

Shure Cartridge 65-07 49 95 

PHILIPS GA407 with GP400 

mag. Cartridge 45-00 34-95 

PHILIPS GA212 Electronic 

with GP400 cartridge .... 64 95 59 95 
PIONEER PLAJSwIth PC50 Mag- 
netic Cart 100-62 69-95 

THORENS 160, C with Ortofon 

M15E Super cartridge .... 9900 78-95 
THORENS TD125 AB Mk. II with 

Ortofon M15E Super Cart, 154-00 122-50 
WHARFEDALE Linton with 

Shure Cartridge 35-11 25-95 



Rec. Retail 

Price 

TURNTABLES— continued £ p 

GOLDRING GL75 Chassis 43-89 

GOLDRING GL75P 56 76 

GOLDRING GL7S Chassis with 

auto slop 53-46 

GOLDRING GL76P/Cover with 

auto Stop 76 89 

GOLDRING GL85P/Cover with Auto 

stop 98-34 

McDONALD MP60 Chassis 13-96 

McDONALD 610 Chassis 17-71 

McDONALD HT70 Chassis 19-49 

McDONALD 710 Crassis 33-44 

McDONALD 810 Crassls 41-80 

PIONEER PL12D with base and cover 51-90 

PIONEER PL61 with base and cover 180-33 

THORENS TD1 25 Mk. I! Chassis ,. 83-60 

THORENS T0125AB 109 04 

THORENS TD 125AB Mk. II with 

TP 16 arm 126 50 

THORENS TO 165/C Including base 

and cover . , 60 50 

THORENS TD 180/c including base 

and cover 71-50 

SPE AKERS 

AMSTRAD ACOUSTA 1500 (Pair) 44 00 

ACOUSTA 2500 (Pair) 55 00 

138 (pair) Teak 28-60 

B and W Model 70 175-45 

8 and W DM2 65-89 

8 and W DM4 46-75 

B and W D5 (pair) 55-99 

CELESTION HADLEIGH (pairj 43 34 

COUNTY (pair) 48-44 

Dltton 15 36-95 

Dillon 25 , 71-50 

Dltton 44 59-40 

Dltton 66 108-90 

FERROGRAPH S1 lie. stand ,... 104-50 

GOODMANS Minister (pair) 46-33 

Havant (pair) 53-77 

Maglster 72-19 

Double Maxim (pair) 63-4S 

Mezzo 3 39-27 

Magnum K2 50-82 

Goodwood 60-50 

Dimensions 78-68 

PLANAX 2 Teak or White ...... 46-20 

DIN 20 NT Kit (pair) 22-95 

KELETRON KS4 (pair) 22-66 

KS6 (pair) 28-16 

KS8 (pair) 36-30 

KS10 (pair) 4686 

KS15 (pair) 6985 

KS20 (pair) 78-76 

LEAK 150 (pair) 46-82 

LEAK 250 (pair) 60-86 

LEAK 600 54-45 

MARSDEN HALL 

NH110<Palr) 35-20 

NH150(Palr) 42-90 

NH200 (Pair) 53-90 

NH300 (Pair) 9900 

METROSOUND HFS 103 (pair).... 27-50 

202 23-65 

Duplex IS 35-20 

Duplex 25 61-60 

PIONEER CS53 56-52 

ROGERS Ravensbourne Compact 

(pair) 61-60 

SINCLAIR 016 8-47 

SOLARVOX TK19S twin speaker 

20 watts Teak (pair) 40-85 

TANDBERG TL 12 Teak (pair).... 55-80 

TL 25 Teak (pair) , 75-16 

TL 50 Teak 79-70 

THORPE GRENVILLE TG100 (pair) 31-85 

TG200 (pair) 46-15 

TG300 (pair) 81-55 

WHARFEDALE Denton Mark II 

(pair) 39-33 

Linton Mark II (pair) 48-69 

Triton III (pair) 60-65 

Melton Mark II 38-50 

Oovedale 3 Mark II 52-25 

Unit 3 speaker kit (pair) 23-40 

Unit 4 speaker kit (pair) 41-80 

Unit 5 speaker kit (pair) 60 50 

CHASSIS SPEAKERS 

GOODMANS Twin-Axiom 8 ,.., 8-58 

Twin Axiom 10 9 47 

Axiom 401 19-45 

Audlom 8P 5-17 

Audlom 10P 5 62 

Audlom 12P., 14-30 

Audlom 15P 23-10 

Audlom 18P 39-27 

Audlom 100 40 watts din 13 20 

ARU 172 ".. 4-95 

Axent 100 7-59 

Mldax 650 14-95 

Attenuator 4-10 

Crossover network XO/950 8 55 

WHARFEDALEBin. Bronze/RS/DO 444 

Super 8/RS/DD 7-95 

Super 10/RS/OD (3-11 



29-95 
38-95 



52-95 

65-95 
8 40 
11-50 
12 SO 
21 50 
27 50 
35-95 
124-95 
66-50 
72 SO 

99 95 

48 50 

56-95 



27 95 
31-95 

13-95 
125-95 
46-95 
35-95 

41 95 
30-95 
34-95 
26-50 
51 SO 
40 50 
78 '75 
74 SO 
31-75 
34 95 
42-20 

42 25 
25 60 
32-40 
39 SO 
51 50 
32-95 
16 50 
13-95 
17-50 
22-75 
29-95 
43-50 
49-25 
35-95 
46 50 
38-50 

23 95 

28-95 
35-95 
64 95 
19-25 
16-95 
26-95 
42 95 
38-95 

49-95 
6 20 

29-95 
45-95 

60 95 

61 95 
19 50 
29 50 
34 50 

27-95 
33 95 
41-95 
26 95 

35-95 
16 50 

29-25 
42-50 



6 25 
6 90 
13 95 
3-75 
410 
10-40 
16-50 
27-95 
9 SO 
3-60 
5-40 
9 50 

2 95 
5 95 

3 20 
5 75 
9-15 



308 



OVER 1000 ITEMS ALWAYS IN STOCK 

All items brand new and fully Guaranteed 
and backed by after-sales service 

— latest models in manufacturers' scaled cartoni 



39 » 
4 75 
2<*5 

4 » 

5 90 



flee. Retail Comet 

Price Prtc* 

CARTRIDGES * P *J 

ADC IDE Mil. IV S P-/^ Ce 1*2 

AUDIO TECHNICA AT 66 598 3 30 

AUDIO TECHNICA UM35F lor CD4 53-36 

•CONNOISSEUR SCU1 ■ ■ 5-7B 

GOLDRING G850 „ 5-78 

GOLDRING G800 Boxed Sp. Price 

GOLDRING G800E Bo«ed ....... -Sp. Price 

GOLDRING 6800 Super E. Boxed Sp. Price 10 95 

GOLDRING G820 JJ'tS 

GOLDRING G820E 16 50 

GOLDRING G820 Super E - 2200 

EMPIRE 1000ZE/X 58-87 

EMPIRE 999VE/X 42- 05 

EMPIRE 999TE/X - 24-73 

EMPIRE 999SE/X 19-98 

EMPIRE 999E/X 15-48 

EMPIRE 909E/X 12-10 



9 41 

5-81 
7-91 
7-52 
7-52 
8-18 
9 24 
1400 
8-18 



11-40 
15-20 

37 95 
16 95 
IS 25 
II 70 
9 95 
7 95 

6 20 

3 SO 

4 40 
4 25 
4 25 

4 SO 

5 25 

7 90 
4 9S 
7-34 
■ 30 

10 25 



EMPIRE 90EE/X 
SHU RE M3D ... 
SHURE M44-G... 
SHURE M44-7 ... 
SHURE M-44C... 
SHURE M44E . . . 
SHURE M55E ... 
SHURE M75G ... 
SHURE M75-6(S) ..- 

SHURE M758 2'95 

SHURE M75EJ 1 *66 

SHURE M75ED ls _ 1 p , 

SHURE M75E/95G Sp ;„ P , r i ce '£'!! 

SHURE M91ED «'« 9" 

SHURE V15-11 37-52 SJS 

SHURE V15-Mk. Ill 3900 " « 

•SONOTQNE 9TAHC Dlsm/Saph 3-58 1-M 

Starred cartridges above are ceramic— al! others 
are magnetic. 
■ ASES AND COVERS 

CONNOISSEUR Plinth BD1 5-28 430 

CONNOISSEUR Cover 3-9| •■» 

CONNOISSEUR P.U. Mount Board 0-88 1-70 

GARRARD WB1 Base 3-56 2-70 

GARRARD WB4 Base 5-28 3 80 

GARRARD SPC1 Cover 3-47 2 SO 

GARRARD SPC4 Cover 4-13 3 00 

Special Offer of Base and Cover to 
fit GARRARD SP2S. St-55, SL6SB 

and 3500 ■■ Sp 

Special offer of base and cover to 

fit Mcdonald mpbo and 6io . , Sp. 

GOLDRING Plinth 75 12-8? 

GOLDRING Plinth 72 11-22 




Price 2 50 

Price 3 50 
8 SI 

7 80 

GOLDRING Covers tor 72P 462 S 20 

Cover for 75P De luie 5-28 3-84 

Covsrtor78P \'9 Hj 

Covr for 85P - 726 so ° 

McDONALD Plinth for 710/810 .... 9-35 6-50 

McDONALD Cover for 71 0/810.... 4-40 2-95 

THORENS TX 25 (for TD125AB).. 8-25 9 40 

THORENS TX11 Cover 4-18 3-4* 

SME Plinth System 2000 with motor- 

hoard 43 '5f 3* « 

MOTORBOARDS Only 5-51 4 M 

SME P1 Spacer 092 8-79 

HEADPHONES 

AKG K180. 30-80 18-50 

AK6 K60 15-50 • 75 

AKG 100 8 80 5 40 

AMSTRAD HPSSA 8-25 3 95 

HPS6A with volume control 11-77 6-95 

KOSS HV1 2200 16 9S 

KOSS ESP-9 Electrostatic 75-90 58 25 

KOSS ESP-6 Electrostatic 49-50 38-50 

KOSS K2 plus 2 Quadrafone 49-50 38 95 

KOSS PRO 5 L/C 3300 28-50 

KOSS PRO-4AA 30-80 22-95 

KOSS KO-727B . 18 15 13-75 

KOSS 747 2200 M 58 

KOSS K-711 11-00 7-95 

KOSS K6 13-75 19-25 

KOSS K6/LC (with volume control) 15-40 11 -58 

KOSS K6/LCQ Quadrafone 2200 11-50 

PIONEER SE 50 26 02 17 95 



flee. Retail Comet 

Price Price 

HEADPHONES-ewiHnued «J * P 

PIONEER SE 30A 1502 1025 

PIONEER SE20A 937 6 40 

PIONEER SEL 20 1252 850 

PIONEER SEL 40 2071 14-25 

SOUND MD806 7-15 111 

WHARFEDALE DD1 tt-JJ 9 75 

WHARFEDALE Isodynamlc 21-95 1650 

HI-FI STEREO SYSTEMS-COMPLETE 

ALBA 832 37-87 

BUSH A1005 66-25 

BUSH 1008 with radio 89-06 

DANSETTE4010 58-25 

OANSETTE 4005 87-73 

OANSETTE 4020 45-50 

DECCA SOUND 613 63-95 

DECCA COMPACT 2 with radio 98-03 

DECCA COMPACTS with radio.. 12709 

DECCA 403 54-45 

FERGUSON 3450 B with Radio 

(new Model! 75-40 

FERGUSON 3451 B with Radio 

(new ModelJ 101-5O 

FERGUSON 3454 39-36 

FIDELITY UA1 Music Master with 

Radio *§*£ 

FIDELITY UA2 Music Master .... 41-23 

FIDELITY UA3 Incl. stereo radio,. 59-73 

FIDELITY Stereo Nina Sp. Price 22-95 

6 EC 2810 74 89 56 95 

GROSVENOR MPX 8400 AM/FM/ 

MPX Tuner/Amplifier, magnetic 

Input, built-in S-track cartridge 

player with speakers 65 75 

HMV2451 115-70 

HMV 2452 62-57 

HMV 2455 16590 

I.T.T. KB1025 with 662 speakers . . 45-65 
I.T.T. KB2250 with 659 speaker* and 

.radio 13683 

MURPHY 920 45 50 

MURPHY940 66-25 

PHILIPS 808 99-53 

PHILIPS 825 46-92 

PHILIPS 826 ■ 71-09 

PHILIPS 835 with radio . , . 65-83 

PHILIPS 836 with radio 9005 

ULTRA 6027 54-55 

ULTRA 6028 56-85 

ULTRA 6450 B (new model) with 

radio 75-40 

ULTRA 6451 75-40 

ULTRA 6454 36-80 

ULTRA 6455 39-20 

TAPE RECORDERS 

AKAI 1721L 93 87 

AKAl 4000 DS 9350 

AKAI X201D 158-30 

AKAI X1810.. 215-18 

AKAI GX221D S 5 ' 18 

AKAI GX1900D 224-57 

AKAI GX370D. 323-95 

AKAI CR80D8-track stereo taoe deck 79-90 

AKAI CRB9 8-track stereo recorder 117-02 

AKAI CR30DSS Quadraphonic .. 149-88 
AKAI CR30T8-track stereo recorder 

and tuner amplifier 

AKAI CRBTT 8-track cartridge 

stereo recorder and tuner/ 

amplifier — 145-65 

AKAI CR81 102-89 

AKAI CR81D • 84-10 

FERGUSON 325B 4-track 68-85 

FERROGRAPH 702/704 Dolby .... 267-30 

FERROGRAPH 702H Oolby 278-30 235 95 

FERROGRAPH 722/724 Dolby .... 303-80 258 95 

FERROGRAPH 722H Oolby ■ 316-80 28895 



27-95 
47 95 
64-95 
39 95 
44 95 
29 95 
47 95 
72-95 
99 95 
42 95 

55 50 

79-95 
28 50 

67 95 
27 95 
41-91 



33 95 
19 95 

43 95 
119 00 
35 95 

105-95 
35 95 
47 95 
71 95 
33-50 
45 95 
41 59 
62 95 
39 50 
41 SO 

5! 95 

54 95 

25 95 

29 95 

66 95 

(8 15 
123-95 
159 95 
159 95 
166 95 
244 95 
S3 95 
66 95 
103 00 



69-76 



18 50 

36-85 

38 95 
43 95 
72 95 

53 85 
94 95 
99 85 
35 85 
99 95 
137 95 

114-95 

114 95 
153 95 



13 50 



140-78 84 95 



102 00 
71 95 
58 95 
45 50 

225 95 



flee. Retail Comet 
Price Price 
TAPE RECORDERS— continued £ P £ p 

FERROGRAPH 702/704 220 00 167 95 

FERROGRAPH 722/724 258-50 194 95 

FIDELITY Braemar 4-track 32-64 

GROSVENOR 900 8-track record, 

play-bach deck — 51-15 

GRUNDIG TK 121 (twin-track) .. 53-95 

GRUNDIG TK 141 (4-track) 58-47 

GRUNDIG TK 147 (4-track auto) .. 92 87 
GRUNDIG TK 148 (4-track auto 

2 speed) 

GRUNDIG TK 246 4-track stereo deck 126-78 
GRUNDIG TK 3200 HI-FI (Battery) 135-15 
MARCONI 4248 4-track, 2 speed.. 49-66 
PHILIPS 4416 4-track stereo recorder 137 45 

PHILIPS 4418 4-track stereo 189-59 

TANDBERG 3321 X 2 track stereo 

deck (Teak) 137-38 

TANDBERG 3341X 4-track stereo 

deck 137-38 

TANDBERG 5041 X 4-track stereo.. 187-62 
TANDBERG 9021 X 2-track stereo 

deck 236-00 198-95 

TANDBERG 9041X 4-track stereo 

deck 236-00 191 91 

THORPE GRENVILLETD145 8-track 

player deck 20-28 

TAPE RECORDERS (CASSETTE) 

AKAI CS35D tape deck 75-13 

AKAI CS35 Stereo incl. Speakers 105-71 

AKAI 6XC 40D tape deck 89-74 

AKAI GXC 40. 106-71 

AKAI GXC 40T recorder, tuner/ 

amplifier -•-■ 157 40 

AKAI GXC 45D tape deck 112-28 

AKAI GXC 46 Dolby taoe recorder 143-30 
AKAI GXC 46D Dolby tape deck. . 131 09 
AKAI GXC 65D Dolby auto-reverse 

deck . 145-18 

BUSH ARENA C440 58-11 

BUSH Discassette DC70 19-55 

BUSH TP 66 Battery/Mains 26 70 

BUSH RTP 100 Radio/Cassette 

Recorder 41-66 

DECCA2000 27-29 

FERGUSON 3253 (mains) 41-15 

FERGUSON 3256 (mains) 36-61 

FERGUSON 3257 53-45 

FERGUSON 3257/7 speakers for 

above 15 20 

GEC CR200 AM/FM Cassette/Radio, 

Battery/Mains with slide controls Sp. Pricp. 34-95 
GRUNDIG C210 Battery/Mains. . . . 4600 32-95 

GRUNDIG C250 60-65 46-95 

HANlMEX 3030 cassette batt/malns 

with AM/FM radio 43-65 19-95 

HARVARD Elite Cassette/AM/FM 

Radio (battery /mains) So. Price 22 95 

I.T.T. KB SL53 3100 23-95 

I.T.T. KB SL75 with VHF/LW/MW 

radio 48-95 

I.T.T. KB Studio 60 38-95 

JVC Nlvlco 9420 LS with AM/FM 

radio, battery/mains 57-84 

JVC Nlvlco 1710 Radio/Cassette, 

AM/FM Sp. Price 37S5 

PHILIPS RR 322 AM.'FM Radio/ 

Cassette Recorder Batt/Ma Ins .. 43-36 

PHILIPS 2202(2203 22 59 

PHILIPS 2204 battery/mains 2B-25 

PHILIPS 2211, with built-in micro- 
phone 27-30 

PHILIPS 2405 Stereo with 2 RH40IL/S 67-78 

PHILIPS 3302 20 24 

PYE 9116 Stereo 65-aO 

PYE 8140 -• 20-24 

WHARFEDALE Dolby DC9 Mk. II 111-41 



48 95 
77-95 
67 95 
73 95 


109 00 
S3 95 
98-95 
91 15 


101 95 
46-95 

1195 
18 95 


29 58 
21 50 
26 95 
23 95 

37 95 



10 95 



39 58 
30 75 



39 95 



32 95 
IS 95 
20 95 

20-95 

50 95 
13-95 
47-95 
14 SO 
82 50 



FREE Technical Advisory Service. If in doubt ask us! Price list on request. 

Comet guarantees that all prices quoted are genuine. All offers subject to availability. Make cheques. Money 

ORDERI°NG a ! 1 NST^U C C1 M ONS" cartri does-add 22o for postage, packing and insurance, all other goods sent 
via Securicor Delnerr— add £2 15 to each co-nolete order for Securicor Deliver? 



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BIRMINGHAM: 

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LONDON. Hackbridge: 

(Nr. Croydon) 

LONDON, Hayes: 

LONDON, Rochester: 

NORWICH; 

NOTTINGHAM: 

READING 

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SHEFFIELD: 

SOUTHAMPTON 

STOCKTON: 

SUNDERLAND: 

WIGAN: 



Heeley Road, Selly Oak, B29 6EY -».,-. 

Tlvoli Shopping Centre, 1570-1572 Coventry Road, Yardley B2B 1BJ 

1 Newhaven Road, EH6 5QZ ...„ 

Blythswood Trading Estate, Argyle Avenue. Renfrew, RA4 SEL 

389 Victoria Street, DN31 1ER 

Reservoir Road, Clough Road, HU6 7QO 

56/64 Ellison Street, Jarrow NE32 3MT 

78 Armley Road. LS15 2EF 

Syston Street 

Ralnharn Road South, Dagenham, RM10 8ST 

190 London Road, Hackbridge, Walllngton, Surrey 

For Phone Order Service 
Silverdale Road, Pump Lane, Hayes 
Maidstone Road, Rochester 
Roundtree Way, Norwich NOR9 4P 
121, Town Street, Sandlacre, Nottingham NG10 5OW 
Monarch House, 75-81 Caversham Rd., Reading RG1 8AP 
Corner of Well I' th' Lane and Queensway 
The Mill, 1 Loxley Road, Malln Bridge, 56 4TN 
Chlckenhall Lane, Eastletoh SOS 520 
Teesway. Portrack Lane, Teesslde, TS18 2RH 
4-7 St. Thomas Street, Sunderland, SR) 1HR 
Wharf Mill, Princess Street, WN3 4EZ 



T»l- 


021-472 6181 


TpI- 


021-706 0684 


T* 


031-554 4454 (9 lines) 


Tel: 


041 -886 5731 


r*#: 


0(7S 5952.1 


Tpi; 


0482 46441 (6 lines) 


TH- 


0632 892211 


Trt 


0532 40551 


Tfl 


0533 52236 


tM 


01-595 5111 


Till 


01-669 0271/0106 


Tfl 


01-643 8989 


TpI 


01-573 1S41 


Ts! 


Medway 49171 


Tfl 


0603 411831 


T»l 


Sandlacre 6116 


Tel 


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TpI 


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Tfl 


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TpI 


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TpI 


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Tel 


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-e! 


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nnBivnfY? """""■ 



OPEN DAILY TO THE 
PUBLIC FROM: 

9am-lpm Monday 
i»m-1pm Tuesday 
9am-Bpm Wednesday 
9am-8pm Thursday 
lani'Spm Friday 
lam-5.38pm Saturday 



309 



TRANSISTORISED F.M. tuner head with A.M. gang slow 
mohon drive. 88-10BMcs. with circuit diagram. £2 30p 

c!?0-£1 CI " E L ° W NO ' SE CASSETTE S C60-50P-C9O-75P 

P-C BOARDS {not computer panels) 
1 off 6 transistors single wave band 
1 oft 4 transistor audio 
1 oft 3 transistor £1 60 the three. 

Encapsulated bridge rectifier (ilt usd 3 3mdh) 100 PIV 2 amos 
50p each, 3 for £t 35. <""»j:>. 

Transistor F.M. Stereo Multiplex Decoder. Size: 5± x 24 * U- 

As used in well known British stereo units with circuit. £3- 75 

GARRARD SP25 MK. II less Cartridge. £10-00. 

!™? LUME CO NTROI.S consisting of 2 oft each. 

100K log. ganged L/S-20K log. ganged US. 

470K log. DP Switch-10K lin. L S-50K lin. L»S £1-35 

4 PHONO SOCKETS ON PANEL, to panels for £1 25. 

12 PLASTIC KNOBS. Chrome and Gold. 3 types— 4 off each 

—spring clip £1-25. 

10 COMPUTER PANELS packed withe omponents inclu- 
ding one panel with 2 Power Transistors. £1-00. 
SLIDER CONTROLS (less knobs) 
25K Log of Lin single 30p, 
10K—100K Log ganged 50p. 
100K— 100K Log ganged 50p. 

*'i GI !£ ° EPENDENT RESISTORS (RCA sq3536) 30p each 
4 tor £100. 

CRYSTAL CALIBRATOR No. 10 crystal controlled hetero- 
,«.".?. wave - me,er covering 500 KHz-10MHz (harmonics up to 
30MHz) power required 300V. DC. 15mA. 12V. 0-3A DC Test 
equipment for 62T M.RC. £2-50 each. 

ALL ITEMS INCLUDE VAT 

All items post paid in GREAT BRITAIN 

SURPLECTRONICS 

216 LEAGMVE ROAD, LUTON, LU3 IJD, BEDS. 




PHOTOELECTRIC KIT 

Light Ph<^. s »it C b/c«2ii"?iB™iu i£^T^wi. r ? a . n « d t0 bullrf " staa r 

PHOTOELECTRIC KIT 

£285 

Postage and Pock. IBp (U.K.) 

Com mon wealth 

SURFACE MAIL 26p 

AIR MAIL £1 40 

Australia, New Zealand, 

S. Africa, Canada and U.S.A. 

Also Essentia) Data Circuits 

and Plain for Building 

10 advanced Designs 

INVISIBLE BEAM OPTICAL KIT 

and Pack. 10p W-kT^S^H^^^^*™^**- &C 

BIOFEEDBACK AMPLIFIER KIT 

* iu.K. } . oS^rB^x.^r*^™'* *•■" posuse and psck - 

A^SL^ T J ,E J\ BR ? ,HW * Vi MONITOR KIT 

YORK ELECTRICS Mail Order Dept 

335 BATTERSEA PARK ROAD, LONDON, S;W 11 

Send S.A.E. for f H u dcWU. „ brief de.crtplion of a U Kit, ond project.. 



Home Radio 

COMPONENTS 



250 "age* 1 r/4 " x 8 ' 




The Catalogue 
you MUST 
have! 



Details of our popular 
Credit Account Service 
and our Easy Ordering 
System are included 
in the catalogue. 



0nly55p. 



. -,_. POST AND 

plUS 22p PACKING 



J&i 



POST THIS COUPON 

with cheque or P.O. for 77p. 



Address. 



The price of 77p appliet only to canlocues purchased by 
ruitomen in the U.K. and to BFPO addr«u«t. 



HOHE RADIO (Components) LTD. FVegd. No. 9)2964 London 
Dapt. PW. 234-2-40 London Read, Mitcham CM 3HD 



310 



Announcing our 
improved range of 
constructor modules 



ENTERTAINMENTS LTD 

STANDARD & CUSTOM-BUILT AUDIO A ELECTRONIC EQUIPMENT 
NEW & SECONDHAND MUSICAL INSTRUMENTS. 
DISTRIBUTORS FOR A.K.G. HIGH QUALITY MICROPHONES. 



TWO NEW PA/MIXER CONTROL UNITS 



FOR DOMESTIC 

& COMMERCIAL 

USE 

New Versions using 3A 
■Plastic Power' Driver 
Transistors Now Available. 
To meet demand, we have 
included a more powerful 
module In our well- 
established and proven 
range. These power 
amplifiers are carefully 
assembled, tested and 
guaranteed. They offer 
superb value for reliability 
and versatility. 






#><#* 



SA35 



35 watts RMS. Uses 1 

transistors and 7 diodes 

Carr. paid. 



£4-45 



A NEW ADDITION IS THE 

SA50 at £5'65 

Carr. paid. A rugged, well built unit, capable 
of 50 watts R.M.S. out, with all the advan- 
tages of Saxon Amplifier design and quality. 
Ready now. 



£10-90 



AIJ ft ft makes an idea! unit in 

NQI I disco assemblies. A 

*"■ * **» fea | glutton tor work. 
Reliable, tough and compact. 11 transistors, 6 diodes. Carr. paid. 

BRIEF SPEC. FOR ALL THREE MODULES 

AH modules Incorporate OPEN AND SHORT CIRCUIT PRO- 
TECTION, plus prool against over-dissipation and faulty Inductive 
loads In the SA.100. 
Freq. response 15-40,000 Hi ± 1dB 
Distortion ■ 2% at 1 kHz 

toads 4 to 16 ohms 

Ouleacent current 15 mA 
Noise Better than -75 dB 

Supply voltage SA35 25-45 volts 

SA50/SA100 40-70 volts 
Slie 4+-I4-X l-(SAIOO) 

4-x3'x1*(SA35/SA50) 
Circuits, connecting Instruction and application data ate supplied 
free with all modules. 



POWER SUPPLIES FOR 

THE SA25 35 & SA100 AUDIO MODULES 



PU45 
PU70 



MT45 
MT30 



PS70 
MT70 



Unstabiliied supply for 2 SA25 35 £4 » 
Unstabiliied supply for one or two SA100 

£7-75 carr. 40p 
Stabilised module tor 2 SA25's or two SASS's 

£3 50 carr, free 
Transformer tor above, heavy duty £2 IS carr. 20p 
Transformer for unstabiliied supply complete with 
rectifier diodes mounted £3 50 carr. 20p 

Stabilised supply module lor one or two SAIOO's 

£4 M carr. free 
Transformer for PS70 £«'» carr. <0p 



ALL MODULES ARE BUILT ON GLASS 

FIBRE P.C. BOARD AND SUPPLIED 

FULLY TESTED 



Using grouped pairs of inputs and outputs 
(high Z and low 2 inputs) with individual 
bass, treble and volume controls on each 
pair, plus master control. These low-noise 
units will feed all makes of amplifiers, 
making them ideal for clubs, discos etc. 
Standard jack sockets. Compact design. In 
strong metal cases. Ail units guaranteed for 
3 years. 



#M.4H 

4 high Z 4 low Z inputs. 4 sets of controls. 
Case t4"x8"x2±* Carr. od. 

£1850 vat 

• M.6HL Case IS" 3" ■ 2;-- 

12 Inputs (6 high Z, 6 low Z). Carr. pd. 

£27*50 vat 

A Channel section modules, 
for building your own 
mixer. Sain— 16 x <24dB). 
Tone controls— 18dB swing. 
Carr. pd. £3-50 + V.A.T. 



SAXON CONTROL UNITS 
Mono (as shown) f» C ■ C A 

Carr. 20p.«*#O OU 



Stereo. Carr. 30p. 



£15-80 




deep 
urns, ban, 



Two decks and full headphone monitoring. The unit is mains operated and measutes 1lj- u 
and Is finished with a smart white on black facia. The controls are: Lett/Right deck fader vol 
treble Headohone Selector and volume. Microphone volume, bass, treble, mains onjOfl. 
COMPARABLE TO UNITS AT OVER TWICE THE PRICE. (N.B.— Stereo only has mlc Input.) 




120 WATT HEAVY DUTY MODULE 

Rugged class A driver stage, this module will run from all our mixers, 
etc., and most othe; makes. Delivers 120 watts Into an eight ohm load 
and employs 4 T03 can (115 watt) output transistors. These are the 
modules where extra power Is demanded. 



ISO watt version £27 90 

tu' P vr ef £27"50 

(Carr. 50 p) 



Power output 120 watts into 8 ohms 
Freq. response 20-20.000 HZ ± 2dB 
Input sensitivity 200 mV into 1DK 
Construction Flbreglass board 
Size 8" x A" x *" (5" with 

supply) 
Low distortion parallel push-pull 
output stage. 



EC" £13 a 90 

(Carr.20p) 



Module & 
power 
supply 
(Carr, 40p) 



£18-95 




SOUND AND LIGHT UNITS 

Our popular 3 channel model handles up to 3KW £3000 watts) of 
lighting and Incorporates versatile sound control arrangement to 
enable professional standards to be achieved. Both units are 
excellent examples of Saxon ouallty and value. 



3 CHANNEL UNIT 

Includes bass, middle and treble as well as master 
controls. 2 amplifier sockets eliminate need for 
split leads. Up to 3KW lighting load. Smartly 
finished steel ease. Carr. 30p. £4 Q* y C 



SINGLE CHANNEL UNIT 

Operates from 5 to 100 watt amplifiers. Supplied 
for bass note operation, is easily adapted for 
treble or mid-range at a cost of about 5p. 



Carr, pd. 



£8-90 



COMPLETE AMPLIFIERS 

CSE 100. £34 90 carr. free 
This versatile unit is now available in a black vynlde 
case and so represents even better value than ever 
delivering speech and music powers of up to 100 
watts RMS and continuous signal outputs of 
70 watts. Two Individually controlled Inputs with 
wide range bass and treble controls. 



SAXON 100 £48 50 carr. free 

(v w C v C i, Tl 
• • • •»AXpN * J 




With an RMS output of 120 watts speech and music. 
100 watts continuous power, four Individually 
controlled FET Input stages and wide range bass 
and treble controls, this amplifier has established 
Itself as a unit offering quality and reliability at low 
coat. 

GOO Watt 3 colour Llgh 
Boxes Smart Rexlna 
finish £15 carr free. 



LOUDSPEAKERS British made bargains!! 

12- 25 watt 8(15 ohms £§ M carr. 30p. 15" 50 watt 8/ 15 ohm £14-10 carr. 50p. 
12* 40 watt 15.000 gauss magnet system B'15 ohm £11-50 carr. 40p. 



A.K.G. MICROPHONES 

D11 DHL IOEAL DISCO MIKE ONLY £9 4S (rrp £11 M) 



Prices quoted do NOT include V.A.T. 10% miirt be added on to total 

value of order for V.A>T. s.a.e. (or special once HA 



Orders and personal shoppers to: 

SAXON ENTERTAINMENTS LTD., 327 Whttehorse R d., W. Croydon, Surrey. CRO 2HS. 
Telephone 01-684 6385 TERMS OF BUSINESS 

Hours 9.30 a.m.-5.30 p.m. Cash with order (C. W.O.I For C.O.D. please 

TRADE & EXPORT ENQUIRIES INVITED 



311 



THE SMALL PRINT 

AT some time or other, in hire purchase agreements, 
*^ forms of guarantee, or simple purchases, most people 
encounter a moment of uncertainty and often wonder if the 
forms are really worth the paper they are printed on. What 
are the buyer's rights under signed guarantees or the 
Supply of Goods Act? 

To go some way to tidying up the situation the "Supply 
of Goods (Implied Terms) Act 1973" has been introduced. 
The purpose is to make it a criminal offence to use mislead- 
ing or invalid guarantees or exclusion clauses in any con- 
tract or guarantee, including hire purchase, credit sales and 
cash sales. Goods must compulsorily correspond with 
their descriptions, whether in advertisements or on the 
package, be of merchantable quality and "fit for the purpose 
intended". The phrase in quotes is often a disputable 
factor and does not sufficiently define how it is to be 
applied to technical products. If the magistrate is pre- 
sumably the deciding authority in the event of such a case 
being brought to court, he will need authoritative technical 
advisors to sort this one out, but it is very common for 
suppliers to exercise their Initiative in offering substitute 
components if the requested item is not currently available. 
These often serve to enable a project to be made opera- 
tional but will not necessarily guarantee the optimum per- 
formance as achieved with quoted component types. It can 
be found that faulty conditions occur in a circuit which can 
cause chain reaction damage to other components. If sub- 
standard or substitute components are used, one takes this 
risk, but the constructor has no redress on the supplier 
unless the supplier has stated that the substitute 
component is suitable for that project. 

The act stipulates that where redress is justified, the 
onus is on the seller, usually the retailer. The manufacturer 
is only responsible for supplying the seller with products 
that correspond with their trade descriptions. If such a 
description is inadequate then It is the responsibility of the 
purchaser to satisfy himself that the goods are what he 
wants. 

Exclusion clauses are made void but not illegal, so that 
customers should not be led to think that his rights are 
adversely influenced by such statements. Guarantees 
should now make clear to the consumer that additional 
rights are being given; no guarantee that offers less than 
the implied rights of the Supply of Goods Act will be valid. 

M. A. COL WELL— Editor. 



The September Issue, on sale 3rd August, will 
be the first of our special series of Autumn 
issues. Special attractions include the very 
easy-to-rnake two-i.c. radio that uses a choice 
of popular speakers from 8 to 16 ohms, and only 
a handful of other components; no complicated 
alignment is needed. Also featured will be a 
multi-purpose low voltage power regulator and 
a short-wave converter for insertion between 
aerial and receiver to convert signals in the 
short-wave bands into one fixed frequency of 
1600kHz or 190 metres on the MW band. Also in 
the September issue there will be a special 
announcement on 04 and other extra attractions 
for Issue Number 800. 

Further details on page 335. 
iniuiniiiiiiiiiiiiiiiiiiiiniiiiPiiikiiiiiiiiiiiiiiiiiiiiiiiNiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiNiNiiii 



NEWS. 



• • 




Practice! Wireless 
and Television 
In Berlin 

FOR the first time Practical 
Wireless and Television will 
be taking part in an over- 
seas exhibition at the end of 
August. The "International Radio 
and TV Exhibition," to be held 
in Berlin August 31 to September 
9, is one of the largest commercial 
and public exhibitions of its kind. 
Of special significance is the cele- 
bration of 50 years since the first 
German radio station began trans- 
mitting officially in the former 
Reich capital,, 

This will be the 29th national 
and second international exhibi- 
tion organised by the "Division 
Radio and Television" in the 
German Electrical and Elec- 
tronic Manufacturer's Association 
(ZVEI). 

There will be 88,000 sq metres 
of space in 23 halls and 4 
pavilions, as well as 40,000 
sq metres of open-air grounds. The 
truly international flavour is due 
to participation by 20 countries 
including Hong Kong, South 
Korea, China, Norway, U.S.A. and 
several European countries. 

Displays will embrace all 
aspects of electronic home enter- 
tainment systems including asso- 
ciated equipment for servicing, 
studios and transmission installa- 
tions. Programmes will also be 
transmitted from a 2,100 seat hall 
that will be converted into a tele- 
vision studio. 

Practical Wireless and Television 
magazines will participate in the 
Technical Press section and 
visitors will be able to see much 
of the recent work that these two 
magazines have published as well 
as some new ideas for the 
autumn. 

We cannot possibly tell you 
everything about this gigantic 
operation in just a few lines but 
we hope to be able to publish 
much of the exciting events that 
will take place in a future issue. 
So if you are around West Ger- 
many about that time we cordially 
recommend a visit to this show. 



312 



NEWS... NEWS... NEWS 




Texas Instruments Seminar 



TEXAS Instruments Ltd. held 
their successful Interface 73 
technical seminar at the 
Talk of the Town, London on 
June 12, 13 and 14. 

Richard Mann of "Texan" am- 
plifier fame introduced delegates 
to the programme. Bob Spoene- 
man, Marketing Manager (Nor- 
thern European Semiconductor 
Div.) then gave a short talk 
entitled "Market Overview." 

A lecture on the TTL system 
followed and Mick Mimmack and 
Bob Parsons reviewed new TTL 
products especially the range of 
low power Schottky devices. 

The next talk was given by 
Roger Banks, Senior Product 
Marketing Engineer for military 
ICs, who spoke on Beam Lead 
ICs. 

Adrian Tarr, Product Market- 
ing Engineer for Metal Can 
Power Products and Bryan Norris, 
Applications and Contracts Mana- 
ger lectured on Power Devices 
and discussed practical applica- 
tions of Plastic Power, and High 
Voltage Transistors, SCRs and 
Triacs. 

A lecture on Optoelectronics 
followed. This was presented by 
Millis Miller, a specialist in opto- 
electronics who also gave a 
demonstration of solid state 
targets for low light level TV 
applications. 

Lunch followed at 13.05 and 
when delegates had finished their 
steak and tutti fruitti, the lectures 
continued. 

All delegates were presented 
with a data pack which com- 
prised : 

Semiconductor Circuit Design 
vol. 2. over 200 pages hard bound. 

A totally new TTL Data Book 
providing comprehensive cover- 
age of Texas Instruments 5 
families of 54/74 TTL ICs. 640 
pages hard bound. 

A Seminar Data wallet con- 
taining a selection of the very 
latest product information, to- 
gether with a book reproducing 
all the Seminar Slides. 




Delegates being presented with data packs, 
by Mrs Gina Penman. 



BSR Award 



BSR Limited of Warley, the 
manufacturer of record 
changers has received an 
award for the 810 transcription 
turntable. 

The "Component Design Award" 
presentation was made recently 
at a conference held at the 
Excelsior Hotel, Birmingham 
Airport. Viscount Caldecote, 
Chairman of the Design Council 
presented the Design Award 
Certificate to Mr. G. R. Wool- 
dridge, Director of BSR Limited. 

BSR introduced the 810 trans- 
cription turntable into the range 
of Hi-Fi record changers in late 
1971. Its pre-programmed sequen- 
tial cam system introduces a new 
experience in featherlight push- 
button operation. 



Logic design lor Digital systems 

A one week residential Vacation School intended for practising engineers 
scientists and teachers, who need have no previous knowledge of, but 
are interested in the fundamentals of logic circuit design is being 
organised by the Electronics Division of the Institution of Electrical 
Engineers. The School "Logic design — for digital systems" is intended 
to give an appreciation of both formal techniques and their application 
in practice and will be held at the University of Kent at Canterbury 
from 23-28 September 1973. 

Lectures will cover the follow- 
ing subjects: historical and 
mathematical background; design 
of memoryless (combinational) 
circuits; design of circuits with 
memory (sequential); introduction 
to automata theory; microcircuit 
logic; array networks; complete 
design of a system; CAD tech- 
niques; testing and diagnostics; 
and recent advances in logic 
design. 

Further details are available 
from Senior Divisional Secretary 
(Electronics), IEE, Savoy Place, 
London, WC2R 0BL. 



Northern Hi-Fi 

THE Northern International 
Hi-Fi Festival, called "Audio 
73" will be held at the 
Hotel Majestic, Harrogate, from 
August 31 to September 2. 




Mobile rally diary 

August 19— The Bristol "Mobile 
Picnic" will be held at Ashton 
Court, Bristol. 

August 19 — Preston Amateur 
Radio Society will be holding their 
rally at Kimberley Barracks, 
Deepdale Road, Preston, Lanes. 
There will be a free car park, 
trade stalls, bring-and-buy stalls 
and refreshments. Talk-in stations 
will be operating on Top Band 
and 2m. All the gen from G. W. 
Earnshaw, G3ZXC, 12 Withy 
Parade, Fulwood, Peston, Lan- 
cashire, PR2 4JN. 
August 26 — The Town and 
Country Festival Mobile Rally will 
be held at the National Agricul- 
tural Centre, Kendworth, War- 
wickshire. 

313 



GajaKgaM 



RG.RAYER 



RECEIVER 



You do not have to leave this receiver behind 
when going camping, caravanning, or when 
pressed for space, as it is small in size, with 
internal battery and loudspeaker. Despite this, it has 
a very good performance for the reception of AM, 
CW and SSB on the short wave bands, in addition 
to normal medium wave reception. 

CIRCUIT 

Fig. 1 is the complete circuit; except for the BFO 
which is necessary for receiving CW and SSB. As 
this section is not required for general listening it 
is wired as a separate unit. 

Sockets Al and A2 are alternative aerial input 
points. Al is most suitable for a reasonably long wire 
aerial, while A2 is better for a telescopic rod or short 
aerial. The "Blue" aerial coil is tuned by its own 
365pF variable capacitor VC1, so that it can always 
be peaked up for best results with any aerial, no 
separate trimming being needed with this arrange- 
ment. 

Trl is the OC170 BF amplifier, with the RF gain 
control VB1. The "Yellow" mixer coil is tuned by 
VC2, which is one section of a 2-gang tuning 
capacitor. The panel trimmer VC4 allows this circuit 
to be trimmed when coils are changed, or at any 
point of the band covered. 

The "Bed" oscillator coil is tuned by the second 
section of the ganged capacitor, VC3. VG5 is the 
bandspreading capacitor, which greatly simplifies 



: - 



accurate tuning on the congested SW bands. A 
3-gang component, giving simultaneous tuning of 
aerial, mixer and oscillator circuits could have been 
used, but was felt to be unnecessary because aerial 
and mixer circuits can be peaked up for any setting 
of VC5, by means of VC1 and VC4, if necessary. 
There is thus no loss of efficiency with this simplified 
arrangement — in fact, all circuits can be tuned for 
best results at any frequency. 

Bands are covered by inserting a set of three coils 
for each waveband. Provision is made for four wave- 
bands. The "Bed" oscillator coils require series 
padders of 350pF, lOOOpF (or HOOpF) and 3000pF for 
the lower frequency ranges, and a direct connection 
for the highest frequency range. These padders, 
CF1, CP2 and CP3 are wired to separate holder tags 



iwmtic. 








Fig. I : Circuit of the Mini-Comm receiver. The circuit of the optional BFO is shown in Fig. 6. The photograph above shows the complete receiver, 

the speaker being mounted on the tighthand side panel. 

314 



; 



as in Fig. 1, so the correct padder is automatically 
included in circuit when the "Red" coils are changed. 

The 2-stage IF amplifier has five tuned circuits in 
all, and although more complicated amplifiers were 
tried, this one was adopted on the grounds of easy 
construction, good gain and selectivity. Transistor 
Tr5 is a grounded base emitter detector with AGC 
fed from the collector through Rll to Tr3. 

A 150mW packaged audio amplifier is fed from the 
volume control VR2 and gives sufficient output for 
most circumstances using the small internal speaker. 
A panel jack allows headphones to he plugged in 
when preferred. 

Using the circuit in Fig. 1, the receiver gives AM 
reception over all usual short wave and medium 
wave bands. For the reception of CW and SSB signals 
on amateur or other frequencies a beat frequency 
oscillator has to be added, and this is covered later. 
Should CW7SSB reception be omitted, two panel 
holes for the BFO "pitch" capacitor and AM-CW/SSB 
switch will not be necessary. 



Capacitor VC1 is mounted with three countersunk 
4BA bolts, washers or spacers about 1 &in. thick being 
placed between the capacitor and panel, the spindle 
passing through a 3 ain. or ^in. dia. clearance hole. 
Take care that the bolts do not penetrate beyond 
the thickness of the capacitor front frame. Before 
mounting VC1, solder a lead to its rotor (chassis) tag, 
to go to a tag MC bolted at the "Blue" coil holder as 
in Fig. 2. 

Gang VC2/3 is mounted in the same way and two 
leads are soldered to its central rotor tag. One runs 
directly to a tag at the "Yellow" coil holder and the 
other to a tag at the "Red" coil holder. The small 
drive used for VC5 is fixed to the panel with two 
8BA bolts while VC5 itself is fixed to a bracket cut 
from scrap. Drive and capacitor should be lined up 
carefully. 

The controls are positioned as in Fig. 3. As men- 
tioned, 52 and VC6 will be required for the BFO 
only so if these items are not wanted VR1 can be 
moved to the VC6 position, for a symmetrical layout. 




Fig. 2: Layout of the major components on top of the chassis. 



GENERAL CONSTRUCTION 

The receiver chassis is an 8 x 4in. "universal 
chassis" flanged member punched to take the coil- 
holders as in Fig. 2. A second 8 x 4in. flanged 
member forms the panel. The end flanges of the 
chassis member are cut so that they fit inside the 
flanges of the panel and bolts pass through the front 
flange to secure the chassis at a height of l 1 4 in. 

Both sides are 1 ain. or similar hardboard, 4 3 a x 
4 5 a in. Bolts hold the sides to the chassis and panel 
flanges. The right side has an aperture for the 
speaker with perforated zinc or speaker material 
placed behind the opening. It is as well to leave the 
speaker off until construction is otherwise finished. 

The case back is a third 8 x 4in. member. A bracket 
is cut from scrap or a spare member so that a PP9 
battery can be placed as shown. Both top and 
bottom are 8 x ^ain. and can be metal or other 
material such as hardboard, paxolin sheet, or ply- 
wood. Self -tapping screws hold these parts to the 
front and back flanges. 




As there is not much spare space under the 
chassis, the panel holes for these items come almost 
against the front flange of the chassis. In order that 
the controls are not tilted by this, it is necessary to 
fit one or more washers on each bush and to cut 
the flange to clear these. Alternatively, use five 
washers such as those punched out for the coil 
holders and cut a flat on each to clear the chassis 
flange. 

Most of the wiring in Figs. 2 and 3 can then be 
done, mounting resistors and capacitors iirectly on 
the coil holder tags, as shown. Some 20 or 22swg 
tinned copper wire is suitable for other connections, 
with insulated sleeving. 

The leads from Trl and Tr2 are left almost full 
length. It may be preferred to use coloured sleeving 
on the wires say green for emitter, blue for base, and 
orange for collector, with the shield wire bare or 
red. 

The small circuit board in Fig. 3 carries the com- 
ponents shown in Fig. 4 and is wired separately. For 
external connections, insert Veropins or leave a pro- 
jecting wire. 

315 



i 



• components list 



Resistors 
R1 10k« 
R2 £*7b£i 

R3 1-5kO 
R4 27k» 
R5 1kn 
R6 iOfcu 
R7 2-2kQ 



R8 
R9 



2-7kU 
1kU 



RIO 10kQ 
R11 47kft 
R12 22k£i 
RlSMkti 
R14 4*7ka 



R15 1ku 


[ 


R16 ZlkLi 




R17 ikn 




R18 1(ui 




R19 22kiJ 




R20 4-7ku 




R21 390^ 
watt 





VR1 5ku linear VR2/S1 5ka log. with switch 



Capac 

a 

C2 

m 

C4 

cs 

C6 

C7 

C8 

C9 

C10 

C11 

VC1 



itors 
22pFSM 
0*01 ^F 
0-047,uF 
0-OUF 
0*01 *<F 
0-047nF 
0*01 *F 
22pF SM 
10^F 6VW 
0-047/-F 
0»047pF 



C12 
C13 
C14 
C15 
C16 
C17 
C18 
C19 
CP1 
CP2 
CP3 



0-047kF 
0*01 #.F 
8mF6VW 
O'tfiF 
0-1aF 
0*01 **F 
0-01 *<F 
SpFSM 
3S0pF SM 
lOOOpF SM 
30G0pF SM 



365pF variable (Jackson type O with slow 

motion drive) 
VC2/3 365 4 365pF variable (Jackson type O with 

slow motion drive) 
VC4 50pF variable (Jackson type C804) 
VC5 25pF variable (Jackson type C804) 
VC6 15pF variable (Jackson type C804) 

Semiconductors 

Trt OC170 Tr3 AF117 Tr5 OC71 
Tr2 OC170 Tr4 AF117 Tr6 OC45 

D1 Zener diode 6-SV 

Miscellaneous 

i.1/2/3, Transistor miniature plug-in-coils, 'Blue', 
'Yellow* and 'Red* for ranges required (Denco). 
U, BFO coil (Denco IFT14). Valveholders B9A for 
coils (3). Audio module, PC1 (Newmarket). Slow 
motion dial Hin. (Eagle). Output jack. AM-CW/ 
SSB switch, 2 pole 2-way wafer. Speaker, 2|in. 
30-60n. Veroboard0-I5in. matrix. Universal flanged 
chassis members, 8 x 4tn. (Home Radio). Hard- 
board, knobs, etc. IFT1/IFT2 (Denco IFT18/465). 
IFT3, (Denco IFT14/465), 



A - 2 in. 6BA bolt is fixed to the chassis in the posi- 
tion shown in Fig. 3 and an extra nut put on it, so 
that the board will be clear of the metal. The board 
is then placed as in Fig. 3, and fixed with a further 
nut. 

The tag MC (Fig. 4) under the board is the 
chassis return. 



Trie 





Fig. 4 : Layout of the RF board. 

IF AMPLIFIER 

A piece of Veroboard is cut having 7 rows of holes 
one way, and 23 rows the other way, or 3*2 x l^in. 
Components and leads can then be placed exactly 
as in Fig. 5 with the minimum of difficulty. 

Drill holes for 6BA bolts to fix tags MC, place the 
board on the chassis as in Fig. 2, and drill matching 
holes in the chassis. Holes have to be drilled for the 
IFT's so that the pins are located as in Fig. 5. 
Probably the easiest method is to secure the board 
by one long edge in a vice and drill the holes, then 
if some do not match the pins with sufficient 



Fig. 3 : Arrangement of parts and wiring 
underneath the receiver. Top centre is seen 
the audio module and to its right the BFO 
board. The board at centre right carries 
some of the RF components and wiring. 




316 



accuracy, to use a very small round file to enlarge 
the holes until the IFT's fit. A central hole is 
necessary under IFT1 and IFT2 to reach the lower 
cores. 

Components can then be placed as in Fig. 5. In 
most places the wire ends of resistors and capacitors 
are long enough, so they are bent over, soldered and 
snipped off. Sleeving is put where needed to avoid 
shorts. The tags MC are secured tightly with ^in. 
6BA bolts and nuts and one screening can tag of 
each IFT must also be wired to this earth circuit. 

Fit four Veropins or wires as shown. At the right- 
hand end of the board "9V negative" has a black 
flexible lead and negative battery clip. A lead from 
C14 positive will run to VR2, as shown. At the other 
end of the board, IFT1 pin 2 will be connected to 
tag 8 of the "Red" coil holder. A wire from the 



pin "negative for RF and mixer" will run to R3 and 
R7 on the under-chassis board. 

Pieces of sleeving about 3 8 in. long on the tran- 
sistor wires will prevent shorts here and raise them 
a little above the board. Solder these wires directly 
to the points in Fig. 5 and snip off excess wire. 

The IF amplifier can be tested by connecting a 
battery and phones (or AF amplifier) and injecting 
a signal at pin 2 of IFT1 from a signal generator. 
As the IFT's are pre-aligned by the maker, the cores 
should be left as they are until proper results are 
obtained, and only touched up as required after- 
wards. 

The IF amplifier is mounted with lock nuts, making 
sure that there is no possibility that leads or joints 
will touch the chassis. Leads can then be connected 
as shown. 




Fig. 5: Details of the wiring and construction of the IF strip. This can be tested and roughly aligned before being piled into the chassis. 




A useful view of the receiver with the back removed to enable the IF strip to be seen. 



317 




Most components shown in Fig. 3 can be identified in this photograph of the underside of the 

receiver. 



-9V 



C19 

-IK 



5pF 



IFT3 
pin 4 




n in 






390 CW/5SB 

♦■ IF-ve 




RIO 



Fig. S : The circuit of the optional BFO. The leadout connections for the OC45 can be found on Fig. 5. 



AF AMPLIFIER 

Figs. 1 and 3 show the packaged amplifier from 
the top. It is mounted clear of the chassis by a l 2in. 
6BA bolt with extra nuts, also securing a tag which 
forms the positive or chassis return connection as 
in Fig. 3. 

Run the lead to VR2 slider (centre tag) against 
the chassis. Take two blue wires as shown for the 
speaker circuit. The one connecting point here also 
has a black lead, which passes to the 9V negative 
pin of the IF board, and thus to battery negative. 

IF ALIGNMENT 

This is carried out with a weak but stable signal, 
from a signal generator, or from a BBC MW station. 
VR2 should be at maximum, but signals can be 
reduced with VR1 so that the AGC action does not 
mask adjustments. 

318 



Adjust each core, if necessary, using a properly 
fitting tool (such as the Denco TT5 trimmer tool). 
Each core should have a quite sharp peak, but much 
adjustment ought not to be necessary. 

Once this has been done, no further adjustment 
to the IF amplifier is necessary. 

TUNING 

As the coil cores are screwed right in for packing 
purposes they require adjusting so that some length 
of brass thread projects. Band coverage is set by 
means of the core of the "Red" coil. This adjustment 
is made at the low frequency end of the band. 

Tune in a signal near the high frequency end of 
the band, and rotate VC4 for best volume. Now tune 
to a signal near the LF end of the band. Leave VC4 
untouched and rotate the core of the "Yellow" coil 
for maximum volume. It should then be found that 
VC4 will require only a little adjustment, for best 



volume, at any frequency in the band. To retain dial 
calibration, the core of the "Red" coil is locked with 
a 6BA nut. 

In all cases VC1 should peak up signals when in 
a similar position to VC2/3. Adjust the core of the 
"Blue" coil at the LF end of the band so that this 
condition is obtained. It is then only necessary to 
keep VC1 approximately in step with VC2/3, while 
tuning, and to adjust VC1 for maximum signal 
strength with the wanted station, or for the narrow 
band of frequencies to be tuned by VC5. 

The listed single capacitor VC1 and 2-gang capa- 
citor VC2/3 have integral reduction drives and direct 
and slow-motion Vn. shafts. An "Electrovalue" type 
CK4 knob was fitted to the direct drive part of each 
spindle, by tapping out the metal insert or disc. A 
type J VI 8 knob was then fitted to the slow-motion 
part of the shaft. An alternative is to fit pointers to 
the direct drive part of each shaft, or to use direct 
drive (not slow motion) capacitors, with pointer 
knobs or scales. 



11 




° c \ *< C16 r» 
Tr6 ) o 



¥. 



> H C17 \ -» o 



7J7 



■R21 



2£x 




BEAT FREQUENCY OSCILLATOR 

The circuit for this is shown in Fig. 6. When 
switched on, it produces an oscillation which can be 
tuned to approximately the receiver's intermediate 
frequency by the panel control VC6. This signal is 
coupled into the IF amplifier. 

When CW is being received VC6 is adjusted so 
that the difference between the signal received and 
the BFO frequency will produce the wanted audio 
tone. With VC6 tuned to the receiver IF, no tone 
is produced. Moving VC6 either way produces a 
tone which rises in pitch. In some cases placing the 
BFO one side or the other of the IF may give 
greater freedom from interference. 

When receiving SSB (single sideband) the BFO 
frequency is adjusted with VC6 so that it simulates 
the carrier which was removed before transmission. 
The speech will then be resolved. For this purpose, 
VC6 has to be adjusted carefully as required, for if 
the BFO (or carrier oscillator) is the wrong side the 
SSB signal, the latter cannot be resolved. 

As the receiver has no separate product detector, 
it is essential to keep the level of the received 
signal down on SSB, as required, by means of the 
RF gain control VR1. For AM reception, VR1 will 
usually be at near maximum, while volume is con- 
trolled by VR2. But for SSB, VR2 will usually be at 
maximum (except when using phones) and gain will 
be reduced by VR1. (An exception is when strong 
AM signals cause cross-modulation of other AM 
signals, when VR1 should be turned back.) 

The stabilising diode Dl is not absolutely neces- 
sary but as the current drawn by the AF amplifier 
varies considerably with audio level this can tend to 
cause modifications to the oscillator frequency due 
to fluctuations in oscillator voltage. A 10%F or 250 «F 
capacitor from battery negative to chassis will help 
reduce this. For a similar reason, connections to Tr2 
can be modified so that this stage is supplied from 
the regulated 6-8V line, though this again is not by 
any means essential. 



Fig. 7: The two sides of the board for the BFO components. 



Coverage of the sets of "Blue", "Yellow" and 
"Red" coils is approximately as follows, and only 
those coils necessary for the frequencies wanted 
need be obtained. 

Range 2T 515— 1545kHz (580-195m) 
Range 3T 1-67— 5-3MHz (180-57m) 
Range 4T 5— 15MHz (60-20m) 
Range 5T 10-5— 31MHz (28-9 -7m) 




L 



RF G*1H E FO MfX TRIM Off VOL ;- ASH CW'SSB 



BFO CONSTRUCTION 

Fig. 6 shows wiring and components on the small 
BFO board. This is positioned as in Fig. 3, so that a 
short, stiff lead can run from pin 3 of the BFO coil 
to VC6. When first setting up the BFO, tune in a 
weak but stable AM signal. Put VC6 half closed, 
switch on the BFO, and rotate the VFO coil core 
until a strong audio heterodyne is produced, which 
is then adjusted to zero. Turning VC6 either way 
from this position should then cause an audio tone 
which rises in pitch. 

When the BFO is in use, this produces some 
AGC voltage which reduces the IF gain. The second 
pole of the 2-way switch is wired as in Fig. 6 to 
avoid this. Rll is disconnected from the pin of IFT1 
and colour coded leads are run from Rll and pin 6 
through the chassis. A 68kfl resistor is added at the 
IF board, connected to the IF board negative line. 
These circuits are connected as in Fig. 6 so that 
AGC is only applied to the first IF amplifier when 
the switch is in the AM position. 

At the same time R13 can be disconnected from 
the positive fine and a lead can be soldered on to 
run to VR1, as also in Fig. 6. This gives manual 
control of the gain of both the RF and the IF stages. 



319 




TELEVISION INTERFERENCE MANUAL 

By B. Priestley G3JGO 

Published by Radio Society of Great Britain 

35 Doughty Street, London, WCf 

92 pages, 8* x 6in. spiral bound. Price: 80p 



I BBC ENGINEERING 1922-1972 

By Edward Pawley, QBE, M.Sc.Eng., C.Eng., 

= CIEE 

| Published by the British Broadcasting 

m Corporation, 

1 35 Marylebone High Street, London, WIM 4AA. 

= 569 pages 10 x 7±in. Price £7.00 

THIS book is one of those "Bibles" that should 
be on the bookshelf of any man whose interest 
is in the earlier days of radio. 

Chapter 1 explains what broadcasting is and takes 
the reader through the pioneering days of radio 
transmission. Chapter 2 tells of the period between 
1922 and 1926 and is sub-divided into sections which 
include such things as transmitters and reception, 
studios, outside broadcasts, international relations 
and the Keston Receiving Station. 

The years 1927 to 1939 are covered in chapter 3 
and such items as the forming of the Corporation and 
short wave broadcasting are covered together with 
the story of the regional scheme of transmitters and 
the beginnings of television. There is also a section 
covering the BBC's preparation for the war. 

The whole of chapter 4 is devoted to the war 
years and chapter 5 covers the post-war reconstruc- 
tion of the BBC from 1946 to 1955. 

The sixth and final chapter is entitled "The Years 
of Expansion" (1956-1972) and tells how the Cor- 
poration has progressed to the present day. A rather 
interesting section in this chapter deals with re- 
search and development. 

Mr. Pawley has comprehensively covered the 
growth and progress of broadcasting throughout the 
six chapters of this book and traces the history from 
the experiments of Hertz, Marconi, Oliver Lodge 
and other great pioneers right through to the present 
day. 

This is a text that it is well worth putting on the 
"birthday present" or "Christmas present" list as 
it will, I am sure, provide many many hours of 
interesting reading to anyone who regards radio as 
bis hobby. CB.R. 

320 



THE average transmitting amateur in this country 
is beset by two major problems — the com- 
plaints of neighbours who will persist in 
wanting to watch interference-free TV programmes 
and, having reluctantly agreed that the neighbours 
have a point, finding the relevant technical informa- 
tion to enable him to fix his transmitter and/or the 
TV set and live in peace ever more. 

Unlike the United States, TV set manufacturers 
here are under no legal obligation to fit any kind of 
filter to their sets so the poor amateur is forced to 
do a PR job for them by visiting the complainant 
and, hopefully, finding a solution. The amateur soon 
finds out that every TV set has its own particular 
problems and that the filter that clears the X model 
set is useless on the Y model. So far, information on 
the subject for the amateur has only appeared in 
dribs and drabs, mainly in "Radio Communication" 
the monthly magazine for members of the RSGB 
and not on general sale. However, this new RSGB 
publication, long overdue, is a welcome collation of 
such information from many sources on just about 
every method of TV interference suppression that 
has ever been tried on transmitters and TV sets. 

The eight chapters of the manual are packed with 
practical information ranging from an all-important 
explanation of the nature of TV signal through pre- 
liminary investigation of TVI to the design of trans- 
mitters. With the deluge of hi-fi gear that has now 
descended on the populace the amateur is often 
faced with the problem of audio breakthrough and 
this has been given a chapter to itself. The author 
makes much, and rightly so, of the great tact and 
diplomacy needed between the parties involved if 
there is to be a successful conclusion to TV break- 
through investigations. The Radio Interference 
Service of the Post Office usually comes into the act 
and their actions and responsibilities when investi- 
gating complaints are very clearly laid down in this 
manual. 

So far, very little concerted effort has been made 
to form effective TVI investigation groups among 
the amateur fraternity and those that do exist are 
no doubt sitting on masses of useful information. 
For the amateur who must go-it-alone, this excellent 
manual will be his greatest ally. With some 18,000 
licensed amateurs in the UK the RSGB should be 
able to sell at least that number of copies without 
any trouble at all. AED 






STARTING IN THE OCTOBER ISSUE . . . 

... a new series of articles devised specially for readers 
who want to experiment with simple circuits to find out how 
they work and how to alter their functions. This series Is an 
entirely new approach to learning for P.W. readers: you 
actually make up simple projects that demonstrate circuit 
principles. It takes the tedium out of theory by getting you 
directly involved in practical work. For those readers who 
lack experience with delicate components, now is your 
chance to get started the easy way. This series will be fully 
illustrated and employs common components. No extra 
construction work before you start— you buy your compo- 
nents and dive straight in! 

Since this is a continuing series, we strongly recommend 
students and teachers to order now— don't miss the first 
part. And don't forget the free P.W. Datacards to help you 
OCTOBER ISSUE ON SALIE SEPTEMBER 7th. 




'lilLr u LnJLS LKaJUULkjULju 



LA.J. IRELAND 



Number 40 



LP1000 STORED ENERGY REGULATOR 



Visual power indication in battery operated 
equipment is usually absent so as to conserve 
power, except in the case of equipment in- 
corporating high capacity or re-chargeable batteries. 
In some cases the power drain from a small filament 
incandescent bulb would be greater than the total 
consumption of the set. With the advent of the 
LED with its far greater light output efficiency it was 
possible in some cases to incorporate these as visual 
indicators but even here a 30mW or so power drain 
would be quite typical. 

An alternative approach to reduce power drain 
even further to a mere 300 microwatts or so would 
be to pulse operate the LED every few seconds in 
addition to keeping it in operation only for a speci- 
fied portion of the peak pulse thereby giving rise 
to maximum light output for minimum energy con- 
sumption. 

A new monolithic integrated circuit type LP1000 
manufactured by the Lithic Systems Inc. Co. of 
America performs just this function and is described 
as a 'Stored Energy Regulator' or 'Miser* for short, 
due to its extremely low power drain. This, however, 
is only one of a number of very interesting applica- 
tions of this particular IC to be considered this 
month. 



Circuit 

A circuit diagram of the LP1000 IC together with 
a functional block diagram is illustrated in Fig. 1. 
Power for the device is usually obtained through 
a resistor capacitor network. The output power gate 
consisting of Tr4 is kept biased off as long as Trl 
is kept in a non-conducting state set by the voltage 
drop across D4 which is in series with the D1-D3 
diode chain. As soon as Trl conducts the voltage 
drop produced across R2 saturates Tr2 which in 
turn forces the power gate Tr4 to change state. 

The feedback signal to the base of Tr3 via Rl, 
reduces further the voltage drop across D4 as it 
saturates Tr3 which is connected in parallel with 
D4 and this accentuates the turn-on time resulting 
in a sharply rising output pulse at the collector of 
Tr4. 

As the LP 1000 then discharges the capacitor CI 
through the load, the voltage across CI begins to 
drop but before it can reach zero level Tr3 will 
be biased off giving rise to an equally abrupt turn- 
off pulse. The peak and valley voltages for the LP 1000 




+ve 



a! 



Load connection 



r 



* 



$- — 




High and low 

threshold 

limits 



Power 
gate 






9 I 



Fig. 1 



Circuit diagram of the LP1O00, together with a functional block 
diagram. The IC is produced in a TO-18 package. 



lie between 2-4-1-9V so peak power is only con- 
sumed with the inherent advantage of maximum 
efficiency. This sequence of events continues so long 
as power is suppled to the device with the flashing 
rate set by the external RC time constant. 

A high intensity light flash visible even in direct 
sunlight is possible using a 500 /*F capacitor. How- 
ever, as the maximum voltage applied across this 
capacitor is in the region of 3 volts, the actual 
physical dimensions of the capacitor can be kept 
quite small. Less intense flashes are produced with 

321 



smaller value capacitors with a corresponding in- 
crease in the flashing rate provided the charging 
resistor remains constant. 

Oiher uses 

Due to the built in load resistor in the collector 
circuit of Tr4 the IC can also act as a free-running 
multivibrator with the frequency again controlled 
by the RC time constant. Frequency rates from as 
low as one cycle per minute to as high as 20kHz 
are possible using this simple arrangement with a 
typical power consumption of a mere 500 microwatts. 
Fig. 2 shows the LP 1000 connected as a 1kHz oscil- 
lator. 



+3Vi 




UHoaor . 
Fig. 2: LP10Q0 in a multivibrator circuit at 1kHz, 

A further development from the oscillator appli- 
cation above is to power the IC from a solar cell 
giving rise to a self-contained unit which could find 
interesting applications as an aid to the blind. By 
replacing the load resistor with a miniature earphone 
an audible tone is available as a light indicator with 
the frequency of the note indicating the intensity of 
the light. Turning the cell towards brighter areas 
will be reflected by a corresponding increase in the 
pitch of the note. Solar cells capable of delivering 
500 microwatts are relatively inexpensive and the 
light-to-sound indicator could prove to be a invalu- 
able asset to any blind person, Fig. 3, 




Fig. 3: Circuit using the LP1000 In a light-to-sound Indicator. 

Finally the last application to be considered is 
again a rather unusual one but the experimental 
possibilities it opens up are intriguing. If the load 
is replaced by a small step-up transformer voltages 
as high as 90 volts or so are obtainable. Naturally 
the available current from such a source is small 
but it does offer the possibility of trickle charging 
small capacity batteries from solar energy in a 
pretty efficient manner. 

The Lithic Systems Inc. Co. have also recently 
released one of the first monolithic microtrans- 
mitters — a complete radio transmitter on a single 
chip with a 100 mW output. In the near future it is 
hoped that an article featuring this IC type LP2000, 
will be published in this column. ■ 

322 



IHIJ'iHliliI 



AUGUST ISSUE 



RECEIVER DEBUGGING 

When you've built a TV receiver and tested it you 
will probably find all sorts of faults present. The 
aim of this new series is to run through the likely 
faults and to pinpoint the areas where action 
needs to be taken. The series will aid the under- 
standing of fault-finding generally of course, and 
is a follow up to our series earlier this year on 
assessing receiver performance. In the first part 
the operation of the timebases is considered and 
the resons for non-linear scanning outlined. 

UHF FAULTS 

When a dual-standard set is first switched over to 
625-line operation all sorts of unsuspected faults 
are often encountered. George Wilding runs 
through the common ones and their causes, and 
the action necessary. Reception on u.h.f. has 
proved to be rather more troublesome generally 
than at v.h.f. 

VALVE AND TRANSISTOR 
SUBSTITUTION GUIDE 

It is not always necessary, and sometimes impos- 
sible, to fit exact valve and transistor replace- 
ments. This guide has been compiled to indicate 
generally what can and can't be done, list 
numerous helpful substitutes and lay down guide- 
lines for the more difficult situations. 

SERVICING TELEVISION RECEIVERS 

This month Les Lawry-Johns deals with problems 
on the final GEC group dual-standard chassis, the 
GEC/Sobell 2032/1032 series. 

SBF AERIAL FOR BAND V 

Following the great interest shown in his short 
back-fire aerial for the lower u.h.f. channels Reg 
Roper presents a design suitable for the higher 
channels. 

PLUS ALL THE REGULAR FEATURES 



TO 



(Name of Newsagent) 



Please reserve / deliver the AUGUST issue of 
TELEVISION (20p), on sate JULY 16 and 
continue every month until further notice 



NAME.. 

ADDRESS 



I 



LARGE STOCKS 
ATTRACTIVE DISCOUNTS 
DEPENDABLE SERVICE 

Everything brand new & to makeri specs. 



TRANSISTORS BY 
SIEMENS AND 
NEWMARKET 

2X3055 npn silicon power 60p 

AC1S3K pup germanium low power 8£p 

AC176K npn germanium low power 82p 

AD161 npn germanium medium power 42p 

AJD162 pnp germanium medium power 40p 

AF139 pnp germanium UHF 49p 

BC 107 13p; BC108 l£p; BClOa 13p; 

BC167 lip: BCies IOp; BC169 lip 

BC177 21p; BC178 lBp; BC179 21p; 

BC267 18p; BC248 lip; BC259 18p 

Standard groupings available. 

BD135 opts med power 87p 

BD136 pnp med power 88p 

DIODES 

OA90, OA91 , OA9S each 6p 

OA200fip; OA202 10p 

Other lemicondnctoti 

AC128 17p: AF117 SSp 

EFY51 lBp 

Full lists and technical data will be found in 
Catalogue No. 6. See also amendments list. 



Jupii 



SIEMENS' 
THYRISTORS 

0-8A 400V 58p, 600V 70p 
3A 400V 80p. 000V 8Sp 



ZENER DIODES lull range E24 values: 400mW: 2- 7V to 
36V, Up each; Iff: 6-8V to 82V, Sip each: 1-5W: 4-7V 
to 76V, 48p each. Clip to Increase 1-5W rating to 3 watts 

{type aee*') 4 p. 



ELECTROVALUE 

Electronic Component 
Specialists 



ELECTR0LYTIG CAPACITORS 

AXIAL LEAD Prices subject to amendment by the manufacturer. 

Bated voltage: IV IV 10V 16? 8ST 40V «SV 100V 



DIN PLUGS & SOCKETS 

by Hlmhmann. 4 A ratiiii 




2 way L3— socket IOp; plug 12p. 3 way ecr. socket IOp: 
plug 12p. B way scr. socket ISp; plug If p. 



TRANSISTOR 
ACCESSORIES 

To3 cover 7p 

Heat sinks l°C/w, type 6W1. nndrllled 60p 



SWITGHES 

1011C 8P8T 

toggle 20 p: 

409 DPDT toggle 

29p. (These are chrome plate 

2-5A rating} 

7201 Sub -miniature DPDT 

260V a.c/2A 48p 

ROTARY SWITCHES 

Badiospares Miniature Maka-switch (in assembly kit form) 
Shalt 48 p. 

Wafers, MBB-2PBW, 1P11W: rtRM-lP12W, 2F6W, 
3P4W, 4P3W, 8P2W, each, flp. 



WAVECHANGE 
SWITCHES 





Capacity UV 
047 
10 

M 

47 
10 

M 

47 
100 

220 
470 
1000 

2200 

4700 
10,000 



IOp 



IOp 



7p 
Sp 

I' 

8p 

IOp 



10» 

I 9 

7p 

m 

10p l£p 



0« 




'p 


Sp 




7p 


SP 


7p 


7> 


Sp 


7p 


Bp 




7p 


7f 


up 


sp 


'P 


«P 


12p 


7p 


Sp 


lip 


iyp 


Bp 


IOp 


17P 


K7p 


to 


17p 


24p 


4Sp 



14p 17p 
2op 2Sp 
40p 43p 



12p 12p 17p EOp S4p 40p 



87p 



S8p IOp 
*lp 54j> 



Polycarbonate 
—5% Tolerance 

2B0V up to 0'lfiF: lOOV/OlpF and 

above * 

0-01; 0012; 0019; 00X8: 0022: 

0-027; 033; 0047; 056; each 4p. 

0008; 082: 0-1; 012; 15 neb 4p. 

0-18; :-22; Mich Sp. 

0-27 ; 33 ; Sp. 0-39 7p. 47 Bj. 0B6 IOp . 

0-68 lip. 1/iF ISp. 

Prices subject to amendment by the 

manufacturer . 



STLVEEED MICA non-polarised 
capacitors In 34 values from 2-2 pF 
to 880 pF, each Sp 



RESISTORS 10%, 5%, 2% 



Power 

1/20W 

1/8W 

1/4W 

Iw" 

1/2W 

1W 

3W 

7W 



6% 
o% 
6% 
0% 

•€ 

2% 

10%±1'20C1 

6% 

B% 



Range 

82 n-220K a 

4-7 £1-47 OK fi 
4-7 tl-lOM £1 
4-TQ-10MQ 
4-7 O-10M £1 
10fi-lMfl 

o-22a-39n 
i n-ioK n 
i n-ioK a 



i'olut* 

a::aiiaMt 
£12 
E24 
E12 
£24 
E12 
E24 
E12 
El 2 
E12 



10 (o 99 100 up 

I nee note below) 
8 



1 

12 

2fi 



7-S 

0-76 nett 
76 nett 
9 nett 
IB nett 
2 nett 
S 
B 
3 



Codes: C— carbon Sim, high stability, low noise. 

HO — metal oxide, Electros!! TR5, ultra low noise. 
WW — wire wound, Plestey. 

V aloes: 

E12 denotes series: 10. 12, 18. 18, 22, 27, 33, 39, 47. 58. 88, 82 

and their decades. 

E24 denotes series: as El 2 plot 11. 13. 16, 20, 24, 30, 36, 43, SI, 

82, 7B, 91 and their decades. 



// you aare alreodp oat your Ho. 6 calalagut and teant io 
Snow total additional ilemi and prtee amrndmenli, send 
S.A^. for special mpplcmtntary lilt. 



KNOBS 



All grab screw fitting lor t" shafts. 
Black. For other types — see 
Catalogue No. fi. P.B4 






K.14 (20mm) pack ot 2 SEp 
F.13 (26mm) pack of 2 B8p 
F.I2 (33mm) pack of 2 40p 
F.19 (20mm) pack ot 2 32p 
F.18 (26mm) pack of 2 BBp 
F.17 (38mm) pack of 2 40p 
KB.4 (20mm) pack of 4 40p 
K.30/3 (17mm) aluminium, each S4p 



IT'S ALL IN THE LATEST 
ELECTROVALUE CATAL0BUE 

with 

25p 

refund 
voucher 



No. 6 (4th printing) contains details 
of 100 'a of semi-conductors; ICa with 
circuit diagrams, R'e and C's of 
practically every kind, accessories, 
components, tools, materials, etc. 
information and equivalent tables, 
etc. Well Illustrated (96 pages 54" x 
8i") B6p. post free with refund 
voucher for 2Bp. allowable on orders 
over £S or more. 



Prices are in pence esen tor Quantities of the aams 
ohmjc value and power rating. HOT mixed nlaei. 
(Ignore tractions ot one penny on total value ot 
resistor order). 

if Please remember to add V.A.T. to your order. 



POTENTIOMETERS 




Rotary carbon track, doable wiper 
SIHGLE P20 lln 10OC1 to B-2JI Q 
12p, P20 log 4-7K n to 2-2 meg. 12p 
JP20 Log, 4-7K£l,to 2-2Mn 12p, 
Dual gang lln 4-7K Q to 2-2mO, 
42p: Dual log, 4-7K£l to 2'2m £1 
42p; Log/antilog, 10K, 22K, 
47K, IMQ only 42p; Dual anti- 
log, 10K only, 48p. Any type 
with 2A D.P. mains switch, 
12p extra. 

Only decades ot 10, 22 ft 47 avail- 
able In ranges quoted. 

DUAL C0NCEKTR1C DP20 In any 
combination of F20 values, 60n; 
with switch, 72p. 

SLIDER ' 

Lin or log. 10K to lmeg. In all 

popular values, each SBp, 

Escutcheons — White, grey, black. 

XOp each. 

Control knobs: btk/whlte/redfyet/ 

gr.fbtue/dk. grey/It. grey, each Sp. 

CABBOK SKELETON PRE-SETS 

Small high quality. FR lln: 100 £1 
220 £1, 470 £1, IK. 2K2. 4K7, I0K, 
22K. 47K, 100K, 220K, 470K, 1M. 
2M2, BM. 10M£L Vertical or 
Slider horizontal mounting, Sp each. 



All items oflered for sale In accordance with onr stated 
terms of business, copy of which available on request. 
Prices quoted DO NOT Include V.A.T. 
Orders from U.K. customers mast be accompanied by 
an additional 10% of nett value lor V.A.T. 

DISCOUNTS A' of allowed on ntlt price Itemt. 
10% on order! lor £6 or more, 19% on orders for US or 
more. Prlcci »uB/ec( to alteration without prior notice. 

PLEASE SEE LATEST AMENDMENT LIST. SEED S.A.E. 



POSTAGE AND PACKING FREE 

STJBCHAHtxE IOp on small mall orders under £2. Overseas 
orders carriage and insurance charged at cost. 



f Dept. P.W, 8) 28 ST. JUDES ROAD., EMGLEFIELD GREEK, EGHAM, SURREY, TW20 0HB 

Hours: 9-5.30: Sat. 1 p.m. Tel.: Egham 3603 Telex 264475 

ESQ, ESQ. SO. 1047768. B.O. 28 8T. JUDES BOAD, EJOLEFIELD QBEEJ, EQHAM, SUBSET. TWBO OBB 



323 



SURPLUS BARGAINS 

BLOWER MOTORS small double ended blower will work 
on 6 to 28v DC, outlet size H sq. new boxed £1-79. HEAD/ 
MIKE SETS for 19 set m.c. type new boxed £1 -70. PANEL 
METERS 4 different for £1 25. MULTICORE CABLE 25 
core coloured new In 5' 9" lengths 2 for 86p. YAXLEY SWTS 
4p 11 w 4b with low value resistors and knob 76p. 4p 4w 2b 
with res. and knob 40p METER UNIT X pointer type dual 
115 Ua for use with 1155 Rx new £1 -58. TRIMMERS 20pf air 
spaced ceramic type new 10 tor 55p, £4-40 per 100, JOY 
STICK CONTROL UNITS operate 4x micro swts 1p c/o 
£1 35. HEADPHONE MATCHING TRANS. & LEAD, 
hiflh to low impedance 5ft lead with standard plug new 60p. 
LARGE TRANSISTOR PANELS with 2N560 transistors 
Sil N.P.N, type also conds. res. metal fittings etc. panel size 
13' x 12" new cond. two panels for £150 with min. of 40 
transls. PANEL LAMPS aircraft type suitable car Inst, panel 
with 24v m.e.s. bulb red or green two for 33p. METERS 500 
Ua scale to 5 \{" OSD on panel with 3p 3w swt. £1-25. 
WAVE METER & OSC. UNIT covers range 150 to 230 Mc/s 
with charts, spares, instructions etc. new boxed £16 50, 
MINIATURE FUSE HOLDERS take ±" fuse 4 for 33p. 
PLUGS & SKS Belling Lee type with cover 25 way 33p, 12 way 
22p, 8 way 16p. YAXLEY SWT UNIT with 4p 12w 4b &. 2p 
12w 2b with shorting wafer part of xtal selector 64p. POWER 
UNIT l/P 115v 50c/s O/P variable to 26v D.C. at 3 amps 
smoothed with circ. tested £7-70. CRT, type 7BP7A 7" dia, 
flat face tube 6-3v heater 7Kv E.H.T. emag focus and Del as 
Blue/Yellow phosfor suitable slow scan T.V. etc. new with 
base conn. £1-73. SILICON DIODES type ZR22 200 P.I.V. 
8 amps 4 for 66p also 800 P.I.V. 750 Ma new 15 for £1-10. 
INDICATOR UNIT 266 with 6" tube green screen 18 valves, 
slow motion dial, tuning conds. etc. with outer cover £4-95. 
POT CORES miniature pot cores wax dipped £ x i new 
10 for 33p. RADIO TELEMETER UNITS with 6 valves, tape 
unit, speaker, low speed motors, can be converted to Radio 2 
for use on 20Q,'250v mains in new cond. with circ. and mods. 
£4 18. SELSYNS for Ae position Ind. etc, for use on 115v 
50C/S supplied in pairs with a 360 deg. compass Ind. scale & 
pointer new £4. LAMPS aircraft type double filament with 
silvered reflector dual 14 watt 28v new 5 for 65p. NEONS 
wire ended type 1 /25th watt 470K res. for 240v new 10 for 55p. 
PRESSURE GAUGE thought to be oil press vehicle type 
elec. operated scaled to 120 2\ dia. new boxed 44p. CODER 
UNIT part of IFF equip. American surplus contains 10 valves 
12AT7, 6X4, 12AU7 etc. 13 miniature relays plug in type coil 
550 ohm 2p c/o will work on 12/24v also 12 miniature micro 
swts. complete in case good quality unit £2-70. VI D I CON 
CAMERA TUBES standard 1" type with base conn. etc. 
graded according to scan marks A £9, B £6. 
TAG STRIPS solder type 24 way new 10 lor 30p. SPEAKER 
UNITS P.A. type made by Truvox 8 ohm with line trans, in 
case 9" x 9" x 8" semi weather proof new cond. £3-13. BAT- 
TERIES 6 volt 40 A/Hr. type metal cased new with filling inst 
£3-19. XTAL OVENS with 12 type Hc6/u xtal holders these 
can be removed and used separate 76p. VALVES 5U4, 6X5, 
6SN7, 6SL7, 85A2, 12AT7, 12AU7, 12AX7, 6AK5, 6BH6, 6H6, 
6SK7M, 6SA7, 6N7M, 5Y3GT, 6J6, 6X4, VC173, EF50, 6BA6 
6SA6, CV2179 (Sim N78) any 3 for 55p. BATTERY BOX will 
take 4x U2 cells connected for 6 volts 48p. POLARISED 
RELAYS as 2 colls of 25 ohm each 1p c/l new 33p each. 



THE ABOVE PRICES INC. POSTCARR. & 
V.A.T. CHARGES 

Carr. charges apply to mainland only, all goods ex 
equip unless stated otherwise, S.A.E. with enquiry. 



A. H. SUPPLIES 

57 MAIN ROAD, 
SHEFFIELD, S9 5HL 

Phone 444278 (0742) 



VISIT LONDON'S LIGHTHOUSE 



our lighthouse keeper 
wants to meet you! 

Jim Roche has been Imhofs Eddystone tight- 
house keeper for a good few years now - so who 
better than he to guide you into the right channel, 
for an Eddystone communications receiver: 



Model 1001 - general- 
purpose receiver with 
reception facilities for 
CW,MCW,AMandSSB 
Provision for crystal 
control on 10 channels. 




EClOMkllstM'Topof 

the Pops' in the modest 
price range of communi- 
cation receivers. Em- 
bodies features usually 
only found in the more 
expensive designs. 



IMHOFS 




112-116 New Oxford Street 
London WC1 A 1HJ 

telephone 01 -636 7878 rsi 



Train for 
television 

Course commences 5th September, 1973 

This is your opportunity to train as a television 
and radio engineer on our full-time Two-Year 
* College Diploma Course specially designed to cover 
the examinations of the City and Guilds Radio, 
Television and Electronics Technicians' Certificate. 
Full theoretical and practical Instruction on all types 
of modern receivers— including the latest colour sets. 

Minimum entrance requirements are Senior 
Cambridge or 'O' Level, or equivalent In Mathematics 
and English. 



I Please send free prospectus to: 
| Name 



Address 



I THE PEMBRIDGE COLLEGE OF ELECTRONICS I 

(Dept. PW5) 34a Hereford Rd.. London W2 5AJ 
I— — — — —.—. — _., J 



324 






LOW POWER CLASS A AMPLIFIER 



R. A. Pen 



IN some applications, such as in small pocket 
receivers, only comparatively small output powers 
are required, and small modern loudspeakers 
produce adequate volume for a small room from 
only a few milliwatts of power. In fact most minia- 
ture speakers have a maximum power handling 
capability of only 100-200mW. 

While in the interests of battery economy class B 
amplification is usually used in the output stage of 
battery operated equipment, where only low output 
powers are involved, a simple class A circuit is quite 
suitable. Bearing these points in mind, the simple 
amplifier described below was constructed. 

Circuit Explanation 

A circuit diagram of the amplifier constructed by 
the author is shown in Fig. i. This uses three inex- 
pensive silicon n.p.n. transistors. 

VR1 is the volume control, and CI the input 
coupling capacitor. Trl — Tr2 — Tr3 are direct coupled. 
R2, and R5 bias the input transistor (Trl) so that the 
voltage present at its collector (approximately 0-65V) 
is at the correct level to in turn bias Tr2. Likewise, 
Tr2 is biased to just the right level to produce a 
voltage at its collector which is suitable to bias the 
output transistor, Tr3. In effect Trl— Rl form a 
potential divider which biases Tr2, and Tr2 — R3 
form a potential divider which biases Tr3. 

As each transistor inverts the signal between its 
base, and collector terminals, the input and the out- 
put of the entire amplifier are 180° out of phase. 
The two biasing resistors, R2, and R5 being con- 
nected between the input and the output therefore 
introduce a considerable amount of d.c., and a.c. 
negative feedback. While the d.c. feedback is very 



desirable as it gives stable biasing to a system which 
would otherwise be very critical, the a.c. negative 
feedback decreases the gain of the amplifier. This 
does however, give the amplifier improved quality 
(hi-fi). 

The gain of the amplifier can be increased by 
connecting a capacitor of a suitable value between 
the junction of R2 — R5, and earth. This decouples 
the a.c. signals through the biasing resistors, and 
virtually eliminates the a.c. feedback at audio 
frequencies. 

A compromise between gain, and output quality 
can be achieved by placing a feedback limiting 
resistor in series with the decoupling capacitor. In 
Fig. 1, C3 is the decoupling capacitor, and R6 the 
feedback limiting resistor. The value of R6 is the 
highest one which gives adequate gain for the ampli- 
fiers intended purpose, a value of 22kfl being used 
on the prototype. Its value can be varied to suit 
individual requirements, the required value being 
found by experimentation. 



2 3 t 5 g 7 g 9 10 « 12 13 H To S1 




fiffnasi 



C2 

30>JP 



r 



VR1 

5k 



Rl' 



ci 

9-1 pF 



ll- 



C4 330pF 




:" ::::■ 



R2 
470k 




R4 660 




R6 

Wv — 

see text 




O-lpF 



.R5 
-470k 



Fig. 2: Component layout on 
the Ver aboard. 



Fig. 1 ; The low power class A 
amplifier. 




R4, and C2 are the supply decoupling components. 
The loudspeaker itself forms the collector load for 
Tr3. Speakers of other impedances can be used, but 
must have an impedance of at least 35ft. Due to the 
large amount of d.c. negative feedback used in the 
circuit, altering the speaker impedance should not 
drastically change the operating parameters of the 
circuit. 

The low value capacitor, C4, is required in order 
to reduce the upper frequency response of the circuit, 
and so maintain good stability. Without this com- 
ponent, direct pick-up of radio signals can become 
a problem. 

SI is the on-off switch, and can be ganged with 
VR1 if preferred. 

The unit requires a 4-5V supply, an Ever Ready 
1289 battery being a very economical source of power 
for the amplifier, although if small size is required, 
three U16 batteries connected in series can be used. 

As the amplifier uses only a few components all 



of which are of a small size, it is easily miniaturised. 
A diagram giving a suitable Veroboard layout for 
the unit is shown in Fig. 2. The prototype built, to 
this layout measures only 1-4 x 0-9 x 75in. For 
obvious reasons miniature resistors, and components 
must be used. On the prototype a tantalum bead 
capacitor was used in the CI position, but a minia- 
ture electrolytic of 8-10,uF can be used providing it 
will fit into the available space. 

There is only one break which has to be made in 
the copper backing strips, this being between the 
negative side of CI, and the collector of Trl. A 
soldering iron with a fine bit is required when solder- 
ing the components to the board, and a continuity 
tester should be used to ensure that no excess solder 
is shorting two adjacent copper strips together. 

One cannot expect too much in the way of output 
quality from the amplifier, mainly because such a 
small speaker is used, but the unit is economical to 
run, small, inexpensive to build, and sensitive, and 
is very useful for many purposes. ■ 



CASSETTE RECORDER IN THE CAR 

ON a long trip it is often desirable that one 
can play one's cassette tape-recorder, but 
then it's battery life becomes very short. 
Since most cars use a 12 volt battery, the tape 
recorder cannot be run directly from the car's 
electrical system. One often used method is to con- 
nect a heavy resistor in series with the tape-recorder, 
but on a radio-cum-tape-recorder this method does 
not work since the tape recorder draws far more 
current than does a radio. 

This problem can be overcome by using a very 
simple stabilising voltaged supply consisting of only 
three components — a transistor, resistor and a zener 
diode. Before one selects any components, one 
must know exactly what one's requirements are — 
the figures given at the end of this article are for 
a typical cassette tape-recorder that draws a maxi- 
mum of 350mA. It is however easy to modify one's 
design to cope with almost any portable tape-re- 
corder. 

Firstly, what is the voltage of the machine? This 
is easily determined by counting the batteries and 
multiplying by 1-5, — most recorders are either 6, 
7-5 or 9 volts. Once the voltage has been determined, 
it is neccessary to find the maximum current that 
the machine will draw. To do this, remove one bat- 
tery and solder wires onto the ends of it. Connect 
an ammeter in series with the battery and by dabb- 
ing the wires where the battery was and by playing 
the tape recorder with it's volume fully turned up, 
the maximum current can be determined. 

Our next job is to choose a transistor. The only 
specifications that need concern us are it's power 
and current rating and it's current gain <hf<»). For 
a tape recorder, a 2N3054 is normally sufficient, but 
for a large machine, a 2N3055 might be neccessary, 
while for a small radio, a 2N1611 might suffice. To 
determine the power rating, we use the formula 
Power = IxV 

= I(V iu -V ou t) 

The zener diode is a low power device (250mW) 
and it's breakdown voltage is the required output 
voltage plus 0-6 volts, the latter being the emitter- 

326 



M. Vlietstra 

base voltage of a silicon transistor. The zener need 
not be specially selected, since a volt either way 
will have very little effect on the tape-recorder. 




Fig. i : Stabilising circuit for cassette recorders. 



The resistor (R) is the most difficult to calculate. 
The current that passes through it performs two 
functions: 

i) A current of normally at least 5mA to maintain 
the voltage across the zener diode. 

ii) The base current of the transistor. As a rule 
of thumb, this should be twice the maximum re- 
quired output current divided by the current gain 
of the device- 
Adding these two we get that the current through 
the resistor is (5 + 2 I ou i/hf e ) mA and assuming that 
the car uses a 12 volt battery, the value of the 
resistance, using Ohm's Law, is found to be: 



R m 



((12-V out +0-6)\ / V\ 

(5 + 2 Whfc) / \ 1/ 



The components given below are for a typical 
tape-recorder that draws 350mA. No list of prices 
is included as a person who cant build this for less 
than £1 just isn't trying! 



180fl 



Components. 


6V 


7-5V 


Resistor (* 2 W) 


330ft 


270ft 


Zener diode 


6-6V 


8 -IV 


Transistor. 




2N3054 



10V 




Build yourself aTRANSISTOR RADIO 



ROAMER 10 WITH VHF INCLUDING AIRCRAFT 



10 TRANSISTORS. 9 TUNABLE WAVEBANDS, MW1, 
MW2, LW, SW1, SW2, SW3, TRAWLER BAND. VHF 
AND LOCAL STATIONS ALSO AIRCRAFT BAND 

Built In Ferrlte Rod Aerial lor MW/LW, Betractable, chrome plated 7 section Telescopic 
Aerial, can be angled and rotated for peak short T a« and VH Flutening Push PuU output 
using OOOuw Transistors Car Aerial and Tape Record Sockets. 10 Transistors plus 3 
Diodes. Fine tone moving coil speaker. Ganged Tuning Condenser wuh ^ HF section. 
Separate coil lor Aircraft Band. Volume on/off. Wave Change and tone Control. Attractive 
Case in black with silver blocking. Size 9" x 7" x 4". Easy to folio* Instruction,, and 
diagrams. Parts price list and easy build plans 30p (FREE with nana). 



Total building cost 

£9-35 

F. P. & Ins. 5-'p 
(Overseas P. & F. £1 05) 



1 



1 ' '■■■<*wm 




ROAMER 

EIGHT 

Mkl 

NOW WITH 
VARIABLE 
TONE CONTROL 

7 Tunable Wavebands: MW1, MW2, LW, SW1, SW'i, 
SW3 and Trawler Band. Built in Ferrite Rod Aerial 
for MW antl I.W. Retractable chrome plated Tele- 
acopio aerial for Short Waves. Push pull output using 
6OO111W transistors. Car aerial and Tape record sockets. 
Selectivity switch. 8 transistors plus 3 diodes. Fine tone 
moving coil speaker. Air spaced ganged tuning con- 
denser. Volume/on /off, tuning, wave change and tnne 
controls. Attractive case in rich chestnut shade with 
gold blocklDg. Slie 9 X 7 x 4ln. appro*. Easy to 
follow Instructions and diagrams. Farts Price List 
and Easy Build Flans 25p (FREE with parts). 

Total building cost <C7>f|fl pp 



ROAMER 
SIX 



(Overseas P. & P. £105) 



Ins. i"p. 



POCKET 
FIVE 



7 Tunable Wuve- 
l.ands:MWl, MWil, 
LW, SW3, SW2. 
SW3 and Trawler 

Band. Extra Medium waveband provides easier tuning 
of Radio Luxembourg, etc. Built in ferrlte rod aerial 
for MW and LW. Retractable 4 section 211n. chrome 
plated telescopic aerial for SW. Socket for Car Aerial. 
Powerful push-pull output. 7 transistors and 1 diodes, 
fine tone moving coil speaker. Air spaced ganged 
tuning condenser. Vol unit fon /oil. tuning and wave 
change controls. Attractive case with carrying handle 
Size x 7 x 41 n. approi. Easy to follow Instructions 
and diagrams. Farts price list and easy build plans 
25p (FREE with parts). 

Total building costs £>Ci CD P. F-& 

(Overseas P. * P. £10S) d&U W Ins. 47 



S Tunable Wavebands: 

MW, LW, Trawler Band 

with extended M.W. 

band for easier tuning 

oi Luxembourg, etc. 

7 stages — & transistors and 2 diodes, 

supersensitive ferrlte rod aerial, fine 

tone moving coil speaker. Attractive black and gold 

case. Sire Ij X 1| X 3|in. Easy build plans and 

parts price list lOp (FREE with parts) 




TRANSONA 
FIVE 



5 TRANSISTORS , 
AND 2 DIODES 



3 Tunable Wavebands: MW, LW and Trawler Band. 
7 stage— S transistors and 2 diodes, ferrlte rod aerial, 
tuning condenser volume control, fine tone 
moving coil speaker. Attractive case with red speaker 
gTille. Size 6t x 4 t x Uln. Easy build plans and 
parts price list 10p (FREE with parts), 




6 Tunable Wave- 
bands: MW, LW, 
8W1, 8W2, SW3 
Trawler, band pi u s 
an extra Medium 
waveband lor 
easier tuning 
of Luxembourg 
etc. Sensitive fer- 
rite rod aerial and 
telescopic aerial 
tor Short Waves. 
31n. speaker. S 

stages — S transistors and •! nlooes. Attractive black 
case with red grille, dial and black knobs with pollsbed 
metal inserts. Size 9 X Ei x 2iln. approx. Easy build 
plans and parts price list 3Sp (FREE with parts). 

Total building costs £tAm^Q p. f. a 

(Overseas P. * F. £105) «*&™ WW Ins. 31p 



Total building costs OII.EA p.p. * I Total building costs £9* 75 ? F n C 

(Overseas P. A P. 65p) 3& tfi UU Ins.SJp - (Overseas P. & F, B*P> A£i ■ ** Ins, 25 



TRANS 
EIGHT 

8 TRANSISTORS 
and 3 DIODES 




S Tunable Wave- 
bands: MW, LW, 
SW1. SW2, SW3 
and Trawler Band. 

Sensitive ferrite rod aerial for M.W. and L.W. Tele- 
scopic aerial for Short Waves. 31n. Speaker, 8 Improved 
type transistors pins 3 diodes. Attractive case In 
black with red grille, dial and black knobs with polished 
metal Inserts. Size X oi X 2|in. approx. Fusil pull 
output. Battery economlser switch for extended battery 
life. Ample power to drive a larger speaker. Farts 
price list and easy build plans £5p (FREE with parts). 

P.P. A 

Ins. 33p 



Total building costs 

(Overseas 1*. * P. £1-05) 



£4-95 



"EDU-KIT" 



(Overseas F. « P. £105) 



BUILD RADIOS, AMPLIFIERS. ETC.. 
FROM EASY STAGE DIAGRAMS. FIVE 
UNITS INCLUDING MASTER UNIT TO 
CONSTRUCT. 

COMPONENTS INCLUDE: 

Toning Condenser: 2 Volume Controls: 1 Slider 
Switches: Fine Tone Moving Coil Speaker: Terminal 
Ferrite Rod Aerial: 2 Plugs and Sockets: 
Ratterv Clips: 4 Tag Boards: Balanced Armature 
Transistors: 4 Diodes: Resistors: 
Capacitors: Three \* Knobs. Units once 
] constructed are detachable from Master 
l_"nit, enabling them to be stored for 
future use. Ideal for Schools. Educational 
Authorities and all those Interested In 
radio construction. 

Farts price list and easy build plans Sap 
(FREE with parts). 

All parts including J?fi*f)R 
Case and Plans *° "•* 



Ins. 33 p 



RADIO EXCHANGE CO 



61a HIGH ST., BEDFORD, MK40 1SA. Tel. 0234 52367 

Reg. no. 78B372 

I enclose £ please send items marked. 

ROAMER TEN □ ROAMER SEVEN Q 

ROAMER EIGHT □ TRANS EIGHT □ 

TRANSONA FIVE Q ROAMER SIX O 

POCKET FIVE □ EDU-KIT □ 

Parts price list and plans for 

I Name 



FULL AFTER \ * 
SALES 1 * 

SERVICE i 



> * « * w****f*^ » »* «** * Address 



Calls is aide entrance " La veils" Shop 
Open 10-1 , 2.30-4.39 Mon.-Fri. 3-11 Sat. 
PLEASE NOTE: ALL PRICES INCLUDE VAT 



1 



I 

PVV55J 




Stereo 60 £7 80 
2000 Amp £22 00 
Transformer for PZB £2 95 
EXECUTIVE CALCULATOR £S0M 



PROJECT 60 KIT £250 

Our ertremely popular kit contains I he extra 
capacitors, din plugs and sockets, cable and fuse- 
holder needed to complete Project 60. 



IC RADIO CHIP TBA6S1 £210 

The world's most advanced IC radio Chip, Con- 
alns RF Amp, oscillator, mixer, tF Amps, wide 
range AGC circuitry and voltage stabilizer. With 
data £2 '10. Send S.A.E. for free leaflet. A kit of 
restators, capacitors and IF filters Is available to 
So with the chip for £1-75. 



S-OECS AND T-OECS 
S-DECS £1 44 

T-DECS «U 
M-DEC A £3 00 
16dll IC 
carriers £1 20 




SINCLAIR SUPER ICtl 



ONLY £2 00 




Max, supply volts 28. Power 6 Watts rms. Com- 
plete with free printed circuit board and 44 page 
instruction book. 



SWANLEY IC TOMORROW £2-50 

The World's most powerful IC amplifier. Similar 
to the above but operates at 35 volts max, supply 
and Hives 12 Watts rms output. Manufactured for 
us by a leading semiconductor company. Supplied 
with our Instructions and a 6 month guarantee, 
but no printed circuit. 



KITS FOR IC1Z AND IC TOMORROW 

Excspt for the power kits and speakers, all Items 
suit both Integrated circuits. 
DELUXE KIT 

nctudes all parts for the printed circuit and 
volume, bass and treble controls needed to com- 
plete the mono version £1 '45. Stereo version with 
balance control £3-30. 

BASIC KIT 

Contains components for the P.C. board and 

volume and simple tone controls. Mono version 

£1 25, Stereo version with balance control £2 90. 

POWER UNITS FOR THE IC12 

A set of components to construct a 28V 5 Amp 

power supply £2-27. Also suitable Sinclair PZ5 

fully constructed £3-97. 

POWER KIT FOR IC TOMORROW 

A set of components lo construct a 35V t Amp 

power supply £2-97. 

LOUDSPEAKERS FOR THE IC12 

Specially chosen for the IC12. 5* 8 ohm £100. 
5* x 8' 8 ohm £1-45. 10- t 6' 15 ohm £2-27. 
PREAMPLIFIER KITS 

Type 1 for magnetic pickups, mlcs and tuners, 
with 3 position equalization switch. Mono model 
£1 20. Stereo model £2 20. Type 2 for ceramic or 
crystal pickups. Mono 60p, Stereo £1 20. 
SEND S.A.E, FOR FREE LEAFLET OH KITS 



BATTERY ELIMINATOR BARGAIN £3 40 

Introducing tha most 
versatile battery 
eliminator ever offered, 
with a high current 
output that makes it 
suitable for operating 
most battery tape recor- 
ders, record players, 
cassette recorders and 
shavers. Input 200/240V . 
Output voltage selected 
by front panel switch 

may be set to 3V, 4-5V, 6V. 7 5V, 9V and 12V at 
500 ma. Housed in a very strong, attractive, plastic 
case and fully guaranteed for 12 months. 




SWANLEY ELECTRONICS 

32 Goldsei Rd., Swanley , Kent 

Post lOp per item. Please add 10% extra to total 
cost of order for VAT. Official credit orders 
welcome Irom schools etc. Full lists lop post free. 
Mail order only. No callers please. 



H.A.C. 

WORLDWIDE RECEPTION 



SHORT-WAVE 
KITS 




FamouN fur over 35 year* for Short-Wave Equip- 
ment r>i quality, "H.A.C" were the Original 
suppliers of armrt-Wavt; Receiver Kits lor the 
amateur constructor. Over 10,000 satisfied 
cuwtdiners— iticluilinn Technical Colleges. Hos- 
pital^ Public Bchoola, R.A.F., Army, Mains, etc. 

HEW "DX" RECEIVER 
Complete kit —price 43 85 (Incl. p. A p. & V.A.T.). 
Customer writes: "'AuHtraJla, India, and America 
at loud volume." — "I am 14 years ol urc and 
have liuriteil over 130 Htatlons, plus countless 
Amateurs from all over the world." 
This kit contains all genuine short-wave com- 
ponents, ilnili'i] chansls, valve, accessories and lull 
instructionri. Ready to assemble, arid of coarse, 
as all our products — fully- guaranteed. Full range 
ol other 8.W. kits, including the famous model 
"K" and "K plus" (illuslratcd above). All orders 
despatched by return. Send now for free descrip- 
tive catalogue, test report and order form. 
EXCITING COMPETITION for Short -Wave 
listeners. Bend stamped envelope for details. 



"HXC" SHORT-WAVE PRODUCTS 
29 Old Bond Street, London W.I 







UHF TV AERIALS 

SUITABLE FOR COLOUR AND MONO- 
CHROME 
RECEPTION 
All U.H.F. aeri- 
als now fitted 
with tilting brac- 
ket and 4 de- 
ment reflector. 
LOFT MOUNTING ARRAYS 
7 element 2-25. 11 element 2-75. 
1 4 element 3 25. 1 8 element 3 75 
WALL MOUNTING c-w 
WALL ARM & BRACKET 
" clement 3-25. 11 element 3-75, 14 clement 
4 25. 18 element 4 75. CHIMNEY MOUNT- 
ING ARRAYS c-w MAST & LASHING 
KIT. 7 element 4 00. II element 4-50. 
14 elemenl 4-75. 18 element 5-25. MAST 
MOUNTING arrays only. 7 element 2 25. 
11 element 2-75. 14 clement 3-25. 18 ele- 
ment 3-75. Complete assembly instructions 
with every aerial. LOW LOSS coaxial cable 
9npyd. KING TELEBOOSTERSfrom 3 75. 
LABGEAR PRE-AMPS 4 25. 

BELLING LEE CONCORD BOOSTER 

V.H.F., F.M., U.H.F., mains operated 8-20. 
State clearly channel number required on all 
orders. P. p. on all aerials 50np. Aces. I5np. 
C.W.O. Min. C.O.D. charge 25np. 

F.M. Radio Aerials 

P.M. RADIO loft S/D 1-00 3 element 3-25. 
4 element 3 50. Standard coaxial plugs 9np. 
Coaxial cable 5np yd. Outlet box 30np. 
P.p. all aerials 50np, Aces. 30np. C.W.O. 
Min. C.O.D, charge 25np. Send 5np for fully 
illustrated lists. 

CALLERS WELCOMED 
OPEN ALL DAY SATURDAY 

K.V.A. ELECTRONICS 

40-41 MONARCH PARADE. LONDON 

ROAD. MITCHAM, SURREY 

Telephone 01-648 4884 



«&> 



LOUDSPEAKER 
BARGAINS 



n 



Fane Pop 100 watt 18" 8/15 ohm £21-45 
Fane Pop 60 watt 15" 8/IS ohm £12-26 
Fane Pop 50 watt 12" 8/15 ohm £10- 17 
Fane Pop 25/2 25 watt B/ 1 5 ohm £5 94 
Fane Pop 15 12" 15 watt 8'I5 ohm £4-40 
Fane 1 22/ 10a or 122/12 ... ' ... £9-90 
Fane Crescendo 15° 8 or 15 ohm £27 50 
Fane Crescendo 12" 8 or IS ohm £24 20 
Fane 8" d/cone 808T 8 or 15 ohm £2 64 
Fane 8" d/cane, roll sure 807T 

8 or 15 ohm £3-16 

Baker Group 25 3, 8 or 15 ohm £6-00 
Baker Group 35, 3, 8 or IS ohm £7-50 
Baker De Luxe 12" d/cone ... £9-62 
Baker Major ... ... £7-50 

EMI 13 x 8 3, 8 or 15 ohm ... £225 
EMI 13x8 type 150 df'cone 3, 8 or 

15 ohm ... £2 58 

EMI 13 x 8 type 450 t'tw 3. 8 or 

15 ohm £3-85 

EMI 13x8 type 350 8 ohm ... £8-25 
EMI 6|" 93850 4 or 8 ohm ... £2-80 
Elac 9x5 59RML09 15 ohm ... £2-53 
Elac 9x5 59RMLL4 8 ohm ... £2-53 
Elac 6i" d/cone 6RM220 8 ohm ... £2-59 
Elac 6|" d/cone, roll surr. 6RMI7I 

8 ohm ... £3 22 

Elac 4" tweeter TW4 8 or 15 ohm £1-21 
Cetestion P58 for Unilex ... £2 16 

Celestion MFI.000 25 watt horn 

8 or 15 ohm £10-45 

Elac 5" 3 ohm £1-75 

Elac 7" x 4" 3 or 8 ohm ... £1-52 

Elac 8" x 5" 3. 8 or 15 ohm ... £1-93 
Wharfedale Bronze 8 RS/DD ... £3- II 
Wharfedale Super 8 RS/DD ... £5-50 
Wharfedale Super 10 RS/DD ... £9-80 
Goodmans 8P 8 or 15 ohm ... £3-80 
Goodmans I0P 8 or 15 ohm ... £4 49 
Goodmans I2P 8 or 15 ohm ... £11 55 
Goodmans ISPS or 15 ohm ... £17 05 
Goodmans I8P 8 or 15 ohm ... £29-70 
Goodmans Twinaxiom 8 ... ... £6-79 

Goodmans Twinaxiom (0 ... £7-61 

Goodmans Axent 100 , £6 60 

Eagle DT33 dome tweeter 8 ohm £5-45 
Eagle HTI5 tweeter 8 ohm ... £3 66 
Eagle CT5 tweeter 8 ohm ... £1-25 

Eagle MHT10 tweeter £3-74 

Eagle CTI0 tweeter ... ... £2-54 

Eagle FR4 £4-45 

Eagle Xovers CIM23. 28, 216 ... £1 IS 

Kef T27 £4 67 

KefTIS £5-50 

Kef Bl 10 ... £6 16 

Kef B200 £7 42 

Kef BL39 £10 72 

Kefkit 2 £24 75 

Richard Allan 12" d cone 3 or 

15 ohm £2 20 

Richard Allan 8" 3, 8 or IS ohm £2-27 
10" x 6" 3, 8 or IS ohm ... £1-92 

8" x 5" 3 or 8 ohm £1 38 

7" x A" 3 or 8 ohm £1-38 

3" 8 ohm or 80 ohm ... ... -65 

2±" 64 ohm 65 

Speaker matching transformer 3, 

8 or 15 ohm £1 - 10 

Adastra Hiten 10* 10 watt 8 or 

IS ohm £2 80 

Adastra Top 20 12" 25 watt 8 or 

15 ohm £632 

Stephenspeaker kits and cabinets — send for 
illustrated brochure and list of recom- 
mended speakers. 

Car stereo speakers — ask for leaflet. 
PA/Disco amplifiers (carr, and ins. £1 -00): 

Baker 100 watt £46-00 

Linear 30/40 ... £25-00 

Linear 40/60 £30-00 

Linear 80 100 £50 00 

FREE with speaker orders over £7 "Hi-Fi 

Loudspeaker Enclosures" book. 
All units guaranteed new and perfect. 
Prompt despatch. 

Carriage and insurance 2Sp per speaker. 
(Tweeters and Crossovers ISp each.) 
All prices quoted inclusive of V.A.T 

WILMSL0W 

AUDIO, Dept. PW 

Swan Works, Bank Square, 
Wilmslow, Cheshire, SK9 1HF 



328 








A COMMON circuit arrangement in 
the popular construction journals 
is that which allows temperature to 
control something— a sort of elec- 
tronic thermostat. 

Perhaps the most featured circuitry 
is that which has some, form of tem- 
perature sensor (say, a thermistor) 
followed by a transistor or two which, 
in turn, drives a meter (for tempera- 
ture to be read from a pre-calibrated 
dial) or a relay to actuate some form 
of control circuit. 

Out on to the electronics market 
has come a new type of reed switch 
which can perform this kind of func- 
tion—and without the need for any 
further electronic circuitry. 

Basically, the reed switch has two 
contact blades which form a simple 
on-off switch. Around the glass tube 
which houses these contacts is a coil. 
Energising the coil causes the con- 
tacts to open (or close) while remova 
of the energising source causes the 
blades/contacts to return to their 
original state. 

The new devices have the glass 
capsule and reed relay blades. In- 
stead of a simple coil of wire, the 
capsule is surrounded by torroidal 
magnets which are separated by a 
ferrite material. Because the ferrite 
material separates the magnets, it 
also has the effect of separating their 
individual magnetic fields. 

However, the particular make-up of 
the ferrite employed is such that there 
is a certain critical temperature point 
called the Curie point. Below this 
point, the ferrite no longer isolates 
the magnetic fields of the separate 
magnets and thus the switch can be 
caused to activate. 

Once the temperature rises above 
the Curie point, the magnetic fields 
are again separated. Thus there is a 
complete switching action actuated 
only by temperature, and the reed 
blades themselves can be used to 
form a switch. There are many uses 
which will come to mind; standard 
units in the range extend from 0°C to 
100 e C in 5C steps. 



LIGHTS UP 

Turning to the "lighter" side of 
smoking, solar cells are being used in 
electronic lighters to keep the bat- 
teries charged. One set of experi- 
ments shows that some 50 cigarettes 



ON RECENT DEVELOPMENTS 



a day can be lit for a month before the 
batteries need recharging by expos- 
ing the light-cells to a light source. 
It seems reasonable to assume that 
one could leave such a lighter out in 
the open for various periods of time 
and thus the batteries would remain 
charged for far longer than a month. 
Work is proceeding to improve the 
efficiency of solar cells as a means of 
supplying energy from ordinary day- 
light, i.e. without any sunshine at all. 
This should be a useful project for 
people living in or around Manchester 
on a rainy day. 



ALL TOGETHER 

Electronic calculators have become 
very real practicalities over the past 
few years. Progressing from the 
realms of theory they are now offered 
by the van load in a wide variety of 
shapes and sizes. Many things have 
contributed to the progress of elec- 
tronic calculators not the least of 
which is the development of the i.e. 
which does all the calculating. The 
aim has been to be able to boast "A 
calculator on a chip". 

Well, the dream gets closer every 
hour. A company has now brought 
out a chip which very, very nearly 
achieves this title. The low power 
calculator circuitry is on the same 
glass panel as the liquid crystal dis- 
play. Thus the thing is literally a com- 
plete calculator on a single substrate. 

But what of the buttons or keys 
which input the information? Well, 
the manufacturers have thought of 
that too — yes, and it's on the same 
panel. The inter-digitised contacts 
are shorted by a conductive rubber 
button whenever a key is depressed. 
Standby power is only 12mW and the 
calculator runs for about 100 hours 
from a single pen-sized cell. Sorry, 
they are not for sale in the U.K. as yet. 



VERY HIGH-BROW 

Capacitors are one type of com- 
ponent which seems to be getting 
ever smaller. The photograph on this 
page shows five tantalum chip capa- 
citors from the range manufactured 
by Union Carbide. The T400 series 
has nine case sizes; values range 
from Q'l^F and can withstand tem- 
peratures of up to 300X. Those 



8*U(j 




PPH 



shown in our photograph are for a 
very "high-brow" application — at 
least, "eye" think they are. 

Down in the forest something 
stirred, so we're told. In a certain 
Bavarian forest it is more than stir- 
ring. Laser equipment, supplied by 
Siemens, measures the trajectory of 
survey satellites. Power of this laser 
is 100MW (100 megawatts or one 
hundred million watts). One wonders 
if, in the decades to come, this type of 
equipment will be towed away from 
Lisle Street shops as surplus stock 
by delighted Amateurs who may have 
just given £1-75 for them. If this 
happens one must ask whatever will 
replace such equipment? 



LITTLE THINGS 

Little things please little minds so 
we're told, but sometimes it's not 
that cynically simple, Cramming a 
few thousand semiconductors into 
a dual in-line package is a common 
occurrence today, but what of the 
devices which are very difficult to 
integrate? Items such as tuned 
circuits are a problem. However, 
solutions are on the way, in the form 
of subminiature inductors or "coils". 

Described as monolithic chip in- 
ductors, these minute devices are 
made by stacking U-shaped con- 
ductor patterns which have been 
screened onto a special ferrite tape. 
The U-shaped patterns are stacked 
such that when the individual ends 
of each U are connected to the U's 
above and below, a continuous "coil" 
pattern is achieved. When this has 
been done, the complete stack is 
"fired" resulting in a monolithic 
structure. 



Q*£4W< 






LOOKING AT THE 



London 




SHOW 



THE four-day London Electronic Components 
Show at Olympia, London opened on Tuesday 
22nd May, the guest of honour at the inaugural 
luncheon being H.R.H. The Duke of Kent, who later 
made quite an extensive tour of the Show. 

The Show's sponsors, the Radio and Electronic 
Components Manufacturers Federation, celebrating 
their 40th anniversary this year, managed to get no 
less than 480 companies to exhibit the very latest 
developments in electronic components and asso- 
ciated instruments, equipment and services. 

Olympia 's two main halls were utilised for this 
massive event and special preparations were made 
to receive and attend to the needs of the many 
visitors from abroad. Almost one-fifth of the stands 
belonged to exhibitors from overseas with represen- 
tatives from more than sixteen countries including 
Australia, Austria, Belgium, Canada, Denmark, 
Hungary, Japan, West Germany, Spain, Sweden and 
the USA, 

During the Show three discussion and question 
sessions were held outside at the Royal Westminster 
Hotel, being arranged jointly by the RECMF and 
the Institution of Electronic and Radio Engineers. 
The subject "European Component Survey" covered 
the aspects of component testing, evaluation and 
development. 

Visitors to the Show were invited to try their luck 
in various competitions in which very attractive 
prizes such as an 8-track tape recorder, a £100 watch 
and even bottles of whisky could be won, not to 
mention a holiday for two in Rome! 

All the components in the world would not be of 
much use if the many units into which they are fitted 
could not be connected together by means of efficient 




Specirol Reliance Ltd. were justifiably proud of this large number of 
permutations of their Model 534 'Universal' potentiometer. 

330 



connectors. In 1971 over £22 million of the electronic 
components market was accounted for by the sale 
of just such connectors. 

About every possible variation of connector was 
on show with Amphenol making them their main 
theme on their stand together with switches, lamps, 
relays and indicators. Ultra Electronic Components 
featured a new range of connectors and accessories 
for use with printed circuit boards as well as an 
improved version of their 0-lin. pitch modular edge 
connector, Other products on their stand included 
plugs and sockets, terminal blocks, rotary wafer 
switches and water activated batteries. 

AMP of Great Britain also had a wide range of low 
cost pin and socket and flat flexible cable connectors. 
They manufacture just about everything needed in 
solderless, crimped terminations and can supply 
everything from a single terminal to computer- 
plotted wiring system components. 




In spite of their long and world wide reputation for testmeters, only 

now have AVO Ltd, started producing a line of pane! mounting meters. 

Two of the new Dinline series are shown above. 



AVO celebrated their Golden Jubilee with the 
introduction of their first-ever range of panel mount- 
ing meters. The new Dinline Fifty range marks, not 
only fifty years of Avo, but also their entry into 
Europe, with styling based on the rectangular DIN 
(IEC 51) specification. The matching series of eight 
models is available in two presentations, a moulded 
black finish and glass window or clear Macralon 
ensuring entirely shadow-free readings. 

Sealectro's stand had their complete range of pro- 
ducts which includes RF connectors, multi-pin con- 
nectors, plugboards, insulated terminals, rotary 
switches and punched card readers. Centre piece of 
this display was the new series of punched card 
readers, the new 4mm grid plugboard system and the 
new FR/SR series of two-piece insulated terminals. 
New items in the RF range include a high isolation 
coaxial switch and a range of 75 ohm connectors 



to 



DIN 47295. Sealectro's technical staff demonstrated a 
miniature RF connector assembly using flexible and 
semi-rigid cables. 

Filler International Limited, were exhibiting in the 
United Kingdom for the first time. Piher are already 
among the world's leading suppliers of carbon film 
resistors with a daily output of some seven million 
resistors from their headquarters at Badalona near 
Barcelona. Over 90 per cent of their production goes 
to export markets, principally the United States, 
Germany and the United Kingdom. On Piher's stand 
could be seen many samples from their range of 
carbon film resistors, trimming potentiometers, small 
signal and medium power transistors and capacitors, 
and particular interest centred on a new range of 
preformed resistors. 




One of the Series C16 Cermet pocentiometers by AB Electronic 

Components Ltd. Standard models range from 100CI to 2-SMCl, linear, 

but special models down to SOU and up to 10MQ are aval/able, with 

soldering tags or printed circuit terminals. 



Hungary was represented by Elecktromodul who 
were showing components for telecommunication, 
engineering and electronics. Products on display 
included ferrites, electrolytic capacitors and ceramic 
capacitors. 

Audax SA, from France, exhibited examples from 
a wide range of loudspeakers, while Societe Franc aise 
de l'Eleetro-Resistanee had on display metal film and 
ni-rel resistors, carbon and cermet track potentio- 
meters and trimmers, plastics potentiometers and 
cermet film micro-circuits. 

Cosmocord-Stolec Limited were showing, for the 
first time in the United Kingdom, a range of low- 
cost multimeters and insulation testers, plastics 
mouldings and audio transcription transducer 
equipment. 





One Item from the vast range of drives, dials and tuning capacitors 

from Jackson Bros. Ltd., a miniature ball drive with a 10:1 reduction, 

Type 5870. 



New ranges of DIN plugs and sockets and instru- 
ment components were featured by Tape Recorder 
Spares Limited. Audio and electronic components, 
switches, mains units, wire measuring and storing 
equipment and wire cutting and stripping equipment 
were among other products shown. 



were am 





Watson Anodising Limited had a range of name- 
plates, labels, instrument panels, plain and printed 
chassis as well as examples of the general printing 
they undertake for the electronics industry. 

Rectifiers, thyristors and triacs from Raytheon-TAG 
Components Limited included glassivated and planar 
plastics encapsulated thyristors and triacs, plastics 
encapsulated 10A rectifiers to 1300V, fast turn-off 
rectifiers and diffused SCRs up to 35A and triacs up 
to 25A RMS. 

Radiatron Components Limited stand had a display 
of components and accessories ranging from collet 
knobs, instrument cases and housings to relays, con- 
nectors, switches and automation modules. 

For visitors to the show interested in television, 
AB Electronic Components Limited makers of the 
only touch tuner made in the United Kingdom, which, 
when announced last year was the only one made 
anywhere in the world, is. perhaps the best known of 
their products. Connectors, potentiometers, switches 
and thick film microcircuits are among others. 
Sharing AB's stand was Wolsey Electronics, a division 
of AB, showing various aerials and their range of 
radio and television master aerial and amplifier 
svstems. 




This 25-turn preset potentiometer by AB Electronic Components Ltd. 
is of carbon composition construction intended for use with var/cap 
tuners. Resistance ranges up to fOOkQ in linear, logarithmic or diode 
characteristic law. 

Solder, one of the most important materials used in 
electronics, was shown in all its forms by Multicore 
Solders Limited. Cored solder, solder creams, bar 
solders as well as liquid fluxes and chemicals for 
hand and wave soldering were included in their 
display. Some 50 per cent of Multicore products are 
exported to 107 countries throughout the world — one- 
quarter of the exports going into the competitive 
U.S.A. market. 

Soft solder, fluxes, chemicals, solder preforms and 
samples from a wide range of solder products were 
to be seen on the stand of Enthoven Solders Limited. 

A heavy duty aerial rotator was among communi- 
cations, marine, television and radio aerial equipment 
featured by J-Beam Engineering Limited. 

Communications cables, instrumentation cables, 
equipment and connecting wires, winding wires, 
mineral insulated heating cables and thermocouples, 
solder coated copper wire, silicone insulated fine 
wires and connectors were displayed by BICC. 

The wire-wound component is one of the oldest 
devices used in electronics and remains an important 
adjunct in the industry. Gardners Transformers 
Limited, who specialise in this field, have orders 
currently valued at £450,000 — a quarter of which 
come from overseas. They were displaying trans- 
formers, inductors, filters, delay lines, inverters, 
converters, power supplies and modules. 

331 



Having recently merged with the Allen-Bradley 
Company of Wisconsin, USA, Morganite Resistors 
Limited had a wide range of resistors, potentiometers, 
switches, thin film and thick fiim networks, capacitors, 




from a single master oscillator. Three packages can 
be cascaded to produce a complete octave of semi- 
tones, while further octaves can be generated by 
using compatible six-stage binary divider circuits. 

Among new transistors by Milliard for use in high- 
power, high-quality audio amplifiers are families of 
complementary pairs that can give outputs of up to 
100W. For example, in applications where an output 
of 6 to 15W is required, pairs from the transistor 
family BD433 to BD438 are suitable. (Odd numbers 
are n-p-n types, and even p-n-p.) These have a maxi- 
mum Vceo rating of 22 to 45V and a total dissipation 
of 36W. 

Silicon power transistors type BD266 and BD267 
form a complementary pair that can give a high- 
quality, audio output of 25W; they are also suitable 
for use in general purpose amplifiers and switching 
applications. Both are monolithic epitaxial-base 
Darlington transistors. 

Other new Darlington devices seen were types 
BDX62 to BDX67, which are power transistors with 
TO-3 encapsulations. Complementary pairs selected 
from these for use in audio amplifiers will give out- 
puts of 25 to 100W. 



A Tekdata Ltd. flat flexible cable in FibaTEK p.v.c. material. This 
custom-made cable uses 710-193 and 1410-193 wires. 

filters and industrial controllers from both of their 
product lines. Not previously shown in the United 
Kingdom, the Morganite cermet single turn potentio- 
meter, type 90, with a power rating of ■ 5 watt and a 
resistance range of 10 ohms to 2 megohms, is designed 
for commercial and industrial applications. New from 
Allen-Bradley is the "Mod-Pot", a variable resistor 
available in single, dual, triple and quadruple con- 
struction plus potentiometers, line switches and 
vernier drive modules. 

A. F. Bulgin & Company Limited commemorate 50 
years as electrical and electronic component sup- 
pliers. During the last 12 months some 40 new 
products have been introduced, the complete range 
now containing over 15,000 items. Examples on show 
included fuses, fuseholders, knobs, switches, signal 
lamps, and plugs and sockets. 

Custom-built specialists in MOS, bi-polar and 
hybrid thick film technologies, GEC Semiconductors 
Limited had a new phase control circuit for con- 
trolling triacs when driving small electric motors. 
One interesting device also on display was the 
MA 1705, a MOS integrated circuit developed for 
use in electronic musical instruments and syn- 
thesisers. It generates four notes on an equally 
tempered scale by dividing successively by 1 0595 




The Series 880 focus control has been specially designed by AB 

Electronic Components Ltd. for colour TV receivers and can be 

mounted on a metal chassis. The maximum continuous operating 

voltage is 10W. 

332 




Rather large, but a component never-tf.e-lessl The A51-160X Pre- 
cision in-Ltne colour TV tube assembly features a slotted shadow 
mask, Integral neck components and factory-set static/dynamic 
convergence and purity adjustments, The June issue of our com- 
panion magazine Television featured a technical article on the new 
Thorn tube. 

The use of Mullard circuit modules and integrated 
circuits can reduce the design costs and assembly 
times of good radio receivers, a.m. and f.m. Different 
arrangements, demonstrating the ease with which a 
variety of receivers can be designed, were shown. 

New to the United Kingdom and exhibited by 
Bird Electronic Limited, was the Bird model 4370 
wide-band Thruline wattmeter and model 4342 com- 
bined power meter and VSWB monitor. Coaxial load 
resistors, attenuators, coaxial switches, filters and 
calorimeters were also shown. 

Included in the Spear Engineering Company 
Llmited's display were power transistor holders, 
connectors, valve and tube base mouldings and 
printed circuit assembly fixtures. ■ 








R.PENFOLD 



on. This causes the voltage at the collector of Trl 
to be at a very low level, and Tr2 receives only a 
very small amount of base current through R3. This 
means that Tr2 is turned off, and the relay will not 
operate. 

When light falls on the ORP12, its resistance will 
decrease and it will have an earthing effect on the 
base of Trl. This will cause a decrease in the current 
flowing through Trl, and the voltage at the collector 
will swing to a high level. Tr2 can now obtain quite 
a heavy base current and will turn on, operating the 
relay. The voltage at the collector of Tr2 will now 
be at a low level, and it is Trl that is unable to 
obtain any appreciable base current, and will thus 
be turned off. Even if the light is now taken off the 
photocell, the circuit will still remain in the same 
state, as Trl will still be unable to draw sufficient 
base current due to the low voltage at the collector 
of Tr2. 

The circuit may be reset by two methods. A push- 
button switch may be connected between Tr2 base 
and earth. When this is operated it will have the 
same effect as when light fell upon the photocell, 
except it will have the opposite result. Alternatively 
the unit may be turned off, and then turned on 
again. 

A protective diode is connected across the relay in 
all the circuits shown. This is to prevent the high re- 
verse voltage, which is induced into the relay coil by 
the collapsing magnetic field as the relay is turned 
off, from damaging the transistor. Almost any diode 
will work in this position. 



LIGHT operated switches are extremely useful 
devices which have a number of uses in 
burglar alarms, automatic parking lights, etc. 
Most designs for these switches work along the 
lines of the circuit shown in Fig. 1. The ORP12 
photo-resistor is a device which in total darkness 
has a very high resistance (usually a few megohms), 
but when light falls upon it, the resistance will fall 
to a very low level (usually a few hundred ohms). 

It will be seen that in the circuit shown in Fig. 1, 
when there is no light falling on the ORP12, there 
will be very little base current flowing. In conse- 
quence very little collector current will flow and so 
the relay will not operate. However, when a small 
amount of light falls on the photocell, its resistance 
will drop, and a larger base current will flow, causing 
a larger flow in collector current, which will operate 
the relay. 

Latch on circuit 

The relay will only remain on for as long as light 
is falling on the photocell. This renders this type of 
circuit unsuitable for many applications. For ex- 
ample, if a burglar alarm which is meant to be 
triggered by the light from the torch of an intruder 
is required, if the circuit of Fig. 1 is used, the alarm 
will only sound for the period the torch is aimed at 
the photocell. This is of course of no use. A circuit 
which will remain operative once it is triggered is 
required. 

A suitable circuit is shown in Fig. 2, based on a 
bistable multivibrator. When the circuit is turned 
on, as there is a far lower resistance to the base of 
Trl through the relay and R2 than there is through 
Rl and R3 to the base of Tr2, Trl is switched hard 



-I-9V 




Fig. f : Typical photoelectric switch. 



+9V 







Fig. 2'. Circuit suitable for applications where the relay must remain 

on once operated. 

333 






Higher sensitivity 



The circuit of Fig. 2 does lack sensitivity and the 
ORP12 has to be almost fully illuminated before the 
relay is triggered. A more sensitive circuit is shown 
in Fig. 3. This circuit requires an extra transistor, 
and although BC183L is specified, the circuit should 
work equally well with any high gain, silicon, n.p.n. 
transistor. 



+9V 




Fig. 3 : Sensitive circuit using three transistors. A 25kQ potentiometer 
may be placed in series with the ORP12 to control sensitivity. 



With no light falling on the photocell it will have 
a high resistance. Trl will receive very little base 
current, and will have a high resistance between the 
collector and emitter. Rl also has a fairly high 
resistance and this will prevent much current flowing 
to the base of Tr3. This transistor will cut off while 
Tr2 is turned on, as occurred in the circuit of Fig. 2 
when a small amount if light falls on the photocell, 
its resistance will fall, causing the resistance of Trl 
to fall by a far greater amount. 

When this resistance reaches a low enough value, 
the voltage at the collector of Tr2 will be at a fairly 
high level. A large base current will now flow, 
turning on Tr3, and operating the relay. The voltage 
at the collector of Tr3 will drop, turning off Tr2. 
If the light is now taken away from the photocell, 
the resistance between the collector and the emitter 
of Trl will again be very high. The resistance of 
Trl and Rl will be just sufficient to give enough 
base current to Tr3 to hold the relay on. 



Broken light beam alarm 



Another type of alarm sometimes used is one in 
which a beam of light is aimed from one side of a 
room, or a doorway, to a photocell the opposite 
side. If anyone then passes between the two, break- 
ing the beam, the alarm is sounded. A suitable 
circuit for an alarm such as this is shown in Fig. 4. 

This works in very much the same way as the two 
previous circuits. When light is falling on the photo- 
cell it will have a resistance very similar to that of 
R2 in Fig. 2, and the circuit will behave in the same 
way initially. When the light to the photocell is 

334 



•+9V 







Fig. 4: Circuit for operating in a dark room. 



interrupted, it will exhibit a high resistance. Trl 
will receive very little base current, the voltage at 
its collector will rise, Tr2 will be able to obtain a large 
base current, and will turn on. The voltage at the 
collector of Tr2 will drop and, even if light is now 
restored to the photocell, Trl will be unable to draw 
any appreciable base current. Thus Tr2 is able to 
draw a heavy base current and the relay remains on. 

The circuit may be reset in the same way as the 
two previous circuits. For the circuit to function 
correctly, the room in which the photocell is situated 
has to be fairly dark, of course, or the light in the 
room will keep the relay off, regardless of the light 
beam. 

These circuits are all fairly simple, and inexpen- 
sive, but should prove useful and interesting. With a 
little imagination a number of uses, other than those 
mentioned, may be found for the circuits. ■ 



OCTOBER IS 

issue Mo sop 

Will you be celebrating with usP 



If so. you ivf receive with your October copy of 
Practical Wireless the first pair of PW Datacards 
absolutely free. A special "Going Back" feature 
with reproductions from early issues of Practical 
Wireless; the introductory article in our new series 
on Q4; "Experimental Workshop" and many other 
special and regular features wilt also appear. 
Further details next month. 

The October issue is on sale September 7th. 




THE FIRST OF OUR 
SPECIAL AUTUMN ISSUES.... 

. . . will give full details of how to make our 
two-band, two-i,c. "pop" radio receiver, 
... will give full details of the PW Datacard 
System announced elsewhere in this issue. 
. . . will reveal the identity of Q4, 
. . . will contain straightforward constructional 
projects designed around integrated circuits, 



Specially designed to simplify construc- 
tion, this smart looking radio uses two 
integrated circuits: a ZN414 for processing 
radio signals and an SL4G3D as the ampli- 
fier to drive an 8- or 15-ohm loudspeaker. 
Medium wave stations and Radio 2 (long 
wave) are covered with a very simple 
aerial coil; no alignment problems arise. 
The amplifier is designed to give 1 to 3 
watts of output power and is ideally suited 
for a teenagers' room, kitchen, bathroom, 
in fact almost anywhere. 




SIMPLE 2-BAND RECEIVER 



* 



ANALOGUE D.G. 
VOLTMETER 




This very simple instrument is based on the 
popular 741 i.e. and with a minimum of other 
components is capable of voltage measurements 
up to 100 volts d.c. in five ranges. Accuracy on 
low voltage ranges is very good and the input 
sensitivity is much greater than in the conventional 
multimeter. 



Short-Wava 

Converter for 

your MW 

receiver, 

i.c. & 

POWER 

REGULATOR] 
MODULE 



DON'T MISS ANY ISSUE OF PRACTICAL WIRELESS • SEPTEMBER ISSUE ON SALE AUGUST 3rd 



335 



Student 
OSCILLOSCOPE 



Parti 

SIMPLE TO BUILD 



INEXPENSIVE • ONE 



IT occurred to the writer that many readers, being 
'brought up' on transistors, would not have had 
the opportunity to learn about the oscilloscope 
from the 'bottom up' and that a basic transistorised 
design, with modern construction methods, would he 
welcomed. 

An oscilloscope should be a substantial piece of 
equipment, and in view of the high voltages 
employed (700V for the e.h.t. and 300V for the 
deflection amplifiers) it must be emphasised that 
the rather solid nature of the model is deliberate. 

Another feature is the simplification of the controls 
on the front panel, these being; brilliance, focus, Y 
attenuation (Y amp), Y shift, timebase coarse control 
in 6 ranges, timebase fine control (fine), timebase 
amplitude (X amp), and sync on/off. 

There is a Y input socket and an external timebase 
input socket. 

The writer has noticed that it is usually necessary 
to attenuate the input signal rather than amplify it, 
and with transistorised equipment the signal which 
is being examined can be dealt with quite effectively 
by an attenuator of the 'volume control' type. This 
makes it necessary to turn the Y attenuator down 
to zero before connecting a signal to the Y input 
socket but once this habit has been formed, the 
simplification of having just one continuously 
variable gain control with a d.c. amplifier is evident. 
The d.c. amplifier is necessary to maintain a good 
low frequency response, especially with square wave 
signals. 



The Cathode Ray Tube 

The cathode ray tube (c.r.t.) itself is a form of 
valve, having a heater and a cathode, a control grid 
and anode — which must be at a high positive poten- 
tial (e.h.t.) with respect to the cathode. 



For a 3in. cr.t. the e.h.t. should be of the order 
of 900/ 1000 V. 

Between the control grid and the final anode are 
the first and focusing anodes. There are also two 
pairs of deflection plates, one pair — the Y plates — 
for vertical deflection, and the other pair — the X 
plates — for horizontal deflection. The deflection 
plates are usually operated in push-pull and with 
1000 volts across the c.r.t. the push-pull voltage 
swing needs to be about 150V. This makes it neces- 
sary to have a 300V supply to the deflection ampli- 
fiers and the deflection transistors must be able to 
withstand this voltage. 

The design utilises the 3BP1, c.r.t. which has a 
heater requirement of 6-3V at 0-6A. The c.r.t. has 
a 14 pin base with a locating spigot and the base 
connector should be obtained (if possible) when 
purchasing the c.r.t. 

The tube gives a green trace of medium short 
persistence and a useful trace height is 5cms. The 
cr.t is approximately 10 inches in length including 
the base- 
Cathode ray tubes are sensitive to stray magnetic 
fields, such as those produced by mains transformers, 
and even when a mu-metal shield is utilised to screen 
the c.r.t., transformers on the same chassis usually 
cause some interference to the spot. Mu-metal 
shields are quite expensive (when available). 

In the present design, the mains transformers are 
fitted on a separate chassis, connected together by 
a multiway lead. By using this method, the problem 
of interference from the mains transformers was 
eliminated. 



The Y {Vertical) Amplifier 

The input to the Y amplifier is through a 'volume 
control' type attenuator VR1, and it is taken directly 
to the base of Trl, which with Tr2 forms a boot- 






336 




G.A.COZENS 

^SSEMBL* BCMRD 



strapped amplifier with an input impedance of about 
lmfi. If the reader wishes, a 0-l^F capacitor (CxJ 
can be inserted in the lead from the slider of VR1 
to the base of Trl, with a shorting switch across it, 
to give a.c./d.c. facilities, but it must be pointed out 
that this is a sensitive part of the circuit, and all 
leads must be kept as short as possible to avoid 
stray pick up. 

The output from the signal amplifier is passed 
through a resistor network to the long tailed pair 
which form the vertical deflection amplifier Tr3 and 
Tr4. This stage performs two functions: 

1. To give two outputs which are 180° out of phase 
and supply the push-pull voltages to the vertical 
deflection plates. 

2. To provide a voltage swing of 150V at each 
deflection plate. 

When the base of Tr3 goes positive its collector 
goes negative. That is, the signal is inverted at Tr3 
collector. 

Also Tr3 emitter goes positive. This means that 
Tr4 emitter goes positive. The' base bias of Tr4 is 
held at a fixed level by the bias network VR2 R15. 
As the potential difference between Tr4 base and 
emitter is decreasing the base of Tr4 is in effect 
going negative. 

This causes the collector of Tr4 to move in a 
positive direction, which is the same as the original 
signal at Tr3 base. Thus Tr3 collector is the inverting 
output and Tr4 collector is the non inverting output 

The network R7, R8, R9 is designed to bias the 
base of Tr3 and prevent overloading, and the base 
bias of Tr4 is made variable to balance with Tr3 base 
and centre the trace on the screen. VR2 is therefore 
the Y shift. C2 by-passes any a.c. signals present at 
Tr4 base. 

The collectors of Tr3 and Tr4 are connected 
directly to the Y plates. The values of the collector 
resistors were chosen by trial to balance the collector 
outputs, and the emitter resistors Rll and R14, and 
the coupling resistor R12, which controls the gain of 





SPECIFICATION 

Y Signal 
Input via co-axial lead 
Attenuator continuously variable 
Input Impedance 1MH 
Sensitivity on full gain 100mV r.m.s. gives trace 

height of 3cms p, to p. 
Bandwidth d.c. to 1MHz. 
Useful trace height Scms. 
X Deflection 
Sensitivity on external timebase tOOmV r.m.s. 

gives trace width of 1cm p. to p. 
Useful trace widths cms. 
Timebase in 6 ranges. 
Range; 

1.19— 100Hz 

2. 32— 170Hz 

3. 150— 550Hz 

4. 520Hz— 3-5 kHz 

5. 3 0— 20kHz 
5. SO— 40kHz 

Controls 

Front Panel 
Brilliance ■ Y gain 

Focus Y Shift 

Timebase fine frequency ~) 
Timebase range (course) )^X Signal 



Timebase amplitude 
Sync onfoff 

Side of Chassis 
X linearity 
X shift 



J 



Astigmatism 



the stage, may also be altered to match the transis- 
tors. When the trace is centred and no signal is pre- 
sent the collector voltages shoud be 180V. The maxi- 
mum height of the Y trace when using a lOOmV 
input signal (VR1 at maximum) is 3cms. 

The Timebase Generator and X Amplifier 

The timebase waveform generator Tr7 is a uni- 
junction transistor (TIS43) with Tr6 acting as a 
constant current device to regulate the charging of 
the timing capacitors (C5, C6, C7, C8, C9 and CIO) 
and to give a linear rise time. 

The fine frequency control (VR3) should be wire- 
wound and it should be possible to steady the trace 
at any part of the frequency range without using 
synchronisation. There is some loss of amplitude on 
the upper timebase range. 

The sawtooth signal is taken from the emitter of 
Tr7 to the base of Tr8, via a closed circuit jack JK1 
and a 0-1/^F capacitor C12. The output signal from 
Tr8 collector is fed via capacitor C13 to the timebase 
amplitude control VR4. 

The horizontal deflection amplifiers Tr9 and TrlO 
are a long tailed pair with a common emitter 
resistor R31. Bias for Tr9 is by potentiometer net- 
work R28 R29 and as in the Y amplifier, the base 
bias of the second transistor TrlO is made variable 
to act as a shift control to centre the trace on the 
c.r.t. screen. C17 by-passes any a.c. signals and 
stabilises the trace. 

337 



Synchronising 



The purpose of synchronisation is to lock the time- 
base frequency to the Y signal and so hold a given 
number of complete waveforms steady on the screen. 

The Y signal is taken from the emitter of Tr3 and 
is passed via C4 to the base of Tr5. Tr5 is driven 
hard by the Y signal and this produces a square 
wave at the collector of Tr5. 

C3 and R16 form a pulse shaper and the diode Dl 
passes the positive going pulse to b2 of the uni- 
junction sawtooth generator Tr7. 

The d.c. potential to b2 is stabilised by the zener 
diode D2. R24, Cll and the decoupling resistor R23 
all contribute to improved synchronisation of the 
timebase. 



The Power Supplies 

Five a.c. supplies are required from the mains 
transformers, they are: 

1. 6 ■ 3V at • 6A for the c.r.t. heater (T2) 

2. 250V at 2mA for the e.h.t. multiplier circuit (T2) 

3. "15 to 22V at 500mA for the low voltage line (T3) 

4. 250V at 50mA for the high voltage 300V d.c, 

line (Tl) 

5. 6 ■ 3V • 6A for indicator lamps (Tl ) 

The leads from the oscilloscope chassis are taken 
to the transformer subchassis and terminate in a 
multiway plug. It is suggested that constructors 
utilise a 10 way Jones plug and socket, for the 
inter -connection. 



* components list 



tesis 
R1 


tors 

4-7kQ 


R2 


2-2K1 


R3 


47kQ 


R4 


100Q 


R5 


8-2kD 


R6 


1k0 


R7 


8-2kfi 


R8 


2-2kQ 


R9 


1-8kO 


R10 


68kQ 


R11 


390£2 


R12 


sen 


R13 


82k« 


R14 


470O 


R15 


5-6kQ 


R16 


1MQ 


RT7 


22kO 


R18 


1-$Mtt 


R19 


tDkQ 


R20 


82kO 


R21 


8-2fcG 


R22 


47H 


R23 


470H 


R24 


680O 



R25 
R26 
R27 
R28 
R20 
R30 
R31 
R32 
R33 
R34 
R35 
R36 
R37 
R38 
R39 
R40 
R41 
R42 
R43 
R44 
R45 
R46 
R47 



10MO 

12kil 

12kU 

3-3Ma 

18k£2 

47kQ 1W 

120Q 

47kQ1W 

3-3MQ 

2-2MQ 

2'2MO 

lOkfi 1W 

10kQ 1W 

1-2kfi1W 

39QC1 1W 

12kfilW 

1-2k£21W 

390kQ 1W 

BZkQ. 

1MQ 

6B0KCI 

lOOkQ 

tookfi 



AH ± 10% iW carbon except where stated otherwise. 



Transistors : 
Tr1, Tr2, Tr5, Tr8 BC109 
Tr3, Tr4, Tr9, Tr10 MJE340 
Tr6 ASY26 

; Tr7 T1S43 



Diodes : 

D1 1N4148or1N914 

D4, D5, D6 1NS054 or PL4007 

D7, D8 400 p. lv. 1A 

D2 12V tW 

D3 18V 1W 



Transformers: 

T1, T2 Primary 200-250 V 50Hz 

Sec. 250V 60mA, 6-3V 2 A 



T3 



Primary 200-250 50Hz 
Sec.18Vi-25A 



Capacitors : 




C1 


100^cF elect 25V 


C2 


47^ 250V 


C3 


0-vF 




C4 


022/*F 




C5 


0-68/*F 




C5 


0-VF 


C7 


02^F 


C8 


005mF 


• 


C9 


O00VF 




C10 


OOOOSjuF 




C11 


100/* F elect 


25V 


CT2 


0-1 M F 




C13 


100fiF elect 25V 


C14 


100mF elect 25V 


C15, 


C16, C17 0-47/*F250V 


C18, 


C19, C24 50/^F + 50/aF -f 50j*F elect 350V 


C20, 


C26 32^F -j- 32^F elect 350V 


G21 ( 


C22 SOO^F elect 25V 


C23, 


C25 250/*F elect 50V 


C27, 


C28, C29, C30 0-47,uF 1000V 


Cx 


see text 





Potentiometers: 

VR1 2 MCl carbon 

2-5kfi w.w; linear 

50kQ w.w. linear 

25kQ w.w. linear 

25kfi w.w. linear 

250kfi carbon "j 

250kft carbon I j ,<- ., , .. .■■ 

250kO carbon f Q QU '^ We " ,nsul ^ ed 

50k£2 carbon; J 



VR2 
VR3 
VR4 
VR5 
VR6 
VR7 
VR8 
VR9 



CRT: 3BP1 



Switches : 

St 2 pole c/o slide 

52 1 or 2 pole 6 way rotary. Or# 1 pole used 

53 On/off mains toggle switch 
JK1 Closed circuit p.o. type jack 

Miscellaneous: 

Veroboa rd , ■ 1 5fn matrix 3i i n s. x 1 7i ns. Veropi ns, 
% 4,, 6BA screws, nuts, washers and spacers, panel 
lamps, coaxial sockets, systo flex, cleats, grommets, 
chipboard, laminated plastic sheet, 4 instrument 
handles, 8 rubber feet, aluminium for metalwork. 



333 







339 



;*nona;i 



To SI T C VR4 



n roton i 



ffc 



'!~1£ 



F G H 



'pole 4 frotor rotor-4 | 1 1 
C fi 



To LP1 



To JK1 



Earthing connection to chassis 



To VR5 



-A 



- 



"^ 



To VR6 



3=^ 



1 



To VR7 



3 



ToT3 



*^i 

, 18V. 
-— 



" X J 



K L H K1Q P 



To VR1 
^ r\ 

1 1 1 1 i irotor 



R_21 

HUGO-* 



U V W X 



, 'R23 ^ 
-Tr7 



V V 



•HMD*-* 

R15 



V input 



To SK1 




R24 Tr2 



R26 

»-ifflry « 

+ _OT_ Tr8 XU- 



* C3 



R25 




*fflEh _r|_ 

W« — mm — • 

Tr5 R18 

* — fi?n-^— 



Earthing connection to chassis 




pin 8 



To CRT 



pin 7 



— >n. . ■ ■ •»-— — - ~ 




»b R28 



R3.1 



H_5ZH 



AMD— 






To T1 






» » *. -lit •*. 



]_n 






r~ 



To CRT 



pin 9 



pin 11 




pin 10 

In one car 

ToC18+ve, 



ToCl9 + ve 



To Cia,Ct9,C?4 - ve 



To CBQ +ve n< 
ToC26+ve[ . 



ToC20,C26 ~ve. 



T 



53 



4 & •' f f f u h I . « L M 1 U P 3 8 5 I D V W X 

Fig. 2 . 77je complete Veroboard layout for the oscilloscope 



340 



The tube heater winding must withstand 1000 V 
to the chassis. If the insulation breaks down it will 
put the whole e.h.t. voltage between heater and 
cathode of the cx.t. The writer has not had this 
fault occur on any standard mains transformers that 
he has used. Well insulated twin flex of the type 
used for mains wiring is suitable for the c.r.t. heater 
leads. 

Three rectifier diodes are used in the e.h.t. multi- 
plier circuit. Although this type of circuit suffers 
from poor regulation, in this case, where the current 
required is only about 1mA it is quite stable. 

The capacitors C28, C29 C30 help to maintain good 
regulation. The diodes are arranged to give a nega- 
tive output, the positive end of the chain is at earth 
potential. 

The circuit is so arranged that the 700V e.h.t. 
supply and the 300V line are in series. Therefore the 
voltage across the c.r.t. from the grid to the final 
anode, is equal to the sum of the two voltages. 

The c.r.t. resistance network acts as a bleeder 
across the e.h.t. and the smoothing resistor R47 and 
the network should be fitted before the circuit is 
tested. It will limit the e.h.t. voltage and prevent 
possible damage to the smoothing capacitor C27. 

The IMft resistor R44 may be included in the 
circuit if flyback blanking is to be added later. 
Because of the unusual layout of the e.h.t. multiplier 
circuit extra care must be taken in layout and 
wiring. 

The low voltage line is supplied from transformer 
T3 which gives an output of between 15 and 22 volts, 
the bridge rectifier being rated at 400V pi. v. at 1A 
and the reservoir and smoothing capacitors at 50V. 
The smoothing resistor R42 has a value of 390fl and 
the zener diode D3 stabilises the line at 18V. The 
Y amplifier and the timebase circuit have separate 
smoothing components to reduce inter-action. 



The high voltage 300V d.c. line is supplied by the 
bridge rectifier D8 which is rated at 400V 1A. The 
reservoir capacitor C26 is 32/<F and is of the can 
variety. Each deflection amplifier has its own de- 
coupling components to prevent crosstalk and the 
astigmatism and X shift potentiometers are in 
parallel across the 300V d.c. line and act as bleeders. 

When the writer commenced his experiments with 
this oscilloscope, the method used for X and Y shift 
was similar to that employed in valved instruments, 
where the deflection plates were coupled to the valve 
anodes through capacitors and the shift voltages 
were determined by potentiometers across the posi- 
tive end of the network. This method has been 
retained for the X deflection plates, the X amplifier 
being a.c. coupled throughout. 

The Y amplifier is d.c. coupled and the Y shift is 
determined by the potential at the collectors of Tr3 
and Tr4. This means that the signal level at Tr3 base 
must be matched by that at Tr4 base to keep the 
trace on the screen. The X shift can be set and needs 
no further attention, hut the Y shift must be adjusted 
for positive or negative going signals and for changes 
in amplitude. 



The Veroboard Panel 

The Veroboard panel is 24 holes (or strips) wide 
and 83 holes long. This is cut from a standard 17in. 
x 3 3 4 in. Veroboard panel. The matrix is 0*15in. 
When working on the panel it is essential to make 
all joints with the minimum of solder. Where flexible 
leads are taken to compoi ents on the Veroboard, 
Veropins or the wire ends of components already 
attached to the copper strips should be used as 
anchoring points. 




Photograph showing the com- 
pleted oscilloscope. The three 
controls on the right hand side 
of the chassis are X linearity, 
X shift and astigmatism. 




— to be continued — 
341 




SHORT WAVE DX 

by MALCOLM CONNAH 

JUDGING from some of the letters and enquiries 
that I receive it would appear that many of you 
do not know of the existence of The World Radio 
and TV Handbook. 

The book contains a list, by countries, of all the 
Broadcasting stations in the world. Each entry shows 
details of the station schedule including frequencies 
and language used; other details given are the 
station address and its QSL policy. The interval 
signal of the station is given along with the opening 
announcement which is the easiest way of identifying 
the station. 

The first section of the book has various articles 
on Broadcasting subjects, which are useful to 
beginners and experienced DXers alike. The final 
pages of the book contain a listing, by frequency, 
of all the stations complete with call-sign and trans- 
mitter power. 

The book is available through most good hook- 
shops, the price is £3 which is a small price to pay 
for such a mine of information. 

DX News 

BANGLADESH: Radio Bangladesh now starts the 
English service at 1700 instead of 1715 on frequencies 
of 11650 and 15520kHz. 

GABON: Plans are afoot for the installation of 
several 300kW shortwave transmitters to be used 
by both ORTF and Radiodiffusion TV Gabonaise. 
Libreville has been heard on the new frequency of 
7130 from 1230 to 1430. 

GRENADA: Radio Grenada, formerly Windward 
Islands Broadcasting Service, has moved from 11930 
to 15105kHz for its transmissions to the UK at 
1945-2130. 

MONGOLIA: Radio Ulan Bator now also broad- 
casts programmes in English and French to Africa 
at 2000-2030 on 17780 and 17860kHz. The pro- 
grammes in English are broadcast every Wednesday 
and Saturday, and in French every Tuesday and 
Friday. There are also programmes in English daily, 
except Sunday evening and Monday morning, at 
1200-1250 on 17780 and 17860, and at 2200-2230 on 
11810 and 11860kHz. 

342 



Readers' Logs 

The first log this month comes from Roy Patrick 
of Derby who returns to the page after a consider- 
able absence, Welcome back OM. Roy's equipment 
consists of a Trio 9R59D receiver and an Eddystone 
840. Stations logged included : 
3240 R. Baghdad, Iraq in Arabic at 2000. 
4945 R. Colosal, Colombia at 0700. 
4980 Ecos del Torbes, Venezuela at 0605. 
4995 R. Brazil Central at 2200. 
11650 R. Bangladesh in English at 1700. 
11710 RAE, Argentina noted at 2300. 
11720 R. Nacional, Brazil, fair at 2100. 
11725 R. Ceylon in English 1800-1830. 
11790 R. Australia to SE Asia at 1800. 
11800 R. Ceylon in Hindi, good at 1830. 

Michael Johnson of Hockley in Essex describes his 
equipment as follows: "I use an ex-radiogram, 6 
valve, Ferguson receiver; coupled with the dipole of 
an old 405 line TV aerial which works better than 
my 50 foot dipole on 31 metres!" This equipment 
enabled him to hear the following stations : 
6050 RAI, Italy in English at 1935. 
6070 R. Sofia, Bulgaria in English at 1930. 
6185 R. Norway in English at 1700. 
6580 R. Pyongyang, N, Korea at 1900. 
7290 Trans World Radio in English at 1045. 
9545 R. Ghana, Accra in English at 2145. 
9670 R. Trans-Europe in English at 2000. 
9840 Voice of Vietnam at 1915. 
11880 Voice of Turkey, Ankara noted at 2200. 
15185 R. Finland in English at 1800. 
15415 R. Kuwait in English at 1645. 

Messrs. Wormleighton and Fletcher of Rencomb 
College, Cirencester have sent in another excellent 
log using the following equipment: HRO with 8 
metre folded dipole; Astrad-Altair with 150 foot long- 
wire, Bush PB63 with 35 foot long-wire. 
5990 HCJB, Quito, Ecuador in English at 0825. 
6050 RAI, Italy in English at 2030. 
7235 R. Australia in English at 1500. 
9525 RSA, South Africa noted at 2215. 
9710 HCJB, Quito, Ecuador in English at 0715. 
9715 R. Nederland, Bonaire, English at 0845. 
9805 R. Cairo, U.A.R., in English at 2200. 
11745 HCJB, Quito, Ecuador in English at 0730. 
11880 Voice of Turkey, Ankara. English at 2200. 
11920 RNE, Spain in Spanish at 1300. 
11945 R. Voice of the Gospel, Ethiopia at 1930. 
11970 RSA, South Africa at 1900, News in English. 
15415 R. Kuwait in English at 1730. 
21545 R. Ghana, Accra in English at 1500. 
21595 R. Canada International noted at 1640. 



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electronics and show how easily the subject can be mastered. 
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343 



BENTLEY ACOUSTIC 
CORPORATION LTD. 

7. GLOUCESTER ROAD, LITTLEHAMPTQN, SUSSEX 
AMprieei include of V.A.T. Telephone 674J 



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64 1 All goods are unused, feoxed, and subject to the standard 90 day guarantee, Tcnne ol business— 

: i2lf.' a9 " ^ r ™ e ? ue ™ (t ^ ordet ,ml 7- Despatch charge 9u per order up to three items, then each additional 

JS 6 -*! il ™ , 3 ,P «*». Orders over £500 po 9 t/p»ckinK Uif.. Same day despatch by Brat claaa mall. Any 

KTfif! ' So S ar< i ln ™ red ae, a 'i lst damage in transit Jor only 3p extra per order. Terms ol bualneas free on request. 

Ji-HO .49 Buelness hours Mon.-Fri. 9-5.30 p.m. 

™ I 'mLY 8 .? ,, not J handl . e . seconds nor reject*, which we oftea descrit«d as "New and Tested" but have a 

lkr * 2 d tt nd unreliable life. No enquiries »n»wered unlesn S.A.E. is enclosed lor reply 



tife" 



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8 oage instruction leaflet 3^Nf 
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344 



BROADWAY ELECTRONICS 

« MITCHAM ROAD, TOOTING BROADWAY, 

LONDON S.W.I7 01-672 3984 

CARTRIDGES — Stereo Sonotone 9TA H/C Diamond £1-47 

?p2^i% s 1 05 . Medju m Outpuc < I • 40. SI 06 High Output £1-40, Acos 

B.S?R TC8 P s P £'| re 80 Sapphire £1-95, Japanese equivalent to 



CARTRIDGES— Mono GP9I 
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Stereo Compatible £1 29. B.S.R. 



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HI-FI STEREO HEADPHONES Fadded ear 
cushions seal out room noise. Perfect coupling 
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impedance B ohms, frequency range 20-20,000 Hi 
6ft. cord and standard stereo plug. Only £3-57. 

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Simple unit connects direct to amplifier and speakers 
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XUHiffc? Widl | is ,f tT, 5 V° S f '"■• * S P ** off ™l". i yard 57p. Send Sp 
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MASSIVE CLEARANCE BARGAINS 

Bargain component parcels contain Resistors, Capacitors, Switches, 
Potentiometers, Knoos, IPs, Tag Strips, Drive Drums, Transistor 
Panels etc., etc. Save yourself £s on these well selected parcels 
bibs net weight £1 -00, p. p. 40p. 

Assorted Electrolytic Capacitors. 6lbs net weight £t-00, p. p. 40p. 
Brand new Wire-wound Resistors. Good Selection. 100 for £1 
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Hullard Ferrite Bar Magnets ff* x ^"x ^". 100 for £1 M, p. p. 16p. 

Assorted Computer Panels. These panels are exceptionally good 

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plus Trim Pots, Polyester Capacitors, Resistors and: include a few 

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Mullard Ferrite Cores. LA3 up to 500kHz. 50p. LA4 up to 30kHz 75p 

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MAIL ORDER ONLY 

XEROZA RADIO 
I, EAST STREET, 

BISHOPS TAWTON, 
DEVON 



ON THE 

"?\ AIR 



MEDIUM WAVE BROADCASTS 

by CHARLES MOLLOY 

JOHN THORBURN (Glasgow) has used his Vasco 
Gold Star radio to hear CHER Sydney, Nova 
Scotia on 950kHz; WBT Charlotte, North Carolina 
on 1110kHz; Radio Bermuda 1340kHz; Voice of 
America Kavalla, Greece 791kHz; Radio Zagreb, 
Yugoslavia 1133kHz. John also logged the BBC local 
radio outlets at Blackburn on 850kHz. Sheffield 
1034kHz; Leeds 1106kHz; Newcastle 1457kHz; Stoke 
1502kHz; Bristol 1546kHz and Manx Radio, Isle of 
Man on 1594kHz. 

Dominic Glynn (East Grinstead) has a Philips 
transistor receiver and a 100ft, longwire antenna. 
He reports hearing programmes in English from 
Radio Sweden 1178kHz at 2300hrs GMT; Trans 
World Radio Montecarlo 1466kHz at 2230hrs and 
Radio Berlin International 1511kHz at 1815hrs. 
Dominic has also logged Radio Tirana, Albania 
1394kHz at 2230hrs and BBC Radio Stoke 1502kHz 
at 1045hrs. 

From the BBC comes news that Radio Solent is 
now broadcasting on two frequencies, 998kHz and 
1594kHz. The new outlet on 1594kHz brings the 



VHF/FM by SIMON DAVID 

HAVE you been suffering from "Sporadic — E" 
lately? If so we would like to hear from you. 
Sporadic — E is the name given to a disturb- 
ance in the "E" region of the ionosphere. It is most 
likely to occur in the summer months (U.K.) and 
gives rise to some odd goings-on on the v.h.f. bands 
up to about 100MHz. 

Although almost impossible to predict accurately, 
such manifestations are in long distance reception, 
interference on television and radio and interaction 
between signals from one source and another, often 
several hundreds or even thousands of miles apart. 
Stations operating on close frequency allocations 
are susceptible and in particular those on v.h.f. 
mobile radio systems often fall victim. 

Greetings in particular this month to listeners who 
can now pick up local radio on their portables and 
in cars in Leeds, Huddersfield, Barnsley, Dewsbury, 
Wakefield, Castleford, parts of Halifax, Bradford 
and Harrogate, Barnsley, Doncaster, Worksop, East 
Retford and Rotherham. In case you are not aware, 
you should now be able to drive to the Hit of BBC 
Radio Leeds (92-4MHz) or Radio Sheffield (97-4MHz). 

The old Meanwood Park transmitter on 94-6MHz 
and Boston Park, Rotherham, transmitter on 
95 05MHz have closed and all transmissions from 
these two stations now come from Holme Moss 
near Huddersfield. Sheffield listeners can still tune 
in on 88-6MHz, but all others tuning to 97-4MHz 
may need to turn their aerial round so that it is 
directed at Holme Moss (also home of BBC tele- 
vision). Aerials that are already rigged on the roof 
or chimney outside and directed at Holme Moss 
for Radios 2, 3 and 4 are likely to be suitable for 
the local radio stations also. 



service to Bournemouth, Poole and Wimborne Min- 
ster while the existing service on 998kHz for the 
Southampton and Portsmouth areas is unaffected 
Medium wave DXers who go abroad for their 
holidays have the opportunity to try the band from 
a new location. In Spain there are many low power 
local stations, some of which would be rarities if 
heard in this country and even a pocket sized 
transistor portable will pull them in. For those 
interested in keeping in touch with events at home 
there is the BBC Radio 2 transmission on 200kHz 
(150Qm) on the long waves which can be heard 
over a large part of Europe after dark. Visitors to 
Majorca can hear Radio Maliorca (EAJ13) on 
800kHz; Radio Popular de Maliorca (EAK18) on 
1268kHz; Radio Juventud de Palma Maliorca 
(EFJ45) on 1385kHz. On the Costa Brava there are 
Radio Barcelona (EAJ1) on 827kHz; Radio Juventud 
Barcelona (EFJ15) on 1025kHz; Radio Espana de 
Barcelona (EAJ15) on 1124kHz; Radio Sabadell 
(EAJ20) on 1475kHz; Radio Gerona (EAJ38) on 
1520kHz. At Benidorm there are Radio Popular de 
Alicante (EAK31) on 1394kHz; Radio Gandia 
(EAJ23) on 1457kHz; Radio Alicante (EAJ31) on 
1520kHz and La Voz de Alicante (EFE8) on 
1570kHz. Those going to the Costa del Sol have the 
opportunity to hear Radio Gibralter on 1484kHz 
which broadcasts in English and Spanish; Radio 
Ceuta (EAJ46) on 1106kHz which is located in a 
Spanish enclave in Morocco; Radio Juventud de 
Malaga (EFJ56) on 1133kHz; Radio Popular de 
Malaga (EAK11) on 1430kHz and Radio Costa del 
Sol (ECS15) on 1570kHz. 






Some transmitters use slant polarisation to assist 
where vertical receiver aerials are used (such as on 
cars). One such is used for Radio Derby which is 
transmitted from Sutton Coldfield, Birmingham, on 
96 -5MHz. If you are not sure on the polarisation 
for your area you can ask at any local BBC radio 
offices or write to the Engineering Information Dept., 
BBC, Broadcasting House, London W1A 1AA; please 
enclose a stamped addressed envelope. 

Now for some quick quotes from some of the 
letters received: W. f. Kitching in Shropshire has 
a Grundig "Yacht Boy" 210 with telescopic aerial 
and has picked up Radio Telefis Eirean 95-3MHz. 
He looks forward to police inactivity so that he can 
hear Radio Na Gaeltachta, Eire, on 97-OMHz. 

On the other side of the Irish Sea, Des Walsh in 
Tipperary uses a Leak Troughline-3 and a BASF 
CC9300 Radio recorder and points a J-Beam FM6S 
and FM4S at South Wales and South West England. 
He has bagged Wenvoe, Haverfordwest, Blaen-plwyf, 
North Hessary Tor, Redruth and Radio Bristol. Turn- 
ing north-east he can pick up Belfast and Radio 
Merseyside. Here's the crunch! With the help of 
tropospherics he can hear ORTF from N. W. France. 

D.J. is a 14-year-old from Egham, Surrey, and is 
one of many who has heard the London Independent 
Radio transmissions on Radio Classic 94-4MHz, Hope 
his parents won't get annoyed when they find out 
that he was listening to "an extra programme" at 
01 05 Easter Sunday morning. Was this a "Jolly 
Roger" operation? 

Anybody heard broadcasts from the North Sea 
Radio Telephone Company? Graham Wilson has 
in Borden Hampshire and wonders who was res- 
ponsible. The transmission was heard on much of 
the 88-108MHz band (but was strongest at 91MHz) 
on March 5th. 

345 



ON THE 
AIR 




SHORT WAVES 

by DAVID GIBSON, G3JDG 

IT'S getting hotter in more senses than one. The 
summer season brings great hotness with it and 
it is known in this scribe's shack as the Equinox 
of the molten ear'ole — a disease common to all 
wearers of headphones during periods of great 
warmth. 

The other sense is a rumour to ban a.m. from the 
Amateur bands, notably the l.f. regions of 1-8 and 
3-5MHz. What do readers think about this? Shall we 
settle for s.s.b. and c.w. only? 

A staggering piece of news for professional call- 
sign changers. The latest act in the callsign circus 
is to change it just for a particular contest. The 
result is CR6 becoming CQ6 (a really clever choice — 
CQ) for the WPX contest. A little bird also tells me 
that MP4TEE is now A6XF. 

Best piece of news on the callsign front, and one 
for some genuine rejoicing in Amateur circles, is 
that the People's Republic of China will probably be 
allowing/issuing callsigns in the not too distant 
future. It'll make the bands even more crowded but 




a big welcome to the Chinese Amateurs as and 
when they appear on the bands. 

In the April issue, mention was made of photo- 
graphs showing readers' stations. First person to 
take up the gauntlett is Graham Bleakley who is 15 
and lives in Cumbernauld New Town, Scotland. The 
gear shown is a "trusty old CR100". Graham is the 
one on the left with all the hair, and the CR100 is 
on the right, with all the knobs. No mention of what 
the tape recorder is for but Graham does say he 
reckons to become a G8 with a bit of help from 
the May 1974 RAE. No word of the antenna, but 
whatever it is, it pokes out of the windows of 82 
Ash Road. 

Info from G3RPJ that the Stratford on Avon Radio 
Club will have rigs working on 1 ■ 8MHz, 14MHz and 
144MHz (a.m. f.m. and r.t.t.y.) at the Town and 
Country Festival on August 25/26/27. Place is the 
Royal Showground, Stoneleigh, Kenilworth, Warwick- 
shire. The stations will stay on the air in the evenings 
after the show. 

Karl Muller (Mbabane, Swaziland) has a JR-500SE 
7MHz inverted V and a lot of patience. Rewards for 
same has given him 148 countries heard on 7MHz. 
On 7MHz c.w. Karl bagged; CE3ED, CE5HP, 
CX1BBL, CX9BT, FC9VN, FG7TG, FH8CY, K0ALL, 
KH6AQ, KH6RS, SV1DO, TI2PZ, VP9GR, WN3TGR, 
WN0HYN, ZP5AL, 4K1A, 9F3USA, 9L1GC. On s.s.b., 
the latest log reads; CT2AJ, KC6SK, MP4BJP, 
OY7BD, WB6VGI/VQ9, ZC4EJ, ZD9GC, 4W1AF, 
6W8DY. 

Before going on with logs, I see that the May 1973 
issue of Radio Communication, the journal of the 
RSGB, publishes a full list of intruder stations com- 
plete with all sorts of information; frequency, date, 
location, source etc. This seems a useful coincidence 
in view of previous remarks made in this column. 
Single copies of the journal are available to non- 
members at 30p plus postage. 

J. Wright (Loughborough) homebrew converter, 
960 receiver, 3-element beam at 30ft, sends in a log 
for 70MHz (Yippee). Stations bagged include: 
G3CDG/P, G3HCW/P, G3HVI, G3LVP/P, G3NQV/P, 
G30NP, G3SFT/P, G3TOM/P, G3VER/P, G3VPF/P, 
G3VPK, G3WMR/P, G3ZVK, G4ALE/P, G4BEZ/P 
G4BLQ, G4BPY, G4BZO, G5DF, GD2HDZ, GW3MHR, 
GW30BD/P, GW3WOS, GW4ABR/P, GW4BGG/P. 

P. Newman (Thame) sends in a "Heard in the 
144MHz and 7Gcm Contest" log. Pickings on 70cm; 
G8DOR/P, G88GHR/P, G3NNG/P, G5DF, G8FBG/P. 
Two meter goodies were; G8DWC/P, G2DRT/A, 
G8CIB/P, G8GSX/P, G8GTD, G8FBG/P, G8FTL, 
G8FZL/P, G3FZL/P, G3K1N/P, G30SS, G3NNG/P, 
GW4ABR/P. 

Contests for the month of July include ; July 7/8, 
v.h.f./u.h.f. Jubilee contest (R.S.G.B.); 14/15, s.s.b. 
field day; 15, DF qualifying round at Coventry; 22, 
432MHz portables contest; August 4/5, YO DX Phone 
and c.w. contest; August 5, DF qualifying round 
(Salde). 



BROADCAST BANDS 

Short Wave Reports by 15th of the month to Malcolm Connah, 59 Windrush. 
Highworth, Swindon, Wiltshire, SN6 7DT. 

Medium Waves Logs to Charles Molloy, 132 Segars Lane, Southport, PR8 3JG. 

VHF/FM Reports to Simon David, c/o Practical Wireless, Fleetway House. 
Farringdon Street, London, EC4A 4AD. 



AMATEUR BANDS 

Short Wave/VHF 

Logs in alphabetical order please 
by 15th of the month to David 
Gibson, G3JDG, 12 Cross Way, 
Harpenden, Hertfordshire. 



346 



ZR4/4 M2S7& 

The I.C. Radio in a T013 can. Supplied 
complete with data sheet No. 10 which 
contains specification, circuit and details 
and prices of components such as farrEte 
rods, compression trimmers etc. 

AC Sockets 

DuaMrMine or Zig-Zag jQin!i U ant! IS pm 
Our Price 1p p«r pin 



y//V«/ />*<* 




VDRs S Thermistors 

A15B TSp E298 ED A253 10b VA1005 ISp 

CZ1 15p E288ZZ06 lOp VA1026 f3p 
CZ4 ,3p VA1033 lOp 

CZl3A13p VA1034 lOp 

CZ19 13c V At 039 15p 

GL16C1 00 VA1040 10p 

GL23E1 00 VA1053 lOp 

RS3 £1 32 VA1055S10P 

R54 £1 46 VA1077 Up 



Resistors 



$ watt 6% Carbon Film - tow noisa 

Hi-Stabs 

All E24 values 1 peach plus p. 4 p. Tp for up 

to 50 Resistors and a further 2p for each 
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1 W 1 TO Carbon Composition 3p each 

2 W 10% Carbon Composition 6p each 
2 1 W 5% Wire wound 9p each 
SW Wire wound 9p each 

10W Wirewoumd lOpaaeh 

plus p. St p. 7p for up to 25 resistors plus 1 p 
for each additional 25 



Diodes & Rectifiers 



AA119 9p 
AA120 9p 
AA129 9p 
BA102 25p 
8A11517p 
SA130 10p 
8A145 20p 
SA14S 20p 
BA154 13p 
8A155 14p 



BA156 1Sp 
BA243 56 p 
OA47 Ipp 
OA79 9p 
OA90 7p 
OA91 7p 
OA20010p 
BriOOIBp 
BV125 ISp 
BV127 IBp 



BY176CI SO 
BY182CV60 
BY 260 23p 
IN4Q01 6p 
IN 4002 Tp 
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,!'.■; "J H So 
IN40O5 10p 
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IN4O07 16p 




OUR PI1IC* 

u a 

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1 Well 

AiiplineT 



Potentiometers 




5KO SOKil 500K.fi 

10KIJ lOOKfi IMfi 

25Kfi 250KI1 2MO 

loo or lin lass switch (& TKfi I in) 

fog or lin with switch 

dual less switch ■ 

duel with switch 10K. 10OK & 1 H 

log only 

10K loo 10K antilog less switch 



12p 
24p 
40p 

52p 
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eliminators 




6 rail " SOmA 
9 volt rji SOmA 

6 ■ 6 volt. 50mA 
9 • 9 volt, SOmA 

7 J volt for cassette recorders 
6. 7 J or 9 volt 



£1.50 
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3, 4J. 6, 71. 9. 12 '« 500mA (illus.) £3.99 

Car Battery Converter fully stabilised to 

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(p. & o 15p on all types) 



Presets 






Vertical or Horizontal 

1 watt Gp 25 watt 7p 

100 IK ',.■ 1 ■'■ k l .■ 100KU 1MU 

2S0 2-6K 11 2SKU 250 K U 2 5M I 

6O0 5KU 50KL! 500K11 5M« 



Capacitors 





low voltage 


01 (if 19* 


5P 


VF 30v 5p 


022,iF ia* 


Sp 


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047^F 12v 


5p 


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ceramic plate 


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4700pf lOp 


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56 pi 220pt 


47pf 


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mylar film 100V 

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2000pt 2p 02uF 3p IpF dp 

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polystyrene 1S0V 

10pf to lO.OOOpf in multiples of 10. 15, 22, 33, 

47 & 68. 3p each 

metallised polyester 250V (C280) 



oi iif 3p oesiiF 3jp 

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047(jF3p 33pF 6jp 



47pF 
68 uF 



1 5uF 

2 2nF 



Bp 
lip 
13p 
20p 
24p 



metallised polyester 400V (C2S1) 

01 pF 41p -047iiF Sp 22pF lOp 

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022 M F4Jp 1nF 7p 47pF ISp 

033uF 5Jp 15uF Sp 

silvered mica 1% ( 50pf) 500 V 

2-2pf— 820pf 7p 4 7nF— SflQOpf 19p 

InF— 2 2nf Sp SSOOpf— OVF 29p 

2-7nF— 3 6nF 1Sp 

mixed dielectric 600V 

01 pF 7p 047pF 7p 22mF ISp 

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033m F 7p 'ItiF 8p InF 33p 



mwm 



nn 



E electronics 



PRICES DO NOT 
INCLUDE V.A.T. 



MAIL QFtDEHS «Vrw> ' 

a mlnlmtim a I 7p appliflh 

is charged a: con 

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S6, Fortij Green Read. London NIO 1HN 

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lined dielectric 



1000V 



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Veroboard 



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7<¥ 


52p 


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3* 


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Pill Insertion Tool i 






Terminal Pins 


18 


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scios 

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MCI 311 CI M 

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lOOOpt 6p 
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Ceramic 
12KV.d.c. 
10pt 9p 
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82 pf 9p 
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140pf 9p 
150pf 9p 
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SBOOpI 9p 

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BKVd.c. 

200pf 9p 
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250p1 9p 
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1 OOOpf Sp 
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10. OOOpf Bp 



1(iF 12p 
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47 pF 30p 



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1 0OOpf 5p 

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2000pf 5p 

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fend- 
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20 Warts pel cheniiel rnt^rittd stereo irapBfifr atvtloped By engtoeerc o( Tex» Injtnnnentj Ltd. 
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selector; mono/stereo switch. The toratructfon of this kit was featured in 'Practical Wireless' 
May - Aug. 1972. " 



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M~¥ott electrolytes 



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347 



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SOLARTRON CT 316 

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■ 60 CY31 

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45 EF183 
30 1 EF184 

47 EH90 
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PCF88 

PC1'*800 

PCF801 



FCF806 

FCF806 

PCF808 

PCI.83 

PCU3 



■88 PCF803 
24 

•BE 
36 

■ as 

60 1 P0l2l 



PY83 

PY88 

PY800 

PY801 

BI9 

K2ii 

U26 

U26 

U47 

U49 

uoa 

U78 
Ul&l 
UI93 
U8G1 

i:sci 
U329 
U801 
UABC80 



T»Dtllt0H 

AC107 -17 

AC! 27 -18 

AB14Q -87 

AF11S .£9 

AF118 -80 

AF117 -M 

AF126 .17 

AF127 -17 
OC44 



OC40 

OC71 

OC72 

OC76 

OC81 

OC81D 

OC82 

OC82D 

OC170 



READERS RADIO 



85 TORQUAY GARDENS, REDBRIDGE, ILFORD. 
ESSEX. Tel. 01-550 7441. 

PRICES ARE INCIUSIVE OF VAT, ONLV POSTAGE IS EXTRA 

Minimum post packing on I valve 7t»., on each additional valve, 
(3p. per. valve extra) 

Any piu-cel i paired against damage lu transit 3p eitra. 



348 




M.CONNAH 



£AUDRATinG 
SID RCCCIVCRI 



With the Short Wave Bands becoming more 
crowded every year it becomes increasingly 
necessary for the listener to be able to de- 
termine the frequency to which his receiver is tuned. 
Conversely, if the receiver is accurately calibrated 
the listener is able to tune to a desired frequency 
to listen for a particular station. 



i L Aertal coils 



'/■ 



t ; RF coils 
(if fitted) 



■ r Mc 

TCI ! 17 



VC2 



VC4 
M7pF 



,Osc. coils 



JM 

?■ 



7" 

TC2 



'if 



VC3 
VC5 
J17pF 
I 
I 
I 



< m 



"k 



VC6 
|17pF 



_ Main | tuning [ i 



Tkosio; 



Bandspread i added 



Fig. J Circuit showing the band spread ganged capacitor added to the 
existing circuit. 

The latter part of this article deals with a method 
of receiver calibration which costs less than a pound. 
The only requirement is that the receiver has a band- 



spread control with a reasonable scale. The first part 
of the article, therefore, deals with adding a suitable 
bandspread control to a receiver which is lacking in 
this respect. 



ADDING BANDSPREAD 

The addition of a bandspread control to a receiver 
which does not have this facility is probably the 
most effective, yet simple, method of improving the 
performance of the set. The total cost is little more 
than £1 so the project is well within the means of 
the average listener. 

All superhet receivers have a main tuning control 
which is either a two or three gang variable cap- 
acitor. This is shown as VC1/VC2/VC3 in Fig. I. 
The bandspread control required for the project is 
a two or three gang (depending upon the number 
of gangs of the main tuning) miniature variable 
capacitor each section having a capacitance of 
approximately 15 to 20pF. The most suitable type 
is that often used for the tuning of v.h.f. receivers, 
usually having a capacitance of 17pF per section. 

The bandspread control is represented by VC4/ 
VC5/VC6 in Fig 1. Each section of the bandspread 



100 





15000 



15100 



15200 f 15300 15400 

15250 

Frequency (kHz) 
Fig. 2 A typical calibration chart produced by the method described in the article. 



349 



capacitor is wired in parallel with a section of the 
main tuning control. The new control should be 
mounted as near as possible to the existing variable 
capacitor with the wiring as short and straight as 
possible. In order to retain the previous calibration 
of the receiver, the bandspread control should be 
half closed and the trimmers TC1/TC2/TC3 un- 
screwed slightly to compensate for the additional 
capacitance of the bandspread control. 



BANDSPREAD CONTROL 

The bandspread control should be fitted with a 
knob which has a to 100 scale; the larger the 
knob that can be accommodated on the receiver the 
better the tuning performance will be. A knob with 
integral slow motion is better still. 



CALIBRATION 

The lowest cost method of calibrating a receiver 
is by drawing calibration charts for the various 
frequency ranges of interest, using the bandspread 
control. The best graph paper to use is that which 
has each large division sub-divided into ten smaller 
divisions. A separate chart should be drawn for each 
band hut some of the wider bands will require two 
charts as the bandspread control will not cover the 
entire band with one setting of the main tuning. 

The main tuning is adjusted so that the band- 
spread will cover the band being calibrated. This 
position of the main tuning is noted by sticking 
a piece of tape on the dial or by reference to the 
receiver's logging scale if one is fitted. As an ex- 
ample, the author's receiver was calibrated on the 
19 metre band, being fitted with a 0-100 logging 
scale, and with the main tuning set at 37 the band- 
spread control covered the whole band. 

The next stage is to do some concentrated listen- 
ing on the band, trying to hear those stations of 
which the frequency is known and plotting these 
on a graph similar to Fig. 2. The stations heard by 
the author were as follows: 



Station 


Frequency 


Bandspread Setting 


wwv 


15000 kHz 





Radio Cairo 


15150 kHz 


19 


RSA, S. Africa 


15200 kHz 


26 


VOA, Tangier 


15300 kHz 


43 


RAT, Rome 


15400 kHz 


65 


Radio Moscow 


15450 kHz 


80 



When all these points have been plotted a smooth 
curve is drawn between them giving the result shown 
in Fig. 2. This procedure is repeated for all the bands 
required by the listener. 

The method of calibration by plotting frequencies 
is tedious but, once done, the graph can be used 
again and again very simply. One of the basic ideas 
behind the article was that the minimum of expense 
was involved. The reader will have to spend some 
time drawing up the graphs but will have spent 
very little money. 

The use of a crystal calibrator would, of course, 
speed up the process of drawing the charts. The 
The 3-range Crystal Marker by R. F. Graham was 
published in the February 1973 issue of PW and this 
is ideal for the job, being both simple and inexpen- 
sive. 

350 



USING THE CHARTS 

It is possible to use the charts by simply returning 
the main tuning to the marked position from which 
the chart was drawn. This is not very accurate how- 
ever, and the following method is recommended. 
When returning to a given band a search is made 
for one particular station the frequency of which is 
known, say 15250 kHz. Reference to the graph shows 
that this should appear at 34 on the bandspread 
scale. Roth the main tuning and the bandspread 
are then adjusted until the station appears at this 
bandspread setting. The controls are now set for 
accurate listening on the band. 

Having set up the receiver it is possible to use 
a chart in two ways. First, it is possible to deter- 
mine the frequency of a station which has been 
tuned in by converting the bandspread reading to 
frequency, secondly, it is possible to tune to any 
particular frequency, to look for a station, by deter- 
mining the correct bandspread setting for that fre- 
quency and adjusting the control accordingly. ■ 






PRACTICAL 

WIRELESS 




Practical Wireless will be launching a new series of 
PW Datacards in the autumn. These will provide 
the radio, television, audio and electronics con- 
structor with some of the background information 
he needs to understand his subject. 

The first: series of six cards will be printed: in full 
colour and wili be given away absolutely free of 
charge to purchasers of the autumn issues of 
Practical Wireless, To make sure that you do not 
miss this; unique opportunity you should have an 
order placed with your newsagent at least for the 
October,^ November and December issues, 

PW Datacards wili be inserted in pairs in each 
of these issues; the first pair in October issue will 
help all newcomers and established constructors 
to see at a glance how to read resistor and capacitor 
values and will show how to determine combined 
values of two or more of these components quickly. 
The second pair of PW Datacards in the November 
issue will appeal to all audio enthusiasts. 

PW Datacards are designed specially to fit 
into a jacket pocket, stand on the work benchi hang 
on the wall, use as a place mat, or even as a book- 
mark. No other radio or electronics magazine 
has given such a comparable free service to its 
readers. 

Further details on all of these PW Datacards wiil 
be given in next month's issue of P.W. September 
issue on sale August 3rd; October issue on sale 
September 7th. 






SUPERSLIM 



BSR LATEST 
STEREO AND MONO 

Flays IS", 10* or 7" record*. 
Auto or Manual. A high 
quality en it backed by BSR 
reliability with 12 month)' 
guarantee. AC 200/260v, 
Else 13* x U;in. 
Above in oio i board 81 in. 
Below motor board 2Un. 
With STEREO and MONO XTAL 

PORTABLE PLAYER CABINET 

Modern design, black rexine covered, £4*bU 

silver Iront grille. Suitable lor above player. Poet B6p. 
Motor board cat lor BSR deck. 




ALL OUR PRICES INCLUDE V.A.T. 

ANOTHER RCS BARGAIN! 



£8.25 potts*". 



6 



E M I WOOFER AND /C.7C 
*-■' ■■■• TWEETER KIT *"* "* 

Available separately Post 85p 

Woofer £4 25, Tweeter 11 90. 
Comprising a One example 01 a Wooler 
10! X °ila. with a massive Ceremio 
Magnet, 44<w. Sanaa 18,000 lines. 
Aluminium Cane centre to improve 
middle and top response. Alio the E.M.I. 
Tweeter 3iin . square has a special light- 
weight paper cone and magnet flux 
10,000 lines. Crossover condenser and 
la]] instructions supplied. 

Impedance Standard 8 ohms 

Miwrnmri Power .... . .......1ft watts 

Useful Response SS to 18,000 cps 

Bass Resonance 45 cps 

SUITABLE ENCLOSURE 20 x 13 x 9in. £9-90 POST Up 
MODERN GROOVED FRONT DESIGN. TEAK FINISH 




SPECIAL OFFER 

SMITH'S CLOCKWORK IS AMP 

TIME SWITCH 

Single pole two-way. 

Maker's last list price £4 60. 

Brand new and fully guaranteed. 

Surface mounting with Axing ■ crews, 

Will replace existing wall switch to give light lor return 

home, garage, automatic anti-burglar lights, etc. Variable 

knob. Turn on or oft at lull Or Intermediate settings. 

TWO TYPES AVAILABLE TO 80 MINUTES OR 

TO 8 HOURS. OUR PRICE £1 86, P. & P. 16p OR £3 

FAIR. (STATE TYPE A OR B WHEN ORDERING.) 




WEYRAD PS0— TRANSISTOR COILS 
RA2W Ferrite Aerial . . 7Bp 
Osc. P50/1AC «p 

i.F. pao/ecc 470 kc/s. sop 

8rd I.F. F50,'3CC .... 88p 

P61/1 or P51/8 SOp 

P50/3V 88p 

Mallard Ferrite Sod 8 ■- 



Spare Cores 8p 

Driver Trans. LFDT4 68p 

Printed Circuit, FCA1 SSp 

J.B. Tuning Gang 85 p 

Weyrad Booklet lOp 

OPT1 68p 

Jin. £0p, S x |in. 80p, 



VOLUME CONTROLS 

5 K. ohms to 2 Meg. LOG or 
LIN, L/8 16p. D.P. 2Sp. 
STEREO X/S 55p. D.P. 75 p. 
Edge 5K.S.P. Transistor E5p 



80 Ohm Coax 4p yd. 

BRITISH AERIALITE 
A ERA XI AL- AIR SPACED 
40 yd. f 1 40; 80 yd. MS. 
FRINGE LOW LOSS , A 
Ideal 825 & colour ■ Up yd. 



8in& lOinELAC 

HI-FI SPEAKERS 



Dnal cone pjastiotsed roll 
surround. Large ceramic 
magnet. 50-18,000 op*. 
Bass resonance 55 cps. 
8 ohm coil. 
gin. 10 watt, 
lOin. 18 watt 
music power. 



£3-75 



E.M.I. 13i x 8in. 
SPEAKER SALE! 

With twin tweeters f% M C t\ 

and crossover, 10 watt. A*T S)U 

Post £6p 



State 3 or 8 or 16 ohm 

(As illustrated) 

With flared tweeter cone and ceramic 
magnet. 10 watts. £% f% ■• i? 

Bass res. 46-60 cps. iv/'lS 
Flux 10,000 gauss. «**■* ■ •* 
State 3 or 8 or 15 ohm. Post 2Sp 
BOOKSHELF £5-50 P -°" 



CABINET 



25p 



1« x 10 x 9ia. 



BRITISH MADE STEREO 
MULTIPLEX DECODER 

Brand New. 7 transistors plus integrated 
circuit. Fibre glass printed circuit board. 
Size Si x St x lin. Fre-allgned. Com- 
plete with stereo beacon indicator. 12V 
d.c. operation. 400mV output lor lOOmV 
input. Full inalr actions lor any FM Tuner. 
Some technical experience £ d. Q&t Post 

• ■unti.l '" »' lKn 



essential. 



ISp 




4 Transistor Mono Amplifier 

Powerful 8 watt output. 15 ohm. AC mains operated with 
trans! ormer. 3-Con trots, volume, treble, bass and On Oil 
switch with knobs. Beady made on primed circuit board. 
Fused inputs and outputs. Famous make. 
Size 8in. wide x 4 in. deep • 3 in, high. 

Suitable?" x 4" speaker. El. PRICE £5*95 j^p 

R..G.S. STABILISED POWER PACK KITS 

All parts and Instructions with Zeuer Diode. Printed Circuit, 
Bridge Rectifiers and Double Wound Mains Transformer 
input 800/E40v. AC. Output voltages available 8 or 9 Or 
IS or 16 Or IS or 20v. DC at 100mA or lest, 
PLEASE STATE VOLTAGE REQUIRED. i"> # 10 POST 
Details S.A.E. Sise 3, x 1* x liiu.. *"* Aw 16p 

GENERAL PURPOSE TRANSISTOR 
PREAMPLIFIER BRITISH MADE 

Ideal lor Mike, Tape, P.U., Guitar. Can be used with 
Battery S-18v or H.T. line EOO-800* D.C, operation. 
Size It" x If" x 1". Response 86 c.p.s. to Ei Kc/s. BSdb gain. 
For nse with valve or transistor equipment. QOn Post 
FnU instructions supplied. Details S.A.E. * *Y 10p 




BLANK ALUMINIUM CHASSIS 18 s.w.g. Bin, sides. 8 x 4 in 
45p;8 x 7tn.80p;ll X 7in, 70p; 18 x gin.aopilt x llin. 
95p; 15x1410. 99p; 11 x Sin. 50p; 18 x lOin. £1. 
ALU MINIUM BOX 8x4:- din. 80p, 
ALUMINIUM PANELS 18 s.w.g. 8 x 4in. 9p; 8 x Bin. 15p; 
14 x Sin. 16p; 10 x 7in. IBp; 12 x Sin. SOp: IS x Bin. S8p: 
18 x Bin. SSp: 14 x 8in.S4p;lB x 12in.40p;18 x 10in.50p 
PAXOLDI PANEL 10 x Sin, ISp. 



NEW ELECTROLYTIC CONDENSERS 



2,350V . 
4,350V , 
8 ; 450V 
18/4607 
32,' 450V 
85/S5V 
50/50V . 
100/257 



14p I S50/2SV . 
Up , 500.25V . 
14p 1000,'SSV - 
lap i 1000,50V . 
20p : 8-8450V 
lOp 8 J- lfl,'450V 
lOp 16 . 18,450V 25p 
lOp B2-3S/860V 26p 



47p 

ISp 
£0p 



35p 



14 P , 50 • 50/350 V 

EOp I 80 - 100/S5OV 

35p SB - 32/250 V . . 18p 

32 + 3 2/ 4507 . . SSp 

360 -50/ 325V .. 60p 

38*38-32/3507 48p 

100-50-60/8507 48p 



LOW VOLTAGE ELECTROLYTICS 

1, £, 4, 5, S, 18, 25, SO, 60, 100, SOOmF. 15V, lOp. 

SOOmF. 18V. ISp; 26V. EOp; 50V, 80p. 

lOOOmF. 12V. 17p; 26V. SSp; 60V. 47p; 100V . 70p. 

EOOOmF. 0V. S6p; 26V. 42p; 60 V, 57p. 

E600mF, 60V, 62p; 3000mF. 86V. 47p; 60V. 66p. 

SOOOmF. 8V. SSp; 12V. 48p; £6V. 76p; 86V. 86p; 60V. 95p. 



CEBAMIC lpF to OlmF. 4p. Silver Mica £ to SOOOpF, 4p 
FAPEB 850V -0-1 4p, 5 ISp; lmF 15p; EmF 150V ISp. 
6007-0-001 to 005 4p; 0-1 6n: 25 Sp; 47 85p. 
SILVER MICA. Close tolerance lli 2 E-600pF Sp; 600-8,£00 
pF lOp; 2,70O-5,8O0pF SOp; B,8Q0pF-0 01m F SOp; each, 
TWIN GANG. "0-0" BOSpF- 178pF, B5p; 600pF standard 
45 p; 385-385 with 25 - £5pF Slow motion drive SOp. 
SHORT WAVE, SINGLE. lOpF 30p; 26pF 55p; 60pF SSp. 
NEON PANEL INDICATORS. £60V AC/DC Amber EOp, 
RESISTORS, i w., t w„ 1 w., lp; £ w., 6p 10 ohms to 10 meg. 
HIGH STABILITY, t W, t% 10 ohms to 8 meg., lOp. 
Ditto 6% Preferred valoes 10 ohms to 10 meg., 4p. 
WIEE-WOUKD RESISTORS. 6 wait, 10 watt, 16 watt 
10 ohms to 100K lOp each; £1 watt, 1 ohm to 8 £ ohms lOp. 
TAPE OSCILLATOR COIL, Valve Type SSp. 



COMPACT PORTABLE STEREO HI-FI 

Two lull size loudspeakers 13{ x 10 x 3iin. Player unit 
clips to loudspeakers making it extremely compact, 
overall sise only 13 1 x 10 x 9 sin. 3 watts per channel, 
plays all records 33 rpm, 45 rpm. Separate volume and 
tone controls. £40v AC mains. Attractive Brown colour, 
weight lSlbs. £25 + 85p - arriage. 



BRITISH FM/VHF TUNING HEART 

SS to 108 Mc/s British made. 2 Tran- Oar Price 

sisters ready aligned — requires 10.7 
Mc/s IF. Complete with tuning gang. 
Connections supplied bat tome 
technical experience essential. 



£3-95 



MAINS TRANSFORMERS K %™Z 

Eagle MT1E 12-0-12 v. 50 mA - SOp 

E50-0-E50 SO mA. 6 8 v. 8 5 » 8 3 v. 1 a, or 5 v. 2 a. fS 50 
860-0-350 80 mA. « 8 v. SB I. 6 3 v. 1 a. or 6 v. 8 a. 13 DO 
800-0-800 v. ISO mA., 6 3 v. 4 a. C.T.; 6 8 v. E a. £3 25 
MDITATUBE EOO v. 20 mA., 8 8 V. 1 a. Ei x 21 x £in. 75p 
MIDGET SSO v. 46 mA., 8 3 v. S a. Si x Bj x £in. BOp 

HEATER TRANS. 6.8 v. 8 a SOp 

GENERAL PUBPOSE LOW VOLTAGE, Tapped Outputs 
at £ amp, 3, 4. 6, 6, 8, 9. 10, 18, 15. 18, £4 and SO v. £2 26 

1 amp. 6, 8, 10, 12, IS, IS. SO. 84, 30. 33, 40, 48, 80, £3-25 

2 amp. 6, S, 10, IS, 18, 18. 80. £4, SO, 38. 40. 48. 60. £3 26 
6 amp. 8, 8, 10, IE, 18, 18, £0, 24. 80, 38, 40. 48. 80. £8-76 
S amp. 6, 8 and 18 v. El 00; Ditto 6 amp. £1 80. 

3 amp. 3, 5, S, 10, 13 and 6-0-5 v. £130; Ditto 6 amp. 11-50 
3-0-Sv. 500 mA., BOp, 9v. 1 amp, SSp. 12v. 300 mA.. 75p. 
12v. GOO mA.. B6p. 18v. 750 mA., SSp. 
AUTO TRA8SFORMEES 116v. to 280v. or BSOv. to 115v. 
150w. £££5: SOOw. £8 86; 760w. £10; lOOOw. E15. 
CHABGER TRANSFORMERS. Input BOO/260 v. lor 6 
or IS v., 14 amp. £1 50; S amp. £1 80; 4 amp. £2 50. 
BATTERY CHARGERS, liA. £2; 3A £8; 4A £4, 5A. E4-50 



FACTORY ACT! MAINS ISOLATING TRANSFORMER 

Primary 0-11O-E40 v. Secondary 0-240 v. 3 amps. 7S0 
watts. Insulated terminals. Varnish Impregnated. Fully 
enclosed in steel case with tlxlng feet. Famous make. 
Value £19. OUB SPECIAL PRICE £ I ft Carriage 
DDEAL FOR COLOUR TV W 60 p. 

Can be used as 800 watt Auto Translormer S40-110V. 



ALL MODELS "BAKER SPEAKERS" IN STOCK 
Hi-Fi Enclosure Manual containing £0 plans, designs, 
crossover data and cable tables. 42p. Post Free 



BAKER I lin. MAJOR £10 




P. & p. £5p 

80-14,600 c.p.s., ISin. doable 
cons, wooler sod tweeter cane 
together with a BAKER 
ceramic magnet assembly 
having a Sax density ol 
14.000 gauss and a total flux 
ol 145,000 Maxwells. Bass 
resonance 40 c.p.s. Rated 80 
watts. NOTE : 3 or 8 or 
IS ohms must be stated. 



Mod ale kit. 80-17.000 o.p.s. 
with tweeter crossover, baffle 
and Instructions. /IT.Cfi 
P.&P.SSp. *IA'»U 



BAKER "BIG-SOUND" SPEAKERS P. ft p. SSp 

'Group 25' ] 'Group 35* : 'Group 50' 

12 inch /Q Oft 12 inch fQ Oft . 16' Inch {•)-% 
85 watt «-°*W 36 watt "•W i M witt X.LL 
8 or 8 or 16 ohm ' 8 or 8 or 15 ohm I S or 15 ohm 



TEAK VENEERED HI-FI SPEAKER CABINETS 
For 12iu. or lOin. die. speaker 80 x 18 x 91n. E9-M Post SSp 
For 13 x Sin. or Sin. speaker 18 x 10 x Sin. £6 -50 Post 25p 
For 8 x 6in. speaker 18 x 8 xflin. £4-40 Post 25p 
For Bin. and tweeter IE ■< 8 ■ 81n. £4 Post S5p 
LOUDSPEAKER CABINET W ADDING IBin. wide. 16p It 




8> 



GOODMANS 6^in. hi-fi woofer £4 

8 ohm. 10 watt. Large ceramic magnet. 
Special Cambric cone surround. Frequency 
response 30-12,000 cps. Ideal P.A. Columns, 
Hi-Fi Enclosures Systems, etc 
Suitsble Cabinet 18 x 8 x 6, £4 00. 
Suitable Tweeter. £2 00. 

ELAC CONE TWEETER 

The moving coil diaphragm gives a good 
radiation pattern to the higher Irecjuenciet 
and a smooth extension ol total response 
trom 1,000 cps to 18.000 cps. Size Si x 
S t x Sin. deep. Rating 10 watts, 3 ohm 
or IS ohm models. / I .OQ p<„t iop 

Crjsiover. 96p. *• ' #w 

SPEAKER COVERING MATERIALS. Samples Urge S.A.E. 
Hots Tweeters S-18ke/s. 10W 8 ohm or 15 ohm £1-95. 
De Luxe Horn Tweeters S-1S Kc/s, 1SW, 15 ohm fS. 
TWO-WAY 3000cps CROSSOVERS 3 or S or 16 ohm SSp. 
LOUDSPEAKERS P.M. 3 OHMS. 7 x4in. £1-25; B t in. fl-M: 
8x5in. £1 80; lOin. £8 00; Sin. £1 78; 10 X Sin. £1 SO; lOin. 
££■00. SPECIAL OFFEE: 80 ohm, Ejln.; £|in., 36 ohm, Bku, 
Sin., 25 ohm, 2iin. dia.: Sin. dia,- Sin. dia, f\ EACH 
15 ohm, 8,in. dia.; 8x 4in.; 7 x 4ln.; 8x Sin. *• ■ TYPE 
3 ohm, 2iin.; 2iin.; 8Hn.; Sin. dia, (8x4ln. 8 ohm 11-50) 
RICHARD ALLAN TWIN CONE LOUDSPEAKERS. 
Sin. diameter 4 watt; lOin. 6 wilt; 12in. 8 watt 3 or 8 
or 15 ohm models £2 20 each. Post 15p. 
VALVE OUTPUT TRANS. 85p; MIKE TRANB. 60:1 SSp. 
5 WATT MULTI-RATIO. 3. S and 15 ohms, BOp. 



MAJOR 100 WATT 
ALL PURPOSE 
GROUP 
AMPLIFIER 



All transistorized. 4 Inputs, speech 
and music. 4-way mixing. Output 
8/15 ohm. A.C. SOO/S&Ov. Separate 
Treble and Bats controls. Guaran- 
teed. Details S.A.E. 




£49 



BARGAIK AM TUNER, Medium Wave. £4.95 

Tranaistor Super tut. Ferrite aerial. volt. fc ^ '"* 

BARGAIN 4 CHANNEL TRANSISTOB M01CO MIXER, 
Add musical highlights and sound effects to recordings. 
Will mil Microphone, records, tape and tuner £T.OC 
with separate controls Into single o atput . 6 volt. *■ 

STEREO VERSION OF ABOVE 



£5-95 



BARGAIN FM TUNER 88-108 He's Six Tranaistor. S volt 
Printed Circuit. Calibrated slide dial tuning, f I A.QC 
Walnut Cabinet. Sis* 7 - 5 >. 4 in. * n w 

BARGAIN FM TUNEE as above less cabinet. £9*85 



BARGAIN 3 WATT AMPLIFIER. 4 Transistor f&.C(\ 
Push-Pnll Ready built, with volume control. 9v. fc ^ ■*** 



9Sp 



RADIO COMPONENT SPECIALISTS 



Minimum post I 5p. 






Radio Books & Components Lists I Op. 



COAXIAL PLUG lOp. PANEL SOCKETS lOp. LINE ISp. 
OUTLET BOXES, SURFACE OR FLUSH, 85p. 
BALANCED TWIN RIBBON FEEDER 300 ohms 5p yard. 
JACK SOCKET Std. open-circuit 14p, closed-circuit SSp. 
Chrome Lead Socket 45p. Phono PIuks Sp. Phono Socket 6p. 
JACK PLUGS Std. Chrome 16p: 3 5mm Chrome 12p. DIN 
SOCKETS Chassis 3-pin lOp; 6-pln lOp, DIN SOCKETS Lead 
3-pin ISp; 5 -pin SSp. DIN PLUGS 8-pin ISp; 5-pin S6p. 
VALVE HOLDERS, 5p; CERAMIC 8p: CANS Sp. 

TWO RPM GEARED MOTOR 

240V. A.C, mains. Ideal lor displays/disco 
light wheels. 

E.M.I. GRAM MOTOR 
120v. or 840v. A.C. 2.400 rpm. B-pole 
70mA. Spindle i x Aln. Blse 21 x St 
x 2 lin. 

DELUXE 4 POLE MOTOR 1400 rpm. 48 W sixe Si 
post SSp. 11-86. 

337 WHITEHORSE ROAD, CROYDON 

Open 9 — 6 Wed. 9—1 Sat. 9 — S (Closed for lunch 1.15 — 230) 

illustrated Colour Brochure Buses 50, 68, 159 Rail SelKurst, Tet. 01 -684- 1 665. 

351 



SSp. 

£1-00 

Pott SSp. 



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ing, plus your determination to study, we can turn your 
interest into the technical knowledge you need for success. 
Once you've got the qualifications you need, you'll be in a 
good position to take full advantage of the opportunities 
which exist today in all fields of electronics - in television 
(colour and black/white) and in radio. (We teach you the 
theory and practice of valve and transistor portable cir- 
cuits while you build your own 5 valve receiver, transistor 
portable and high grade test instruments). 

With ICS you study at home - at your own pace, when 
you choose, in the time you've got available. Your ICS 
tutors will give you all the help and encouragement you 
need to pass any exams you want to take. 

Don't waste another day. Take your first step now 
towards a better paid, more assured future. Send for your 
FREE Careers Guide today. 

! your key to the door 
I of opportunity 

Tick or state subject of interest and post to: 
International Correspondence Schools, Dept 2325, 
Iflterrext House, Stewarts Road, London SWS 4UJ. 



Subject of interest. 



[J Society of Engineers Graduateship (Electrical Engineering) 
Lj C & G Telecommunications Technicians Certificates 
P] C & G Electrical Installation Work 
_j C& G Certificate in Technical Communication Techniques 
I I MPT General Certificate in Radio Telegraphy 
LJ Audio, Radio & TV Engineering & Servicing 
Q Electronic Engineering, Maintenance, Engineering 

systems, Instrumentation & Control systems 
Q Computer Engineering and Technology 
□ Electrical Engineering, Installations, Contracting, Appliances 
I I Self-build radio courses 



Name 



Address _ 



Occupation^ 



-Age_ 



■Accredited by (he Council for the Accreditation of Correspondence Colleges ■ i 




-GLADSTONE RADIO 

66 ELMS ROAD, ALDERSHOT, Hants GU11 1LP 

No export. Min. order BOjj. ft/Hi include VA T. Cloted Wednetdttyi 



F.X. TUHEK.AJOTJFIBR lor 88-102 MHz. Bell. 
powered lor 200-280v, a.c. double wound mains 
trans. Valves ECCflB, EF89, EFBO, recto. Chassis 
10" x 6" X fl". Audio module output stage giving 3W 
Into 16-objns. Price *I8 (p. & p. 8flp). 



MAINS TRANSFORMERS. 240-260 v. Input. Deduct 10% tor more than two trans- 
formers. Trade enquiries invited. 

B. Charger 12?. at 1JA, Mn <20p post) 

E, 2G0v. at 50 m.a., ft 6-3v. at IfA, Sop (20p) 

H, 90v, at lOOm.a., & 220 v. at 50m.*. SS? (2 Op) 

3. 37v, 2A, 34-0-24T. 150m.a. *87B ("Op) 

K. 250-0-250v. 150m. a. 20 v. J A. 19 v. 1A. 8Sv. DA. tSSO (70p) 

M. 110r. inpnt; 2Q0-O-200v. flOm.a. 8*.)v. HA, 60s (26pJ 

P. Driver, S to 1 + 1 suitable BOW. axip. 42p (20p) 

Q. 10 Or, lOOma, 28 v. 250ma, 6-3v. Al. double shrouded 6Ep (2fip) 

R. 230v. 60ma, 8-3v. 2JA, 60p (33p) 

8. 260-O-260V. 80ma. 8-3v. 2JA. 76p (Mp) 
100 Resistors i"W. ft JW, 27p (lup) 
100 Slivered Mica 49s (10pi 
100 Diodes AE2 - CG82 = OA90 13 (lOp) 
100 Ceramics 60s (lOp) 
100 Sigh Stabs. 60s (12p) 
i lb Tag Strips 2 to 10 war *1 (10p), 
100 Shskeproof washers f clear l.d. 25s (8p) 



MW/LW TRANSISTOE RADIO 
Complete set ol parts tor this MW/LW 
Tnuiiistor Radio, Coverage 182-GoSra + 
10!'0-1870m. 9 volt 6 transistor superhet 
using 3 AF11T In EF and IE stages 
powered by a two stage AF amplifier using 
3 X AC 128. Output approi. 600MW. 
Also works off car-aerial, Ply case, rexlne 
covered. Requires FP? battery, price 
87ji extra. 3|tn high-quality speaker, 
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KAIL ORDER ONLY 



NEW VALVES I 

24-HOUR SERVICE 



GUARANTEED AND TESTED 

PRICES INCLUDE VAT 



IRS 


•28 


30Pia 


J3 


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EL33 


•63 


PCF8K 


N 


PT801 


■an 


1S5 


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30FL1 


54 


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17 


EL4) 


■47 


PCF801 


>>■? 


B19 


p- 


1T4 


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DAi'91 


:;« 


ECC83 


: J 1 


EL84 


■20 


PCFB02 


,<:■■■ 


U26 


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364 


■28 


DAF96 


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■31 


E;yi80 


35 


PCF805 


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23 


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6/30L2 


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30 


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80 


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DH77 


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■87 


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31 


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■87 


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47 


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;;.-• 


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•67 


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KT61 


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6P23 


84 


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EF39 


•43 


K'J?66 


■78 


PL38 


4S 


UCH42 


KB 


6F25 


•40 


DL94 


43 


EP41 


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£100 


PL81 


a 


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17 


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FC88 


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PL82 


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2SLBGT 


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EF80 


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Pt'88 


42 


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49 


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FT82 


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83 


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25 


PY800 


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42 



Post/Paeklng on 1 valve 7p. plus 3p. per valve on eaeh eitra valve. Any pareel lctured 
agauut damage la transit 3p. extra. Office addnn, no callers. 

GERALD BERNARD ^«2SSX»... 



352 



GOING BACK 




MR. J. TURNER tells us that he managed to 
purchase a Marconiphone model V2 receiver 
at a local auction. He has restored it to work- 
ing order and it performs very well — especially on 
long waves. Tuning is accomplished by sliding in 
various ebonite slabs — each covering a different 
range. Each contains an "embedded" coil which is 
tuned by copper "spades." There is a "regenerator 
unit" which does not seem to fulfil any useful purpose 
and Mr. Turner would like to hear from any readers 
who can comment on this. The valves are of the 
D.E.R. type (dull emitters). The h.t. supply is 90V 
and l.t. 3V. The set still bears its original transfers 
and is in very good condition throughout. Inside the 
lid there is an ivorine plate giving the serial number 
of the set as "installation no. S/A 2535. 

Mr. Turner would like any information on this 
set that readers could supply. 

We found a reference to the V2 in a catalogue 
kindly lent to us by Dr. Brodribb — another vintage 
radio coEector. It reads: "The Marconiphone V2 
gives excellent results as a long-range instrument. By 
its reflex circuit, two valves do the work of three. It 
holds a remarkable record of results from overseas 
stations, including America. Cost of upkeep is com- 
paratively negligible, and is perfectly simple to 
operate." 

In c!926 the V2 could be obtained from Upfield 
and Sons (Motors) at Hastings, for the sum of £10.5s. 




The receiver complete with accessories, including 
two D.E.R. valves cost £14.1 Is. 2d and a dry cell com- 
bination including two D.E.3. valves cost £14.13s.8d. 
There was also a Marconi royalty of £1.5s to pay. 

Our old friend Chris Petsikopoulos from Greece 
tells us he has recently returned from holiday and 
writes : 

"During that time I had the opportunity to make 
a great search which brought great finds, the most 
important of all was a French radio-set of the era 
1917-1918, made by "DUCRETET", Paris, providing 
a 100 watt spark Transmitter and crystal detector 
receiver connected in a common tuning circuit 
through a change-over switch. 

The tuning circuit consists of an Oudine coil with 
a slider for the aerial and a variable capacitor used 
only for reception, this meaning that the transmitter 
works on a standard wave length (450m). The whole 
unit is housed in a compact wooden case 17 x 12 
inches, and is in nice condition. In the case are 
housed the tuning coil, variable capacitor, send- 
receive switch, mica condenser, high tension coil with 
interrupter, and a 10 amp. meter. Also connectors 
for key and headphones. On top of the set are aerial- 
earth connectors, crystal detector, and spark-gap. 
Connectors for 12V d.c. are on the right side of the 
case. 

Connecting a 12V battery, a 100 foot aerial and 
an earth, the set was able to work. The aerial was 



j Regenerator 



Fig. 1 1 The circuit of the Marconi 
V2 receiver re-drawn from the 
information supplied by Mr. J. 
Turner. 



X 0+ 



353 




The "Thomson-Houston" receiver. 

tuned with the slider for maximum current, 5-6 amp.. 
giving a nice audible buzzing signal in a range of 
about 5-8 miles depending on the position of the car 
which was used for checking the range. The receiver 
has a range from 250-600m and the reception of 
several broadcasting stations was able with good 
volume, the only difficulty being in finding a sensitive 
position on the crystal although the change-over 
switch provides a third position where the tuning 
circuit is off and the buzzing of the interrupter is 
then used to adjust the detector. 

Shown are pictures of the above set and of a 
1922 two valve Heterodyne made by "Thomson- 
Houston", Paris, valves are type R-5 of "La Radio- 
technique" still working. The set is accompanied 
with a band switching frame aerial covering a wave 
length from 400m to 3,000m in three ranges " 

354 



Mr. H. E. Hunt, 68 Oundle Road. Thropstoji, 
Northants, quotes some prices he noticed for making 
one's own components. 

"Your feature "Going Back" has caused me to 
reach for Vol. IV of "The Amateur Mechanic" whose 
mildewed covers contain the inspiration that set me 
building my first "Wireless Telegraph" set (1920-21). 

There is no "Components List" because there were 
no components in those days but a "Specification of 
Materials" and I quote that portion for the variable 
condenser only: — 

s. d. 

1 sq. ft of l 4 inch teak (to make box) 6 

1 sq. ft. of thin sheet ;:inc 2 

2 small nuts and bolts 2 

1 knob (off rubber stamp or screwdriver) 

2 small brass terminals 3 
8 ins. electric light flexible wire 2 
6 old quarter plate negatives 



Total cost 1 3 



(The last item was for di-electric, not P.C.Bs.) 
These were the days of ebonite, teak, brass turning 
and 21b. soldering irons (gas heated). 

Such was the success of this "Long Distance 
Receiver"— Poldhu, Eiffel Tower and numerous 
spark transmitters were received— using a 6ft. twin 
spreader aerial. 50ft. long and 30ft. high, that I was 
able to obtain parental financial backing (30/-) to 
build a single valve receiver. 

The valve was an ungettered one of Dutch 
manufacture (15/-) which not only furnished 
sufficient light to work to but formed the nucleus of 
a receiver that occupied one half of the work bench. 

But what a new world it opened up, the Hague 
concerts on Sundays, and England's first and unsur- 
passed compere P. P. Eckersley frorri 2.MT. at 
Writtle, Essex on Tuesday evenings. 

There were also at this time some excellent 
telephony transmissions from local Northampton 
amateurs (2.TV.-5XH-5XG). 

I started using the d.c. mains for h.t. long before 
eliminators were on the market, except that one had 
to put up with a complete loss of signals every time 
a tram passed 200 yards away. 

One could write a book on the early days of 
amateur "wireless' but for myself I must hurry off 
to change an under-rated thyristor in the speed 
control of my wheel chair (or something like that). 
Tern pus fugit! ! 



FUTURE PLANS 

Let us tell you why you should know about some of • 
o u r f utu re p 1 an s i n Practical Wireless. 
First, our autumn issues are being planned as the 
best yet; secondly, we will be doing what no other 
magazine has ever done before; thirdly, if you don't 
find out about these and order your copies in 
advance, your newsagent is very likely to self out 
before you get there. 

Naturally, we cannot tell you everything now, but 
we can tell you what to look for next month, and in : 
the following issues. Want to know more? Then 
keep your eyes on' our "Leader" page and turn to 
pages 320, 334, 335 and 350 for further details in 
this issue. 




YOUR COMPLETE AUDIO-ELECTRONIC STORES 

More of everything at the right price. All your electronic requirements 
within 200 yards - csfi and see for yourself. 



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20 19 018 
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0-BO 018 016 
23 22 20 
42 40 86 
80 27 25 
SO 27 25 
80 OS? SS 
20 18 18 
48 44 40 
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48 40 35 
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SO 18 16 
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BN7442 0-76 0-78 0. 70 

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BOO 1-75 1 W 
BOO 1 75 1 60 
1-76 1-60 1-45 
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1/11 12/24 25/! 
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20 18 
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87 0-80 

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BX7491AX1-00 95 
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8 60 2 

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6 25 6 
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800 1 
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ISO 1 
1-90 1 
1-65 1 
700 6 
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BX7418SA 8-40 2 
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2 00 1 
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1 85 1 
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1 60 1 
400 3 
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■V. 2 
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■:iB i 
Z0 2 
50 S 
SD 3 
£B 5 
55 3 
75 1 
27 1 
3d 1 
35 1 
30 1 
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85 I 
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PRICES OF 7400 SERIES ARE CALCULATED ON THE TOTAL NUMBER 
ORDERED REGARDLESS OF MIX 
LARGER QUANTITY PRICES PHONE (01) 402 4891 
HIGH POWER SN 74 HOO 1 Now in stock — jertd 
LOW POWER SM 74 LOO / for list No. 36 



A SELECTION OF SEMI-CONDUCTORS FROM STOCK 



AAY30 


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ACI07 


Sip 


AC12S 


25? 


AC127 


24 s 


AC128 


Ml 


A CI 7 6 


25 p 


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AC188 


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ACT17 


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Mb 


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£0p 


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S5p 



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its 

15p 

35? 
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SOp 
75P 
SOP 
25 p 
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15p 
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BU105 2-26 
BY100 16p 
BY126 " 
BY 127 
BYZ13 
C106D 
OET111 55 p 
GET115 69p 
GETSVJ 45p 
EM 309 K 
(T03) 1-87 
MAT121 25p 
MJE340 5 Op 
MJE370 70p 
MJE520 7Sp 
MJE29S5 

110 
MJE3055 

76p 
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XKT214 SOp 
XKT216 40p 
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OA5 60p 
OA10 
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OC20 
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35i> 
lOp 

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esp 

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ORF60 4 Op 

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55p 
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TIL209 SSp 
TIP29A 60p 
TIP 30 A 90p 
T1F31A 80p 
TIF32A 70p 
TIP33A 

1 00 
TIP34A 

150 
TIF3SA 

2 50 
TIP36A 

800 
TIF41A 76P 
TIF42A SSp 



Ma 

35 p 
15p 

15p 

m 

20p 
45p 



TIS43 8Sp 
V405A 26p 
2TX10B 12p 
ZTX300 12p 
ZTX301 16p 
ZTX302 18p 
ZTX341 SOp 
ZTXSOO 15p 
ZTX603 17p 
2G301 80p 
2X404 
2X527 
2X696 
2N697 
50p I 2N706 
~ 2X930 
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2X1131 86p 
2X1132 86p 
2X1302 18p 
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2X1308 26p 
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2X1671 1-00 
2X2147 75p 
2X2160 G9p 
2X2217 SSp 
2X2221 SOp 
2X2222 A 

25 p 
2X2389A 

15p 
2X2906 £0p 
2N2926 (all 
crils) lOp 
2X3053 SOp 
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2X3056 55p 
2X3440 75p 
2X3442 1-25 
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2X3614 59p 
2X3815 75p 
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2X3704 10p 
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2X3714 1 SO 
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2X3773 S Ofl 
2X3790 2 25 
2X3319 SSp 
2X3820 SOp 
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2X3903 15p 
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2X4871 35 p 
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28001 100 
28012 10 00 
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28026 
28301 
28303 
2S324 
40250 
40360 
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40636 
40430 



890 
SOp 
65p 
9Sp 
SOp 
40p 
40p 
SOp 
SOp 
75p 
110 
100 



VAT pr 



NOT include 
Value Added Tax. From 
1st April, 1973 10% muse be added 
and shown separately to your total 
order (incl. carr/psckingj. Help 
us to help you receive your order 
without delay. E. & O. E. 



QUANTITY DISCOUNTS 

10% 12+ ; 16% 25+ AXT ONE 

80% 100+ ; SS% 850- TYPE 

From above sections except Integrated 
Circuits and Special Offers where dis- 
counts are Included. 
Minimum- order value II please. 
Postage 7p on alt orders. 



SPECIAL OFFERS1 
SEMI-CONDUCTORS 



BFY90 59p 

IO00 MC S 

IS + SOp 
100 + 45p 
500 + 40p 



2N2926 lOp 

All Colours 
25 + 9p 
100 + 8p 
500 + 6p 
1000 + 5p 



AFII7MuHardI5p 
25 + i7p 
100 + 15p 
500 + I2p 



0CI70Mull3rd25p 
20 p 

itp 

ISp 
Up 



25 

100 
500 
1000 



BYI27Mul!ard ISp 

25 + lip 

I0O + lOp 

500 + 9p 

1000 + 8p 



OA202 
25 

100 

soo 

1000 



lOp 



+ Bp 
+ 7p 

+ *P 
+ 5p 



OC35r1uNardS0p 

25 + 4Sp 

100 + 40p 

500 + 35p 

1000 + 30p 



2N3B19 Texas 35p 

25 + 30p 

100 + ISp 

500 + 20p 

1000 + ISp 



BCI07, BCI08, 
BCI09 I Op each 
All Makes 
25 + ftp 
100 + 7p 
500 + 6p 
1000 + 5p 



FLESSEY INTEGRATED CIHCCIT 
3 Watt Amplifier 8L403D 
Complete with 8-page 
booklet, circuits 
tad ■ : .:i\-K 



£1.50 ^ 



ADI6I. ADI62 3Sp 

each 

25 + 32p 

100 + Z8p 

500 + ISp 

I0O0 + 12c 



2N3053 

25 + 

100 + 
500 + 
1000 + 



20c 



[8p 
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I Op 



2N3055 

25 + SOp 
100 + 45p 
500 + JBp 
1000 + 33p 



55p 



TRIACS 

STUD WITH ACCESSORIES 

Type Volts Price 

F.I.V, 1-11 
3 AMP RANGE 
8C35A 100 76p 

8C35B 200 7Bp 

SC3SD 400 B5p 

6 AMP RANGE ;T043> 
SC40A 100 SSp 

8C40B 200 SOp 

SC40D 400 £100 

8C40E 600 £1-20 

10 AMP RANGE (T048I 
SC45A 100 SSp 

BC40B 200 £100 

8C45D 400 £125 

8C45E 500 ti-ii 
15 AMP RANGE (T048) 
SC50A 100 tl-SS 

8C50B 200 £1 85 

SC30D 400 11-86 

SC60E 600 £185 

DIAC U32 S6p 
TRIACS— 
Additional Types 
40430 (T066) SSp 

40660 (Plastic) 

i^- £100 



3 Amp 
T048 




15 Amp 
T048 



ZENER 
DIODES 

400 M/W 6% 
Miniature 
BZY 88 Range 

All voltages 
3-3-33 Volt 
lOp each. 



25 + 




n 


100 + 


ap 


500 + 




9 5p 


1000 + 




5 P 


Any one 


type. 




1^ Watt 5% 




Wire Ends 




Metal Case 




All voltages 




8-8 - 100 Volts 




SOp each 




25+ 




in 


100 + 




i«p 


500 + 




1% 


1000 + 




10p 


Any one type. 




3 Watt Plastic 




Wire Ends 61 




3SZ Ka&ge 




All voltages 




6-8 - 100 Volts 




SOp each. 




SILICON 




RECTIFIERS 




WIRE ENDED 




FLA8TI 


3 





Type P.I.V.1-11 
1 amp miniature 
IN4001 50 6 



1N4002 
1N40O3 
IN4004 
IN4005 
IN 400 6 
IN 4007 



100 7 

200 8 

400 8 

600 10 

800 12 

1000 15 

1-6 amp miniature 

PL4001 



PL4002 
PL4003 
FM004 
PL4005 
HuMM 
PL4O07 



100 
200 
400 
600 
800 
1000 



10 



in 



LINEAR 
(O/P AMPS) 



702C 
70LK; 
709C 
723C 
TiSC 
72SC 
741C 
741IJ 
747C 
747C 



TOS 75p 
TO09 35p 
D.I.L. 3Sp 
T099 £100 
D.I.L. SSp 
TO99*4-60 
TO 99 SSp 
D.I.L. 55p ' 
TO09 £110 
D.I.L. 

£110 

72741F D.I.L. SOp 

72748P D.IX. SOp 

SINCLAIR 

IC12 £1 80 

TOSHIBA 

TH9013P 

20 WATT AMP 

£4-47 POST PAID 

TH9014P Pre Amp' 
£1-50 

DATA AND 

ClRCIriTS REF. 
42 lOp 

FREE WITH 

PURCHASES 



TRANSISTORS, 
IC'f, TRIACS, 
BRIDGES, 
SCR'i, LDR's 



NEW BRIDGE 
RECTIFIERS 

SMALL SIZE AND LOW COST 

Tj-pe Volta Price 

P.I.V. 1-11 
HALF AMP 
BO6/06 50 

BO5/10 100 
ONE AMP jx|H 
TUBULAR 
Bl/05 60 

B.1,'10 100 

HI, "JO 200 

Bl/60 600 

ORE AMP (O.I.) 
TUBULAR 
W005 50 

W01 100 

woa 200 

W00 600 

TWO AMPS i H 



SOp 
S6p 



SSp 
B5p 
SOp 
35p 



SOp 
SSp 
40p 
45p 
■ L 



B2/0S 

B2/100 

BS/OM 

B 2/600 

BshMO 

FOUR AMPS 

iH - jL - ft 



100- 
200 
000 
1000 



Mnso 

B4/*200 
B4/400 

Hl/l-.llii 

H4/H0O 

SIX AMPS 
IB x jL I 
BS/100 
B8/200 
B3/400 

B»;/fioo 



100 
200 
400 

SOS 

soo 

: A 

100 
V00 
MM 



SSp 
40p 
4Sp 

SOp 
60p 



SOp 
SSp 
70p 

7Sp 
1100 



70p 
76p 
»0p 




NEW FREE 
BOOKLET 

(No. 36) 
OVER 1500 
TYPES— 

Send for yoi 
today I 



Type 

ONE AMP 

CRS 1 ^05 

CRSl/lO 

CRS lf20 

CRS 1/40 

CRS 1/80 

TttKEE AMF (T048) 



100 

SM 

600 



£5p 
SOp 

SOp 
SSp 

ISp 



100 



SOp 
SGp 
SSp 
400 46p 

600 56p 

FIVE AMP (T086) 
CRS 5/400 400 SOp 

SEVEN AMP (T048> 



CBBS/Ofi 

CRS 3/10 
CRS 3/20 
CRS 3/40 

CRS 3/60 



CRS 7/100 100 
CRS 7/200 200 
CRS 7/400 400 
CRS 7/600 600 
SIXTEEN AMP 
BCR 16/100 100 
SCR lfi/200 200 
BCR 16/400 400 
SCR lR/noo fino 



«0p 
SSp 
70p 
SSp 

6Sp 

70p 

SOp 

£1-00 



Henry's 



RADIO 
LIMITED 



EDG WARE ROAD, VV2 



4U4-406 Electronic Components and 
354-356 High Fidelity and Tape Equi[ 
309 PA- Disco-Lighting High Power 
303 Special offers and bargains stoi 
All mail to 303 Edgware Road. Lond 



d Equipment 01-402 8381 , Open- 
ipmentOI-402 5854,4736 f !'''**;' 



it 01-402 5854 4736 
nd 01-723 6963 



355 



TAKE 2© 



DAVID ANDREWS 



No. 51 

TOUCH-SENSITIVE SWITCH 



A series of simple transistor projects, 
using not more than twenty components. 



Nowadays there is a tendency to veer away 
from electro-mechanical switches to elec- 
tronic versions which have no moving parts. 
The reason is twofold; first there is less likelihood 
of failure and secondly there is a strange fascina- 
tion in setting something in motion or switching 
on something without any apparent mechanical 
intermediary. This is already happening in applica- 
tions such as lift control buttons and desk calcu- 
lator keying so why not in a few domestic situations, 
or as a replacement for the Morse operator's key? 
This month's circuit is a very simple way of pro- 
viding touch sensitive keying and is capable of 
several types of output including an output that 
illuminates a low voltage lamp but the circuit can 
be quite easily modified to provide a relay drive 



(rather negating the original sentiment of avoiding 
mechanical components!) or, better still, a logic 
(TTL) compatible output. 



Operation 

Touch sensitivity is achieved by detecting the 
minute current that passes through the finger when 
a pair of contacts is bridged by the touch of the 
operator. The touch transducer in the prototype 
was made from a 1 in. square of 0*1 in. pitch Vero- 
board, with alternate copper strips paralleled to- 
gether to form a contact pattern. 

A more attractive touch plate could be made by 
printed circuit techniques and if this is done it is 
better to use a fib re- glass base. In either case the 
copper contacts need some protection from corro- 
sion and this can be effected by lightly tinning the 
strips with solder. 

The touch plate is connected between the supply 



. 



R1 , 
22k > Tr1 

SC108 



Touch 
plate 



o 

BC1Q8 



LP1 

6V 

40mA 

Tr4 
BC108 



+ 9V 



'R7 
• 5- 6k 



i 4 mi ) Tr2 L Tr3 Tr4 

\i^7 BC108 R5< BC108 BC108 

; 3 C l R2 *± 

^ y >470k L <<P 



TTL 
compatible 
output 
-■ -O 



01 

sv zetw 



4- 



ov 
—o 



iAHQtm: 



Circuit of the touch-sensitive switch, with alternative TTL output circuit. 

1 2 3 l S G 7 I 9 10 n 1Z 13 It IS IE 17 



Touch plate 

din. square piece of 

0*1 in matrix Veroooard) 




2zz ezz 

R2 ES R4^ 

222 E C| 

T T! 




+9V 



To 
lamp 



0V 



Layout of components on the Veroboard with details of the touch plate. 



356 



rail (through Rl) and base of Trl which should have 
low leakage current (beware of cheap "reject" tran- 
sistors). When the plate is touched a very small cue- 
rent flows in the base/emitter circuit of Trl and this 
in turn permits a much higher current to flow be- 
tween collector and emitter. Tr2 and Tr3 are 
connected as a Schmitt Trigger circuit; the emitter 
current from Trl flows mainly into the base of Tr2 
and turns it on; this causes Tr3 to turn off and the 
potential at its collector starts to rise until base 
current in Tr4 is established. When this occurs the 
lamp LP1 ^lights. Alternatively, considering the TTL 
version, the output level falls to "0". 



* components list 



i P 
ip 
ip 
ip 
ip 
ip 

10p 
10p 
10p 
10p 
10p 
20p 

76p 



No allowance is made for minimum order costs or 
for postage and packing and these points should be 
checked carefully before ordering. 



Ri 


22kO 


R2 


470kQ 


R3 


1kQ 


R4 


150Q 


R5 


22kQ 


R6 


12kO 


Tr1 


BC108 


Tr2 


BC108 


Tr3 


BC108 


Tr4 


BC108 


LP1 


6V 40mA 


Veroboard :; : ■': .■; 



Removing the finger from the touch plate causes 
the base current to stop flowing in Trl; current 
into the base of Tr2 thus stops and the latter starts 
to turn off. As this occurs Tr3 starts to draw base 
current through R3 and R5 and begins to turn on. 
As this happens the potential at Tr3's emitter starts 
to rise slightly and this (due to the feedback in- 
herent in a Schmitt Trigger) causes Tr2 to turn off 
faster. At the same time the potential at Tr3's 
collector falls until sufficient base current into Tr4 
can no longer be maintained. Tr4 thus turns off 
and the lamp goes out. Alternatively the TTL output 
goes to a logic level "1". 



TTL Output 

To obtain the TTL output version R7 and zener 
diode Dl should be in circuit and lamp LP1 omitted 
For relay operation LP1 should be replaced by a 6 
volt relay. The components list has not taken the 
alternative versions into account. 



Note 

A word of warning — the touch plate should not 
be used out of doors or with wet fingers because 
droplets of moisture bridging the conductors will 
provide sufficient current to make the circuit switch. 
Possibly this problem could be overcome by carefully 
painting in the gaps between the strips with a good 
quality water repellent paint having a high gloss 
finish. 



A.SYDENHAM 



LOCATOR 



The easily built unit to be described is used to 
provide a signal in the 2 metre Amateur band 
(144-146MHz). When constructing or modify- 
ing apparatus for 2 metre use it can be very difficult 
indeed to locate the band or any part of it. Indeed in 
some areas, amateur activity is so low that many 
hours of experimenting may be wasted in tuning 
for non-existent transmissions. Experienced con- 
structors will know to their cost that at v.h.f. 
finicky adjustments are often required and in the 
case of a tuning coil for example just one half turn 
too little or too much may result in the circuit 
being so far off frequency as to be useless for the 
purpose required. To overcome problems such as 
these this unit was quickly assembled — and at small 
cost. 

The circuit of the device is shown in Fig. 1; it is 
by no means unique but rather the practical outcome 
of some earlier experiments. Basically a crystal- 






MHz 



controlled oscillator — Trl and associated items — 
provide harmonic output which is lightly audio 
modulated due to Tr2 circuitry. The modulating 
section is by no means essential but it does enable 
the user to aurally recognise the v.h.f. signal being 
generated which is, in the case of the 6025kHz 
crystal utilized, the twenty-fourth harmonic (6025 x 
24 = 144-6MHz). Whether or not the final generated 
frequency is exactly at this figure is not too im- 
portant provided it is in the 2 metre amateur band. 
Inductor LI is tuned by trimmer TCI to the crystal 
harmonic frequency, L2 merely being a low im- 
pedance untuned output link closely coupled to 
LI. In the f.e.t. source "circuit inductor L3 is tuned 
to the crystal frequency by capacitor CI, final fine 
tuning being accomplished by means of the dust core 
which when once set can be so left. The drain current 
taken by Irl when oscillating correctly is approxi- 
mately 2mA from a 9V d.c. supply. 

357 




\"/ output 
Fig, t Circuit of the complete unit 

+ 9V 

JL Imc 




Wff. 2 s Component layout and wiring. 



The circuitry around Tr2 enables audio oscilla- 
tions to be generated, transformer TI providing 
the required collector-base feedback. The trans- 
former used is a sub-miniature type driver trans- 
former removed from a defunct broadcast band 
receiver. Such items are not difficult to come by 
and in any case the type is not critical provided 
the primary and secondary windings have measured 
resistance values approximating to 500 and 150 
ohms respectively. If difficulty exists in finding a 
smtable surplus transformer for Tl a readily avail- 
able item is the Ardente type T1079 interstage 
model. In some cases — and particularly if the 
Ardente transformer is used— it may be necessary 
to increase the value of resistor R3 to say lOOkii. 
The frequency due to the audio generator is of 
little consequence provided it is recognizable. 

Constructional 

Since it is essential to screen the apparatus the 
ubiquitous 2-oz tobacco tin provides a cheap and 
convenient housing which also leaves sufficient in- 
ternal space for a small battery if desired. The 
location of components is shown in Fig. 2 which is 

358 



* components list 






Resistors 

R1 lOOkfl 

R2 39fflQ 

R3 56kfi 

Capacitors 
CI 15QpF 

C2 SQOOpF 
C3 lOOOpF feed-through 
C4 001jaF 

C5tO0/*F 10V electrolytic 
CTt ; 50pF miniature trimmer 

Miscellaneous 
Coil former, }in. diameter with dust core, 
tobacco tin, 9V battery, wire, solder, etc. XI, q 
crystal 6025kHz with holder to suit— see text 
see text. 

Transistors 
Til 2N38T9 
Tr2 BCtOS 



2-oz. 
uartz" 

T1- 



self-explanatory. As will be appreciated only the 
crystal, output socket and supply connectors exist 
outside when the tin lid is placed in position. In the 
prototype the negative supply lead is soldered direct 
to the case, the nearby positive supply being taken 
inside via a small feed-through capacitor. 

The inductors are home-made, LI consisting of 
3 turns of 24 s.w.g. copper wire wound on to a 3 8 in. 
diameter 'former" and allowed to spring off; L2 
is similarly made using but V 2 turns. Both windings 
are spaced wire thickness. Some 24 turns of fine 
d.s.c. wire (30-38 s.w.g.) are close-wound on to a ] 4 in. 
dust-cored former to make L3. 

Testing 

With one end of E2 temporarily disconnected 
and a crystal plugged in, a meter set to read 0-lOmA 
placed in series with a 9V battery supply may 
initially read full scale or thereabouts, this indicat- 
ing, as is likely, a non-oscillating condition. The core 
of L3 is then carefully adjusted until the current 
being monitored falls suddenly to around 2mA, this 
indicating correct functioning. 

With R2 reconnected the current reading obviously 
increases whereupon the secondary winding of Tl 
is briefly short-circuited with a metal blade whilst 
carefully noting the test meter pointer. If no current 
change is detected as the short-circuit is made and 
broken the audio oscillator is not working and it 
will be necessary to reverse the connections to either 
the primary or the secondary windings of Tl— but 
not both — to phase the feed-back correctly. 

If a short rod aerial is then plugged into the 
output socket, SKI, and is brought close to a 2-metre 
receiver — or as is more likely a 2-metre converter 
working with a receiver — a signal due to the unit 
should be tunable whereupon trimmer TCI may 
be peaked for maximum output. 

Thereafter crystals in the frequency range of 
6005-6083kHz may be used to give harmonic output 
between 144-146MHz. Alternatively crystals in the 
frequency range of 8005-81 11kHz may be utilized 
provided inductor L3 is re tuned to this region thus 
affording eighteenth harmonic output, ■ 







MULLARD AMP 

Sensational 'Once In 
a Llfe-tlun: Ofler' 
L-nrepeatable once 
"locks arc cleared. 
The amplifier is made 
by Mullard. Carrie* 
maker's Guarantee, In 
neat cane. May be 
useit for Mono or 

Stereo. Husk or speech. Works off dry battery. 

or batt. or mains power puck. PTtEE —all ne 

purchase »t send copy of Mnllard booklet DIV 

stereo, 11-60. 

DRILL CONTROLLER 

NEW iKW MODEL 
Electronically change* 
speed lrorn approxi- 
mately in revs, to 
maximum. Full power at all 
speeds by finger-tip control. 
Kit Includes all parls. cu>, 
everything and full ln*truv- 
tlons. 11-66. Mp I'"i' and p. 



X0NTROL 

DRILL 
SPEEDS 



Mr. if 



m 



»Ect also available, £2 48. 





MIGHTY MIDGET 

Probably the finest possible radio, as ilcscribril 
In Practical Wireteit, Januarv 73. All electronic 
parts IB 20 pnst paid. 

TIME SWITCH 

Smiths mains driven clock with 
15 amp switch, »I*o nob^ 
showing how yon can wake tip 
with music playing, kettle 
boiling or come lionns to a warm 
house, warn oft burglars, keep 
pets warm, halve vour heating 
bill. etc. £1 95. 

I CHIP RADIO 

t-'errantl'a latest device ZN414 — itva* remit*- 
better than superhel. Supplied complete with 
technical notes ami circuit". 11-34 each, in for 
111-11. 

Hl-Q TUNER COMPONENTS 

For experimenting with the ZN414. 

KIT NO. 1. Plcsscy Miniature Tuning Condeiit-r 

with built-in L\V switch and 3" Ferrite slab ami 

lit! wound 31 W coil, 7Sp. 

KIT NO. '2. Air spaced tuning condenser if 

ferrite roil litz wound MW anil LW colls, 94 p 

KIT "SO. 3. Air spaced TV with slow m.:ti.m 

drive 8" lerrlte roil, with litz wound LW and MW 

colli., 11 -10. 

KIT No. 4, Permeability tuner with la»t and 

•low motion drive and LW loading colls. 45p. 

12 VOLT U AMP 
POWER PACK 

This comprise* diiQhif- 

wmmt uso/'j-iov iiiAin. 

' trans torn iev with full whit 
■ectlfter and t!Ct(M> mF 
stneothing. Price IB 20. 
plus SOp post \- [lacklinr. 
Heary Duly Mains Power Pack. Output mltagr 
adjustable from J5-4QV In steps — majjmnui 
load 260W— that ft from II amp at 4ilV In j5atiip 
at 15 V, This really is a high power heavy dut> 
unit w-ith donas .if workshop peg, Ou'imt 
▼olusre adjustment is very mi l c fc — al inply int. r- 
change push on lead*. Hilicnn nrotuVr* and 
smoothing hy a.OQOm !■'. Price 16-33 phi* Hap pail 

MICRO SWITCH 

atnp cliangeover contacts, lip each 
10 for 89p. 1(1 amp. 5p Model ISp 
Changeover 15p each. 

MAINS RELAY BARGAIN 

Special tliid month are muir stride, 

double and treble pole chmip--.ii. r 

relays. Unotsi-l» rat«l at IS aiu|M>. 

Olicratlng enll wound lor 340V A.i'. 

Ilnod British Make linoKMl. 

Bi« appro*. I!" >. I", Open e"H- 

sl ruction. 

tttagat pole Jap each Mi tor 12-48 

Treble pole 39p each 10 fnf 13-57 

MAINS OPERATED SOLENOIDS 

Model 772 - small hut 
pow-crtul I in . pull appro* 

(Cj-^fcpt xize 1} x 11 x i;in- 68p. 

XTlB. Model 4001/-- Jin. pull. 

JaMtr^a. Bize -i * - '■ Hi' i. 83b. 

^^S»*** Model TT1— i;tri. pull. 

^^ Size 3 .< li M '.'in £1-98 

plUH L'Op post and insurance 

MAINS TRANSISTOR 
POWER PACK 

Designed to operate transistor sets and iniLniiUi.-r-., 
Adlustable output fiv., llv,. 12 vnltn for up to 
500mA (class li working). Takes the place of any 
of the following batteries: PP1, PP:i. P1M. PP6. 
PPT. PP3. and othem. Kit 1 1 m il n lis main* 
transformer reetiHer, BUKJothing ami load resistor 
eondeiiserN and instruct inns. Real snip al only 
11-10 pins 20p postage. 

DESK TELEPHONES 

Er tl.P.O. (Hack standar.1 
model with d lulling dial hut nu 
internal hell. Supplieil with con- 
nection diagram 84p each - 
■ -. 40]i forsingte (hen ilop 
per pair. T»itlo, with bell but 
without dialling dial 98p each 
plus 40p post for "ingle then Htlp 
per pair. 



PAPST MOTORS 

Est. l/40th h.p. Made lnr 110-130 volt worttiig. bat 
two ol these work ideally together oB our standard 
•J 40 to It mains. A really heaaUfal motor, eltremely 
quiet running and reversible. J1-6B each. Postage one 
'ISp. t«-o 33p, 2S0V mo-lei 13-80. 



10 AMP DIMMER CONTROL 

For the control nf lighting on ntage or in a studio or lot control ol portable 
equipment in work-hop^, eke W» taw two 13 amp socket outlets each is con- 
trolled by a o amp Mid <tatc regulator. The overall length le 17in., width 3iin. 
anil depth I Jin. In the end is lined a mauler On/Off switch indicator, lamp and 
fuse. Price 18 85. 





bt-tw litH 


id/j: IJ" wafer- silver -plated 3 amp contact. «tandartl J" e 


p indie 


"J" hm»— 


with loikin 


: vaul 


cr liml nut. 






No. of P. 


les -Jwav 


I wai 


Ivi ay ...w.:i> 


tiway ^way llway 1 0^vay 


] if way 


1 pole 


Mp 


*4p 


44p 44p 


44p 44 p 44p 44p 


4«p 


■ ;■■■■■ 


•s 


44p 


44p 44p 


44p 44 p 44p 77 p 


77p 


3 pole- 


44p 


44p 


Mp 44p 


77p 77p 77p £104 


£104 


4 pole- 


Mi 


44p 


44p 77p 


77p 77p 77p £1-32 


£132 


9 pole- 


Mj» 


44p 


77p 77p 


11-04 1104 1104 £1-60 


11-00 


(1 pole* 


44p 


77p 


77p 77p 


11 04 £104 1104 £1 87 


£187 


7 potes 


77p 


77p 


77p 11-04 


11-3S 11-32 11-32 £215 


£216 


8 pole- 


77p 




77p £104 


£132 £1-32 11-32 12-42 


£2-42 


9 pnle- 


77p 


77p 


£1 04 £104 


11-60 11-60 £180 £2-70 


£2 70 


10 poles 


77p 


77p 


1104 £132 


1160 f 1 80 £1-60 £300 


£3 00 


1 1 poles 


77p 


SI 04 


£1 04 11-32 


£1-87 £187 11-87 13-26 


£3 26 


1? poles 


77p 


1104 


£1 04 £1 3E 


£1-87 £1-87 1187 13-52 


£3-62 




CAPACITOR DISCHARGE CAR IGNITION 

This system which baa proved to be amazingly 
reliable was ft rat described In the 
about a year ago. We can supply 
' an improved and even more emclenl 
{Practical trfrebtt, June). Price 16-55 pi in 
nop i«M.t. When ordering pleas* stale whether for positive or negative eyeteni". 
Also available, ready inade ignition systems for HY. vehicles £7 '85 plus 20p. 



(.ArHLt I \jn uiiLriMRue i-hi 
y- ' ^ This syatem wh 

/ X jiBniin.t and re] 

I~ aerreMir mtfnai I Wlrttrn World t 
f °' I ' I I «»" W Aklt of parte for a 

\^ v-/ verilon tPraatca 



MULLARD UNILEX 

This D. I.T. SteriNi Auipliflcr In utill available complete at £7*00 for the 

four Milliard Modules, or Modules van ba boogbl separately as follows:— 

4 wall amplifier tundule (*t required > Mullard Kef, N'o. H.P.fWOfl— £1 60. 

Pre amp module MuUanl Ref. No. E.P.flOOl — 11 98 each. 

Power Module Mullajd Kef, No. R.P.SCK)--'— 12 53 each. 

In addition anil made r,, Mullard sneciflcatlnu we offer: — 

Standard Control Fnit uith c-cutcheon ami knobs— £3 30 

Knobs— Bet of -l -50p. 

Special oiler the complete 1'idles uiih eontro) panel at Pre VAT price 

£10-00 po-i paid 




ZPM MODULATION MOTOR 

It'ould abo l>e o"t:d lf> open ventilators, dnor^. I'alve. damper, etc. 
particularly sllllahle for remote control. Made by Satchwell 
y a rcver-dhle geared motor tltted with internal limit 
^v-t.!e'- io -iop H at tin.- ami of its travel. Size app rose, 6in. x 
Bin. >: jjiii. and weighing approx. 10 lb. This is extremely 
powerful and would lift a heavy door or open a long line of 
litatom, To operate this motor ynu put the 511 cycle supply 
irougb a chaugenvar -witi-li. For instance a thermostat with changeover 
ontacts oralri automat ically regulate Liu- liinperature In a growing bouse, 
hickcii batelierv , etc An indicator on the motor graduate I 0-10 stn™« the 
late of ojjcti or c]om>, AImi intcriiully tit led is a variable resl-tor. wircn from th i-v 
a a v.ill meter ^-uutd give a remote indication of the open or clo-e position. A 
cry cvjietisive motor if holli direct from Batetwelt. our price coniptete with 
tep down Tnuufntmer i- 110 50. 



CENTRIFUGAL FAN 
Main-- Hp raited, turlio blower type. P r e s a e J -teel h i 
contains motor and Impeller. Motor is I/10th h.p. giving 
considerable air How but virtually no noi.se. Approx. dinieu- 
1 10J in. wide ■ t-j in. .lia. rnOet into trunking 10! • 
In. 10 55 pin- £1 pomI and [ntttrauee. 




THIS MONTH'S SNIP 



TAPE PLAYBACK UNITS 

Main- opei^t-d. Ktvie by Red I tunc the famous 
"om-ic in background people". These are com- 
plete unit- ready to work and we understand 
that they are in good going order. We have not 
f'>-(i-d them bui would exohanga any thai do not 
vrorit properly. These haie a superior motor 
driven tly wheel to oontral ilic tape through the 
capstan anil al-o an ewa t-nually useful valve 
amplifier with E184 output, in a ptccl case with carryi: 
itinilels oftured, good as new £060 anil somewhat used at 
rait.'.- up to 200 miles then •■pOp per l')0 miles extra. 





24-HOUR TIME SWITCH 

Made he Hiuith*, these are AC mains operAted. SOT 
CLOCKWORK, ideal for mounting on rack or shelf 
or can he built into box. with ISA eocaet. Two com. 
pletely adjustable time period* per 24 hours. 0A 
changeover contact* will switch circuit on or iid 
during these periods. IB 76po«t Slid Ills, gftp, Adil itimial 
time contacts 56p pair 



MULLARD AUDIO AMPLIFIERS 

All En modulo form, each re*dy built enuiplel 
heat sinks and connection tugs, data supplied. 
Mode) 1163 600m W power output 72p, 
Model 1171! 750mW power output 94p. 
Model BPSOtrO 4 watt power output £1-80, 
EP00O! twin channel ..r stereo pre amp £1 TO 
]0°„ dlwnii! If in at runrr vrrleptii. 




NEW ITEMS THIS MONTH 

MINIATURE SEALED RELAY 

American made. Our Ttef. : TIKL Al. Measures 
only |" wide x ;" thick and |" high and it'» a 
double change over, w *.- don't know the contact 
rating but estimate this at 3/J amps. The coil 
resistance is 600 ohm* and 9- lv! volt will close It. 
Ideal for models and miniaturised equipment. 
It's a plug in relay but we nupply complete 
with base. Price 28 p ineludliu; bane. 
SUB. MINIATURE 
MtCROSWITCH 

Maeie by Burgess, their rel. V4T6 our ref. 
MS. Al. These measure only 3" x i" * I" 
Ihick — have change over contacts and tag 
connection. Price 18p each or 10 for £1-44. 
3 CORE MAINS FLEX 
Metric size Smni which Is approx. equivalent In 
the old 14/3B rating. Suitable therefore for 
mower or similar portable tools. Corea are 
colour coiled to the new European utandarit. 
lirown— live: Blue — neutral: Yellow/Green— 
earth. Orey P.V.C covered overall, 100m colls 15. 
SOiii culls £3 and SMf coils £1-75. Post 40p on 
] O'Jin. 25p lor 50m coils and 20p lor 26m colts. 

PANIC SWITCHES 

Tough enough to he foot switches and elegant 
enough to be panel switches. RakHite construction 
with white push rod. Price 40p less quantity 
discounts. Switch is rated 200v-2 amp. 

20 WATT CAMPING LIGHT 

Also makes good car emergency light. This uses 
a standard 'i ft 20 watt tube and operates from 
a Itfv car battery drawing approx. 1A. This 
givea Illumination per amp/hour of battery life 
tar in excess to filament lamps and in fact to the 
miniature H-13 watt camping lights often offered, 
t'omplele unit ready to operate. In strong white 
enamelled metal frame. These would normally 
»ell at 18 are unused but slightly eoiled and we 
offer these at £3 50 plus 40p post and packing. 

6 MAINS TRANSFORMERS 

Our Bet.: MTK1 87 volt at 8 amp. C'urlghi 
mounting fully shrouded — flying leads — -fully 
tapped primary. Price 13 30. 
Our Rel.: MTM2 1'Jv al 1 amp. Upright mounting 
with fixing lugs, tag connection. lM0v primary-- 
I2v 1 anip secondary. Price 82p. 
Our Bet.: JITHS tl-3v '2 amp upright mounting 
with fixing lugs, tae connect inne. 240v primary 
fi-3v *2 amp secondary. Price 77p. 
Our Bet. MTM4 li>v-\ amp with thermal cut-out, 
upright ninuiuiiig with fixing logs-tag connections- 
Primary '240v — ^econdarv lSv at # amp. Price 
SSp. 

Kains Iiolation UTH5 350 watts earth sh I elder! - 
flex lrodn —upright mounting lugs for fixing. 
Price £440 each. 

6 VOLT RELAYS 

Our ref.: EEL Ml. Removable clear plaevie 
enclnsed two screw fixing. Have a 6 volt D.C. 
operate. I coil but two change-over contact*, 
each rated . to uiake and break -40 v A.C. at 
lo amps. Price OSp each. 

P.O. TYPE 3000 RELAY 

Our rel.: RKL M'2 — 100 ohms coil and •! pair 
normally open heavy duty contacts. Price 7Bp 
each. 

6 DIGIT COUNTER 

Rentable, 440 ohm coil 
up to 20 impulses per 
second , K % -eqn i pti ic n t but 
guaranteed perfect, £2-20 
each. 

COMBINATION SWITCH 

This comprises of 112 minia- 
ture change - over micro 
switches. Joined in bank* of 
3 and mounted on frame 
w-lth four digital numbered 
thumb wheel* and a remov- 
able lever for locking the 
thumb wheel — the thumb 
'■ 3 banks. Over 4,000 combinations 
are possible hut by re-wiring the switch con- 
nections underneath then thousands more 
variation- are possible. If you are moklng 
equipment which you don't wont switched on 
accidentally or without authority then this la a 
switch to consider —this can also be used as a 
coding switch for many other operations. Very- 
neat and compact and measuring approi. 4" >, 
l|» X 1 i" deep. Priced at £308. 

PUSH BUTTON SWITCH 

Type 14 Il.M.fl. A very fine switch made by 
HoricyueH. The switch is intended for mounting 





vheel operate 



Ideal for Instrument or qualitv gear. Price 60p 
each. 10 lor £4 50. 100 for 140. 

PHOTO-MULTIPLIER TUBE 

American R.C'.A, type No. 4050. These lubes 
have a gain of a million or more. Regular Price- 
over £15. We have a limit t-d quantity and offer 
these at 14 50, 



TEBMS : 10 "„ diicount it len ol an item 
ordered, send poitaxe where quoted other 
items, poii free it order lor these itemi is 10 00 

other WISH add 20p. 



J. BULL (EnmtfCAL) LTD, 

(Dept. P.W.) 7 Park Street, Croydon CRO I YD 

Callara Io : 10! 3 Tamworth Road, CROYDON 



359 



Fully guaranteed 

Individually packed 

VALVES 



£1-75iECH84 
•Hip ! ECLSO 



ECL82 

ECLS3 

ECL86 

EF3B 

EF37A 



40p EF40 
40p i EF4I 
29P EK90 
£8p EF83 



30l> 



B13H 

CY31 

DAF98 

DF96 

DK96 

DL92 

BE94 

DB96 

DM70 

DT38 

DYB7 

DY802 

ESSCC/01 

£108 

E130CC 87p 

E1SICO 90p 

E182CC 

1108 

EA50 ISp 

EABC80 I7p EL34 

EAF43 18p EL4 l 
20p EL84 
Up F.W5 
5 Op I E LUG 
Sip F.I, 'JO 
S8p ELM 
KL500 



40p QA'J 
40p 0B2 



EF8, 

EFH6 

EFS9 

EF91 

EF92 

EF9G 

EF183 

EF184 

EFL200 



EB9I 

EBC33 

EBC41 

ECC81 

EBFRO 

EBF83 

EBFB9 

ECC81 

ECC82 

ECC83 

ECC84 

ECC83 

ECC8S 

Eccsa 

ECC189 
ECF80 
ECF82 
ECF83 
ECF801 
ECH81 
ECH83 



EL504 
EM31 
EM SO 
EM 84 
27p EM87 
Mp'EYSl 
75o | EYB6 

4o! EYBI 
*«» I EY88 

S5p EZ41 

Sip EZSO 

EZ81 

GZ34 

GZ37 

KT68 

KT88 

S78 



31p FABC80 3Sp 



63p PC97 

36p l'<J!)M) 

50p FC0S4 
SSp I PCC89 
SOp I POC189 
85b PCE800 
25p i PCF80 
BOp FCF82 
Sip | PCF84 
27p ! PCFB6 



25p I PCF200 60p 

*7n ! DflMOfl AJlr, 



27p|PCF201 
31p : PCF801 
Sip i PCF802 
26p FCF805 
Sip PCF806 
37p IMFS09 
45 p PCH200 
SSp IPC LB 1 
JSlp PCE82 
S7p ! FCL83 
38p:PCI,84 
81p ; PCL8S 
31p PCL86 
78p ' PFL20O 
76p , PL38 

e«piPLfli 

38p I PL82 
31p!PL83 
62p P L84 
38b < PI-500 
38p i PL504 
ttylFLSM 
40b I PLSOO 
45pjFL802 
22p|PX4 
B4p I PY33 
58p I PY80 
8Sp|PY81 
£2-35 1 PY82 
£8-85 ! FY83 
£1-68 PY88 



OA5 

OA10 
OA70 
OA71 
OA73 

OA74 



TRANSISTORS, ZENER DIODES etc. 



20p OC71 
B6p OC72 
10P|OC73 
lOp OC75 
7p ! OC78 
7p ' OCS1 



OA"9(6Dlo jOCSUJ 



40p 
4Sp 
8Dp 
8"<; 
£5- 
65, 
40;; 
30|i 

S[:n 

So: 

3S; 

iZ 

SOp 

50p 

40b 

35p 

36b 

30b 

62p 

82p 

70p 

£105 
95b 

£2 50 
S5p 
35p 
30p 

zap 

30p 

32p 



OA81 

OA91 

OA200 

OA202 

OA'210 

OA211 

OAZ2G0 

OAZ201 

OC22 

OC25 

OC26 

OC28 

OC29 

OC3S 

OC3S 

OC38 

OC44 

OC4B 

OC70 



lOpiOCSlDM 2Op|2C+03 
Sb OC82 2Spl2X91B 
7 B iOC82DM SOp 2X1304 
7b OC83 

10n OC83B 

£6p OC84 



OC122 
OC139 
00140 
OC170 
OC171 
0CI72 
60p ! OC200 
60 p OC201 
5 Op OC206 
Sep ' IX21B 
ie_|lK25 

SbSs 

17 ' I.S'70 
1*» 1 1X677 
18p I IN702- 



12p : IX823A £1-30 3X154 95p BC108 
BOp 1.N4785 501 3X159 £l-45jBC113 
SOp 1ZMT5 SSflSEKS 45p|llCllS 
SlplIZMTIO 88p 12FR60 73p BCY72 
25p|lZTJ 87p ! 40914 II 25 BF115 

SOp IZTIO 68p'4MM 
tOp 2G385 Sip] 40636 

8tP| 40668 

37p | 40069 

22p ! AC126 

S5P, AC 127 

|5l>iAC128 

8*B|aCI76 



PY8O0 36b 1*AF42 
PY801 45p UBC41 
QQVO3-10 L'BFSO 

£110iUBF89 
B17 45p UCC85 

R 19 Up 1ICF80 

STV280/4O UCH42 

I3 20HCH81 
8TV2S0/80 UCL82 

M 20 , t'CL83 

£3 83, L FSO 
70p UF89 
?0S>'UL41 



25p 2XK1II':. 

15p I 2X1307 
£5p 2X2147 

SOp 2X2411 11.50 jliH 17 

25p j 2X2904A 25p ; AC V'B 

40p 2X2939 £4.00! AD 149 

25p 2X30B3 20p ADlfll 

SOp ! 2X3004 G0p|AD182 

37p. 2X3055 64p AFI18 

40p 1 2X3730 50p.AFI27 

75b!2N3731 £2-75 AK139 

95p 2X4172 60p AF178 

30p 82303 SOp AF18G 

SOp I 3F100 82p I ASY26 

lOp 3FR5 32p!ASY28 

7p 1 3X128 87p A3Y67 

18j 3N139 £175jBAW19 

2536p l 3X140 87plBC107 

BOp UY85 



£1 35 li) 1 
fl-BSlBKYSl 
*12S BFY52 
£1-40 '■■■-: 
25p B82 
g5p B9Y29 
20p 



lOp GET115 4Gp 
lOp GliTlie BOp 
20p I GES66 £1 -50 
15p NKT222 20p 
25p|XKT304 SOp 
20p RAS310AF 
20 p , 33 p 

20p 8D918 26p 
45b BD92S 81p 
47b HT>ns3 3Sp 
2Sb SUS4 21p 

BG100 £1-80 SHS8S 48p 
20l BVZ13 25b V405A 40p 
25 1 BYZ16 83b Z2A51CF 78p 
17p!CRBl/10 £SplZRll 33p 
5Qd>CR31/20 38p'ZR21 46p 

85 B CBai/30 48p ZR22 42p 

85p CR31/35 43p 
60 B CR81/40 4SB 
20d CKS3/05 30b 

30b ratearao ssp zener 

4Sp CH33/30 43b DIODES 
40p CEB25/025 A ll pretfrrfd 

25p 56p voltage 

E5p CR83/40 BOpjfW 8-17 

4Sp C32A 651 1 W 0-87 

B8p|cVl02 25p I-svr o-BS 

lOp I HIT J 03 23b I 7 W 0-40 



35bi3Q4 55p <:\h.r, 

48p! VR106/3P35pl3S4 33p ■i'iAKS 

35p.VR15<.'/30 35p 3V4 «Sp|6AK8 

34p Z80OU *l-40 3B2D4MIS-75 SALS 
35piZ801U £1-40|5B/255M 6AL5W 



aoplzsoar tiio 

SOp ZSDOT 80pi5R4GY 
35 p I IE4 13p ; 5U4G 

35p IRo 35Bj5V4r; 

30BI5Y3OT 

30B,5Y4f! 

30p j ozj 

£7 50| 6z4l,T 

48p 6AB7 

15p ' 8AC7 

MAXY OTHERS [N STOCK include Cathode Ray Tubes and Special \>alvet 
Postage Up to £1 12p, £l-£8 I7p, £2-*3 22p. Over £3 post tree. C.O.D. 25i> extra. 



TT3 i 
,l.'2S 
U26 



45p 



7Dn ' 



LLS4 



70p 



:?4 
135 

rT4 

1X2A 



UABC80 30p UY41 45p I 3D0 



SOp , 6BA6 
35p SBEii 
30b i SBG6G 
ISp 0RJ6 
3Sb SBQ7A 
35b iiBR7 
60p;8BW6 
3Qp 6BW7 
4Sp I 8C4 
SOp 6Cti 
SOp 1 6CHS 
20p SCL6 

75p|6AX*GT 50p I f^Is 

8Sp 8AX3UT BOp ,;p2 3 

25b,0B7 SSp 6E33 £L35 

45b I 0BK7 80b 8H6M 25p 



c°» 



ALL valves 
guaranteed 



6J7M 

SE6GT 

6K7 

0K7G 

6K8GT 

6K25, 

BLfiJll 

63.A7 



68J7 
68J7GT 
88 S 7 

■J3L7<i , r 



£5 75 
£5-75 
£5 25 
*1'00 
45p 



£3-18 B AMS 
8Sp I SAXS 
30p.tAQ5 
45p SAQ5W 
35p 8AS0 
85p ] 6AT0 

70p|bal:o 



8Y6G 
6-30L' 
6Z4 
7B7 



47p 

'• 5 P 

12,, 

H5|l 

SOp 

SOp 9D3 

25p 11E2 

20p "" 

55,1 

U |3 

li„ 

tscp 



B5p l..-ii7 

35p|14s>7 

30p'l9AQ5 

£5pll9G3 

SOp 19G6 

SSp 19H4 

55b 1 20F4 

40p 25L8(1T 

17p 30CL5 

40p 3CCJ7 

70p 1 30C18 
14S 3078 

40p aOFLl 
63A7UT 26p ! 30FEl2 
63C7GT £0p 30FL14 

40pj30L15 

40p]30L17 

28pl30P12 

45p(30P19 

36p 30PL1 
83S7GT 35p 30FL13 
6SQ7 45p 30 FBI 4 

8SQ7GT 82p 35L6GT 
8V5G ISp [ 35W4 
8V T 50T 85p 3SZ4UT 

33p I 50C5 

25p I oOL'OeG £1 10 

35p 50F.JI5 Sop 

75p i j SOp 

SSp ; 78 55p 

40p 78 50p 

50p 80 oop 



40p i 6060 
70b I B064 
40b 6085 



6080 
8140 
B020 
9001 
8808 



GOp 

45p 

SGp 

£1-55 

£1-75 

£3-75 

ISp 

40p 

45p 

12p 

12p 



C.R. Tubes 
VCK97 

£400 
VCB517B 

£S00 



Op 90U3 
SSp 9004 
75p S008 
SOp 
70p 
tiii 
SO? 

so- 

30- 
7op 



^8X4 

25p I 6X.5G 
25p 6X5GT 



80p VCR517C 
70p 

h:o 

SOp 

Sap 
45p 



£7 00 
S8D £8 10 
88 J £8 10 

SSL £810 

Photo Tabes 
CMG25 

£250 
931 A £5 00 
S097C 

£1800 

Special Valves 



80p 723A/B £700 CV2339 



liA'CT 



12AV8 
12 AX 7 
SOp! 12BA6 
- 12BE8 
12l:H7 
12C8 
12E1 
12K5 



3 Op 803 
£370 

3Sp 

3Sp 

24p 

40p 

SSp 

SSp ■ 954 

35p ' 955 

23p 1 256 

30p : 957 
£2 85 qv 

B5p ■ 



s;:s 



86JA 
R31A 



£558 £1800 
£12 00 JP9/7B 

50p £35-00 

£400 K301 £4-60 

£2-70 ' K305 £1100 

£1-25 , K308 £14 50 

£4-75 K337 £14-50 



V.A.T. 

Please add 10% to all 
orders 



METERS 



JrFuil List of our very large 
stoclt of meters on request. 



TEXAS INTEGRATED CIRCUIT SN 76131 N Stereo 
pre-a-«p £0 65. VACUUM CONDENSERS 12, 50, 
55pF each 20,000v. £1 SO. P. A P, 20p. 4, 5 and 3 bank 
25 way uniselectors, 24V, guaranteed perfect, £3-75; 
£4-50; £6 87 respectively. MODULATION TRANS- 
FORMERS made by COLLINS. Freq. resp. 200-5000 
CPS; Prl. eOOOzCT 3000 TV Sec. BOOOOz 3000 TV Audio 
power 20W. £1-25. Post and packing 25 p. 



12K7GT 45b! 



>051 
12E8GT 46pj5933 
12Q7GT 40b 1 6057 



K UXi 
35 i £315 

30p WL417A 
Son £135 

™ p £3500 

7 °P SOU £22 00 

£100 7I4AY £3-80 

55p 725A £28-50 



Colornor (Electronics) Ltd. 

170 GOLDHAWK ROAD. LONDON W12. 

RETAIL; 7434946 TRADE: 743 0899 

Open 9-12.30, 1,30-5.30 p.m. Thursday S-1 p.m. 



Give us six months, 

and we'll turn your hobby 
into a career. 



You have a hobby for a very 
good reason. It gives you a lot of 
pleasure. 

So if you can find a job that 
involves your hobby, chances are 
you'll enjoy your work more, and 
you'll do better work. 

Now CD1 can help you find 
such a job, A job where you'll be 
responsible for the maintenance 
of a computer installation. A job 
that pays well too. If you're inter- 
ested in mechanics or electronics 
(without necessarily being a 



mathematical genius), have a 
clear, logical mind and a will to 
work, then we can train you to be 
a Computer Engineer inside six 
months. 

So give us a call. CDI. We're 
the Training Division of one 
of the world's largest computer 
manufacturers. And we have the 
experience lo know if you can 
make it. A ten minute talk with us, 
and you could be on the way to 
spending the rest of your life with 
your hobby. 



Ring 

01-6372171 

between 9 a.m. and 9 p.m. and ask for Mr PRENTIS 



I It's quicker and easier to phone, but if you 
| prefer, send this coupon to: Control Data 

I Institute, Wells House, 77 Wells Street, 
London, W.I. 
Please give me further information. 

. Name ____ 

I Address_ 

Age Phon_e pvvb 



1 

LThe Training Division of one of trie world's 
largest Computer manufacturers. 
mm e^sn —— » ^■^■■■^ mmmmm > mmmmm ^^# 



CONTROL DATA 
INSTITUTE 



CONTROL DATA 



360 




AGncnc 

HHIPIIPIERI 



PART 2 



SELF-SATURATING MAGNETIC AMPLIFIERS 

(continued) 

If the control current is zero, the core is taken 
through a small magnetisation cycle and has an 
inductance determined by the average flux contri- 
buted by the secondary current. If the control current 
is in the opposite direction, the flux due to control 
current opposes it and the core can be made to 
change from negative to positive saturation when 
signal current flows. In this state, flux change is 
maximum and inductance is large so that the voltage 
drop across the secondary winding is large. 

In a core operated in this way, the amplification 
obtained depends mainly on the shape of the magnet- 
isation B — H curve, and a steep sloped curve with a 
very low value of saturation magnetic field strength 
is desirable. To obtain this shape of curve, cores are 
usually made by winding tapes of suitable material 
(permalloy etc.) round a former to form a toroid 
and winding the coils round these cores. 

When such materials are used in such a core, the 
B — H curve is of the type shown in Fig. 6, where the 
scales of the graph are such that the values of B 
are large and those of H small. Saturation occurs at 




Fig. S : 8-H curve for material used for cores of magnetic amplifiers. 



such a low value of flux (measured in milliamps of 
current X turns of coil) that the cores will saturate 
with the output current even with no control current 
applied, and so the control current must be applied 
so that its flux always opposes the output flux. 

The circuit of a full-wave self -saturating magnetic 
amplifier is shown in Fig. 7. Since the secondary 
current in each core must be in one direction, a 






LR.SINCLAIR 



rectifier is used in series with each secondary 
winding and two windings are used so that control 
can be exerted over the whole of one cycle. Note 
that the voltage across the load is alternating, despite 
the rectifiers. The output waveform of such an 
amplifier is also shown in Fig. 7; except for the 
value of voltage at minimum signal, the waveform is 
similar to that obtained from a thyristor circuit. 

The transfer characteristic (voltage out plotted 
against current in control winding) is shown in Fig, 7. 
The precise form of this curve can be calculated if 
the B — H curve for the core in use is known, and it 
is one of the considerable achievements of core 
manufacturers that cores and core materials can 
now be made with reproducible values of B — H 
curve. The greatest sensitivity can be obtained if the 
control current is biased to the point on this control 
curve, and for this purpose, if the bias signal cannot 
be obtained from the source, a separate bias winding 
may be used. 

The self -saturating magnetic amplifier will give an 
a.c. voltage output across a load almost independent 




+ control — 



Output waveform 



Characteristic 
of amplifier 



Fig. 7: 



Circuit of fullwave self-saturating magnetic amplifier with 
output waveform and amplifier characteristic curve. 

361 



of load impedance and determined only by the d.c. 
control current, so that a d.c. signal at the control 
winding produces an amplified a.c. output. The output 
power obtained depends on the size and type of 
core used. 



DC OUTPUT FEEDBACK 

The magnetic amplifiers described so far give an 
a.c. output for a d.c. input. Where the load of the 
amplifier must be supplied with d.c, or where one 
magnetic amplifier feeds a second (as when very 
large power amplification is required) the output of 
the magnetic amplifier must be rectified. This may 
be done by taking the output terminals to a bridge 
rectifier and connecting the load across the other 
two terminals of the rectifiers (Fig. 8a). A more 
economical method is to make use of the rectifiers 
which feed the cores, and add two more to form a 
bridge rectifier circuit (Fig. 8b) or to use a centre 
tapped transformer as power source and use the 
core rectifiers to provide the d.c. output (Fig. 8c). 

When linearity of control is particularly important, 
this may be improved by feedback. To apply feedback 
to a magnetic amplifier a direct current must be 
obtained from the output and applied to a feedback 
winding in the direction opposite to the current in 
the control winding. The feedback ratio which by 
the usual feedback theory is approximately the new 
gain of the amplifier, is the ratio of control winding 
ampere-turns to the feedback ampere-turns. 



DESIGN AND CONSTRUCTION OF 
PRACTICAL AMPLIFIERS 

Because magnetic materials vary so much, it is not 
easy to give a "circuit" for a magnetic amplifier for 
home construction; it is rather like giving a circuit 
for a radio in which all the transistors had to be made 
at home as well! We can, however, outline the steps 
in design, so that the experimenter can construct 
reactors, determine their characteristics and make 
use of them in the circuits shown earlier. Since com- 
mercially obtainable reactors are £10 and upwards, 
there is a strong incentive for home construction ! 



CORES 

The type of core material which can be used 
depends on the power available to drive the control 
winding. When large powers (about lkW) are being 
controlled, and several watts can be used to drive the 
amplifier, an old transformer core can be rebuilt, 
provided that the transformer was rated to take such 
power loads. This requires some trial and error unless 
the core material is known and information on it is 
available. If this is not the case, the best cut-and-try 
method is to keep the original windings on the bobbin 
and reassemble the core with no gap, by replacing the 
E and I sections facing alternatively in opposite direc- 
tions. The inductance of the main winding should 
then be checked for saturation point; this is easily 
done if an oscilloscope is available by feeding the 
winding from an a.c. supply through a large variable 
resistor and checking the voltage across the winding 
with an oscilloscope. As the current is increased, the 
voltage waveform becomes flat-topped when satura- 
tion point is reached, and the current flowing at this 
point is saturation current (the saturation current 



here is peak current=l-4Xrms meter reading). Al- 
ternatively an a.c. voltmeter and ammeter can be 
used and voltage plotted against current on a graph, 
saturation being when the graph becomes flat-topped. 
Note that the a.c. current must be varied by a resis- 
tor, if a constant voltage source such as an auto-trans- 
former is used, the current waveform will be the one 
which appears distorted. 



AC 



a 



-o- — AC- 



i 



t 



To 
load 




Fig. 8a, top, shows rectifiers needed to rectify AC output of amplifier 

when the load requires a DC supply. Fig. 8b, centre, and Fig. 8c, 

bottom, illustrate alternative methods of achieving DC output. 



Once saturation current in the main winding is 
known, the saturation current in the other windings 
can be calculated, for it is inversely proportional to 
the voltage of the winding when used as a trans- 
former. For example, if the saturation current in a 
250V winding is 100mA the saturation in a 350-0-350 



winding, total 700V is 



250 
100 X =r^ mA = 36mA 
700 



and this 700V winding can be used as the control 
winding. If the control winding has resistance of 
lOOfl, the voltage across it at saturation is 36V and 
this will be able to control currents of ± 100mA at 
250V in the other winding. The voltage gain in this 
case is not impressive, but the power gain is fairly 
high and is achieved at less cost than many com- 
parable devices. 






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bond.d. MS, 
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av equiv. to OC10QI I 

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PNP, AF and RF 



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NPN Silicon TOO Can, 




MAKE A REV COUNTER 
FOR YOUR CAR 

The 'TACHO BLOCK'. Thii 

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£1*10 each 




600,000 



pwwwp 

TRANSISTORS IN STOCK 
We hold a. very large range of fully marked, 
tested and guaranteed transistors, power 
transistors, diodes and rectifiers at very 
competitive prices. Please send for free 
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Silicon planar plastic transis- 
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factory clearance. A random 

sampling showed these to be of remarkably 

high quality. 

Audio PNP. similar to ZTXSOO, 2N3702/3, 

BCY70 etc. 

Audio NPN, similar to ZTX300, 2N3708/9. 

BC 1 07/8/9, BC 1 68/9 etc. 

Please state Audio NPN or Audio PNP when 

ordering. 

ALL AT 500 for £3-10. 1.000 for £5-50, 10,000 

for £44 P ft P. Up/ 1. 000, 

OUR VERY POPULAR 4p TRANSISTORS 

TYPE "A" PNP Silicon alloy, TO-5 can. 
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TYPE "G" NPN silicon similar ZTX 300 range 
TYPE "H" PNP silicon similar 2TX 500 rinse 



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Full of Short Laad Semiconductors ft Elec- 
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and a host of Diodes ft Rectifiers mount- 
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Please ask for Pak P.I. Only tip. 
lip P i Pon this Pak. 



A CROSS HATCH GENERATOR 
FOR €1.81 I 1 ! 

YES. a complete kit of parts including 
Printed Circuit Board. A four position switch 
gives X-heteh, Dots, Vertical or .Horizontal 
lines. Integrated Circuit design for easy 
construction and reliability. This is a project 
in the September edition of Television. 

Th/s complete kit of ports costs 13 JS, 
port paid. 

A MUST for Colour T.V. Alignment. 

STEREO DECODER £495 

A ready built unit, ready for connection to the LF. 

stages of your txiicing FM Radio or Tumr Unit* 

A tell-cile light can b* connected to show the 

pretence of t Scared trinimtnion end correct 

operation of the Unit* 

The UniL is in the form of i imiil printed circuit. 

and no further alignment: it necessary, as all preset 

adjvatnienta have already been carried out at the 

factory. 

It Ji recommended thgt e L.E.D. it used am th« 

indicating light end i luiitble device ii available 

from ui <fc Mip. 

Supplied with necessary initructioni and 

guarantee. 



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FOR 




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NOW IN TWO RANGES 

These are 40W end SAW Silicon Ptaatic Power 
Trenail tori of the very latest deaiin. available In 
NPN or PNP at the moic lhaiterin|lr low prim of 
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quantity to ill parta of the world and we ere proud to 
offer them under our Tested end Guaranteed tsrmt. 
FUnse I. VCE. Min 15. HFE Kin IS. 



40 Watt 
•0 Watt 
Rani* 2. VCE. Min 40. 



l-ll ll-M 26-M 

up iop lip 

l**p Mto Up 

HFE Mln 40. 

l-ll ll-U 16-H 

40 Watt »p Dp Mp 

JO Watt j||p 2s, p Up 
Complementary pain matched for gain it 1 am pi, 

lip extra per pair. Please atate NPN or PNP on 
order. 

INTIGSATID CIRCUIT! 
We tt«k a large range of I.Ci at very competitive 
pricei (from lip each). Thete are all titled in our 
^REE Catalogue, aee coupon below. 

MITRICATtON CHARTS now ..atlahla 
Thii fantaltically detailed convention calculator 
Carrie ■ thou land a of c la Mined references between 
metric and iritiah (and U.S.A.) measurements of 
lenith, area, volume, liquid meature, welghta etc. 
Pocket Slaa Up, Well Chart tip. 

LOW COST DUAL IN LINE I.C. 
SOCKETS 

14 pin type at ii,p each \ Now new low profile 
It pin type at Itp aach/type 

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We have a large selection of Reference and 
Technical Books in stock. 
These are fust two of our popular lines: 
B.P.I Translator Equivalents and 

Substitutes: 4t> 

This includes many thousand! of British 
U.S.A., European and C.V. equivalent). 
The lliffe Radio Valve ft Treneistor 
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Character it tics of 3,000 valval and tubes. 
4.500 Transistors, Diodes, Rectifiers and 
Integrated Circuits. 

Send for fists of publications 
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363 



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items purchased separately, ^ 
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just give name, address, Access or Barclay- 1. 

card No. — that is all ! ! ! w 



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The Space Age WORLD RECORD award winning 7' 6" 
long All Band JOYSTICK VFA Antenna— JO YMATCH 
A.T.U.— TRIO RECEIVER or TRANSCEIVER— Match- 
ing HEADPHONES— A COMPLETE STATION IN 
ONE COMPACT PACKAGE— THE FLAT DWELLER'S 
DREAM ! 

* JOYSTICK VFA £12-54 (A) ; JO YMATCH 
ATU III or MIA £12-54 (B) ; JOYMATCH ATU 
LO-Z500 £18 10 (C). 

COMMUNICATIONS HEADPHONES £286 (0) 

(All including carriage, packing, accessories and insurance) 



PARTRIDGE PACKAGE No, I 

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'Items (A); (B); (O) above £12-10 

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Station ... ... £126-00 



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I BOW ... ... £231-00 

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NEW: World-wide reception on the amaxing "DX — CRYSTAL 
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NEW: INSTRUMENT CASES, easily drilled in Strong black rifid 
polystyrene. S ft" x 3H" x 1\". ONLY 20p. 

PARTRIDGE BUDGET LINE- 

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SILICON! 
ELECTRONIC IGNITION SYSTEM 

This Capacitor-Discharge Electronic Ignition System was 
recently described in Practical Wireless and has proved ex- 
tremely popular. We are able to offer the kit in two forms; the 
standard kit containing the electronic components only, enab- 
ling the customer to tailor these to his own layout, pr the 
de-luxe version containing a ready-drilled roller-tinned printed- 
clrcuit board and fully machined die-cast case with A.M.P 
Electrical Spade Connector Block. Each kit is supplied with a 
custom wound transformer, first grade components and full 
constructional details. 

The original circuit employed Germanium Power Transistors 
for the negative earth version. WE NOW SUPPLY SILICON 
P.N. P. POWER DEVICES AT NO EXTRA COST! All 
components available separately. Case size 4}" x Zl" x 2". 
Complete assembly and wiring manual 25p, supplied with de- 
luxe kit only, refundable on purchase of kit. 

Suitable for 12v systems with Pos. or Neg. earth, 

Price: Standard Kit £7-97 U.K. Post Free 

De-Luxe Kit £9 62 U.K. Post Free 

Quantity Discounts: 
Trade and Overseas 1-5 Nett 6-9 Less 10% 

Enquiries Invited 10-49 Less 15% 50-99 Less 20% 

Mail Order Only 100-999 Less 25% 1000 up Less 30% 

PLEASE STATE POS. OR NEG. EARTH WHEN 
ORDERING. 

DABAR ELECTRONIC PRODUCTS 

98A LICHFIELD STREET, 
WALSALL, STAFFS. WS1 TUZ 
Tel. Walsall 34365 



COMPARE OUR PRICES 



Speaker Bargains 

E.M.I. 13 x 8 In 3, I A 15 OHMS 

PLAIN £200 

WITH TWEETER .. £2 25 

TWIN TWEETER .. £3 50 

Type 350-20 watt with Tweeter 

B. OHM p. A p. 37p. .. £7-25 

8x51n3, 8 A15 OHMS .. £110 
61* (93850) 8 ohm .. £2 20 

8* (HA/1000) 8 ohm 10 wat' £4 00 

E.M.I. 3i" TWEETER O 
MAGNET 8 ohm .. 

FANE 7x4 ln3AB OHMS 
8*8. OHM DUAL CONE -- 

CELESTION8"15,OHM 

BAKER GROUP 25 12" 25 
WATTS or 15.0HM 
5" 8 ohm C/MAGNET 



ACOS GPJ01 COMP, CRYS. 
1S-TI SONOTONE STEREO 

CRYSTAL 

POSTAGE 5p per CARTRIDGE 



£100 



£2 10 
£1-40 



£6 00 
SOp 

p. A p. 10p 



2i"8or 64 OHM p. A p. 10p. -45 

P O S TA GE asp per SPEAK E R 

Kit-Form Cabinets Teak 

(17" x 10" x 6") with a 13* x 8" 
or 8" CUT OUT 

18x11 x 9 with 13" x 8" cutout 
for EMI 350 

(12" x 12" x 6") with a 8" x 5" or 
8" CUT OUT 

(PLEASE SPECIFY CUTOUT) 

Ad d 35p p er Cab inet lor p. A p. 

Cartridges with standard fittings & 

styli 

ACOS GP91/2SC or GP91' 
3SC STEREO COMPAT- 
IBLE . . 90 

ACOS GP94 STEREO CER. 

ACOS GP95 STEREO CRYS. 

ACOS GP96 STEREO CER. 

OTHAC SONOTONE STEREO 
CERAMIC (DIAMOND) .. 

9THAC/G SONOTONE 

STEREO CER. fDIAMOND) 
SLIMLINE 

ACOS GP67/2C MONO CRYS. 



£2-9S 
£3 35 



£2 25 



£1S0 
£MS 

£1 SO 

£(■70 



£1 70 



' Microphone Bargains 
CM 20 Crystal Hand .. -45 

DX143 Dynamic, catiette- 

type Bllck .. .. .. £1 00 

I CM70 PLANET stick metal. 

switch crystal .. .. £1-45 

DM160 Dynamic uni-dlr, ball 

metai £3 75 

UD130 50K/S00 OHM unl-dir. 

ball netal .. .. . . £4 50 

TW209 LESSON DUAL IMP 

ball metal, unl-dk. £1-75 

CONDENSER MIKE uni.-dlr. 

600 OHM £7-95 

GUITAR MIKE . . .. 45 
LAPEL TYPE, crystal . . -40 
POSTAGE 17 p each. 

Battery Eliminators 

240v Input 6 or 9v d.c. output 

at 150 mA £199 

12v d.c. input [lot cars, fits In 
lighter socket) 6, ~H or 9v 
' d.c. output at 300 rrsA £2 50 

j P, A P. 10P 



Tapes — "•MYLAR" base flrtaal 
quality British made. 
5" 600 It 3Sp Si" 1800 It alp 
5" 900 ft 45p 7" 1200 It 55p 
5" 1200(1 (Op 7" 1BO0(t (Op 
SJ" 900 ft 49p 7" 2400 ft 95p 
Si" 1200 ft 55p 
POSTAGE 9p each, 

PLASTIC LIBRARY CASES 
lor Sin Reels 16p 
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P. A P. 5p each 



THIS MONTH'S SPECIAL OFFER 
E.M.I. Loudspeaker Enclosure kit. (LEK 450,8) comprising 2 EMI 450 
Speakers (8 ohm 10 wait TjTweeler. plus cross-over) and 2 EMI Cabinet 
kits 18' r 10' x 11* plus Acoustic Wadding, Glue, Screws. Instructions. 
Recom. Retail Price £29 20. Bargain at£18 00 inc. V.A.T. plus50pp.Ap. 



SENDtSpfOR COMPLETE CATALOGUE Add 10% VAT on prices, inc. P. A P. 

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~ ALL OUR MERCHANDISE IS FULLY GUARANTEED 



364 



FROM SCRATCH 

Much more efficient magnetic amplifiers can be 
obtained by designing from scratch. If the control 
power is more than about 200mW, transformer steel 
cores (such as Hypersil) can be used either in tape 
or C-core (with no gap) form, for lower powers a 
."-metal or permalloy core is available. For any core, 
the power which can be controlled is approximately 

D2ABf 
equal to where D is the diameter of the 

20v 

whole core (in cm), A the area of cross section of core 

















A 



























r a ~i 



Fig. 9: The cross sectional area of the core can be obtained by 
multiplying 'a' and 'b' measured In cms. 

(in sq.cm) in the bobbin, B is the saturation flux 
density of the core in Teslas (Weber per sq.m) and 
f is the frequency in Hertz (cycles per second). 

The wire size may then be selected if the output 
current is known. Using a table of wire size which 
shows area in "circular mils" choose a wire size of 
about 1 circular mil for each milliamp of output 
current. The number of turns for the voltage required 

25 V 
at the output is then —r- where the area of 

A 

cross-section of the core (Fig. 9) in sq.cm and V is 
the voltage of the winding in volts. 

After this, the design depends on the core material 
used, whose characteristic must be known. The 
ampere-turns for control should be obtained from the 
maker's information, and the control winding de- 
signed to suit amplification required and to fill the 
available bobbin shape. 

In the case of a commercial design, considerably 
more would be done to calculate leakage flux, winding 
thickness, etc. but a cut-and-try approach is better 
for the amateur who is more interested in making a 
working device than in establishing a production 
line. 

FINAL NOTES 

Voltage gains are of the order of 8-40 with straight 
saturating circuits and up to 1200 with self -satura- 
tion. Feedback lines should include a choke to 
prevent a.c. feedback. 

The frequency of the input signal should not be 
more than one-tenth of the frequency of the operating 
a.c; for 50Hz operation, the input signal bandwidth 
is d.c. to 5Hz. ■ 




The colour- 
coded sections of the 
Milliard Data Book list all you'TT 
want to know about valves, integrated 
circuits, semiconductors, picture tubes and 
other components. It also contains equival- 
ents and comparables lists. 

The Mullard Data Book 1973/74 is now 
available from your bookseller, or direct, 
cash with order, from the Selray Book Co Ltd 
60 Hayes Hill, Hayes, Bromley, Kent BR2 7 HP 



Tl 



RETAIL PRICE - 30p (plusSp postage) 



M54 

365 



. 



PRODUCTION 

JLIlVliS colin riches 



STEREO 21 

I didn't think it was possible, but, for 
the amazingly low price of £17-95, 
Radio and TV Components are 
marketing a stereo record playing 
outfit, 

In kit form, it comprises a BSR 
C129R 3-speed record deck with 
cartridge, a pre-assembled amplifier 
module, giving 2-7W per channel, 
two Sin. x Sin. speakers, easy-to- 
assemble woodwork for the plinth, 
cover and speaker cabinets and all 
the wire, nuts and bolts, etc. 

The "Stereo 21" is particularly 
suitable for beginners to home con- 
struction because no soldering is 
required, All electrical connections 
are made through push-on tags. The 
plinth and speaker enclosures employ 
pre-mitred, wood grain covered chip- 
board sections, the mitres being cut 
in such a manner that a hinge is 
formed. Glue is applied to the mitred 
sections which are then simply folded 
over to form a cabinet. 

Another new item from the R & TV 
stable is an 8-track cartridge player 
retailing at £9-90. Housed in a smart 
wooden cabinet, the unit claims a 
frequency range better than 50- 
10kHz. Four track-indicator lights 
show which track is being played and 
the unit switches automatically from 
one channel to the next. This unit 
can easily be played through the 
Stereo 21 system, making it a compre- 
hensive good-value-for-money stereo 
set-up. 

Further information by sending 
s.a.e. to Radio & TV Components 
(Acton) Ltd., 21 High Street, London, 
W3 6NG, 



ADVANCE TIMER/COUNTER 




Mentioned last month, the TC17 
measures frequencies from d.c. to 
50MHz with resolution of 0-1 Hz, 

366 



GL78/P/C 

This is the latest addition to the range 
of Goidring/Lenco Turntable Units. 
The Model GL78/P/C incorporates 
an automatic shut-off switch which 
stops the motor at the end of the 
record and simultaneously raises the 
pick-up, A manual override control 
is built in, in case the shut-off facility 
is not required. Goldring Ltd., 10 
Bayford St., Hackney, London, E8 3SE. 




NEW 'TERRY' CLIPS 

The picture shows the range of 
'clipco' securing clips. 'Clipco' is 
versatile, easily fixed and no screwing 
is required. It is made of unbreakable, 
resilient rust-free nylon, which pre- 
vents damage to articles. 'Clipco' 
solves many fixing problems around 
the home and is a specially designed 
dual purpose plug which ensures 
efficient fixing to walls, tiles, wood 
and pegboard etc. 

The clips are available in three 
choices of visual blisters, containing 
8, 9 or 10 clips dependent on size and 
shape. The recommended retail price 
of blisters is 21 p to 23p. They are 
also available in bulk— 100 at £2-18p. 
Herbert Terry and Sons Ltd., Redditch, 
England. 



S.W. CRYSTAL SET 

Partridge now market a short wave 
crystal set (see picture). Further 
information from: Partridge Electron- 
ics, Broadstairs, Kent. 




VACUUM RECORD CLEANER 

The manufacturers, R.I. Audio, claim 
that their new "Groovac" record 
cleaner is the only unit available which 
removes dust from records by 
vacuum cleaning. 

A tracking force of only 0-7 gram 
has been achieved by using a light- 
weight design with lubricated-for-iife 
bearings throughout. This is con- 
siderably below the 3 to 6 grams force 
of simple brush cleaners. Low track- 
ing force allows fine hairs to be 
incorporated in the Groovac cleaning 
nozzle which ensure efficient removal 
of dust from the bottom of record 
grooves — most brush cleaners have 
hairs with a diameter which is larger 
than the width of the record grooves. 
Low tracking force also means an 
almost immeasurable reduction in 
turntable speed, a reduction which is 
at least 3 times less than that caused 
by brush cleaners. 

The Groovac consists of a pre- 
cision lightweight arm, and a suction 




unit which is acoustically isolated in 
a special enclosure. The suction unit 
has been designed to be inaudible at 
a distance of 2 metres; it has a mains 
switch and indicator, and is attract- 
ively finished in teak. Price is £6-90p 
plus V.A.T. and it is available from 
hi-fi retailers or direct from Rl Audio, 
Kernick Road, Penryn Cornwall. 



tmwft 



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AC107 
AC126 SOp 

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BD124 

44p 8D131 

20p BD1 32 



AC151 

ACIS2 

AC1S3 tip BDY20 

AC176 20p BFS15 

AC153/176K EZp BF163 

AC187K 17p BF167 



30p|CA3O35 
lSp|CA3043 
15p|CA3044 
3Up:CA3046 
ISp CA3048 
75p CA3052 
75p CA3065 
75p CA308SE 



25p BD13i;i32 £1 50 CA3C89E 
92p;CA3090Q 
23pCD4001AE 



£1 52 

£1-73 
£1 42 

Ms 

£134 
£110 
£1 42 
£1 M 
£2 19 



NKT406 

NKT713 

NKT773 

NKT781 

NTGD10 

OA47 

OA79 

OA8I 

OA90 



«2p'IN40O4 



29p 
25p 
25 P 
40p 
tp 
IP 



£4-70 OA91 
S4p OA9S 
3Sp CD4009AE £1 16JOA200 



AC188K 23 p 

AC187/138K 40p 
27p 
20p 
20p 



BF173 
BF177 
BF17B 
BF18Q 
BF194 
20p BF195 
19pSF196 



25p 
23p 

He 

31 p 
35 p 
15p 



fOp 
5Sp 
SOp 
37p 
37p 
74 p 



IBF200 
■8F254 
. BF255 
i BFX13 
i BFX29 
iBFX84 
32 p BFX85 
2Sp BFX86 
25p,BFX67 
2Sp 8FX8S 
25p BFY5C 
44pjBFY51 
2Sp,BFY52 
24p'BFY53 
17p BFY90 
47p BP101 
40p BPX66 
SOp BRY39 
SSp BSX19 
2Sp BSX20 
30p BSX21 
22pBSY27 
30p!BSY29 
15p BSY9SA 
• p BY100 
If p BY127 



CD4011AE 54plOA202 

CD40J2AE 54p ! OC20 

CD4013AE £M1|OC25 

CD4015AE £2 92 OC2S 

CD4017AE£2 92 OC29 

__CD401BAE £2-92 OC35 

15p CD4020AE £3 25:QC36 

15p CD4024AE E2-09JOC41 

3Sp CR1/051C SOp OC42 

14p CR1/401C 6Sp OC41 

15p CRS3/05AF OC45 

25p £1-01 OC71 

25p CRS3'40AF 10C72 

2Sp! £1 53 OC75 

34 p C26 ISp OC76 

25pjDt0 (NTGDfD) IQC77 



i 1 N4005 
I1N400S 
> 1N4007 
1N4148 
1N5400 
< 1N5404 
Ip 1N540B 
6P1S44 
Sp>1S920 
Sp1S940 
6p1S5009 
7p|1S5012 
97p IS5015 
37pllS5018 
70p.tS5024 
7SP1S5047 



10P2N4491 46p 

12p 2N5245 45p 

1Spj2NS457(MPF103> 
Up 49p 

4pl42N5458(MPF10) 
»4p 49 p 

tip 2NS459(MPF105) 
2Sp Up 

4P2N5777 4Sp 

7p 2N6027IO13T1) 



Bp 



SOp 
S3p 
<0p 
40p 



ACY17 

ACY1B 

ACY19 

ACY20 

ACY21 

ACY22 

AO140 

A0149 

ADHJ1 

AD162 

A D1 61/1 62 

AF106 

AFI14 

AF115 

AF116 

AF117 

AF118 

AF124 

AF125 

AF126 

AF136 

AF1B6 

AF239 

AF27B 

ASY26 

ASY27 

ASY28 

ASY29 

BA13B 

BAX16 

BB1Q3 1fpBY127 22p MC146BL £4-»|pN™«,p N ™ 1 9r;Sidwisjk 

BB104 28p BTY79/400S 92p MC1468L £ritl PNW19WN ,«„ raKwlS 

BBJOS 32pBTt06 £1-20 MFC4000B «5p| SCU6D £ |.g5 ?K» L 

BC1Q7 Up BZY83C3V3 13p MC4024P £2»!|5J 46D fi t.™ "™»* 

BC107/BC177 BZY88C3V6 13p MC4044P £*2»Jli 2 u3A SOcMSs 

33p;BZY88C3V9 13p MFCS030 £t 13 IMoia ittn-n 
BC108 12p,BZY88C4V3 13p MFC6040 «.«! SU03A {RectJ 

BC108/BC178 ._ |BZY8flC4V7 13piMFC8010 



Mp 

lOp 
7Sp 
7Sp 



SOp 

Mp!lRTS4 

ISp IR21M 

15p [RC20 

ISp JA424 

17p!lIC709C/5 
£1 05X107090/8 

75p|LIC723C/5 £t 02 
£1-3S|LIC723C/T4£1-00 

40p LIC741C/5 4Sp 



40p 
£2<M 

«P 
4fp 

£2 OS 
<2p 
«P 



16p 
16p 
20p 
20p 
2Sp 
12p 
20p 



LIC741C/8 

MC1303L 

MC1305P 

MC1307P 

MC1310P 

MC1330P 

MC1352P 



40 p 

£1-75 
£210 
£1 65 
£2 95 



OC81 

OC81D 

OC83 

OCB4 

OC139 

OCI70 

OC171 

OCP71M 

ORP12 

ORP60 

ORP61 

ORP69 

PN70 

PN71 

PN107 



2N404 
2N696 
2N697 
2N698 
20p,2N706 
20p 2N706i 
20P2N70E 
20P2N911 
25P2N914 
25P2N918 
40P2N929 
20p 2N930 
20P2N1131 
23P2N1132 
25p 2N1302 
2Sp:2N1303 
25p;2N13Q4 
30PJ2N1305 



3N34 

3N128 
3N140 
3N152 
7SP3015F 
7Sp,30(5G 



23 p 
ISp 
Up 
»p 
lOp 
Up 
Up 
SOp 



7400 
7401 
7402 
7403 
7404 
7405 
7408 
7409 



20p 7410 
42p 7413 



2ip 
MP 

24 p 

24p 



7420 
7425 
7430 
7440 



17p'7442 
17P7443 
I*p 7444 



42p 

SOp 
40p 
40p 

SOp 

sp 



2N1306 
2N1307 
2N1308 
2N1309 



2N1559 (CR1/ 



24 p 
30 i> 
30 P 
34 p 
34p 



.WPPNlOa 

"'"iPNicra 



401 C> 
9pj2N1613 
7PI2N1711 
7p;2N1893 
7P2N2218 



•Op 
15p 

ISp 



28 p 

BC109 13p 

BC109/BCI79 

33p 



BC109C 

BC117 

BC140 

BC147. 

BC148 

BC14B 

BC157 

BC158 

BC1SS 

BCt47/157 

BC1 48/158 

BC149/15S 

BC167 

BC168 

BC169 

BC169C 

BC177 

BC17S 

BC179 

BC182 

BC1B2L 

BC133 

BC183L 

BC134 

BC184L 

BC212 

BC212L 

BC238 

BC238/308 

BC257 

BC258 

BC259 

BC337 

BC308 

8CY30 

BCY31 

8CY32 

BCY33 

BCY34 



14p 
15p 
30 p 
lOp 
9p 
10p 
12p 
Hp 
12p 
22 P 



BZY88C5V1 13p jMF ca040 
BZY8EC5V6 13p! M FC9020 
BZY88C6V2 13p; M j £371 
BZY8BC6V8 13p MJESM 
BZY88C7V5 «p:MJE521 

S5XKS2X? I3°MJE29SS 
BZY83C9V1 13pujE30SS 

BZY83C13V 13p "^ 



60p 
80 p 



BZY88C15V «P L MJB02/MJ4502 
BZY88C16V 13pj M '" ,lK ' MJ, £ Y. st 

£1 SO 



BZY88C58V 13p u IQtln 
20PBZY88C2OV 13p SlJSw 
22p BZY88C22V 13p ""!!™ 
11pBZY88C24V «P KS¥?S 
lOp BZY8BC27V 13p JJS ^ (2NM57 , 
11PBZY8SC30V 13p MPF'03(2N5457) 
I2p BZX61C7V5 23p M pF, ftif , N ,.!?f > 
20p,BZX61C8V2 23p, MPF " M < 2N5 ^8) 

1BpBZX61C9V1 Z3P tM PFio?WN^wf 

20plBZX61C10V 2Sp!MPF10S(2N5459) 

lOp BZX61C11V 23p| WKT(v ,,, «P 

10PBZX61C12V i3pN*jT0033 9Sp 

9pBZX61C13V 23p NKT2n 

10pBZX61Cl5V S9p™5jS* 

Mp BZX61C16V 23p "" 

t2p BZX61C18V 23p 

42pBZX61C20V 23p 

12PBZX61C22V 23p 

10pBZX61C24V 23p 

20pBZX61C27V Z3p 
9PBZX61C30V I3pNKT274 
8p CA3004 £2-25 NKT275 



£1 IS 

^IJ'SL803A 
* 1M SL403D 
rM (IC Amp.) £1-50 

TAA263 75p 

TAA293 97p 

TAA310 £1-25 

TAA320 

TAA861 

TAD100 

TAD110 

TIL112 

TIL209 

TIP31A 

TIP32A 

TIP41A 
£1 S0!tiP42A 
£ * ««TIS43 
3 JP VA10665 



«Sp 

65p 

I2p 

£1 06 

*Sp 

I7p 

£1 25 

£1 35 

£412 



75p 
45 p 

£1-97 
£1-97 

£2 00 



2N2369A 



NKT213 
NKT216 
NKT217 
NKT218 
NKT223 
NKT27I 



9p CA3005 
12PICA3011 
10pCA3O13 
25PJCA3014 
4lpCA3018 



£1 50 NKT279A 

92p NKT281 
£1 30 NKT351 
E1-52NKT401 
88p MKT402 



50plcA3018A £1-19NKT403 
20p|CA3020 £1S5NKT404 
25p'CA3328A 88p l NKT405 



VA1039 

VA1040 

VA1077 

W005 

W01 

W02 

W04 

WOG 

W08 

ZTX107 
48PZTX108 
MP ZTX30O 
Mp 2TX302 
27p ZTX303 
1*P ZTX304 
HP ZTX314 
20p ZTX320 
12P ZTX330 
MP ZTXSOO 
75 p ZTX501 
71 p ZTX502 
77p 2TX503 
MP2TX504 
60P.IN914 
7lp!lN3754 



2N2484 
2N2646 
2N2904 
2N2904A 
2N2905 
2N2905A 
2N2924 
2 N 2925 
2 N 29 26 
2 N 3053 
2N30S4 
2N305S 
35p 2N3228 
60p'2N3391A 
70P2N3525 
S5P2N3702 
£1 00 2N3703 
30 p 2 N 370 4 
15p2N3705 
15p 2N3706 
15P2N3707 
15p2N370fi 
30p2N3709 



31 p 
32p 
33p 
35p 
14p 



2N3710 
2N3711 
2N3773 
2N3B19 
2N3820 



12p;2N3823E 
11p!2N3826 
13p 2M3366 
18p,2M3904 
ISp 2N3906 
23 p 2 N 4058 
llp'2N4060 
30 p 2N406) 
ISp 2N4062 
14p 2N441 
ISp 1N40O1 
1BP1N4002 
I7p 1N40O3 
45p;2N4444 
*p'2N4871 
20pl2N499O 



7445 
7446 
7447 
7450 
7451 
7453 
7454 
7460 
7470 
S4p 7472 
SSp 7473 
44 p 7474 
JlP'7475 
Up 7475 
ITp7480 
17P7482 
17p 7481 
42p7486 
45 p 7490 
44B 7491 A 
4»p 7492 
SSp 7493 
79P7494 
1IP7495 
20P7496 
10 p 74100 
24 p 74107 
. I5p : 74121 
*5p 74141 
£1 10 74150 
Up 74151 
£Vt474153 
10p74154 
10 p 74155 
tOp 74156 
Ifp 74190 
10p74191 
1lp74I92 
Sp 74193 
lOp 74196 
ffp74197 
IOp402SO 
£2 SO 40309 
28 p 40310 
I0p!403t1 
20p403T2 
30p4032O 
£1 10 40360 
2lp|4036t 
Ilp|40362 
13p4Q406 
Up 40407 
Ifp 40408 
11 p 40409 
TOp 40410 
7p|40430 
7p'40432 
16p|4046SA 
£2-2040511 
40pl40512 
66pl40575 



45P 

£! 30 

73p 

Mp 

92 p 

£200 

£200 

Up 

20 P 

Zip 

»p 

35 p 

25p 

25p 

25p 

2Cp 

3fp 

20p 

SOp 

20p 

MP 

£116 

£145 

£1 45 

£2 06 

£1 45 

£1 25 

20p 

20p 

20 p 

20p 

20 p 

4Sp 

32p 

45P 

*6P 

45p 

45p 

■7p 

•7P 

£1 31 

SSp 

70p 

£1 21 

ISp 

75p 

£1-13 

SOp 

£1 48 

£1 64 

S2p 

43p 

£100 

£3 35 

£110 

£1 35 

£3 00 

£1-5S 

£1-55 

£1 SO 

£1 SO 

£1 74 

£1 74 

£1 50 

£1-50 

65p 

40 p 

60p 

42p 

62 p 

42P 

Sfp 

45 p 

SSp 

53p 

40p 

54p 

E2p 

f2p 

£1-13 

£1-60 

44P 

£1 »2 

£1 88 

£1 54 



ELECTROLYTIC AXIAL LEADS 



Mtd. 



Wofklno 
Voltage 

40v 
lOOv 
25v 
63 v 
40v 
25v 
63v 
25v 
40v 
25» 
40v 



Price Mid 



100 
100 

too 

100 

220 

2SO 

470 

1000 

2300 

4700 



Worktno 
Voltage 

16v 
25v 
40v 
S3. 

M» 
«to 

25v 
25v 
25v 



»p 
'P 
7p 

10p 

Ip 
•p 

12p 
IIP 

sop 

13 p 



CAPAC1TORS- 

Stock values: MFD 

0-01,0015.0022.0 033 

047, 068, 0'10 

0-150. 0-220 

33 

0-47 

68 



10 
1-5 
22 

Order as 



METALLISED POLYESTER 

Price each 
? p 

3 P 

7> 
■p 

HP 
«P 
Mp 
Mp 

Polyettaft" + Capacitance. 



CAPACITORS— POLYSTYRENE 

Aiial leads. Clear encapsulation, 5% Tolerance. 160 vol! working. 

Price 
Stock values each 

100pF, 150pF. 220pF, 330pF, 470pF, S60pF, 680pF, B20pF. 
lOOOpF. 1500pF, 2200cF, 3300oF, 4700pF, 56O0pF. BSOOpF. Sp 

Ordsr as: "Polyslyrenes" + Capacitance. 



ALUMINIUM HEAT SINKS 

10ON Mp [Plain All und rilled) 
10DDR SSp (Plain All drilled 2 x To3) 



NEW LOW PROFILE IC HOLDERS 

14 pin Dll tip, 16 pin Oil 26p, S pin DM top. 



NYLON NUTS AND BOLTS 

Cheese head screw bolls. Nuts with integral washer. Moulded 

in nigh density nylon. Ideal tor mounting "live" assemblies, 

power transistors, etc. 

Each pack consists of tour nuts and lour screw bolls. 

Pack No Thread Length Quantity Pack Price 

HSN1 6BA i" 4 Up 

HSN3 GBA |" 4 10p 

Order as "Nuts and Bolts" + Pack No. 



OPTO ELECTRONICS-3 devices 

from our range— OCP71— 42p, QRP12— SOp, TIL2Q9 Red led SSp' 



TEST PROBES 

Probably the beet teat probes ever made. When you push a plunger 
a spring steel forked tongue pushes out and holds the components, 
wires etc., while you take readings etc. It won't let go until you 
release It, 
KLEPS30 Black and Red, per pair £130 



RESISTORS— METAL OXIDE 

Metal Oxide resistors by Electros!). Ultra low noise, i Watt, 
2%, Available In (he range E24 between 10 Ohms and 1 Meg. 
E24 series--1-0. 1-1, 1-2, 1-3, 15, 1-6, 1-8. 2 0. 2-2. 24, 2-7, 3-0, 3-3, 
3-6, 3 9. 4-3, 4 7. 5-1, 5 6, 6 2. 6 8, 7 5. 3 2. 9 1. and their decades. 
Type No. TR5 Price: 4p each 

Order as "Metex" + value. 



RESISTORS— CARBON FILM 

A range ol miniature high stability resistors with very low noise 
characteristics and long life. Tolerances, ranges and waltages as 
indicated, (Wattage ratings are at mai. limiting voltage). 



Type No. 

UPM050 
UPM050 
UPMQ75 
UPM07E 
UPM100 



Wattage 

05 

OS 

075 

75 

100 



Tol. 
5% 
10% 
5% 
10% 
10% 



Range 

10E-1M 

1M-4-7M' 

10E-TM 

1M-4-7M 

10E-1 M 



Series 

E12 

El 2 

E12 

E12 

E12 



Price 
Ip each 
lp each 
Ip each 
Ip each 
lip each 



nranuDUJ service plus 

10% DISCOUNT OVER £4. NO POSTAGE 
AND PACKING. TOP QUALITY PROD- 
UCTS ALWAYS BY RETURN 
COMPREHENSIVE CAT. B— * > 



Important Notice "All prices arc t 
exclusive of V.A.T. Please add 10% V.A.T ^ 
to the final total of your order after # «* 
deducting any discount which may + »* ^fj 
be due" ** . ™ 
->•* \tf ,■ 



DEPT. PW S; 



7 COPTFOLD ROAD 

BRENTWOOD 

ESSEX 



FI^GLL 
ELESTfJEUSS LT9. 









367 




TS*0 POCKET 

MULTIMETER 
High-preclilon at low-oust 
Ranges; D.C. 16V, 160V 
1,000 V (10,000 opv}, A.C 
IBV, )B0V, 100 V (1,0011 
e-py). D.C. Current lSOmA, 
Reslitance 100k ohms. 
II 86. Pott 15p. 

AUDIOTROMIC MODEL ATM.) 

Top value 1000 o.p.v. 
pocket multimeter. 
Ranges: 0/10/50/250/100Qi 
AO and DC 

DC Current u-luiA/lOOiuA 
Resistance 0/1 6 0k ohm* 
Decibels -10 to + 22dB 
Size B0 x 80 x 26mm. 
Complete with test lead*, 
19-60. Pout 15)>. 



LT40I 
MULTIMETER 

Sew style 20,00o 
o.p.y. pocket mulU- 
meter. 6/25/80/260/ 
800 I 2600 V. D.C. 
10 / 60 I 100 / 600 / lumn 
A.C, BQjiA / 280mA. OK / 
meg ohms. -20 to + 22 dH 
ta-76. Post 20p. 




BIOKO MODEL 700X 
100,000 O.P.V, Overload 
protection. Mirror scale. 
■3/0/1-2/1 8/3/6/12/30/60/ 
1 20/300/ BOO; 12O0V DC 
1 ■ 6/3/67 E 2 /30/80/ 1 5 0/30 O/BW » 
1200 V. A.C. 

1 8 /30(i A / 3/8 /30/B 0/ 1 6O/30Qm 
0/12 AMP. DO 2K/200K/2 
Meg/20 Meg ohm -20 to 
+ flaJU. 113-50. P. & P, 20 |- 

MODEL C-7080 EN 






MODEL TH-12 

20,000 o.p.v, Overload pro. 
lection, Slide switch seiectoi 
/ -26 / 25 / 10 / 60 / 250/ 
LOOOV. D.C. / 10 / 60 / 250 / 
1000V. A.C. ) BOftA / 26 / 
260mA. D.C. / 3K / 30K / 
300K / 3 meg - 20 to + 60d 14 
14-B7. Post IS p. 



RUSSIAN 22 RANGE MULTIMETER 
Model U437 10,000 u.p.v. 
A first ctau versatile in- 
strument manufactured In 
U.9.8.R. to the highest 
■tindards. Ranges: 2-6/10/ 
60/280/600/ lOOOv D.C, 2 6/ 
1 0/60/280/600/ 1 OOOv A.C. 

DO Current lOOwA/1/10/ 
lOOinA/lA, Resistance 

MO cniii»/3/S0/300K/3jjiO. 
(Jomplete with batteries, 
test leads, Instructions ami 
sturdy steel carrying ca-e. 
OUR PRICE (8-87. P. * P. 2i>i 




MIOKI MODEL 730X 
10,000 O.P.V. Overloail 
protection. 8/30/60/300/ 
600/1200 VDC. 12/60/120/ 
600/1200 VAC. o0/fiA/30 
in A/300 m A. 2 K / 200 K fJ 
megohm. —10 to + 83dh. 
17 60, P. a P. 15p. 





MODEL PL436 
sokn/Vnit ixc. BkQ; 
Volt AC. Mirror scale. 
•0/3/12/30/120/flOO V 
D.C. 3/30/120/600 V 
A.C. B0/80G(jA /SO/800 
m A. 10/lOOK/l Meg/ 10 
Megfl -20 to +4odtj. 
IS 87. P. * P. 12p. 

MODEL 500 

30,000 O.P.V, with over- 

load protect ion mirror svalr 

0/6/2-6/1 0/26/ 1 00/260/600/ 

l.OOOv. D.C. 0/2-5/10/25 1 

100/280/500/ 1,000 V. A.C 

0/50ti A /a /5 0/50 OmA. 12 

amp. D.C. 0/80/ K/8 Meg.' 

80 Meg CI 

IS 96, Post paid. 

Leal her Case £1-78 

U4JIZ MULTIMETER 

Extremely sturdy instrum' 

electrical use. 867 o.p.v. 

0/-S/l-6/7'6/30/BO/160/30fl/ 

800/800 VDU am! 75mV. 

0/ -3/1 6/7-6/30/80/ 1S0/30O 

600/900 VAC. 

0/300jiA/l-5/8/lS/00/160 

600MA/1 5/0 AMP. D.C. 

O/1-6/6/13/B0/150/B00MA/ 

1-5^6 AMP. AC. 

0/200 C1/3K/S0K fi. 

Accuracy DC 1%. AC 1-6",,. 

Unite edge pointer, mirror scale Complete 

with sturdy metal tarrying cue, lead* and 

Instruct inns. 19- 60. P. A I*. 25 p. 

368 



g#6K0yaJ Cliant 6* mirror scale „4 *■ 

-TX£-~ I M - ot)rt <M».v. / -25 / 1 . I ,.,.., 
— :Q ■* \ 2-6 / 10 / 60 / 260 / 1000 / 1 --"v 

1— ^rr i aooov. ».c. 0/2-5/10 , 1 . ' ■ ■ — 7 s *' 

<--=iJW'.rsl 60 / 250 / 1000 / 6000V "* 
A.C. 0/50)jA/l / 10/ 100, 
SOOmA / 10 amp. D.C 
/ 2K / 200K / 20 meg 
- 20 to + 80 dB, 
118- 1>5, Post S3p. 

370 WTR MULTI-METER 

Features A.C, current range* 

20,000 o.p.v. 0/ -5/2 -8/1 0/5 n 

230/800 1000 V. D.C. 

0/2 ■ 6/ 1 0/5 0/2 80/5 00/ 1 000 V A i 

0/SOuA/l/lO/IOOm A/1/10 Ami 

D.C. 

0/IOOmA/l/IO Amp AC 

O/SK/OOK/BOOK/.i MKIl/ » 

ME«. 

-20 +82dli, 

£15. P. Ill 1'. 2.',!,. 







KAM0DEN 72 200 
MULTITESTER 

High sensitivity teste i 

200,000 o.p.v. Overload pr" 

lection. Mirror scale. Rav.se-. 

0/-06/3/3/30/120/600 

1200V. D.C. 

0/3/ 12/ 80/300/ 11,200\ 

A.C. 

/ 6*iA / I -2m A / 120mA 

fiOOmA/ I2A. D.C. 

/ 12A. A.C. 

-20 to +63ilB. 0/2K/20UK, 

200 meg ohnm. £16 85. Post 30 p. 

TMK LAB TESTER. 
100,000 O.P.V. 8) in. » 
Scale Buzzer Bhort, Cir- 
cuit Check. Sensitivity- 
100.000 O.P.V, D.C. 5K/ . 
Volt A.C. D.C. Volts: | 
■8, 2'5, JO, (0, 250, 1,000 
V. A.C. Volt*: 3. 10, 25. 
30, 2S0, 800, 1,000V. 
D.C. Current: 10, 100|M. 
10. 100, 500mA. 2-5, 10 amy. Kesi stance: 
IK, 10K. 100K, 10MEO. lOOMEdfi. 
Decibels: -10 to +49 db. Plastic Case 
with Carrying Handle. Size: 7I1d, xefln. x 
3iln. 11885, P. A P. 25p, 

ModtlS-IOQTR MULTIMETER 
TRANSISTOR TESTER 

100,000 o.p.v. mirror scale; 

overloail protection. 0/-12/ 

•6/3/12/30/ 120/800 V DC. 

0/B/3O/120/800. V AC. 0/12' 

800jt A/ 12/300niA/12 AMI' 

DC. 0/10 K/l MBfi/lOOMEfi. 

-20 to +5Wb. 001-2 MFD. 
I Translator tester measures 
| Alpha, beta and Ico. Complete 

with batteries, instruction* 

and leads. 118-50. P/P 2Sp, 

KAMODEN HM 350 TRANSISTOR TESTER 

High quality instrument 

to test Reverse Leak 
I current and DC current. 

Amplication factor of. 

NPN, PNP. transistors. 
I diodes. SCR's etc. 4" > 
I 4|" clear scale meter. 

Operates from internal 
| batteries. Complete with 

instructions, leads and 
| carrying handle. 112 50. 

Post aop. 



LB3 TRANSISTOR TESTES 

Tests ICO and It. 
PNF / NP>*. Operate 
Iron: Ov battery. Com 
plete with all in 
struct ions. etc. 13 95 
P. i P. 20p. 

MODEL U43II SUB-STANDARD MULTI- 
RANGE VOLT AMMETER 

Hnnsltlvlty 330 iihms/Vnlt 
AC and DC. Accuracy 
6% 1>.C. l' a AC. Seal. 
length Moulin. 0/300/750/jA 
1-8 I 3 / 7-5 / 15 / 30 / 76 / 
160/ 300/ 760»i A / Mi / 3/ 
7-6 AM I' DCO / 3/7-6 lib! 
30 / 7B / 150 / 300 / 
750niA / 1-5 / 3 / 7-5 
AMP AC O / 75 / 150 / 
300 / 760mV / 1-5 / 3 / 
7 6 / 15 / 30 / 75 / 350 / 3il» / :.jii\ UC 
0/760ni V / 1-5 / 3 / 7-5 / IS / 30 / 75 / 150 / 300 
/750V AC. Automatic cut mil. Hup piled com- 
plete with test leads, manual and teat certifi- 
cates. 14900. Post 50p. 

TE-« VALVE VOLTMETER 

2H ranges. D.C. yolts 

1-5-1, 800v. A.C. volts 

1-5-l.SOOv. Resistance up 

to 1,000 megohms. £00/ 

240v. A.C. operation 

Complete with probe and 
. Instructions. 

117-60. P. J.- p. 30p. 

Adililliiual probes avail- 
able: R.K, 12-181: H.V. 
I £2 50. 




BELCO AF-SA SOLID STATE SINE 
SQUARE WAVE C.R. OSCILLATOR 

Hine t»x-200,00n lit: *ninr» I" .-in.nnn 111 

Output mil. 

- lOdR. • 

(10 K ohms- 

Opera I ion Jn- 

irrnalbatteriei 

Attractive -- 

time case 7J' 

5- x 2*. 

Price 11760. 

Carr. 17^p. 








MODEL 449 A IN 
CIRCUIT TRAN- 
SISTOR TESTER 
Checks true A.L, 
beta iu / out. Check- 
lebo. Checkx dlodr. 
Id / out. Check- 
SCR, etc. Deln. 
HI 10 - 500, 
I.O 2 - 50. Iclm O-SOOOftA, 
operation 117-60. Post 2Sp. 




KAMODEN HM. 720B 
F.E.T, V.O.M. 

Input impedance 10 aut 
• ohraa. 

Ranges : 

/ -26 / 1 / 2-5 / 111 / 60 

260 / 1000V. D.C. 

/ 2-5 / 10 / 50 / 250 I 

1000V. A.C. 

/ 25(tA / 2-5 / 25 / 250 
. MA D.C, 

- 20 to + 82dH 
. 0/6K750K/500K/5iiir K 

600(iteg ohms, 

H4-95. Post 30p 

; TE-40 HIGH SENSITIVITY 
i A.C. VOLTMETER 

1 10 meg. input 10 range.- 

01/003/1 / -3/ 1/3/ 10/30/ 10(1, 

300V. R.M.3. 4cps.-l-2 Hc|> 

Decibels -40 to +50dB. 

I Supplied brand new complet< 

| with leads and instruction- 

■ Operation 230V. A.C. 117 SO 

Carr. 25p. 



TMK MODEL 117 P.E.T, ELECTRONIC 

VOLTMETER 

Battery operated, 1 1 

meg Input, 28 range*. 

Large 4!" mirror scale. 

Size 6!" x 4J" x 2J". 

DC VOLTS 0-3-1200V 

AC VOLTS 3-30QV 

RMS. 8-0-SOOV P-P. 

DC CCRREST 12 

12MA, Resistance up 

to 2000M ohm. Decibels .'ii tn . 41dB. 

Coni plete with leads/Instruct inn*. 117-50. 

P. & P. 20p. 



MODEL L-55 FET 
V.O.M. 

Input impedance 10 uosag 
abnw. / 3 / 1 2 / 6 / 30 / 
120 / 600V. D.C. / 3 / 
12 / 60 / 120/ BOO V. A.C. 
/ 120(1 A / 120mA D.C 
/ JK / I00IC / 10 met 
/100 meg ohms 
116-87. Post 15p. 





L'211/JtU V A.C. 



KAMODEN HMG-500 INSULATION 
RESISTANCE TESTER 

Range 0-1 000 Meg- 
ohms, 600 Volt. 
Battery operated. 
Wide range clear 
meter A\" x ■*". 
Complete with de- 
luxe carrying case, 
batteries, irisi ruc- 
tions. 11995. 1'o.t Shi. 




CI-5 PULSE 
OSCILLOSCOPE 

Kor display of piiJieu 

and pt'riitdic wavefonit'- 

In electronic circuit* 

VEHT. AMP. llaml- 

width Itt.MHz. Men..!- 

llvity at 100 KHz VII MS/ 

mm. -1-25; HOK. AMP. Ilnnduidlli SouK Jlz. 

Hi-iisilivily at KKIKHz. V RMS/imu. -3-26; 
; Pr.'-et triggereil MWivp I -3,000usec, ; free 
: ruuniiig 20-200,000 Hz iti nine ranges. 

Calibrator pips.. 220 x 380 X 430uiiu. 

1 1 5-230 \ . AC iiprratii-n. 139 00, Carr. pal'l. 

T0-3 PORTABLE OSCiLLOSCOPE 

3lli . tube, V amp. Sensitivity 

Olv p-jl/t'M. llaiiilniiltl 

1-5 t'pK-l-5 MHz. Input Imp 

f meg CI 25pi-' X amp 

sen »it h it>- 0-9 v. p-p/CM 

Bandwidth l-Scps-HOOkHi 

Input Imp. U (iicb fi 20pP 

Time base. 6 ranges 10 cpi- 

300 kHz. .Synchronization. 

Intevnal/esternal. Illuiuiiinted 

scale 140x215x330 mm. Welgln loitb. 

•220/24fV. A.C. Supplied brand new with 

linndlHiiik. £47 60. OUT. AOp. 







RUSSIAN CI-16 DOUBLE 
BEAM OSCILLOSCOPE 

5 nic/s Pa.-« Hand. Separal' 

Yi aid Y2 ampliner- 

Rectangniar Sin. x 4iu 

C.R.T. Calihrateil trig 

gered sweep from -2 u/sec. 

to 100 mllli-sec, per cm. 

Free running time base 50 ! 

In time base calibrator mid amplitude 

calibrator. Supplied complete with all 

accessories and instruction manual 

«97. Carr. Paid. 

MODEL AT20I DECADE ATTENUATOR 

Frcqnenev range 0- 
200 h'H:;.' Attenuator 
0-llIdh, Oldb step. 
Impedance 000 ohms. 
Max. input power 
SOdbm. Size IHOxBOx Umn, 
112-60. Post 37p. 

ARF-300 AF/RF SIGNAL GENERATOR. 

All transistorised, 

compact, fully port- 
able. AF sine wave 
18 Hz to 220 KHz. 
AV ariuare wave 18 Hi 
to 100 KHz. Outpul 
sine / square 10v, 
P-P. RF 100 KHz to 
200 MHz. Output Iv. 
niaximiim. Operation 
220/240 v. AC. Com- 
plete with Instructions 
and leads, £29-95. 
Post 60p. 

TE-20D RF SIGNAL GENERATOR 

Accurate wide range signal 
generator covering 120 
Re/a 500 Mc/s on G bamls. 
Directly calibrated Vari- 
able R.t'. attenuator, audio 
output. Xtal socket for 
calibration. -220/240V, A.C 
Brand new with instruc- 
tions £17 '60. Carr. 37 Jp. 
Ske 140 x 215 x 170 nun. 




TE22 SINE SQUARE WAVE 
AUDIO GENERATORS 



Sine: 'iOcps to 200 
kc/s on 4 baiuli. 
Square: 20cps to 30 
kc/a. Output Impe- 
dance 5.000 ohms. 
200/260V. A.C. op- 
eration. Supplied 
brand new and 
guaranteed with instruct mi 
ieads. £17'50. Carr. 37 tp. 




anual and 



" YAMABISM " VARIABLE VOLTAGE 
TRANSFORMERS 

Excellent quality at low cost. Al! modelB — 
Input 230V. 50/60 c/a. Variable output 
0-280V. 

MODEL $-260 
GENERAL PURPOSE 
BENCH MOUNTING 




1 Amp 
2-S Amp 
C Amp 
8 Amp 
10 Amp 
12 Amp 
20 Amp 
2S Amp 
40 Amp 



£700 
£8 05 
11175 
£1580 
£83 50 
£2380 
£4900 
£5800 
£82-50 



MODEL S-260B 
Panel Mounting. 

1 Amp . . £700 
2 5 Amp .. £805 

Carriage and 
Packing Extra 



AUTO TRANSFORMERS 



0/110/250V. Step up or 
anrouded. 

80 W 
150 W 
300 W 
600 W 
1000 W 
1500 W 
2250 W 
6000 W 

■CA. 220 AUTOMATIC 
VCLTA8E 

STABILISER 

Input S8 125 VAC or 17fi, 
250VAC. Output 120VAC 
or 240V AC. 2O0VA rating. 
£11-97. Carr. 60p. 



step down. Foils' 





PS.200 REGULATED P.S.U. 



Solid slate. Variable output 
5-20 volt D.C. up to 2 amp. 
Independent meters to 
monitor vol tape and cur- 
rent. Output 220/240 V. 
A.C. Size 7 J- x 6 1" x 3i". 
£1905. P. * P. 25p. 




PS.I0OOB REGULATED 
POWER SUPPLY 

Solid state. Output 6, 9 
or 12 volt DC up tn 3 
amps. Meter to monitor 
current. Input 220/240v 
AC. size ■»- x 3f * 6i". 
£11-87. P. £ P. 25p. 




130V 240V SMITHS SYNCHRONOUS 
GEARED MOTORS 

Built In gearbox. All brand 
new and boxed. 30 RPH 
OWl 2 RPH CW: 20 RPH 
CW; 2 RPH ACW; 30 
RBII CW; 
60t) »ach Post 12p. 

POWER RHEOSTATS 



High quality ceramic con- 
struction. Windings em- 
bedded In vitreous enamel. 
Heavy duly brash wiper. 
Continuous rating. Wide 
range available ex-stock. 
Single hole Axing, fin. dia. 
shafts. Bulk quantities a rail- 
able. 



85 WATT. 10/25/50/100/250/500/1000 ohms. 
96p. P. & P. lOp. 

60 WATT. 10/35/50/100/250/500/1000/2500 
or GO0O ohms. £1 35. P. & P. lOp. 

100 WATT. 1/6/ 10/2 5/ 50/ 100/250/500/ 1000 
or 2500 ohms. £1-95. F. 4 P. 16p. 



240° Wide Anile ImA Meter* 
itw 1-6 flOmm square £8-87 
!iIW 1-8 80mm square (4 97 

P. & P. BXtffi 






230 VOLT A.C. 
50 CYCLES 
RELAYS 

Brand n*w. a Bets ol 
changeover contacts at 
5 amp rating. 50p each. 
P. * P. lOp {100 low £40) 
Quantities available. 



CLEAR PLASTIC PANEL METERS 

USED EXTENSIVELY BY INDUSTRY, GOVT. DEPTS., EDUCATIONAL 

AUTHORITIES, ETC. 

Over 200 ranges in stock — other ranges to order. Quantity discounts available. 

Send for fully illustrated brochure. 



Type SW. 100 100 x 80 mm 

BOjiA M 16 

50-0-50*1 A £3 85 

10Q*iA £3 95 

10(M>-100*iA £990 

SOOjtA £3-70 

1mA £3 80 

20V. D.C. . . i860 

50V. DC. .. £360 

300V. D.C. £360 

1 amp. D.C. £3 80 



Type MR.SSP. 



Type SD.B3082.5mm x 1 10mm 

I ™ 10mA 

i,;Vl * t./ 50tnA 

100mA . . . 
EOOmA . . . 

1 amp 

5 amp. . . . . . 




Uin. x 4Hn. fronts 

50mA £3 90 

100mA £3 90 

500mA £380 

I amp. ...... £3-90 

5 amp 13 90 



1 'J L.A 

S0-O-6GfA 

lOOftA 

100-0-1 00*i A 

200*lA 

BOOftA 

ImA 

5mA 



£3 -10 
£3 40 
£3 35 
£3 35 
£330 
£8 15 
£310 
£3-10 



10 i 
5V. D.C. 
10V. D.C. 
20 V. D.C. 
50 V. D.C. 
300V. D.D. 
1BV. A.C. 
300V. A.C. 
VU Meter 



Fronts 
. £310 

. £310 

£310 

. £310 

. £310 

. £310 
. £310 
. £310 
. £310 
. £3 10 
. £310 
1810 
. £8 SO 
. £310 
. £3 SO 



.'Hi;."- 14 

5O-0-5Q*iA £4 

lOOj/A £4 

100-0-lOOfiA £4 

200*iA £4 

500mA £3 

S00-O-5O0*iA £3 

1mA £3 

1-0-lmA .. £3 

5mA £3 

10mA £3 



15 amp. 

30 amp 

20 V. D.C. 

60V. D.C. 

150V. D.C. 

300V. D.C. 

I5V. A.C. .. 

300V. A.C. . . 

S Meter 1mA 

VU Meter . . 

1 amp. A.C.* 

5 amp A.C* 

10 amp. A.C* £3 90 

20 amp. AC £3 90 

30 amp. A.C* £8 B0 



£390 
£3.95 
£8-90 
£3 90 
£8 90 
£380 
£3 95 
£3 95 
£3 90 
£466 
£3 90 
£3 90 



TypeMR.38P, I 21 






Type SD.640 63.5mm x 85mm 



50uA £8 06 

50-0-50/1 A £3 05 

100(iA £8 00 

100-0-lOOfiA £3 00 

200*iA £300 

B00*iA ££96 

1mA .. £8-90 

5mA IB SO 

10mA £8 80 

50mA .... £2 90 

100mA £2 90 



500mA 
1 amp 

5 amp 

10 amp 

6 V. D.C. 
20V. D.C. 
50 V. D.C. 
300V. D.C. 
16V. A.C. 
300V. A.C. 
VU Meter 



Fronts 

£3 30 
. . £2 90 
. . £2 BO 

£2 80 
.. £2 90 
. . £2 90 

■ 80 ; 

£8 80 i 

£8 00 
.. £8 00 

£816 



Tvpe MR. 

60/iA 

6O-0-B0*iA 
lOOfiA .... 
lOO-0-lOO/xA 

600*xA 

1mA 

5mA 

Kjii i A 

50mA 

100mA 

500mA 

1 snip 

6 amp 



52P. 2iin. square fronts 



IS 50 ' 10V. D.C. . . 
£8 06 | 20V. D.C. . . 
£3 00 i 60V. D.C. .. 

300V. D.C. 

15V. A.C. . . 

300V. A.C. . . 

8 Meter 1mA 

VU Meter . . 

1 amp. A.C. ' 



£295 
£2 35 
£850 
£2 50 
£2 50 
£8 60 
£3 50 
£2 60 
£8 60 
i8 60 



£250 
£2 60 
12 50 
£2 50 
£2 50 
IS 80 
£800 
£3 60 
f2 50 



6 IIJU A .... 

60-0-5 0*. A 
lOOfiA . . 
100-0-lOOfiA 

200*iA 

500 llA 

B00-O-600(iA 

1mA . . 

1-0-lmA 

2tnA ,. 

5mA . . 

10mA 

20mA 

60mA 

100mA 

150mA 



£2 55 

£2-50 
£8 45 
£2-40 
£8 26 
£8 26 

£22S 
£285 
£2 25 
£2 25 
£2 25 
£2 26 
£2 86 
£2 26 
£8'86 



32ln. square 

20OmA 

300mA 

500mA 

750mA 

1 amp 

2 amp 

5 amp 

1 amp. , . . . 
3V. D.C. . . 
10V. DC, . . 
18V. DC. . . 
20V. D.C. . . 
50 V. D.C, . . 
100V. D.C. 
160V. D.C. 
300 V. D.C. 
500V. D.C. 
760 V. D.C. 
I5V. A.C. .. 
60V. A.C. . . 
180V. A.C. . . 
300V. A.C. . . 
500V. A.C. . . 
8 Meter 1mA 
VU Meter . . 



fronts 

£2 25 
£2 25 
£2 25 
£226 
£2 25 
£2 26 
£2 25 
£225 
£2 25 
£226 
£2-25 
£2 25 
£2 25 
£2 25 
£2 25 
£2 26 
£8 85 
£2-86 
£2 30 
£2 30 
£2 30 
£8 80 
£2 30 
£2 30 
£2 65 



Type MR. 45 P. 2in. square fronts 



6 amp. A.C. * 12 SO 
10 amp. A.C. * £2 50 
20 amp. A.C. * 12 50 
30 amp. A.C. • £2 60 



Type SD.4&0 46mm 

60*iA £2 80 i 

5 0-0-51*1 A £8 80 

IOOjiA £2 76 i 

100-0-lOOnA £875 ' 

200*iA £8-78 

BOOjxA .... £8 56 

1mA £8*80 

5mA £8-90 

10mA £830 

60mA £8-60 

100mA 12 80 

500mA ... £2 80 



x 59.5mm 

1 amp. 

6 amp 

10 amp. . , 
6V. D.C. 
10V. D.C. 
20 V. D.C. 
60V. D.C. 
300V. D.C. 
15V, A.C. 
300 V. A.C. 
VU Meter 



Fronts 

,. £8 30 

. £8 30 

.. £8 60 
.. £8 30 

£2 80 
.. £8 00 
. £8 80 

£8 80 
.. £8 70 
.. £8-70 
.. £2 90 



Type MR.65P 

SOjuA £8 

B0-0-B0*iA £8 

100nA £8 

100-0-100/iA £3 

200*1 A £8 

600*iA .... |H 
600-0-600*iA £8 

1mA £8 

5niA 12 

10mA 12 

60mA IS 

100mA 

600mA 
1 amp.. 
6 amp.. 
10 amp. 
15 amp. 
20 amp. 
30 amp. 
50 amp, 
6V, D.C. 



3tin. x 3iin. fronts 



I0V. D.C. 

20V. D.C. 

B0V. D.C. 

150V. D.C. 

300V. D.C. 

15V. A.C. 

50V. A.C. 

150V. A.C. 

300 V, A.C. 

500V. A.C. 

S Meter ImA £8 86 

VU Meter . , fa- 70 



£8 80 
£2 60 
£2 60 
£8 80 
£8 80 
1880 
£2 80 
18 80 
£8 80 
£8 80 



60*tA 

60-0-50*.A 

lOOfiA 

100-0-100jxA 

200*iA 

600*tA 

600-0-^S00nA 

lmj 

5mA 

10mA 
50mA .... 

100mA 

500mA .... 
1 amp 



£2 70 
£265 
£2 30 
£8 50 
18 60 
£245 
£8 40 
£8-40 
£2 40 
£840 
£8 40 
£2 40 
£8-40 
£840 



6 amp. £2-40 

£2-40 
£2-40 
£2-40 
(8 40 
£2*0 
£8-40 
£2-50 
£2 70 
' £2 40 



10V. D.C. 
20V. D.C. . . 
60V. D.C. . . 
300V. D.C. 
15V. A.C. . . 
300 V . A.C. . . 
B Meter 1mA 
VU Meter , - 
1 amp. A.C, 



6 amp. A.C. * £2 40 
10 amp. A.C. 'it-M 
20 amp. A.C. * £2 40 
30 amp. A.C. • £2 40 



"SEW" BAKELITE 

PANEL METERS 

Type MR. 65. 3|in. square fronts 



80 j 50mA A.C- 



£2 SO 



60 100mA A.C. • £8 80 
so ' onnmi if •anna 



200mA A.C. * £2 80 
600mA A.C. • £2 80 
1 amp. A.C. • £8 80 
amp. A.C. * £8 60 
10 amp. A.C. *£S'60 
20 amp. A.C. •£2-60 
30 amp. A.C. ȣB'80 





"SEW 

Type PE.70. 3 17 32in. 
2}in. deep 

50|i A £8-16 , 500*iA £8 80 

BO-O-50*tA £8 60 1ml i.. M 

lOOmA . . . £3-60 lmA * 8 80 

100-Q-IOO*iA £3 50 SOOV. A.C. . . £8-86 

200mA .... £8-40 I VU Meter ., £3-88 



"SEW" EDUCATIONAL 

METERS 
Type ED. 1 07. Si** 
overall 1 00mm x 
90mm x 108mm 
A new range of high 
quality moving coll 
instruments ideal 

for school eiperl- 
menta and other 
bench applications. 
3" mirror acale. The 
easily accessible to 
Available 



1 25*iA £4 60 

50*. A £3-65 

I 5 0-0-50*1 A £3 05 

' 100*iA .... £3 00 

I 100-0-100*iA £3 00 

600*lA £8-70 

600-0-500HA £8-70 

1mA £8 80 

1-0-lmA .. £2 60 

5mA £8 60 I 10 amp. A.C. * £2 80 

10mA £2 30 ! 20 amp. A.C. * £2-60 

50mA £2 80 I 30 amp. A.C. * £8 80 

100mA £2 60 I 60 amp. A.C. • £8-60 

600mA .... £2-60 I VU Meter .. £3-36 



meter movement 1 
demonstrate internal working 
in the following ranges: 



•MOVING IRON- 
ALL OTHERS MOVING COIL 

Please add postage 



'■";•'• 18-90 

loo*i a £6-40 

1mA £6-85 

5O-n-S0yA £6-40 

1-0-lmA £6-66 

lAd.o £6-06 

5A d.c £806 

10V d.e £5 95 



20V, d.o. . . £6 98 
60V. d.e. . . £5 95 
300V. d.c. . . £5 96 

Dual range 

500m A/5 A d.e. £700 

5V/50V d.c. £700 



5 amp 


£2 50 


1 5 amp. .... 


£2 80 


80 amp 


£2 80 


60 amp 


£2 80 


6V. D.C. . . 


£2 80 


10V. D.C. . . 


£2 60 


20 V. D.C. . . 


£880 


60V. D.C. . . 


£8 60 


150V. D.C. 


£2 60 


SOOV. D.C, 


£2 80 


60m V. D.C. 


£2 80 


lOOmV, D.C. 


£280 


30V. A.C.*.. 


£286 


BOV. A.C. *.. 


£2 66 


160V. A.C. * 


£2 35 


300V. A.C. * 


£8 36 


500mA A.C. * 


£2 60 


1 amp. A.C. * 


£8-60 


6 amp. A.C. • 


£2-80 



Type 5-60 80 mm. square fronts 
£3 50 




©t/WKt- 



ATB 
AT30 
AT50 

ATB 5 

AT58 

AT60 

AT65 

HFS1 

HF88 

HF76 



Mono Transistor Amplifier £4-80 
Mono Transistor Pre- 
Amplifier 12 81 

Mono Amplifier (for 
Stereo use two) £8-81 

Automatic Light Control 12 68 
Photo Cell Switching Unit (6-70 
400 Watt Triac Light 
Dimmer Speed Control £4-80 
1,300 Watt Triac Light 
Dimmer Speed Control £6-70 
2,200 Watt Triac Ugbt 
Dimmer Speed Control £8 90 
Psychedelic Light Control, 
Single Channel £7-80 

Psvehedellc Light Control, 
3 channel £14 55 

Medium Wave Translator 
Radio £3 33 

F.M. Transistor Transmitter 

£2-70 
F.M. Transistor Receiver £8-88 



HF310 F.M. Timer Unit £15-81 

HF325 De Luie F.M. Tuner Unit £24-18 
HF330 Stereo Decoder for use 

with HF310 or HF32B £9 98 
HF395 Aerial Amplifier for AM/FM 

Bands I, II (Mid III £1-77 

OP310 Stereo Pre-Amp to use 

with 2, AF310 £81-87 

O-U330 Tremolo Unit for guitars, 

etc. £7-60 

NTIO Power Supp! T 100 m/a 

9 V Stab., 12 V UnsUb. £816 
NT 300 Professional stab 11 lied Power 

Supply 2 x 30 Volt, 2-2 amp 

£18 61 
NT305 Transistor Converter 1 2/ 1 6 V, 

AC/DC to 8 V, 7-5 V.. or 

9 V DC £4-50 

NTS 10 Power Supply 240 V AC to 

2 it 18 V DC at 2 amps £480 
NT315 Power Supply 240 V AC to 

4-5—16 V DC BOO m/a £9-67 



Pont and Packing 15 p per kit. 
Complete with comprehensive, easy to follow 
instructions anil covered by full guarantee. 



SEND SAE FOR NEW 8 

PAGE LIST OF SEMI 
CONDUCTORS & VALVES 



ALL PRICES ARE 
SUBJECT TO 10% VAT 




369 



UNR 30 RECEIVER 



IE5^ 
4 Vmtmtmanvtkm >'^u l( v.i)i 
B.F.Q. Built-in Speaker aao/'i 
A.C. Brand new with Instruct 



4 ll»J,.|- L-Utt-rltlg .I.JIJ n, 

U.F.O. Built-in Speaker aaO/24U 
A.C. Brnnd new with instructions. 

° ur £15-75 Carr 



Price 



37p 



UR-IA RECEIVER 





-J Hand* coining <VjU kY/»-Stl iih,-- 
FKT, 8 Meter. Variable 13 KO fur 
HSB. Built- In Speaker. Baud- 
spread. Sensitivity Control. 2a0/ 
■-•40 v. A. (J. or la v. n.C. la) lb. x 
4J,ln.x7Jn. Brand [lew with 
Instructions. 

Our 

Price 



£25-00 % 



EMI LOUDSPEAKERS 

Model 3&0, IS" x 
>*lth single tweeter/ 
rnmamrr. aO-ao,000 
112. IB vail liMS 
tvaltoblr M or j; 
ohms, 1726 each 
P. 4 P. 37p. 
Model 4fl0, I 8" x S* 
with twin tweeter/ 
.•rnssover. 63-13.000 
IlK. H watt KMH. 
Available N mt IB 
ohms. £3 02 "Hih. 
* I'. an-,. 



SPECIAL OFFER ! 
STEREO 
SPEAKERS 

V air fin I pair 
.,1 stereo tiook- 
-h*df speakers. 
Deluxe teak 
icneered finish. 
."ii*c I4J* x S>" 

■ 7J". H ohms. 
-t watt BMP. 
lift.' with BIS 



SKYWOOD CX203 
RECEIVER 



Our /I7.0C Ca 

Price ■»■*■ *J 5< 




Hnlid flail-, J I.. 1 1 1. 1 volelllljj ailtl- 

420 KHs ami DO to ;<0 MHz. 
Illuminated slfde rule dial. Jlaixl- 
spreod. Aerial tuning. UFO. AVC, 
1NL, "S" meter, AM/CW/HB fl. 
integrated speaker ami phone 
socket. 2a0/a40 v. A.C. nr V> v. 
n.C, Size 3aB x aOfl x ISO nun, 
Complete with luslrucUoii'. ami 
I'ircult. 

Our 

Price 



~y. z 



HEADPHONE 

AMPLIFIER 
MI silicon 

I rilllHlHtri] 

.■milliner op- 
■■rat i'm from 
inatfnetlc, 
eeran lie ni 
Inner input- Willi 'win sterei 
headphone output* ami separate 
volume controls Inr eaeh channel. 
Operates (iron Mv batlerv. Input* 
oMI'/IOOMr. Output B0MW 



Our 

Price 



£5-97 



£32-50 c 5 "ft 



& P. 

15p 



LAFAYETTE HA-600 
RECEIVER 



1021 STEREO LISTENING 

STATION 




i.eueial coinage IJU-4UU nc,., .ijll 
kc/.-30 ine/s, KF,T trout emt, a 
mech. filter*, proiluri detector, 
rarlable B.F.O., tiol* I In liter, 
n Meter Handsprtnd. \iV tiaiu. 
loin, x Utln. x HJ In. I ft lb. 
■WO/340 v. A.C. nr 12 v. D.C. 
Brantl new with Instruction*. 



Pric 



e £50-00 






50p 
TRIO 9R59DS RECEIVER 




fa.ilitv (m "trrri 
switching, a gain controK speaker 
on -off slide h witch, stereo head 
plmne -ockets, fl" k 4* * 2(" 



Our 
Price 



£2-25 



p. &p. 

15p 




4 l.«ol- uoinnit iiO ke/* l.> an 
uic/s continuous ami electrical 
haudspread on 10, IB, an, 4<> anil 
80 metres. 8 valve plus 7 illinlc 
rlrrult. 4/H nhrri unlpnt ami jilmne 
tatik. ssilH.'ff, ANL, Vurlable 
ItFO. 8 meter. Hep. Iiamlf|irtrail 
lital. 1 K freitm-iiey 44. r i k«7 s > auilio 
millinl 1 Sw. Variable It K ncl AF 
lain rniitroln I Io/lT.o v. A.C. 
Hlie: 71n. x I Mln. x llllu, with 
Inatnietbin manual. 

Our /dQ.rn Carr. 
Price t*ty*DU p aid . 

rrrit banoe of trio stocked 



MP7 MIXER PREAMPLIFIER 

a micro- 
plinnelnputH 
^^^^TTir« tt J "*aeb with 
(pftitSe^SJ individual 
Kaln enn- 
tnil* enabl- 
ing uiimplvti- misiiiD facllitieij. 
Hattery operated. !1J" x 6" X 3". 
Inputs Mlus: 3x3mV 60K : ax 
3niV B00 nhlu. Phoiin me|t. 4m V 
BO K, Phono ceramic lOlliuV I meg. 
Output a&OniV I'iiiK. 



Our 

Price 



£8-97 



p. i p. 

20p 



RANGE OF. 




HAND HELD 2- WAT WALK IE 
TALKIES 

Imlu-trlal tpuillly In min.-r metal 
caneM. Battery operation, Volmoe 
and Aquelch nmlmi*. Call button 
and ore** to talk iiultim. Tele- 
scopic aerial. Complete carrying 
mnmi 

lOOinW iSUBi pair. Packliift & 
Post B0p. 

a channel /CT CrY Pair. 
3O0iiiW W43U Pout 3llp. 
3 channel /7 1 ">F Pair. 
1 watt fc * * •*• po»t OOp, 

Licenct requlrtl lor opeiatlon En 
O.K. 



AHP-8D 8 Track 

high quality Tape Deck 

EQUIPMENT 

AudToiramc Producli are manufactured eicluiirelr lor the Audioitonic 
Group of Compialei and at a member ot the croup we are pleased ;o 
offer you thli labulom range ol high quality equipment. Made to our own 
ipeciScatlam each item provide! outstanding performance and reliability 
at a ralue lor money price! 



ACR.I4 Battery Mains 
Cassette Recorder 

Portable twin 

track mono 

recorder wltl 

automatic 

reconting In 

control. ISui! 

In speaker. 

Earpiece 

socket, I up ip 

for rad lo or 

recorii plsyn 

Fa^t forward 

and rewind. 

Output BOOluW. AC aab/aillv or 

fiv I)C operatlnu. Complete with 

remote control microphone, mains 

lead, earpiece and batteriCH. 




AC D. 660 Stereo Cassette 
Deck 




I I •.!■ " I 

with uiott III tl 

ampllnerM, 

i'ush button 

track eclcctoi 

and Itluiuiua- 

ted track 

indicators. Attractive tabioel 

black and silver trim. Output 

TflOiuv. ac aao/a40v. 




£11-95 



2SJL £10-50 p 



i P. 50p. 



AR.1000 Sportsman 
AM'FM Portable Radio 

5 wavebaml- 
coverintc 
aMb;m 
10B5KH?.. 

km a«- 

lOHMHi. 

AIR IBS 

135MHz. 

PB 147 

174MHz. 

WB lHi. 

5MHj, 

Large bnrl- 

znntal tillde ■ li.>i with logging 

ecaie. Slider volume ami squelch 

controh. 7 aection tefewoplc 

aerial for FM and built In ferrlte 

bar lor AM, «VFC. 3ln. speaker. 

Earpiece Kickei, Creen leatherette 

covered cabinet with metal side 

panels. Size lfla x 79 x Tlflllllll 

Battery/inainM operation. 

m* £ii-5o '■*-'•*■ 




p 

V L .;.'!• 'Oil 
*tykd 4 tnwk ■!,■.- 
deck with an init-stamiuiu sOml- 
Heat Ion offered ai a remarkah y 
Itiw price. Incorporates a host of 
featm-cM including switchable nniiie 
hiter tiiiriual/chroiiie tape selector, 
twin VU meter, ttllder rcctird/ 
playback level controls,, front panel 
headphone socket, recording indi- 
cator lamp, phono/ Din line input 
sockets, 3.5mm HtnK input sockets 
etc. etc, Frei|ueiicv response 
100-SKHz (100-laKH2 Croa) 
B/N-43d B. CwnwtaH 4odB, Separa- 
tlou-35dB. Nui-e litnil.--r-K.lH ti 
lOKHx. CompleSr with phono 
connecting lewlf- 

Our /IO Kt\ <'arr. .1 J 

p r j ce tJ7.JU lns.BOp. 



AHP-8A 8 Track Stereo 

Tape Player 




lueiii-poiau'.- built in ainpUflesa 
giving 4} 4- 4£ watts rmw output. 
Push button track selector, 
illuminated track indicators, slider 
control* for volume, balance and 
tone. Attract ive cabinet with 
black and sliver trim. Output 
impedance 8 ohms. AC aao/S40v. 

our tn.Jt; *■* P-50P- 



AMR-9000 Global 
AMFM Portable Radio 

10 waveband- 
covering 
AM: B3B- 
I BOB kHz. 
LW: 1S0- 
3H0 kHi. 
MB 1B- 
4-00 MHz. 
SW'l : 40- 
K MHi, 
«Wa: 80- 
Ml MHz, 
aW3: 10- 
a4 MHk. PB1J1: 3'1-SO MH^c. 
PBtta: 148-174 MHk, FM SS- 
108 MIU. AIB: lOfi-138 MHi. 
Features time zone map and 
timing dial. Large clear scale. 
Telescopic aerial and built in 
aerial. AFC or FM. rt" x 4" 
speaker and personal earpiece. 
Battery/mains operation. Size: 
34S x 133 x HBfiiiim. 

£& £36.00 '-*. 1 "-** 



I AUDI0TR0NIC DOLBY 'B' 
NOISE REDUCTION UNITS 

1 Reduce tape hiss Iit 3dB at OOOKz 
OdU at laOOHz and lObB lor ali 
frequencies above 3000Hz. 
Size IB J" x 8" x 31". AC aoO/aitlk 

PBOCBSS TWO 

For use with cassette and tap*- 
recorilern. Freii. res. aOHz-aflKHa 
± a,IB, Off tape moni luring. 
Switchable multlplei Alter, Two 
Dolby calibration meters- S/Is" 
better than 70dU. 
Supplied with leal ca^Mettc or tape 
an retjulreil. 

SSL £34-50 p ^s 





Price 



PEOCESS FOUR 

For use with Mnl-pTalaoiuiuu lape 
recorders. Freq. res. 30Hz--20KHi 
± ad 8. S/N better than TOdB. 
Full source tape monitoring*. 
Record/ Replay metering. Switch- 
able multiplex tiller. Supplied with 
test tape. 

Our 

Price 



£50-00 



PAP 

50p 




LOW NOISE TAPE CASSETTES 



S 10 25 

£139 (2 63 £5 99 

C189 £382 £859 

£229 £4 48 £10 83 

IBp. bml fri-e 



Cassette 
Tape He id 
t/leaner 30p 



Stereo Headphones 



LSH.20 Imilvidmil 
volume controlH 
Stereo ntonn 
switch. 8 ohtns, 40 
111,000 Hz. 
■*3-50 P • P 30p 



LSH.30 Open Imrk 
KypOa Individual 
tone and volume 
control", u ohms. 
30-ao,00fl Ht, 
£6 50 V £ P 30p 



LSH.40 Two way 
speaker system. 
Individual volume 
controls. 8 olnun, 

ao-ao.ooo Hz. 

£fl 85 P X f fill), 



ACP-8 8TRACK 

CAR PLAYER 



Atiraetne black and siht-r linisli. 
lav neg. earth. Slider controls for 
Volume, Time and Balance. 
Channel selector button with red 
pilot lamp. Complete with 
Kpe»k«r», jiiounllns brackets and 
Instruct ions. 

ONLY £12-50" 




flCR 3500 

CAR RADIO 



Ma 



,t Me 



... ! 




Liing waves, lav pos, or neg, 

earth. Complete with speaker, 

mounting brackets and io^truc- 
tlons. 

our xA.cn p 4 p 

Price to 3U 50p 




ACR1 PUSH BUnON 

CAR RADIO 



ACA 5SE ELECTRIC 
CAR AERIAL 




Push but lot 1 1 in i n lit ill one LW 
and nve MW stations of your 
choice. VJv pi -m, or licit, earth. 
Complete with speaker. innutitbi« 
bracket- and Instructions. 

Our /O.OC p A p 
Price to * 3 50p , 



■'j section, Fully 
iiutoictatic. lav X>C. 
I'lxteods to approx. 
40". Complete with 
switch, all leads and 
Instructions. 

Our Price 

£5-95 

P & P sop 



370 



IH'MllltilJ.HWg IM .HIlM l ^f 




CMriane and Packing 75)). 

Complete units wltli Stereo cart- 
ridge ready wired in plinth eovtr, 
GARRARD 

2023 TC79TAHCD . , £10-65 

SF25 111/G800 .. ,, 115 95 

SP25 1U,'M44E .. . . £16 45 

SP25 J 1 L/M44-7 , . £1810 

SF'25 111/M35E . . ,. £18 90 

SP25 It] Modnle/'M75-o £1899 

APTWno .. , . £2S-6S 

APTB/fJBnOE . . £2685 

AP7B/M44E . . £24-85 

AP7fi/M551i ., ,. £85<6S 

AP76/M75ED ., (8170 

AP7ii/V75EJ .. £2785 

AP7H Module M75-6 . . £26-95 

APW1 Moilule M75-fi ., £30 40 
ZERO 1008 Module piIOS E £41-85 

b.s.r- Mcdonald 

S10/8C7M . . £8 85 

MP60/C.800 .. £16-50 

MP60fTPDl/RS00 . . £15-20 

UPBO/M44-7 .. ., flO -80 

HT70/TFD1/G800 . . £18 BO 

GOLDRIKG 

«L7'J/(iM0 .. £30-90 

OL7S/<lHf)0 . , £33 80 

OL75/CJ800E . , . . £8675 

GOODMANS 

TDlOOfOSOO Teak . . £46-86 

TD100/G800 White .. £4800 

LEAK 

Delta/M73-fi .. . . £43.98 

PHILIPS 

riAlOS/GP-JOQ . . . . £13 80 

CiAiHO/np-JOO Teak . . £18 50 

r.A212/r,P400 .. ,. £45-25 

OA908 (ten cartridge) . . £83 ■ 95 

OA308 P.O £3275 

PIOITEES 

PL12D (Less cartriilgfO £29 60 

PtlSC (Less cartridge) £4125 

PL41D (Less cartridge] £85-25 

PL50 (Lena cartrirlgoj £89-80 

PLfil (Leas cartridge! , £102-75 

PLA35 (Leas cartridge) . . £68-60 

TEORENS 

TDIIJOC/Ortiion. 3T15ES £8896 

TD125 AB/tl/Ortolon 

M15E Super . . . . £104 25 

TD163/Ortofon M15E 

Super £5860 

WHARFEDALE 

l,int,.n;M44-7Teati £23-70 

[.iiil>>ti/M44-7 WWte £23 90 






*2 X Z30 Stereo till/i'/25 £1586 

P. & P. 37p, 
2 x Z30/Stereo 60/PZfi £18 00. 

P. k P. 37p. 

2 X ZSO/Stereo (50/PZ8 £20 25. 

P. & P. 31 p. 

Transformer lor P28 £3 65, 

Active Filter Unit S4-45- 

Pair of Q16 Speakers £1070 

Project 60 FM Tuner £14-85 

Sinclair Project 605 £20-97. 
P. & P. 37p. 

All other Sinclair Products In stock 

2000 Amplifier £2296 

3000 Amplifier £28-95 

2000/3000 Tuner £26 30 

QS30 Speakers £28-98 pair 

P, & P. 50p each of above Items 



Carriage and Packing 50p 
B.S.B. McBONALD 
C114 Mini 
€129 Mono 

610/TPDl" '.'. '.". 

610 

6I0/TPTJ1 

710 

810 

MPS0 

MP60/G800 

MP80/TPD1 

MP80/TPD2 

HT70 

HT7O/G8G0 

JIT70/TPD1 

CONNOISSEUR 

BD1 Kit 

RD1 Chaasls 

BDl/SAU2/FUnth/Co«r 

£D2/SAi;2/aia88i8 

Mlt! 9AL-2/P) loth/Cover 

GARRARD 

2025 T/C Stereo 

SP25 III .. 

SP35 III Acoa OP104C 

SP2511 1*9800 ,. 

SP25/M75^3 

AP76 

SL65B 

SL72B 

SLS5B 
I 401 
1 ZERO 100A 

ZERO 100S 

GOLDRIHO 

(599 
! O101P/C 

Gxssfa 

GL7-2 
1 GL72/P 

CL73 
1 GL75P 

(SL7SP/C 
GL85P/C 




STEREO 
1025T 




4 speed auloe hanger unit fitted 
with stereo ceramic cartridge. 

Our /4.0C Care 
Price **~ *■* 50p 



SP251H 

WITH ACO 
GP104 




SP25 IfJCJE, 4 speed single record 
player fitted with Acos OP104 
stereo ceramic cartirdge. 

° ur £8*50 Carr 



Price 

Audiotronic AMB 500 
Multiband Radio 



50p 




price £6 * 95 



5 wavebands 
covering 
JTff S35- 
11105 KHz and 
FM 88- 
175MHz. All 
transistor. 
Battery or 
mains opera- 
tion. Built In 
aerial and 8 
section teles- 
copic aerial. 
Complete with 
batteries, 
shouldee strap 
and earpiece. 




£3 95 

£5 50 

£700 
£13 95 

£9 90 
£1485 
£1820 
£24 50 

£7-85 
£10-25 
£1260 
£11-25 
£10-87 
£13 60 
£15-85 

£8 85 
£10-75 
£26 15 
£2270 
£28-20 

£8 40 
£8 50 
£850 
£1095 
£13-90 
£1540 
£1115 
£17-76 
£25 25 
£2350 
£30 30 
£27 85 

£18-85 
£18 85 
£1575 
£17-85 
£2320 
£23-75 
£2930 
£4655 
£4950 



CASSETTE RECORDER with a 
pair of OSS8 Speakers. List £OH10. 

PRICE £56 " 50 [• i p Mp 

CASSETTE (P. & P. 50p) 

CS35D Deck . . . . £44 45 

C335/CS88 Speakers .. £67-85 

GXC40JJ Deck .. .. £57 20 

GXC40 Recorder . . £67 SO 

I GXC40T Deck/ Receiver £8905 

1 GXC45 Deck . . , . £78-25 

: GXC46D Dolby Deck . . £83-55 

GXC48 Recorder . . £89-95 

, GXCSOD Deck . . . . £87-65 

| GXC63D Dolby Deck . . £82 65 

CARTRIDGE (F, * P. 60p) ' 
! CB81 Deck with amps. £65-40 

CR8ID Deck . . . . £53-80 

1 CR81T Recordcr/'Receiver £9875 

CR808S 4 channel Recdr. £114-25 

CRS0D33 4 channel Recdr. £93 65 

TAPE (P. & P. 75p> 
4000DS Deck 
4000 DS Dust Cover 
1721L Recorder 
-X5000 Recorder 
; X201D Deck 
GX220D Deck 
GX221D , . 
r,X'2*0D Deck .. 
GX370 Deck 

TAPE/CASSETTE (P. & P. 75p) 
GX1900D Deck . . . . £144 50 

MICROPHONES (P. A P. SOp) 
ADM. 11 Dynamic (pair) £7-50 

STEREO RECEIVERS (P. & P. 75p) 
AAS300 20-20 watt .. £61-95 
A A8030 25 + 25 watt .. £92-50 
AAS080 40 + 40 watt .. £117 50 
AA8100S 2 x 36 or 4 x 18 w. £175 00 
AA850O 83-65 watt .. £150-60 

STEREO AMPLIFIERS 

(P. i P. 30p) 

AA5200 20 + 20 watt . . £6175 

A A Bo 00 30 f 30 watt . . £78-50 

AA580O 45 + 45 watt .. £117-60 

STEEEO TUNERS (P. & P. 50p) 
AT550 AM/FM . . . . £60-50 

AT580 AM/FM . . . . £94 50 

4-CHAiriTBL UHIT (P. * P. fiOpl 
SSI Synthesiser . . £39-85 

SPEAKERS 
SWISS (each) 



HOMER INTERCOMS 

■Ifri^TJ ^^^_ Ideal for 

f^C -^^^F stores, 

^&^ ^^"Af factories, 

^^ V etc. com* 

PIl-ti; nith Latteries, cable and 

instructions. 

2 Station £2-87. P. £ P. ISp. 

3 Station £5 25, P. * P. 15p. 

4 Station £8-62, P. & P. 17p. 



SH633 STEREO HEADPHONES 

Outstanding 
value. Soft 
ear-pads, 

adjustable 
headband . 
8-16 ohms. 
20-20,000 
Hz. Corn- 
it h lead and stereo plug. 




pk-ie 

Our 

Price 



£1-87 





Our 
Price 



£2-25 



£5100 

STEREO HEADPHONES 

ASB11 £4-75 

ASE20 £7-30 

ASE22 £8- 25 




..hr- 



£4-95 



p. &. p, 

30p 




FM TUNER CHASSIS 

'1 THAN'. 
SISTUH 
BIOS 
Ql'AL- 
I T Y 
TCSKR. 
SIZE 

o s l y 

■ a 4 * Jfjin. S I.F. stagea 
i>ouble tuned dLscriminator, Ample 
output to feed most amplifiers. 
Operates on SV batterv. Coveragt 
88-)08Mc/s. Ready built ready for 
use. Fantastic value for money. 

Our /c.ot: P. & P. 
Price fcJ ' J 12p 



1 3 r i i-. i . - 



i-lqrf 



£4 97 



HiHilHlilllitiliHM l 



fERGUJON EXPORT MODELS 



P. & P. 

30p 



LH02S STEREO HEADPHONES 




FERGUSON 3408 STEREO 
TUNER AMPLIFIER 
Covers FM 88-108 MHz. Five push 
button tuning scales. 8 + 8 watts 
ran. Inputs tor stereo ceramic 
cartridge and tape etc. Separate 
bass treble, balance and volume 
controls. 

£3l50 Pi M p 



TEI0IS DE-LUXE MONO HIGH 
IMPEDANCE HEADSET 

Sensitive ! 
i si a g n e r i c 
headset with I 
soft earpads. I 
Impedance J 
2.600 oli hm 
<d.e. 600 
ohm?). Fre- 
quency response 200-4,000 Hi, 




3418 STEREO TAPE DECK 
■1 track. 74, 3J, i.1 i.p.s. Stereo/ 
mono record/play, 7" reels. Inpats 
for dynamic inttes. radio, grain. 
Complete fvllo cover. 

Our 
Price 



£4l-95 Pi re '; 



P. & P. 

30p 



BH 001 HEAD SET AND BOOM 
MICROPHONE 

Moving Coil* Ideal 
for " language 
leaching coin- 

'Hunications., 
Ilearlpbone imp. 
16 L-hrris. Micro- 
phone Imp. 300 



VAT 

AM pricss art subject to 

IOWATm 



10% VAT (IOp in the C) to 

total value of goods 

including carriage' packing 

end send cash with order, 

PLEASE PRINT NAME & 

ADDRESS CLEARLY. 



SEND LARGE S.A.E. FOR FULL HI-FI DISCOUNT LIST 



GWSMITHBCO radio 1TD 

AIL MAIL ORDERS TO 
UNIT 4, THE HYDE INDUSTRIAL ESTATE, THE HYDE, LONDON NWS 6JJ 
TELEPHONE 01-205 3735 
PERSONAL CALLERS WELCOME AT ANY OF OUR RETAIL BRANCHES 



:Rri\W.1. Tel:01-5BOOB70 



m Court Hd. W.I. 
n Court Rd.W.l. 
m Court Hd.W.I. 
>ton Street. W.I. 
I.W.C.2. 
«t. W C 2 
iRoed.W.2. 
>Roia.W.2. 



Tel 101-637 2232 
Tel- 01 -636 3715 
Tel: 01 -680 3739 
Tel : Ot -437 9369 
Tel: 01-4378204 
Tel: 01 -437 91 55 
Tel: 01 -7239789 
Tel: 01 -7236211 



311. Edguvere Road. W.2. 

382. Edgware Road. W. 2. 

152 3, Fleet Street, E.C, 4. 

378. Harrow Road. W.9. 

ESSEX 

86. South Street, Romford 1 

SURREY 

1046. Whitgifi Centre. Croydon. 

27 & 21. Ed an Street, Kingfton. 

32. Hill Street. Richmond, 



Tel: 01 -262 0387 
Tel .01 -723 41 94 
Tel .01 -353 2833 
Tel: 01 -286 9530 



Tel;01-6S13027 

Tel: 01-546 784 5 
Tel: 01-948 1441 



ALL BRANCHES OPEN 9 a.m. -6 p.m. MONDAY TO SATURDAY 



FAF351 



CHEDIT TERMS FDR 
CALLERS (£50 and over) 



ALL EQUIPMENT IS 
BRAND NEW, FULLY 
GUARANTEED AND 
OFFERED WITH FULL 
AFTER SALES SERVICE 



All items and prices 
are correct at 

but subject to 
change without 
notice E 6 E. 



A 



371 



parts for 
PRACTICAL 
WIRELESS 
projects 

After many requests, Electro Spares are now supplying lists of 
components for ALL the projects featured in "Practical Wire- 
less", commencing this month. Just forward an S.A.E. {Pre- 
ferably 9" x 4" minimum) stating which project Is of interest to 
you— we will forward an individually priced list of components 
required. No need to buy a full kit— you need only purchase the 
parts you require at any one time. 

All Electro Spares supplied components are new, branded products 
of reputable manufacturers and carry full makers guarantee. 
We regret we cannot supply lists for projects published before 
this issue. 

"ONE SOURCE" BUYING MAKES SENSE-IT CAN SAVE 
YOU TIME, MONEY AND POSTAGE. 



"p.e." f.m. varicap stereo tuner 

Electro Spares offer a kit of high quality parts to the published 
specification for this remarkable tuner, featured In "Practical 
Electronics" May 1973. 

Features Include push button "Spot On" tuning, with up to 
5 pre-set stations (no difficult tuning dial and drive cord). Easy 
"no problem" construction, requiring only a few simple setting 
up adjustments with a D.C. Voltmeter. Uses NEW pre-set 
modules for R.F. and i.F. Circuits— no circuit alignment. High 
efficiency Integrated Circuit Phase Lock Loop Decoder for 
ported stereo reception, with stereo lamp indicator. Fibre Glass 
P.C. Board, neat slimline cabinet with brushed aluminium front 
panel, push buttons etc. etc. 

IDEAL FOR USE WITH THE "TEXAN," "GEMINI" AND 
ANY GOOD QUALITY STEREO AMPLIFIER 
Please send large S,A,E. for full details. 



"p.e. gemini" stereo amplifier 

QUALITY HI-FI FOR THE HOME CONSTRUCTOR 

30 Watts per channel into 8 ohms! Total Harmonic Distortion 
0'02%l Frequency Response (-3 dB) 20Hz— 100kHz! 
We are still continuing to supply components for this fabulous 
Amplifier, which is now recognised as practically the ultimate 
In High Fidelity. We know of no better unit for the Home Con- 
structor—we can supply a Booklet containing full specification, 
complete constructional Information wiring diagrams, fault 
finding guide, etc. etc. Price 55p, plus 4p postage. 
Our New Low Price List is supplied with each booklet, or 
supplied separately on receipt of a large S.A.E. 
FOR PEOPLE WHO REQUIRE THE BEST, IT HAS TO 

be the «p <e> gemini". 



Note Our New Address— With New Mail Order Department 
For Quick, Efficient Service. 

PLEASE PAY US A CALL— VISITORS WELCOME. 
HO PARKING PROBLEMS 



Electro-Spares 



288, ECCLESALL ROAD, 
SHEFFIELD, Sit 8PE 

'THE COMPONENT CENTRE OF THE NORTH" 




D.I.Y. 

ELECTRONIC 

0R8AN 

KITS 

In use throughout 
the world by 
professionals 



■^Portable — 4 octave keyboard with 10 voices, 3 pitches — 
vibrato, £145-29. * Console— 5 octave keyboard with 
10 voices, 3 pitches. Keyboard can be split into solo and 
accompaniment. Vibrato, built in amplifier and speaker 
£2S0-93. ^Console — 2 x 4 octave keyboards and 13 note 
pedal board, 29 voices. Vibrato, Delay Vibrato, Sustain, 
Reverberation, Percussion, Wah Wart, £406 ■00. ^Console 

2x5 octave keyboards and 32 note pedal board, 32 voices. 

Vibrato, Delay Vibrato, Systain, Reverberation, Percussion, 
3 Couplers, etc., at £572 55. 
V.A.T. please add 10% — show separately on order. 
ALL COMPONENTS CAN BE BOUGHT SEPARATELY. 
SEND 50p FOP. LATEST CATALOGUE WHICH IN- 
CLUDES SPECIALIZED COMPONENTS, HI-FI EQUIP- 
MENT, ELECTRICAL HOUSEHOLD APPLIANCES AND 
MUSICAL INSTRUMENTS. 

ELVINS ELECTRONIC 
MUSICAL INSTRUMENTS 

YOU ARE WELCOME TO VISIT THE ONLY D.I.Y. 
ELECTRONIC ORGAN CENTRE IN EUROPE 
AT 12 BRETT RD„ HACKNEY E8, TEL. 984 8455 




CASED AMPLIFIERS 

Polished wooden cabinet 
14 x 13x8" with hinged 
lid containing a sensitive 
(2&xV) 4-valve amplifier 
wth tone and volume 
controls, giving about 3 
watts output to the 7x4" 
3Q speaker. Also a non- 
standard single motor 
tape deck. Easily con- 
verted to record player, guitar practice amp, baby alarm, 
etc. Supplied In good working condition with circuit diagram. 
Mains operated. Only £3 (£1 up to 200 miles, £1-20 over). 
Special cassettes £1 (25p), Spare heads 40p. Damaged 
machines from £1-50 to callers only, 

COMPUTER PANELS 

Type A: 4 OC35, 4 GET103, etc. SOp ; Type C: 2 OC35, 2 OC76, 
6 OC42 etc. 30 p ; Type D: 4 OC36, 8 GET103, etc. 60p. (5p ea). 
Parcel of 12 top quality boards £2 (25p), 71b of lower quality 
Including some broken £2 (40p), 581b £12 (c.p.). Boards from 
5p to callers. 

7lb BARGAIN PARCELS 

Hundreds of new components— capacitors, resistors, 
switches, crystals, pots, PC boards, etc. Outstanding value 
£.1 -65 (35p). 

500 assorted resistors, good selection £1 (15p); 40 asstd pots 
£1 (25p); 300 asstd capacitors, all types £1 (25p). Heavy duty 
heat sinks 6x5x3". Wf. 3lbs with 2 power transistors, 
OC36 or 2N1146A £1 (25p). Large selection of panel meters 
for callers. Audio oscillator 50Hz-20kHz, BFO No. 8 £10; 
RF Signal generator Marconi TF144G 85kHz-25MHz from £12. 
741CT099 28p; BC107-9 14 for £1 ; 2N3055 35p. Veroboard In 
Stock. Post in brackets, small parts 3p. VAT NOT INCLUDED. 
SAE List, details. 

GREENWELD ELECTRONICS (PW3) 

24 Goodhart Way, West Wickham, Kent. SHOP AT 
21 Deptford Broadway, SE8 (Next to old cinema). Callers 
most welcome. Tel: 01-692 2009. 



372 






MANUFACTURERS OF E LEO RON I C AND 

AMPLIFICATION EQUIPMENT 

SPECIALISTS IN QUALITY TRANSISTOR 

EQUIPMENT 

OPEN 6 DAYS A WEEK. 9.00 a.m. - 6.00 p.m. 



TUAC 




TRANSISTOR UNIVERSAL 

AMPLIFICATION COMPANY LTD. 

163 MITCHAM ROAD, LONDON SWI7 9PG 

01-672 3137/9080 



PRE-AMPLIFER £421 



POWER AMPLIFIER £1518 



POWER SUPPLY £9-10 




All Tuae audio module! ira constructed on glass 
fibre P.C. board, ere ready assembled and fully 
tea ted. Low nolle silicon and FET t ran lit tore 
together with H.S. carbon film resiitort ire uied 
throughout. Extensive research hai gone into tho 
varioui wide range tone control circuit!, producing 
auperb aound quality from any signal. Previous 
range still available. 40V d.o; 30mV o/p. 
VA08 — Vol. Trek., Mid and But Contrail. HI 
M.22 IMP. FET l/P. Suitable Mic, Guitar, Radio, 

lllui. Cry« tat /Co ramie P.U. Seniitlvity 4m V. 

P.&P.20pTreb +35dB at 16kHz, Mid +20-l5dB 

at I kHz, Ban -j-20-IOdB at 40 Hi. 
VA06 — Vol, Treb and Ban Control!. 8mV senii- 
£JT2 tlvity. Treb +28-1 5dB at l2kHi, 

P. & P. 20p Biss ± lodB at 40 Hz. 
MVA0I — Vol, Tone. Vol, Tone Contrail. Ideal for 
£4-50 Disco. Suitable for Mic IIP. Seniitlvity 

P.AP.20p2mV. Tone range +25dB at 12kHz to 

+ 20dB at 40Hz. 
AMF01 — Auto Mic Over-ride for Diaco uie. Feed 
£4-40 Deck and Mie Pre-amps in. Auto fade 

P. & P. 20p O/P to main Amp, 30mV operating level. 

Depth and Vol Control!. 




^ *fJ^ ^^* 1^ 



100 W. "..M.S. 
aina. 200 W. 
R.M.S. square. 
(20.50 + P & p 
Trade & export 
enqulriaa wel- 
come. 

Coll for a 

demonstration 



PS 1 00 — 100 Watt Power Supply for one TPI00W 

£•■10 Module. Complete as illus. above. 

PS50 50 Watt Power Supply for one TP50W 

it So Module. Similar to illus. above. 



Poiuge and Packing 50p each. 

PSU2— 40V. 250mA. Pro-am p./DIaco Mixer 
£2.»S Supply, P. & P. 25p, 

TPIOOW with RCA output transistors— 1 50w device ZN62S4 

TPI0OW 100 Watts r.m.a. continuoui sine wave Into Bfi. 30mV Input into 3kD full power frequency 

£1 J 18 response IOHi-20kHx ± 2dB. Hum and nolle better than — 70dB. T.H.D. at 100 Watts 2%. 

P. It P. This rugged circuit Incorporates a special layer wound driver transformer to give Increased 

45p. reliability under all conditions. Short and open circuit proof. An external haatsink area la 

Illus. required. Just bolt on the module. 

TP50W 50 Watta r.m.a. continuoui sine wave into 8-150. With 115 Watt RCA 2N3055 output 

CIO 36 transistors. Specification aa TPIOOW. 



ACCESS ft BARCLAY CARDS ACCEPTED, JUST SEND US YOUR NUMBER. H.F. ARRANGED THROUGH PAYBONDS 



DISCOTHEQUE MIXER FEATURING 
AUTO-FADE 

" — *""""" ■ "" ■ rrTUAC- — ^—^— 

.#.„.«. # © *■••„,.* 

Panel mounting Cue out 17 x 3iins. 



£2200. P. A P. 50p. PSU £2 »5 
Designed for the discerning D.|. 
of professional standard, Auto 
Fade Is fitted aa standard. 
Controls: Mic Vol, Tone. Over- 
ride depth, Auto Manual Sw, 
Tape Vol, L & R Deck Fiden. 
Deck Volume. Trab. & Bass. 
H, Phon Vol, Selector, Master 
Vol, on/off aw. 



HIGH POWER AMPLIFI- 
CATION 

100 watt 
£60 50 
100 watt 
Slave 
£49 50 
50 watt 
£41 25 
P. & P. 
£100 



Suitable for Disco, 
P. A.. Guitar etc. 
Rugged circuit, rug- 
gadcasa. 



LIGHT MODULATORS 

Triac controlled. Safety isolating 
input transformer. 0-5 Watt 
sensitivity with controls. 



SILMB 

£17 45 
S1LMB 
£6 47 
P. & P. 

30p 



3 1000 Watt outputs' 
Bass. Mid & Treb. 
I I BOO Watt output. 
Operates on all fre- 
quencies, 



ALL TUAC KITS ARE SUPPLIED COMPLETE WITH EASY 
I?.,^ !!* WIRIN <» INSTRUCTIONS AND CIRCUIT 
DIAGRAM. ALL PRICES INCLUDE VAT. 



LARGE 



S.A.E. WITH ALL 

ENQUIRIES 

PLEASE. 



ALL TUAC MODULES ARE READY ASSEMBLED ON 
GLASS FIBRE P.C. BOARD AND INDIVIDUALLY TESTED 



SAVE TIME 
AND MONEY 

pfic* £6-87 1 ?& £5-32 




As supplied by ui to SCHOOLS. TECHNICAL 
OOLLXaU, SHOPS. OFFICII A3TD WDT7STBY. 
Oliver grey stove enamelled steel cabinet with 
4B treniparent ityrene drawera fitted with 
moulded handles and label slots. Dividers can be 
supplied at an extra charge to enable each drawer 
to be sub-divided Into six compartments, Trans- 
parent drawera allow swift selection ol com- 
ponents at a glance and eliminates duplication 
of. itoct, A really first class time saving unit. 
Bile of cabinets 21 t " x U i- x 6f *_ alle , 
drawers OK x 2|* x If. Other sizes available. 
Callers welcome Jfon.-8at. 9 a.m.-l p.m. 2 p.m.- 
fl p.m. SEW aa illustrated 0UH PRICE OsTLT 
£5-38 pins Sap carriage on orders lees than 410. 
Money back guarantee. HID FOB PEEK 

Lira. 

TRADE AIDS 

(0EPT. PWI3), III CHILTERN DRIVE, 
BERRYLANDS, SURBIT0N, SURREY 

01 -Iff 438] 
100 ydj. Bertilanit Railteay Stat (an. 



TRANSFORMERS 

DOUGLAS GUARANTEED 

Prices include 10% VAT A p. & p. 



Output V. & Amps 

'iMlmA x 
500mA x 
1A X 2 



13V x 
13V X 2 
12V N S 

lav x a 
12V x a 

12V x 2 
12 V 



3A x 2 
4A x 2 
5 A 



IB or Hi volt! 
Itef. No, 
MTlllCS't 
MT2I3CT*t 
MT71AT* 
MT18AT 
MT70AT 
MT10HAT 
MT72AT 



30 TOltl. All tapped at 0-12-13-20-30V. 
Output Output 

Amp*. Ret. So. Frit* Amps. Bef. So. 
OOOntA MT112CT* £1'*7 4A MT31AT 
1A MT79AT$ U'H 0A MTS1AT 

2A MT3AT 18 98 

3 A MT20AT £3 89 

SO TOltl. All tapped at 0. 10-35. 33-40-!j(>V. 
800mA MT102AT* fll'88 3A MT103AT 

1A MT103AT 1897 4A MT100AT 

2A MT104AT £393 0A MT107AT 

80 tolti. All tapped at 0-24-30-40-4«-flOV. 
SOOmA MT134AT* £8 03 2 A MT127AT 

1A MT128AT ££64 SA MTI25AT 

AUTO-WOUKD BARGE 



tilt 
£156 
1187 
£270 
13 34 
£3-74 
£4 30 



£4 08 
£8 73 



£4 09 
I960 

£911 

MIE 
16-78 



Power 
output 
20VA 
7SVA 
160VA 
2O0VA 



400V Output at SO HZ. Ret. IT3AT 
C-D Ignition System by R. M. Marstcn, Esq., 
Wireless World 

EQUIPMENT RANGE 
Sec. output (r.m.s.) 
3-0-3 V. 200mA 



Bef, Ni. Price 

XMT113CT £lEt 

XMT64AT £2 3B 

0-113-20Q.230-340 XMT4AT £8-88 

JtMT6flAT £334 

Price 

IE 98 

Ret, No. Price 

MT238CS*t £1-89 

MT13CS*t *1-M 

MT339CS*t £1-84 

MTB«ca-t «184 

MT214CT*± use 
MT307CT** £1-87 

MT20SAT*+ £8-85 

MT303AT* £317 

MT204.4T* U25 

MT221AT* 1I-&8 

AT indicates open universal flzlng with tags; CT l» open 
U-clamp fixing with tagii; C8 is open L T -clamp fixing with 
P.C. spills: * with interwlndlng screen: t untapped 240V 
Primary ;$ tapped at 2 10-240 V; other Primaries lapped 
at 200-320-240V. 
Over 200 types In stock through agents or direct. 
Please send for lists. 
DOUGLAS ELECTRONIC INDUSTRIES LTD., 
Direct Sales Dept. P.W., Thamei Street, LOUTH, Linci. 
Ufll 7AS 



0-0-9 




100mA 


12-0-12 




flOmA 


20-0-20 




30mA 


0-30 X 2 




300 x 


0-S-fl x 3 




500mA 


0-15-20 x 


2 


SOOmA 


0-13-27 x 


a 


500mA 


0-18-27 x 


2 


1A x -. 


90-12-0.12 


4M 


700mA 



4 STATION INTERCOM 




£7.99 



4-S(stion Tramiator Intercom system 11 mailer and 
3 9ubi>, in de-hstM plastic coblncts for desk or wall 
mounting. t^ill/Ulk/listen from Halter to Snbs and 
Sub! In Master. Ideally suitable tnr llusinrss, Riir- 
gtry, Schools, Hoepltal, Olllee and Home. Operates 
on one ov battery. Ou/nff switch. Volume control. 
Complete with 3 connecting wires each Stilt, and 
other accessories. F. & P. 44p 

MAINS INTERCOM NEW MODEL 

No b&tteriel — no wires. Just plug in the mains 
for Instant two-way, loud and clear communication. 
On o(T switch and volume control. Price £18-98 



INTERCOM BABY ALARM 



OUR 
(PRICE 
ONLY 
£3.99 

Same as 4-:SuJ""i I:>utl'l>!n fur two-way Instant 
communication. Ideal as Baby Alarm and Door 
Pbone. Complete with OHIt. connecting wire. 
Complete with RntW-rv. p. * p. 20p 





£3.48 

r Wby not boost 
business effi- 
ciency with [hi.. iutT,Jil.lt De-luse Telephone Amsll- 
fler. Take down long telephone messages or converse 
without holding the hand net. A useful olllee aid. On/ 
off switch. Volume Control. Complete with Battery. 
P. ft P. 24p. Full price retundiid It tint satisfied In 
7 days. 

WEST LOUDON DIRECT SUPPLIES IPW.B1 
188 KENSINGTON I1I0H STBEET, LONDON, W.8. 



373 



ESSENTIAL BOOKS FOR RADIO AMATEURS 



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These are just four of a complete range of technical P ubl 'catior>s. 
log books and maps for the Radio Amateur. Send s.a.e. for complete ll.st 

RADIO SOCIETY OF GREAT BRITAIN 



35 



DOUGHTY STREET. LONDON, WC1N 2AE TEL: 01-837 8688 




VALVES 



1A7UT 

IDG 

IMS 

IN5GT 

IRS 

Bm 

IS5 
IT4 

3A4 
3Q4 
SQ5 

334 
3V4 
5R4C1Y 

5TJ4G 

6V4G 

5Y3GT 

SZill 

6/30L2 

BAT 

GA8tl 

6AK5 

6AM.5 

0AM6 

6AQ5 

8A37Q 

6AT6 

6AU6 

6B4G £100 

C B8G 30 



BBA6 
GBKii 

■ ■•isnii 
6Bjo 

GBQ7A 

6BR7 

KERB 

GBS7 

flBWtl 

SUW7 

6C4 

8CQG 

lecfl 
eoniio 
BCHfl 
6CW-I 
6D6 
6E5 
6F1 
6F50 
6E6G 
8188 
6FM 
6F13 
6FI4 
6F23 
6F24 

epas 

6F3B 
(991! 

nlJB 

snB 

6J5M 
BJ0« 
liJBGT 



23 
S2 
76 
55 
55 
90 
70 
£135 



n.Iii 

(I.I7M 

fiJ7« 

AJ7GT 

GK6GT 

6K7M 

6K.7G 

BK7GT 



90 \ GK8M 



90 
35 
45 
40 

£130 
60 
70 
40 

£100 
78 
90 
45 
55 
SO 
50 
70 



BK8G 
BK8GT 

BK2S 
BL6Q 
CU8 
6Q7G 
SQ7GT 
6SA7M 
69C7M 
BSG7M 
liSFml 
6SJ7RT 
BSK70X 
SSL7GT 
i;.sn-<;t 
.. 8SQ70T 

60 1 >i ("Air'!' 

SOiBUSG 
£1 00 9V«M 
70 BV6H 
80 8VWT 
35 6X4 

60 1 BX5GT 

20i7BB 

4017B7 



45 
30 

4ft 
75 

■;:j 

35 
3;^ 
C^ 
45 
50 
75 
50 
5C 
40 
43 
4ft 
SO 
45 
45 
80 
40 
45 
45 
40 
70 
£100 
80 
30 
45 
40 
40 
45 



TC6 
'CO 
7D5 
7H7 
R7 
737 
7Y4 
7BW6 
10C2 
10F1 
10F3 
10F9 
10F18 
10LB11 
10P13 
1}E3 
VJAT8 
12AT7 
laATJB 
I2AU7 
1L>AX7 
12BAS 
l'JBEB 
1-2CRGT 
12E1 



£113 
75 
75 
70 
75 

£2 85 
75 



70 
83 
76 
SO 
65 
BO 
70 
75 

£480 
40 
40 
45 
33 
33 
45 
50 
35 

£3 00 



129 R7 
14 H7 

1SIAQ5 
20D1 

•20F2 
20L1 
■20 P4 
20P5 
2(5 A6 
2fiL6GT 
2BY5 
2:iZ4 

ar.25GT 

25ZB 

3001 

3UC 17 
3OCI8 
30K0 
3(1 Y LI 



All prie*B in pounds and new pence 



60 

50 
60 
50 
70 

£110 

£110 

£120 

36 



m 



42 

50BH 70 

00C5 80 

3OCD8G£l£0 

50L8GT 56 



501BAF91 
60 ' DAF96 60 
DCC90 £1-35 



75 

7S 
SO 

S5A2 
150 B a 
150C4 



50 

70 

30 

55 i 801 

65 807 



12J5GT 
12J7GT 
F2K7GT 
13K8GT 50 
VJQ7GT 45 
13SA70T 60 
12SG7 46 

T2SII7 45 
12SJ7 60 

123K750 



30 
£100 
£110 

90 
J100 

80 



313UBA£3-75 
8S8A Bfi 

934 30 

1636 TO 

402H AR £5-50 



30FL12 £120 
30FLI4 90 



30L15 

3(11-17 

30P4 

3HF12 

3OF10 

30PL1 



95 
96 

£112 

£100 

95 

B5 



30PL13 96 
3«PL14 81B5 
35 AS 

Si.l.ti 
3PW4 
3SZ3 
3524KT 
3S Z5 



5763 

7193 

747B 

Afil 

ATP4 

ATF5 

ATP7 

AU2 

AU5 

AZ1 

AZ31 

CBL31 £1-00 
50 OCH35 75 
40.CL33 £1'60 
75ICY30 



80 
40 
GG 
46 
60 
60 
7E 
£400 
75 
80 
55 



75!CY31 

50 ' DAcaa 



DF33 
DF70 
DF91 
DF92 
DF96 
DH77 
DK32 
DK91 
BKS2 
DK96 
DL66 
DL92 
DL93 
DL94 
DLM 
DL9B 
0M7O 
DY88 
DY87 
E88CC 
EA50 
EABC80 
EAF42 
EB91 
RBC33 
EBC41 
EBC90 
EBF80 
EBF83 
6BJEBF89 



SO'EBLSl £1- 

" _ EC90 
ECC81 
ECCS2 
ECC83 
EOC84 
ECC85 
ECC88 
ECH21 
ECH35 £1 
ECH42 
ECH81 
ECES3 



£1 25 : ECL80 
40 , ECL82 
40 FGL83 
48 ECLS6 



60 EBL1 
50 EBL21 



50 
55 

SO 
35 
S6 

70 
•■& 
3d 
60 

M 

60 
85 
40 
40 
40 
32 
£100 



ECLL80B 

M 

EF9 

EF37A £1 

EF39 

EF41 

EF50 

EF52 £1 

EF80 

EF85 

EF88 

EF89 

EF91 

EF92 

EFBS 

EF183 

EF184 

EL32 




«l-60 ' FLS00 

£1-50 1 PL504 80 

40 PLS08 80 

40 PL509 SI 30 

95 



HN309 81-50 'PCLflV 
KT38 81-20 FCB«3 
KTB1 81-76;FCL84 



45 PL802 

60!PX4 

60 \ PX'25 

50IPY33 

40 PYSl 

50 PY82 

60 PY33 

30 PY500 £1-00 

35 l PY800 47 

60 PY801 

SO ! R2 

50 R19 

50 SI 3d 

80[SP4 

75 3P41 

85 EF81 



80ITI403 70 

D404 70 

US01 £119 

UABC8Q 40 
._ TJAF42 
£3 00;UBC41 
£3 00 L'BCSl 
83 UUF80 
80lunF89 
85|UCC84 

UCC85 

!!(;!■■ SO 

tTCi!42 

UCR81 

TTCLS2 

UCL83 

Df4l 



50 
75 
50 

£1-75 



KT«B £8S5 
KT81 £1-73 
KT8K7C6) 

8113 
KT88 82-25 
KTW81 81-75 
KT241 60 

Mir* 88 



PCL85 
PCL8B 



60 I ET.33 81 75 



Ml.u 
M8P4 
MLTI4 
MX40 



PD500 81-80;tdD4 
PESA4 £10011' 10 
PEjrB4fl.-O0il.T14 
PEN4S 75IU19 



PES 46 

PL36 

Fl£l 

PL82 

FL83 



50 U23 
65 U'26 
60|U78 
46 U191 
45 l'251 



60 
H 

■15 
4(1 
40 
43 
45 
70 
70 
60 
35 
65 
65 
40 
fl5 
43 
35 
50 
50 
48 
fl-00 1 UYSfi 40 

60 1 VMF4G 85 
75 ; VF4B 81-25 
75-VR105/3O 38 
£3-50]VR130/30 35 
B5:VU111 76 
85 VL'120 £1-00 
85|VU503 £3-50 
75 W81M 63 
80 Y'i3 81-25 
63 ■JTfl'irw" -TO 



701UF89 

83-00 ■ UL41 

75 1T1.84 



35 STV280/30 I UMBO 

66 £12-00 irro 

45 8U25 81 00 UY21 
40 SU2150 75UIY41 
45 T41 



Transistors 



1N9U 

18113 

1S202 

3G3D2 

2G371 

2N404 

2JT697 

2K706 

2N1132 

2N1305 

2N2147 

2S2160 

2N2218 



07:2JT2219 
25 [ 2N2369A 
23S2N2444 81 
22 . 2JT2646 
22I2N2S04 
20 : 2N2936 
1SI2N30S5 
10I2N3702 

m 



IAC128 
ACY20 
ACY3S 
20 AD140 
16. A D.I 49 
■81 ADlfil 
46lAFllb 
20 I AF117 
10 ASY26 
75 BC107 
10 BC108 
«c BC109 
" EC169C 
iu BFSM 
20IBFYS0 
Z5 BFY51 



RY1O0 15 

BZY8S 15 

GRS1-40 47 

DD003 15 

I1ET102 30 

GET882 25 

GJ7M 37 

KS1O0A 20 

HTE520 87 
MJE2965 

81-37 

MJE3055 87 

NKT212 27 

NKT214 15 

NKT223 S3 

NKT251 24 



NKT7J3 
OA70 
OA71 
OA81 

OA85 

OA91 

OA211 

OAZ201 

OAZ207 

OAZ210 

OAZ223 

OAZ224 

OAZ241 

OAZ242 

OAStM 

OC35 



25 OC44 
10 OC4S 
10 OC&7 
08 OC58 
12 1 OC59 
07 OC71 
80iOC72 
50 OC81 
47 OC81D 
32 OC82 
46 OC82D 
45 iOCS* 

22 OC170 

23 OC171 
23iOC200 
60IOCF71 



Integrated 
Circuits 



7400 
7401 
7402 
7403 
7404 
7405 
7406 
7407 
7408 
7409 
7410 



2017411 



■413 
7413 
7416 
7417 
7420 
7422 
7433 
7426 
7427 
74i9 



7430 
7432 
433 
7437 
7433 
7440 
7441AS 
7442 
7450 
7461 
7463 
7454 
7460 
7470 
7472 
7473 



7474 
7475 
7476 
7480 
7482 
7483 
7484 
7488 
7490 



40 74100 
65 74107 
45 ! 74110 
E0 74111 
87 I 74118 
£100 1 74119 
90 1 74121 
45 74122 



75 



7491AN£10C 

7492 76 

7493 76 

7494 SO 
7495 

496 



£100 



7497 88 25 74156 



74123 
74141 
7414S 
74150 
74161 
74154 
74155 



£2-5U 
50 
80 
8145 
8100 
8190 
60 
8135 
82-70 
£100 
£1-50 
13 35 
£1-10 
82-00 
£1-55 
£1-55 



74157 
74170 
.'4174 
74176 
7417B 
74190 
74191 
74192 
74193 
74194 
74195 
74196 
74197 
74198 
74199 



£ 10 
84 10 

62-00 

11 35 

ii eo 

61-06 
1195 

83 00 
£UO0 
££■50 
61-85 
£1-50 
8150 

84 80 
84-Sq 



RST 



From 1st April 1973 all orders sub- 
moemee- KB All t\ W\ F\ P 1*1 AA TELEX Open to caller. Sam-Spm Hon Sat ieet „ V .A,T. « applicable rate. 
VALVE MAIL OKIJtK Vila »4£?08 Clo«d Saturday from lpm-3pm. This must b= added w your order 

16a WELLFIELD ROAD, LONDON SWI6 IBS ie!td iarsc sa.e. for )L' n ^hontth 24241 (4 smy) 

Exprc, postage I p per t«nmtor. over 10 P o» free. Interred Circuit, A V>lvai 5p. pl»» I p for e*=h «Witlon.l i«m. ver £5-00 poK fr-. 



374 



PRICES NOW INCLUDE VAT 



SUPERSOUND 13 HI-FI MONO 
AMPLIFIER 

A superb MH 
ststc audio 
amplifier, Jtrand 
new BTtniVumli 
thro upturn:, i 
a ii icon translstori 
plus 2 power out* 
put transistors hi 
pu.ih-pull. F'ull 
ware rectiilca- 
lion. Output 

apprOX. 13 valt.l 

r.iu.j, into a ohm. Vmptnteg response l'iili!-30KH* 
± 3db. Fully integrated pre-iiiiiplltler stage with separate 
Volume, Uaa» boost and Treble cut controls. Suitable lur 
8-15 oqiu speakers. Input [or ceramic or crystal i-artrhlfre, 
Bettirltivity apprus. 4<>mV few lull output. Supplied ready 
built and tested, with knob*, nscutcbaun panel. Inpul and 
onlpnt plugs. Overall atee 3" high v H" wide \ VI' ilnu, 
AC 2eO/2ROV. 
PRICE £11-80. I'. .V IV ■J.Vp. 




DE LUXE STEREO AMPLIFIER 

A.C. inning 
i'OO-240 v. 
U I I B | 

heavy duty 
f nil y tiola- 
led main., 
transform- 
er ilih full 
nave recti- 
fication 
g vlug *de- 
i| u > I i 
siutiolbittg with negligible Iium. 
Yalta line up:— 9 * KCI."iB Trlotle Pentodes. I X KiCBO 
at rectlller. T«u dual potentiometers are provided for 
baas md treble control, giving baas mid treble boost and 
cut. A dual volume control la used. llHlauee ol the left and 
right hand channel* van he adjusted by menus nl a tape- 
rata 'lluUnca' control lit to' I at the rear nt the chassis. 
Input sensitivity in uptiruxltnately aOOui/v fnr full peak 
output of 4 watts per channel (S watts munn). Into 3 ohm 
•peahen, Full negative ftuidbavk In u carefully calculated 
circuit, allows high volume level. In he used will. negligible 
distortion. Supplied romplele with knob*. cIikssI* alga 
ll"w x *"d. Overall height Including valval !,". Ready 
built £ tailed tu a hlich ilaiidur.l. PRICE U -90 I'. A P. 40 P, 




POWER SUFPLT UNIT MS/SMOv. A.t:. Inpul. K<mr 

switched fully •. .ji )!-?■ I ll.c. outputs giving liv. end 

7(v, ami dr. and I'.'v. it I amti .•..nflnu..u- (I lamp 
lufrniiltteiit). 

filled Insulated output I erm!ti«l> and pilot Inmp Indicator. 
Ham titer mdih metal case uiendlslseiJ" ■ :i|* ,: aj*. 
Suitable lor Translator Radius, Tape H reorders. Ampli- 
fiers etc. etc. Ready DDIfC /C.fW, m * ei „. 

iniiitun.ii.'.ti.,!. mite C3-UU p.&p.35p. 



BLACK ANODISED 18k, ALUMINIUM HEAT SINKS. 
Fnr T03, complete Willi tulua** Mini Im-ties. Six* 8H x 
3' appro*. ESp pair. I', a J\ Op. 

HIGH GRADE COPPER LAMINATE BOARDS W ■ >\" 
o for 5Sp P. and p. Hip. 

BRAND NEW MULTI-RAT10 MAINS TRANSFOR- 
MERS. Giving 13 nl lertiat lira. Primary: ^llu i4Ue. 
Secondary nmihliiatlona II a III 10 W "IS 30-lij 40 tlOr, 
half wave at 1 amp. or ID II 10. '.'» u '.'0. 30(1 3ut. at 
3 ainpa lull nave. Mlia ;iln. hiuu . Slut, nhle x tttt, de«p. 
I'rloa IE-ID I*. A P. 3(tp. 

MAINS TRANSFORMER. i'i>r trnii-Mur power eiippllei, 
1'rl VOOI'iiOv, Hue., 11 U lit MIUluA. £1.00. 1". A I' Kip 
l'rl. afio/'J40v. Weo, la t) I'Jnl I «inp. 11-10. I'. A I'. 13p. 
1'rl, 'iOO/E-SOv. 8«c. 10 10 ut 'j limp. 11-68. I*, A V. 30p, 

OBNTHE ZERO MINIATURE MOVINo'cdlL MKTER. 
lnil^iA. I'ur lialmiL'r fit liiulni;. tpiir..>, al«e )• i J- i 1- 
deep. ijuiiii'ii nnwlni SSp. I'. .V P. I Up, 



OENEBAL PURPOSE HIGH STABILITV 
TRANSISTOR PRE-AMPLIFIER 
I'ur P. I.'. Tape, Hike, (iii)litr. lis, uud jtultalda for 
ma with vatva ur IranaMur ei|iil|iiuriit. W-lBv. 
Iialtery nr from ||,T. linn 'iOfl jIDOv. Krei|uaiier 
rrxpimae IRII/ BdKHl, Main SMU. H.illd aticap- 
lulatlon tine U* « |J" x |*. Ilrntul new wintileta 
villi ln-.<rwii,,ii„. i<rlr«.ll-00 Y. i. I', trip, 



HANDBOOK OF TRANSISTOR EQUIVALENTS AND 

SUBSTITUTES 

A iiiimi fur .,T> lui'iui'i! iLinl iiniiu' iiittnlrui'liirn. lurliMli.a 

many HiilO'™ i.f llrllMi, I'.H.A. Kunipi-Hii and Jtpun^.e 

Iran-lmnr-. ONLY 40p. I'u-t ,1p. 

S Re! ere nee Encjclopaalai lor Elicit on ic Enilnairi tnd 

Deiiitnen. wvvrmff htrtwrvii Ihi-iu ln.ti-i-i.-r rharai'tDr- 

l»th-. illiulp ami 1niii.l-i.ir i-i|iih NtMil". Many 1h'iu<ainla 

o[ up tn .111.' Kuriipi-an lypc. I lain I. 

Diode Equl'aleati 80s 

TriniJjtor Squlvalenli S0p 

Tranifitor Cbiricterlitloi 11 15 

POST KRKK. 

-Ml ll.n-v Tr, K ,.;V.<-r £2 60 



RECORD PLATER BARGAINS 
Mainf modeii. All brand new In maker's paekinie. 
LATEST B.S.R. C108(C12fl AUTOCHANGER UNITS 

with latest sterto/i > compatible. cartri.||-t £7 80 + 

odp P. * P. 

GARRARD SP2S Mk HI vlth heavy preciei™ TiiachineJ 

• lie east turntable £10 58, tarr. OOp. 



PRECISION ENGINEERED PLINTHS 

Ucauttfully cuiihtructed in heavy gauge "Colurcoat" 

pLastic cuated steef. Jievmance tree. Deei^ned to take 

■ Sajrard 10"J5, *»0O. ■.'0-J5TC. 2500. 3000, 3500, MOO, 

SP-li It and 111. S 1.05 it. AT60 etc. ur U.S.R. CI09, 

Ut'J!<. A-21 etc. Black leallierette finish. Bize l-i" - 

]4i" v. LIJ" hifrh (apprm. ~t\" high. imludiiiB ItfM 

smoked acrvlic cover). 

NOW ONLY £4-85. P. * 1*. 3jp, ' 



LATEST AGOS GPSl.'ISC mono compatible cartridge with 
i.'o ntvlui fur LPi'lil*,78. l.'uiveraal mounting bracket, 

fi-M'p. a i'. sp. 

S0NOTONE 9TAHC COMPATIBLE STEREO CARTRIDGE 
T/O Btviim Lilaitiond H'creo 1,1' and Uapphire 73. 
ONLY £2-30 V. & !*. lOp. Alio available tltted with twin 
Diamond T/O itylni for Stereo LP. 12-80. !'■ A P. I0p. 
LATEST RONETTE TO STEREO 'COMPATIBLE 
CARTRIDGE fur i-:l* r,P h«t»<.-78 11-SS I'. A P. I Op. 
LATEST RONETTE T O MONO COMPATIBLE CART- 
RIDGE tor playing KI*LI'/7B muiio w stereo reeoidi 
on mono equipment. Only 11-80 1*. & I', tup. 

QUALITY RECORD PLAYER AMPLIFIER MX II 
A tup quality record player ampHBer employing heavy 
duty duubla wound inalua tranafonner, J-ll'CSa, RLM, 
and recM8er, rteiiarate Bail, Traiile and Volunia conlrole. 
Complete with output transformer matched for 3 uluu 
siteaker. Hiza Tin. wide x Sill, (leap K Bin. lilgb. Krs.lv 
built and tenteil. I'ltR'b: 14-40 P. H P. 4Up 
ALSO AVA1LAHLF, mounted on board with output 
transformer and sneaker. PHR'H 19-88 P. 4 I*. &0|t. 



SPECIAL OFFER ! 

HI-FI LOUDSPEAKER SYSTEMS 

ll.-sntllijlly mails leak llulih envluaitre with most 
atlrai-tlva'Tygau.Vj-nalr frunt. hlu 18* high x JO,* 
»i-Ie j is- deep. Kilted with KM. I. Oratuic Magnet 
13* i S" l.a-» unit, tno II. R tweeter nulla and 
OTn aw m-ar. Maximum BtMrw hatnlllng Id wall-. 
Avallabli) 3 or H or 10 iiIiiiih Inipcdatitii*. 

OUR PRICE £9.25 Cm.**, 

Cablnal As a liable Be para I sly 14 08 I'arr O.lp 

Also nvailul.la in (i oliiui nllti KM I 13* * H' bsaa 

apruker Willi pnraHlilo twrster 17-18 C'an-. 70p 



KAR VIRION '8 1UPER MONO AMPLIFIER 
A an par uimlity gram auiplliler uslugariuulila wound titlly 
lauialetl mains tranitoriuer, r-rtliler and KCI.H'J I Mod* 
peuimle valva as audio aiuplltlar and vower output 
stag*, lmpt , dmii<t 3 ohms, Output appro*.. 3.3 watts. 
Vuluiiis ami tun* control a. Cbaasls slia only Tin, wld* 
x all i. deep X Oh), high overall. AC mains 200HQ-. 
Supplied absolutely llrand .Ssar ruuipleUly wired in. I 
Idled wit ii good ipiallly output transformer. Jt\ "1A 
1'. A 1'. ;>3n IIAlttlAIN flllt'l-: *-•**-»'-' 



LOUDSPEAKER BARGAINS 

Sin. 3 ..lrn II .08, P. A I'. I ftp. 7 x 4bi. 3 uhm 11-18, 1'. A I', 
2llp, 10 x Uhi. 3 ur 1.1 ohm ll.fiO, P A P. r<"n, K.M.I, 
n y Din. 3 ohm with hluli lint msuftiet ILOS, l>. A f. 2(<p 
M.M.I. i3J x tun. with high lto» iTrauilo nnufiint with 
parasitic tweeter 3. H or 18 ohm 1880. P. * P. atip. 
K.M.I. J 3 X Sin. 3, n or IJI nttut with two Inbuilt tweeter* 
and croswuvcr network 14-68, 1'. * P. 30p. 
KM I L'eraiuk- magnet heavy duty tweeter. Appmi 3J". 
Aval lab I a a or M or 10 ohms. 11-88 + I Op p. A p. 
BRAND NEW. lain. ]0w. It' I J Hpeakers, 3 ur ID ohun. 
Currant prudut-tlun by wall-known llrltlib maker. Now 
with Ultlui ceramic farrottar inagnet aaietubly 17-80. 
liulliir modsi.L 'j;,w. 17-80, 3jw. 10-88. P. A I', -pip 



SPECIAL OFFER! 

LIMITED NUMBER OF BRAND 
NEW ELAC 10' TWIN CONE 
LOUDSPEAKERS 

Willi large ceramic unigiuil and 
plait Ei'ist-il cons surround, 
ih n i ImptslBiifc. 11-70. I*. A j'. VO p. 



lain. ■•RA" TWIN CONE LOUDSPEAKER. 10 watts 
peak handling. 3. s ur 18 uluu 11-48, I'. A 1*. "dip. 
88 Obm SPEAKERS 3lu. only 70p |>. a I', lip, 
"POLY PLANAR" WAFER-TYPE, WIDE RANGE 

ELECTRO-DYNAMIC SPEAKER 

Hit* lit* i 14)1* i j,',* d«*p. Weight ISoi. 1'owar 

haiiilllui HOW r.ui.a. (40W peak). Iti.pu.lancs 8 ohm only, 

Kmikiiid* 40ltt-20ktlE. Cim in motiiiUil on cell In sa. 

walls, doors, uml*r lahles, i-u-.. ami used with ur wlthuut 

halite, HsipI H.A.i:. fur full datalls. Only 18-88 each. 

I'. A P. Hflp. 

YYNAIR * REXINE IPEAKEHS It CABINET FABRICS 

app, A4 In. wide. Out price SBp ji. langtb. 1'. ,v P. I ■ ■ | ■ 

per ViL (iiiIm. I yd.). H.A.K. for snnipli". 




HI-FI STEREO HEADPHONES 

Adjustable headband Hlth cutufiirtabli fletlfoam iar- 
iiiufli. Wired and tit ted with standard atereo J In lack 

filug. Kre.ineucy responia .10 lil.OOOII*. Matching 
mpi-ilaiice H-Jtl ulims, Kaslly converted fur Mono, 
PRll'R 18-80. P. A i*. Illp. 

HIGH IMPED AN :E CRYSTAL STICK MIKES. 
OUR PHlL'ti 11 18, P. A I'. Kip 



HARVERSONIC SUPER SOUND 
10 10 STEREO AMPLIFIER KIT 




itEW FURTHER IMPROVED MODEL WITH 
HIGHER OUTPUT AND INCORPORATING HIGH 
QUALITY READY DRILLED FIBRE GLASS 
PRINTED CIRCUIT BOARD WITH COMPONENT 
IDENTIFICATION CLEARLY MARKED FOR EVEN 
EASIER CONSTRUCTION 



A really Ural-class Hi-Fi Ftfcreo Amplifier Kit. lies 14 
transistors including rjillcoti Transistor* In Ihe ilrst "iv* 
alagei on each channel rt-Hiihinft hi n-n Inwrr noise 
level with Improved scusllhliv. Integral cd |>re-nmp with 
llaai, Treido and two Vohiuis t'oi.lrola. Hinlnt.te [ur us* 
willi (Vramic or Crvalal carl rldg.-s. \"i-ry simple in 
mislify In suit magnetic cartridge - iiisliuclbms included. 
Output ilage for any apealtcrs fr.un 5 to i :. nhtiis. Compact 
dealgti. all parts supplied inuIii.iiiiK drilled metal work, 
high quality ready .Iriiled (Ihreglass priutnl circuit board, 
•mart brushed amid lie, I aluminium, (runt panel with 
matching knob", wire, solder, nuts, bulls -noc it ran to buy. 
Mlmple step by step instruct ionn enable any const ruct or 
In hnlbl .in amplifier (o he proud nf. Itrlcf specification: 
Tower output: 14 watts r.tii.e, per clvmiuel lido (J ohms. 
Kreipuhoy response +3dll 12 30,000 III Ncnsiticlty: 
In-tter I linn MiiuV into J Mil. Kull power lunidwldlh: 
I Hdtl l'.> 10,000 Ur.. Itnss lioost npprtn. tu ■)- li.lll. 
Treble cut uppros. to - lOdll. Negullva fed back IHdlt 
oter iiialii amp. Power re<]iilreitieiiH ,10 c. at 1.0 amp. 
Overall Hits I2*w. jt MM. i 2I'b. 

Kully del ailed 7 page const rue Hun manual and part* 
list Ire* with kit or send IHp plus largo K.A.K. 
AMPMPIKK KIT .. £11-55 P. A P. 1 dp 

(Magnetic Input etniipuurtita ,'t,ip exlra) 
POWKit PACK KIT 13-30 P. A P. 3,1p 

CAUIMKT .. 18-30 P. A I", S3n 

(Po*t Tree If all nulls purchased at lama time) 
Kull afier sales service 
Also available reaily built and lesteil C23-10, Pnat Pree. 
Sod: Tki nt. o re ampllflrr Is iHffnuIr fur fr riling tvn incae 
tourtu into In pnii (e.g. m Ik*, r art la. hi'tn rert>r4 deeki t He.) 
fliid n-llt Ikm iiroritt wUhiq «»d fijtlnt fatitltttt far mtd- 

(toil fieicrrerf IN Ft lliiealh rotir i/n rle. 

3-VALVE AUDIO 
AMPLIFIER HA84 XK II. 
Designed for HI-FI reproduc- 
tion nf records. A.C. Main* 
o pent I on. Heady tin lit on 
plated heavy gauge hiatal 
ehnssis, *Ua 7|" w, x 4* d, x 
4f" h. Jticorporate* ECC83, 
V. I.B 4, KZ80 val,ei. Jfaai-y 
duty, doubt* wound mains 
traiiaiiirmer and output trans- 
fonuer luatuhed lor 3 obm 
speaket. Mepaiute volume coutrul and now with Improved 
wide rang* tone controls giving bns* and treble lift and 
cut, Negative feedback line. Output 4* watt*. Front 
panel can be detached and lead* extended far remote 
rii.in--.tiiu- of control*. Complete with knobs, valves, «te., 
wired and teiteil for only iS-SO. P. A V, 30p. 
HSL "FOUR" AMPLIFIER KIT. Similar In appearance 
to IIA34 aWve but ernployi entirely different and 
advanced circuitry. Complete set ol parts, ate. 14-60. 
■■ 40|i. 




British mads solid state all silicon sterToampTlfler. ID watts 
mm per channel output. Fn\ res. -J01U to '-'OK Ha. 
Miiltnhh- for magnetic or ceramic pickup tape nilc. etc. 
lui III In swli citable scratch (liter, rumble (liter and loud- 
ness control. HO iii/ui slider cunlrnls for has*, treble and 
volume, in way push bulttm functloti, selector switch. 
This amplifier has spec Ideation arid performance usually 
only Inuinl In amplifier* costing twice a* much. Keen 
amplUier supplied, tested and fully guaranteed. Finished 
In Ihe most attractive cdiitcmnorary siylo teak cabinet. 
Ml /i- 1 1| | In x HI In x 4 1 in. Makers recommended price 
Mfl.311. (Inc. VAT) Our prlco (while slock* last I 188-78 
(Inc. VAT) + 78p. p. A p. Send «AE for lull details of 
-in cat Ion. 



iSU win »!-H 
AMPLIFIER KIT 

A styllihly finished 
monaural amplifier 
with an output of 
14 wait! from 2 
KIJI4* In push-pull. 
Niiper reproduction 
ol both miislo and 
■ perch, Willi negli- 
gible hum. Separate 
Inputs tor ml k ■ anil 
gram allow records 
and announce men Is 
to follow each other. 
Fully shroud ed section wound output transformer to 
iiint.-li 3-i.'>Il speaker and 2 Inde pendant volume controls, 
ami teparule base and treble enntruts are provided 
giving good lilt ninl cut. Val.e lino-up 2 l"l,K4s, KLt'83. 
KKHtl and KXHO rei'tiner. Simple Instruction booklet 
I rip 4- HAK (Free with parti). All parla aeld separately, 
ONLY IB. SO P. A P. OOp. Aim available ready hunt ami 
tested H1B-10 P. A V. 00p. 



a&M 



v -at' '♦' irl 



t t t f 



Open 9-5,20 Monday to 
Friday. 9-5 Saturday 

Early chiing Wed. ( p.m. 



HARVERSON SURPLUS CO. LTD. 

<D eP t. p.w.) 170 HIGH ST., MERTOH, LONDON, S.W.I 9 Tel.: 0I-S40 3985 

SEND STAMPED ADDRESSED ENVELOPE WITH ALL ENQUIRIES 



(Please write clearly) 

PLEASE NOTEt P. A T. 
CHARGES QUOTED APPLY 
TO U.K. ONLY, F. ft P. OR 
OVERSEAS ORDERS CHARGED 
EXTRA. 



375 



_ 



Sinclair Project 60 



Now-the Z.50 Mk.2 



with built-in automatic 
transient overload protection 

When originally introduced, the Sinclair Z.50 proved how it was possible to 
design and produce a popularly priced modular power amplifier having 
characteristics to challenge the world's costliest amplifiers. Many thousands cf 
2.50's are now giving excellent service day in. day out. But we have also learned 
that constructors do not always use their Z.50's ideally. That is why we have 
introduced modifications whereby risk of damage through mis- use is greatly 
reduced and performance further enhanced, The Z.50 Mk.2 has improved 
thermal stability, more accurately regulated D.C. limiting to ensure more 
symetrtcal output voltage swing and clipping and still less distortion at lower 
power. Z.50 Mk.2 is compatible with all other Project 60 modules, and may be 
incorporated to advantage in existing systems. Eleven silicon epitaxial planar 
transistors are now used, two more than in the original Z.50 ; circuitry has been 
re-designed, making this versatile high performance amplifier better than ever. 



Z.oO the power 
amplifier for quality and 
economy 




with 
free 
manual 

£4.48 



The Z.30 provides excelteni facilities for 
the constructor requiring a high fidelity 
audio system of less power than that 
available from Z.50's Using a power 
supply of 35 volts. 2.30 will deliver 1 5 
watts RMS into 8 ohms, or 20 watts RMS 
into 3 ohms using 30 volts. Total harmonic, 
distortion is a fantastically low 0.02% at 1 5 
watts into 8 ohms with signal to noise 
ratio better than 70 dB unweighted. Input 
sensitivity 250mV into TOOK ohms. Size 
80 x 57 x 13 mm (3£ x 2£ x i) Z.30, Z.50 
and Z.50 MK.2 modules are compatible 
and interchangeable. 



Brilliant new 
technical specifications 

Input impedance 100 K" 

input (for 30w into 8n) 400mV 

Signal to noise ratio, referred to full o/p at 

30vHT80dB or better 

Distortion 0.02% up to 20W at 8a See curve 

Frequency response 1 0Hz to more than 

200KHz±ldB 

Max. supply voltage 45v (4n to 8n speakers) 

(50v 1 5fl speakers only) 

Min. supply voltage 9v 

Load impedance - minimum : 4o at 45v HT 

Load impedarfce - maximum : safe on open 

circuit 




with free 
manual 

£5.48 




H tfl M 07 i a J ■ f * « zo M 1* H I 

WATTS IMTO ID AT *JY HT 
AND AT 1 KHi 



Typical Project 60 applications 



Guarantee 



l(. withm 3 months of purchasing any product direct from 
Sinclair Radionics Ltd.. you are dissatisfied with it, your 
money will be refunded ni once Many Sinclair appointed 
Stockists atso pilar this same guarantee in co-operation with 
Sinclair Radionics Ltd. 

Each Project 60 module is tested before leaving our factory 
and is guaranteed lo work perfectly. Should any defect arise 
in normal use. we will service it at once and without any 
charge to you. if it is teturned within two years from the date 
of purchase. Outside this period of guarantee a smalt charge 
(typically £t .00) will be made. No charge is made for 
postage by surface mail. Air Mail is charged at cost. 



inczlaii— 



System 


The Units to use 


together with 


Units cost 


Simple battery 
record player 


Z.30 


Crystal P. U.. 12V battery 
volume control, etc. 


£4.48 


Mains powered record 
player 


Z.30. PZ.6 


Crystal or ceramic P.U. 
volume control, etc. 


£9.45 


1 2W. RMS continuous 
sine wave stereo amp, for 
average needs 


2 xZ. 30s, Stereo 
60;PZ,5 


Crystal, ceramic or mag. 
P.U.. F.M. Tuner, etc. 


£23.90 



25W. RMS continuous 
sine wave stereo amp 

using low efficiency (high 
performance) speakers 



2 xZ. 30s, Stereo 
60; PZ.6 



High quality ceramic or £26.90 
magnetic P. U., F.M. 
Tuner, Tape Deck, etc. 



80W, (3 ohms) RMS 
continuous sine wave de 
luxe stereo amplifier. (60W. 
RMS into 8 ohms) 



2 xZ. 60s, Stereo 
60; PZ. 8, mains 
transformer 



As above 



£34.88 



Indoor P.A. 



Z.50, PZ.8, mains Mia, guitar, speakers. 
transformer etc.. controls 



£19.43 



F.M. Stereo Tuner (£25) & A.F.U. (£5.98) may be added as required. 



SINCLAIR RADIONICS LTD.. R.O. London Road. St. Ives, Huntingdon*hir«, PE17 4HJ (Phone St. Ivaa 4311) Reg. No. 699483 England 
376 



the world's most advanced high fidelity modules 



Stereo 60 Pre-amp/control unit 



• ••• 



Designed specifically for use on Project 60 systems, the Stereo 60 is equally suitable for use with any 
high quality power amplifier. Since silicon epitaxial planar transistors are used throughout, a really 
high signal-to-noise ratio and excellent tracking between channels is achieved. Input selection is by 
means of press buttons, with accurate equalisation on all input channels. The Stereo 60 is particularly 
easy to mount. 

SPECIFICATIONS— Input sensitivities: Raa o - up to 3mV. Mag. p.u. 3mV correct to R.I, A. A. curve 
:-1dB 20 to 25.000 Hi. Ceramic p.u. -up to 3mV Aux- up to 3mV. Output: 250mV. Signal to noise ratio: 
better than 70rtB. Channel matching: within 1d8. Tone controls: TRE8LE+12 to— 12dB at 10KH*. BASS 
-1 2 to — 12dB at 100Hz Front panel: brushed a jn- mum with clack knabs and controls. Size: 56 x 40 x 207mm. 



Built. Jested and guaranteed. 



£9.98 



Project 60 Stereo F.M. Tuner 



Power Supply Units 
The new £ 

PZ.8Mk.3 




The most reliable power supply unit ever made 
available to constructors. Brilliant circuitry makes 
failure from over load and even direct shorting of 
the output impossible. This is due to an ingenious 
re-entrant current limiting principle which, as far 
as we know has never before been available in 
any comparable unit outside the most expensive 
laboratory equipment. Ripple and residual noise 
have been reduced to the point of almost total 
elimination. This is. of course, the perfect unit for 
Project 60 assemblies, particularly where the new 
Z.50 MK.2 amplifiers are used. Nominal working 
voltage -45. 

PZ.8 Mk.3— E7.98 

(Mains transformer, if required) £5 98 

PZ.5 30v. urtstabilised 

(not suitable for Project 60 tuner) £4.98 
PZ.6 35v. stabilised 

(not suitable for IC. 12) £7.98 



The phase lock loop principle was used for receiving signals from space craft because of its vastly 
improved signal to noise ratio. Now, Sinclair have applied the principle to an F.M, tuner with fan- 
tastically good results. Other advanced features include varicap diode tuning, printed circuit coils, an 
l.C. in the specially designed stero decoder and switchable squelch circuit for silent tuning between 
stations. In terms of high fidelity this tuner has a lower level of distortion than any other tuner we 
know. Stereo broadcasts are received automatically, a panel indicator lighting up as the stereo signal 
is tuned in. This tuner can also be used to advantage with most other high fidelity systems. 
SPECIFICATIONS— Number of transistors: 16 plus 20 in l.C. Tuning range: 87. 5 to 108MH*. Sensitivity: 
7j.lV for lock-in over full deviation. Squelch level: Typically 20jjV, Signal to noise ratio: >65dB. Audio 
frequency response : 10Hz - 15KH2 (-IdB). Total harmonic distortion: 0.15% for 30% modulation. 
Stereo decoder operating level: 2pV. Cross talk: -iCdB. Output voltage: 2 x 1 50mV R.M.S. maximum 
Operating voltage: 25-30VDC. Indicators: Stereo on: tuning. Size: 93 x 40 x 207mm. 



Built and tasted. Post free. 



£25 



Super IC.12 5 




Having introduced Integrated Circuits to hi-fi 
constructors with the IC.10, the first time an IC 
had ever been made available for such purposes, 
we have followed it with an even more efficient 
version, the Super IC .1 2, a most exciting advance 
over our original un \. This needs very few ex- 
ternal resistors end capacitors to make an 
aston. shingly good high fidelity amplifier for use 
with pictc-up, F.M. radio or small P.A.set up, etc. 
The Tree 40 oage manual supplied, details many 
other applications which this remarkable IC. 
make possible. It is the equivalent of a 22 tran- 



Integrated circuit 
high fidelity amplifier 



sister circuit contained withm a IB lead DIL 
package, and the finned heat sink is sufficient for 
all requirements. The Super IC.12 is compatible 
with Project 60 modules which would be used 
with the 2.50 and Z.30 amplifiers. Complete with 
free manual and printed circuit board. 



SPECIFICATIONS 

Output power: 6 watts RMS continuous (12 
watts peak). 6-611 Frequency Response : 5 Hz 
to 100KHz := 1dB. Total Harmonic Distortion; 
Less than 1%. (Typical 0-1%) at all output 
powers and frequencies in the audio band (28V). 
Load Impedance; 3 to 15 ohms. Input Im- 
pedance: 250 Kohms nominal. Power Gain: 
90dB (1 .000.000.000 times) after feedback. 
Supply Voltage: 6 to 28V. Quiescent cur- 
rent: 8mA a: 28V. Size: 22-45 -:28mm in- 
cluding pins and heat sink.. 
Manual available separately 1 5p post free. 

With FREE printed circuit 
board and 40 page manual. 

£2.98 Postf-ee 



Project 605 




.. ■ ... ■■ 



the easy way to 
buy and build 
Project 60 
without 
soldering 

Project 605 in one pack contains one PZ.5. two 
Z 30's. one Stereo 60 and one Masterlink. which 
has input sockets and output components 
grouped on a single module and all necessary 
leads cut to length and fitted with clips to plug 
straight on to the modules thus eliminating all 
soldering. 

Complete with comprehensive f*2Q 9B 

manual, post free 

All you need for a superb 30 watt 

high fidelity stereo amplifier 



Order form 

Please send 



t enclose cash/cheque/money order. 

Name 



Address 



ii 



PW7 
SINCLAIR RADIONICS LTD.. R,0. London Road, 
St. Ives, Huntingdonshire, PE17 4HJ 

■ ■_ ■ 

iindiair— 



ADD 10% V.A.T, ON PRICES ON PAGE OPPOSITE AND ABOVE 



377 



Practical Wireless Classified Advertisements 



Classified advertisements lOp per 
word (minimum 12 words). Box No, 
20p. Semi-display setting £8 per 
single column inch. Advertisements 
must be prepaid and addressed to 
Classified Advertisement Manager, 
PRACTICAL WIRELESS, IPC 
Magazines Ltd., Fleetway House, 
Far rin gdon Street, London EC4A 
4AD. All cheques, postal orders, 
etc., to be made payable to PRAC- 
TICAL WIRELESS and crossed 
"Lloyds Bank Ltd." 



Books and Publications 



i-.rr.ffv-diiu^ 



Handbk of Transistor Equiv and Substitutes 
Handbook of Tested Transistor Circuits 
Had & Eiectr Colour Codes and Data Chart . 



4op 
45 p 
20p 

sop 

23p 

23p 
25p 



8ovs Bk of Crystal Sets and Simple Circuits 
How to make FM & TV Aerials. Bands 1,2.3 

Radio Servicing for Amateurs 

High Fidelity Loudspeaker Enclosures 45p 

Practical Tape Recording Handbook 35p 

Practical Stereo Handbook Jbp 

Practical Radio Inside Out 45p 

Transistor Circuits Manual No. 1 2gP 

Transistor Circuits Manual No. 2 ^Op 

Coil Design and Construction Manual 3Ejp 

Radio TV and Electronics Data Book 30p 

Transis Circuits for Radio Controlled Models . 45p 
Pract Transistor Audio Amplifiers, Book 1 . . . 25p 
Transistor TRS1 Equip and Servicing Manual . . 30p 

Handbook ol Simple Transistor Circuits 40p 

Modern Transistor Circuits for Beginners 45p 

Sound and Loudspeaker Manual 55p 

Resistor Colour Code Diic Calculator 15p 

Manual Transistor Audio Amplifiers 4Sp 

Practical Car Radio Handbook ...... 35p 

Radio TV and Industrial Tube & Valve Equiv 45p 

Practical Transistor Novelty Circuits 450 

Television Servicing Vol. 1 9|p 

Television Servicing Vol. 2. ybp 

Television Servicing Vol. 3 /Up 

Television Servicing Vol. 4 S?P 

Using tin Oscilloscope KUp 

Servicing Transistor Radio Receivers 85p 

Television Timebase Circuits ........... £1 .10p 

Pal D Colour Receiver Questions & A ns. - . 7Sp 

A It prices include postage & packing 
FREE lints nf other titles avail on reouest. Send to: 



RADIO BOOK SERVICE 

40 Elwill Way, Beckenham BR3 2RZ 



DENCO CLACTON LIMITED 

3557-9 Old Road 
Clacton-on-Sea, Essex 

Catalogue 2Qp post paid 

S.A.E. all enquiries 

TRANSISTOR DATA 

THE INTERNATIONAL TRANSISTOR 

DATA MANUAL 

1973 EDITION is now ready. Data on upwards 
ol 18,000 transistors of international oriRin, 
£5-25 plus 3ftp post & packing in the UK. 
Brochure available. Order direct from 
SEMICON INDEX LTD.. 
Freepost, Wokingham. Berks. RG11 SAY. 



DIGITAL COMPUTER LOGIC and 

Electronics. Four volume self-instruc- 
tional course. £2-95 including p & p. 
Money back assurance. Cambridge 
Learning (PW), 8a Rose Crescent, 
Cambridge. 



Service Sheets 



SERVICE SHEETS, Radio, TV etc., 
8,000 models. Catalogue 15p. S.A.E. 
enquiries. Telray, 11 Maudland Rank, 
Preston. 

378 



LARGE SUPPLIER 

OF 
SERVICE SHEETS 

(TV. RADIO, TAPE RECORDERS, 

RECORD PLAYERS, TRANSISTORS, 

STEREOGRAMS, RADIOGRAMS, 

CAR RADIOS) OnlytOp each 

" PLEASE ENCLOSE LARGE S.A.E, 

WITH ALL ENQUIRIES & ORDERS '■ 

Otherwise cannot be attended to 

(Uncrossed P.O.'s please, original 

returned If service sheets not available.) 



PLEASE NOTE 
We operate a "by return of post service. Any 
claims for non-delivery should be made within 
7-days of posting your order. ^^^^^^^^^^_ 



C. CARANNA 

71 BEAUFORT PARK 
LONDON, N.W.11 

We have the largest supplies of Service 
Sheets (strictly by return of post). Please 
state make and model number alternative. 
Free TV fault tracing chart or TV list on 
request with order. 
Mail order or phone 01-458 4882 



SERVICE SHEETS for Televisions, 
Radios, Transistors, Tape Recorders, 
Record Players, etc., from 5p with free 
Fault-Finding Guide. S.A.E. orders/ 
enquiries. Catalogue 15p. Hamilton 
Radio 47 Hohemia Road, St. Leonards, 
Sussex. Telephone Hastings 29066. 



Aerials 



BAINES FOB HIGH FEEQITErTCY AERIALS 
VHF/UHF MULT1BEAMS BY I. BEAM ftOltajgE , paid 
MUM 10 £3 20- HB» is & W. M1SM SO £3 80, SLUM 46 

keoo. mum 70 £11 oo, hum 4 £*&o. sum t g»-95, 

75 to 300 ohm B.ilun £1 00. Aerial Rotators £22 00 
VHF/UHF Masthead Amplifiers— Gryphon complete with 
power unit!*. Postage paid. .-■- 

A/1053 Sinele Stace »% A/1053 Twin Stage £7-75. 
A/1057 Wideband £775, A/1083 FM £5 75. IMS Setback 
£4-72 complete. _ . . 

Accessories: SAB for List. Co-as 6p and 9p. Please add 

10 K for VAT. 

11 DALE CEES., TUFTON, CHESTERFIELD S42 BDB 

Telephone S63765 



For Sale 



MORSE MADE EASY!! 

FACT HOT FIC3T0K. If yon start BIGHT vou will be 
reading amateur and commercial Morse nitbio a month 
(normal progress to be expected). 

Using scientifically prepared 3 *W eed J re ^H , i, r rA u - 
automatically learn to recognise the code Ktntinai 
without translating. You can't help it, tl e as easy *• 
learning a tune. 18 W.F.M. in 4 weeks guaranteed. 

Beginner's Section only 83 30, Complete Coarse £4 -60 
( Overseas £1 ■ 00 extra) details only, 4p stamp. 01-660 -896 
G3HSC (Box IB). 45 GREEN LANE, PTOLEY. SUBSET 



TV LINE OUTPUT TRANSFORMERS 
Tidman Mail Order Ltd., 236 Sandy- 
combe Rd., Richmond, Surrey. TW9 
2EQ. 01-948 3702. 



SEEN MY CAT? 5,000 items. Mechani- 
cal & Electrical Gear, and materials. 
SAE K. R. WHISTON, Dept. PW, 
NEW MILLS, Stockport. 



SPARES, new, for Philips and some 
other Cassette Recorders. SAE en- 
quiries. Harvey, 94 Derby Lane, Liver- 
pool L13 3DW. 



RACK ISSUES Practical Wireless for 
sale May 1966-Oct. 1972. Complete £12 
o.n.o. 01-223 198C (London). 



APPROXIMATELY Three Thousand 
new boxed valves as Lot For Sale. For 
details: write to Cosmo Television Ser- 
vices, 427 Shields Road, Glasgow S.l. 



LARGE QUANTITY Test equipment, 
receivers, transceiver, meters, variacs, 
P S.U.S. over 1,000 items for imme- 
diate disposal. S.A.E. Plus 25p re- 
funded on purchase over £2-00. F. J. C, 
Colnemill, Alvington, Lydney, Glos. 



Radiospares Components 
at Competitive Prices 

3 W Audio Ann. IC £282 ea. (9 oft tor ptereo). 
Heat Sink (or above 23p ea. ('-' "1 for stereo). 
Stereo P.C Hoard lor above . . . ■ 63s> 

14 Resiste.ru lor above BtfaS 

G Potentioinetern tor above . . . - Sfi 

30 Capacitors for almve . . . . ' If ,1 

Boctifier type 4LA tor above . . ■ . fl"J| 

Hygrade t'il. Transformer for above . . £188 

8 ohm Longturov speaker £4-55 ea. ('2 off for stereo). 
Audible warning device, 2-0 KHz mod. tone, 1°-18V 

SlrlpboardK— similar to Vcroboanl, 

Type A 0-15 in. pitch - ■ 8|P 

Type B 010 in. pitch . . B6p 

T05 Voltage Regulator, '2-37 V at 130 m», £1-78 

Numerical Indicator Tabc, 7 Reg. fl I anient, H\Jg-M 

Transistors 11C117, RF504, RC109 . . • 23p ea 

BC107, BC108 23pea 

BF597. BC478. BFY00, UFY51. T1FY52 .. 34p ea 
BU10S, Vco I500v, 10W, tt 7-5 MITz £190 ea 
BU105/02 Vce 1700V, 10W. It 7 5 JIHi £3 S3ea 

2N3054 (NPX Type) fJ'Sf 2 

2N3054 (PSF Type) f?'?| ca 

2N3055 (SPN Type) • •' -• -- f*'l| olk 

■2 N 3055 (P. VP Type) £2-35 ca 

Prices include VAT. Add 80p post and packing lor 
orders under £6. Terms: Cash Wita Order Only 

All R.S. COMPONENTS Avail- 
able from M. A. Austin & Co, 
MA Grosvenor Square, South- 
hampton, Hampshire. 



Wanted 



TOP PRICES PAID lor NEW VALVES 

popular T.V. and Radio types. 
KENSINGTON SUPPLIES (C). 

367 Kensington Street, Bradford 8. 
Yorkshire. 



WE BUY New Valves, Transistors and 
clean new components, large or small 
quantities, all details, quotation by 
return. WALTON'S, 55 Worcester 
Street, Wolverhampton. 



P.W. October 1964 to October 1965 in- 
clusive. Milne. 7 Healey Street, N.W.I. 



CLASSIC MUSIC COMPOSER building 
a complicated electronic organ and 
synthesiser needs drawings and know- 
how for sustain, slew, f or rnants, filters, 
other effects. Robert Lombard!, Hue 
Nagelmackers, 14 4000-Liege, Belgium. 







Educational 



. 



TELEVISION TRAINING 

(MONOCHROME AND COLOUR) 

This private College provides theoretical and practical training in Radio and TV Servicing. Courses of 16 
months' duration, with daily attendance, are available for beginners and shorter courses for men with 
previous training in Electronics and Radio. Next course commencing Sept. 10th. Training courses in Marine 
Radiocommunication and Radar are also available. Write for prospectus to: London Electronics College, 
Dept. A8/, 20 Penywern Road, Earls Court, London SWS 9SU. Tel, 01-373 8721. 



RADIO, TV, RTEB Certs., City and 
Guilds, Computers, Radio Amateurs 
Cert., Practical Electronics (with kit). 
Thousands of successes. Details of 
home study courses and illustrated 
book— FREE. BIET (Dept ZL BPW 29), 
Aldermaston Court, Reading RG7 4PF. 
Accredited by CACC. 



C1E, AMSE, City & Guilds, etc. 
Thousands of exam successes. Postal 
courses in all branches of Engineer- 
ing. Prospectus FREE. State subject Of 
interest: BIET (Dept ZL BPW 40), 
Aldermaston Court, Reading RG7 4PF. 
Accredited by CACC. 



GO TO SEA as a Radio Officer. Write: 
Principal, Nautical College, Broad- 
water, Fleetwood FY7 8JZ. 



Situations Vacant 



MARROW COLLEGE OF 
TECHNOLOGY AND ART 

TECHNICIAN: 
SCHOOL OF PHOTOGRAPHY 

Up to £1.980 

A Technician/Engineer in television and 
sound is required for a new post in the 
Film and Television Department. Duties 
will include the technical operation and 
routine maintenance of a C.C.T.V. Studio 
requiring electronic and mechanical skills 
and knowledge in the television field. 
Relevant City and Guilds or H.N.C. quali- 
fications are desirable and further in- 
service training will be considered. 
Unless otherwise stated all the above 
positions involve a 35-hour week (Monday 
to Friday). 

Application forms from The Registrar, 
Harrow College of Technology and 
Art, Northwick Park, Harrow, Middx. 
HA1 3TP (864 441 1 Ext. 31). 



Receivers and Components 




For valve and 
transistorized re 
corders from £2 ea. 



INTEGRATED CIRCUIT and FET 

modules for construction of low-cost 
receivers, converters, pre-seleetors, 
etc. SAE details.— P. R. Golledge, Glen 
Tor, Torringtou, Devon. 



, 



PRECISION 

POLYCARBONATE CAPACITORS 

Close tolerance. High stability. All 61V d.c. 
0i7ftF: ±C, SOp; ±2', a 40p; ±l°i BOp 
1'OuF: ±ft°. 40?: ±2° BOp: ±JS SGp 
2 3^F: ±6°. 80s; ±2°. BOp: ±l*i Ml 
4'7uF: ±6°. 70s: ±2% tOp: ±l%ill! 
6-Au.K. ±0% 86p; ±2»„ 11-18; ±l°olle(l 
IOuF: ±6«„ 1110, ±'i"oil*0: ±i o o *180 

IB^F: ±0%«l-80; ±li"i *S10: ±l».fg-7« 

TANTALUM BEAD CAPACITORS— 
Values available 1, 021, Q-47. | fj, 2-2, -4-7, 
6 enf at 3SV, IOuF 25V, ISjaF 20V, 22MF 
15V, 33fiF 10 V. 47fiF 6 V. lOO^F 3 V — all 
at 9p each; 6 for 50 p; (4 for CI. Special pick 
6 off each value (78 eipaciton) £5. 
NEW I— TRANSISTORS. BCI07, BCI08, 
BCI09, All st Pp each; 6 for SOp; 14 for £1. All 
brand new and marked. Full «pec. devices. May 
be mixed to qualify for quantity prices. AF17H — 
3Sp each or 3 for £95p. 

POPULAR DIODES I IM9I4— 7p each, 6 for 
Sup; IB for £1. IN9I6 — 9p each, 6 for SOp, 14 
for £1. IS44 — 5p each. 1 I far SOp, 24 for £1. 
All brand new and marked. 
NEW LOW PRICE — 400 mW Zenevrs 
Values available 4-7, 5 6, 6 8, 7 5, 8 1,9 I, 10, II, 
12, 13 5, 15V. Tot. ± 5°i at 5 mA. All new and 
marked. Price 9p each, 6 for SOp, 14 ror £1 00 
Special offer 6 off each voltage (66 xeners) £4-SS 
RESISTORS, Carbon film IWSfi. Rsngofrom 
2-2C1 tollMOin £12 series, i.e. 10, 12, 15, IB. 
22, 27, 33. 39, 47, 56, 68, 82 and their decadal. 
High liability, low noise. All at Ip each; lp 
for 10 of any one value; 70p for 100 of any on* 
value. Special development pack — 10 off each 
value 2-2 CI to 2 2M Q (730 realtors) £5. 
440V A.C. CAPACITORS, OlfiF.iiio I fin x 
tin, 2Sp; 25piF. size I |in * fin. 30p; 47 
and 0-5fiF, size I tin x tin, 35p: lO^F, size 2in 
X tin, 45p; 2-O.^F. size 2in x I in, 7Sp each. 
SILICON PLASTIC RECTIFIERS I 5 Amp 
Brand new wire-ended D027. I00PIV at 8p each 
or 4 for 30p; 400PIV at «p each or 4 for 14p| 
800PIV at I4p each or 4 for 50p. 
5p post and packing on oil orders below £5. 
Please add 10% VAT to all orderi. 

MARCOTRADING 

Dept. W.8. The Malting*, Station Road, 

Wem. Salop 



World-wide acclaim, the incomparable 

GLOBE-KING 

V.H.F. & S.W. KITS 

Precision standard, inexpensive, low-cost 
valve and transistor Kits for Short-Wave 
10-350 m. V.H.F. 80-180 M/cs. Ideal for 
beginners with unique "Easy-Build" dia- 
grams and simplified instructions. Send 
to-day for free literature price list and 
order form, kindly enclose stamped 
addressed envelope (Overseas: Int. Reply 
Coupon). Direct to the sole manufacturers: 

JOHNSONS (RADIO) 

SHAW ST., WORCESTER. 

WR1 3QQ 

Please note new address, city centre. 
Pioneers in DX radio— Established for 
over 30 years. 

(A JOHN BANNER COMPANY} 



TAPE-HEAD reconditioning service. 
Guaranteed satisfaction. Send worn 
head with £2 to; Sara Electronics, 
Fawkham Avenut;, Longfield, Kent. 

MINI MAINS TRANSFORMERS 30x30x 
37mm, Cool, quiet, British. Pri. 220/ 
250V. Type MT3, 3-0-3V rms, 300mA, £1, 
MT7, 7-0-7V, 120mA, £1. VAT included. 
Use MT3 for 3V or 6V rectified d.c, 
MT7 for 9V or 18V. Circuits supplied. 
Mail order only, UK post 5p per order. 
Amatronix Ltd., 396 Selsdon Road, 
South Croydon, Surrey CR2 ODE. 



THE 



TEXAN 

NOW ON DEMONSTRATION 




Designer approved Kit £28 50 
Instructions only 35p 

Pack 1. RESISTORS 80p 

Pack 2. SMALL CAPS £1-50 

Pack 3. LARGE CAPS £1-40 

Pack 4. SUNDRIES £2S0 

Pack 5, SWITCHES £1 M 

Pack 6. CONTROLS £1-45 

Pack 7. SEMI COND. £825 

Pack 8. TRANSFORMER ....£4-95 

Pack 9. P.C. BOARD £2-50 

Pack 10. CHASSIS, etc. £4-20 

Post extra— parts available separately 
Send for list and technical spec. 

Kits also available for 

-*■ Radio Control Systems 

-k Digital Clock Systems 

•k integrated Circuit Amplifiers (to 
SOW) 

• Hi-Fi Pre-amps 

ic Stabilized Power Supply Units 

TELERADIO HI Fl, 325 Fore Street, 

Edmonton, London N.9 01-807 3719 

CLOSED ALL DAY THURSDAY 



BRAND NEW COMPONENTS by 
return. Electrolytics 16V, 25V, 50V— 
0-47, 1, 2-2, 4-7, lOmfds.— 4p. 22, 47— 

44 p. (50V— 5p.) 100— S^p. (50V— 7p.) 
220 — 6p. (50V — 9p.). Subminiature 
bead-type tantalums 0-1/35V, 0'22/35V, 
0^47 /35V, 1/3SV, 2-2/35V, 4-7/35V. 
10/16V— 8p. Mylar Film 100V— 0-001, 
0-002, 0-005, 01, 02— 2p. 0-04, 0-05— 
3p. 0-068, 0-1— 3'2p. Polystyrene 63V. 
E12 series 10 pf,— 1,000 pf.— 2p. 1,200 
pf. — 10,000 pf. — 3p. Miniature Highstab 
resistors, 5%, E.12 series — Carbon Film 
ijW 111— 10MI1 (10% over 1 Meg.) 
Metal Film i„W 10n— 2-2Mil and 1W. 
27H— 10Mn all 3 4P each. Postage 8p, 
The C.R. Supply Co., 127 Chesterfield 
Rd„ Sheffield 58. 






NEW MODEL V.H.F, KIT MKZ 

Our latest kit, Improved design and performance 
plus extra amplifier stags, receives aircraft, 
amateurs, mobile, radio 2, 3, *, etc., this novel 
little Bet will give you endless hours of pleasure 
and can ba built In one evening. Powered by 9 volt 
battery, complete with easy to follow instruction 
and built in Jack socket for use with earphones or 
amplifier. 

Only £3-50 +p.Ap 10p U.K. only. 
Illustrated catalogue of selected kits and com- 
ponents, 20p Inc. VAT. PiP free. 

ALL PRICES PLUS »% VAT 
Galleon Trading Co. 
12, Burrs Way, 
Corringham, 
Stanford- La-Hope. 
Essex. SSI7 DDE 



379 



liempus alaauciK 

ALL BRAND KEW, no reject*. 
Hone; back warranty. 5 V 
DiaiTAL INDICATOR. 0-9DF 
socket and filter £1-45. LEI' 
TYPE J" 0-9DP OIL £2-25 ea. 
LIGHT EBITTIKQ DIODES. All 
with data and panul clip. 
TIL 209 i" ilia. £4p. Red J" dia. 
type 33p. Oreen 75p. INFRA 
BED beam LED £1-1(1. TBS 
GAS detector £189. ULTRA- 
SONIC TKANSDUCER9 £2. 
DALO PCB reiiii marking pen B7p. Copper board 
12" x 6" SRBF 40p FeC etch FAK ISp. 
INTEGRATED CIRCUITS: with data If require.!. 
IC LITE SWITCH: Fboto anip/trigeeT ■tfuna,' 11-20 
relay or TTL 87p. Dil relay £1 10. 

iC d i a i t a I cloch 




MOS/LSl type 3s pin 4 »r B iliKit V>IH br. L'bip 
with Bucket £13. FCB £189. KIT £81 49. 741 Dil 
S pin 28p, 70S Up, Dil BBp. 74* S9p, 710 33p. E55 
TIMER inuDo/aHtahle ns-, clock 89p. ISKfH'LA- 
TORS: 1JA 5 to 20V fl-49. 723 57n. 
RECEIVES 7.X-JI4 £109. Mini ft* kit £1 99. 1310 
etereo decoder for tuners £2-89. Kit £3-45. 
74N TTL- dates 7400 etc. 15p ea. 741a 27p. 7441 
?Bp. 7447 £1 09. 7430 S9p. 749'J 87p. 741*21 45p. 
DIL SOCKETS; New type 8,' 14/ 16 pin 13p. 
SEMICONDUCTORS: 1A reds. 50V 33 n. 400V 8p. 
5 3Ep. UC107 7p. UCIOH 7p. BC109 7p. 
BC147/S,'!t lOp. HCI67/8/9 13p. I5CI 77/^9 15p. 
B0182/3M lOp. BC212/SM il-i. 80^70/73 I8p. 
BIM31/2 65p. BPYSO/61/o'i 13p. T1S43 liJT 24p. 
SB706 lip. SNSaoS 12p. 2H9938 OY 8p. 2N294649P. 
•JN'3053 17p. 2NS6 1 4 55p. 2X3702/3/4/5/6/7/8/9/1 01 1 1 
All 9p ea. FET9: 2N3819E 19p. '-'N'3«19 S7p. 
2»S823B 19p. ZENERS: B27SS Sp. SCR 400V; 
1A 28p. 

TRANSFORMER }A 6/12V 11. RefMors lip. 
430 * 470 mini IF tratmfanuers— Set 3 40p. 
CAPACITORS: Disc 22 pt to 0.1 vf 3p. Elect rolytu: 
2SV: 10, 60. 100 vf 5p, 1000 vf 16p. Presets 6p. 
CARBON POTS lip ea. write* ■*■ lip. [tual 38p. 

HvOLliWi) 
_n fully built with tliftuner. 13W £3-78. 
V A.T. You raui't add 10% (1/10) to all prices. 
FREE CAT. S.A.E. Data ihts. 8p ea. P.«l'. Sp C'WO 
P 0. BOX 89, BRACKNELL, BERKS. 



,JTffl 




TREASURE TRACER 

MK 111 Metal Locator 



ilt v-f i 



:\a\;.i. 



| Wdsns oiU-r Bft 

B SpMfc*r and sorEih-Qfitt OEwabon 

H Knocks down ta oWf 11m, 

■ Pre buhl I tunrch co<1 H ■mmbl j 

■ MfoMty jppf*vfd detign 

B Th-aratjDhi) proi «*!■&«#' finish 

■ Vrju only nWd scltifima iron, itr*W:dfi 



and mips 



I Compteic! 



(nr lEaf f1 



£9-80 



Built. Icsled 
and fluanuyte 
Poil 35p 



£1375 



MINIKITS ELECTRONICS. JSa LANOtEV DRIVE, WANSTEAO. 
I. ON DON Ell ILM. (**»<' <"'*•• ° n '*> 



TRANSISTOR BARGAINS, High 
Quality, individually tested. Similar to 
BC107/8/9, BC168/0, 10 for 3Qp, 25 for 
65p, 50 for £1-05. Package 5p. Mail 
Order Onlv. 305 Eccleshall Road, Staf- 
ford, Staffs. 

BRAND NEW FULL SPEC. DEVICES 

SATISFACTION 

OR YOUR MONEY BACK 

U.K. ORDERS— ADD 10% V.A.T, to total. 
MICROCIRCUITS: 709 24p; 710 36p: 723 Sip; 
741 27p; 74B 37p; PA230 60p; FET Op. Amp. £1 62. 
SOLDERCON IC PIN SOCKETS 5p per pin. 
SOCKETS: 14 pin DIL HI or LO I2p eaeh. 
RECTIFIERS I A: 50V 3fp; 100V 4p; 2Q0V 4 T p; 
400V 5p; 800V op; 1000 V 4p. 
ZENERS: BZY8BC 2V7 to 33V Sp each. 
DIODES:! N9 16 4p; OA90 6p; IN 148 4p. 
LED Panel Lamp with Buih and Data 28p. 
DALO PC RESIST PEN 68p. 

TRANSISTORS: 2N2926 BROWN 5p; 2N3053 
I5d: 2N3055 35p: 2N3702 lOp; 2N3704 lOp; 
2N38l9 26p; 2N40S8 I2p; BCI07A 8p: BCIOBBBp; 
BCI09B 8p: BCI09C Bp; 8CY70 ISp; BFVS0/5I/52 
ISp; OC44/4S/71/72 12p; AF1 U/S/6/7 I4p. 
(Above prices on May 16th. Check our list.) 

JEF ELECTRONICS (P.W.8) 

York House, 12 York Drive, Grappenhall, 

Warrington WA4 2EJ 

Mail Order Only. 

C.W.O. P. & P. at co»t. lOp min. List free. 



5 N CHANNEL FET* JI19E- £1 

Full specification devices complete with data and 
circuit detail* tor building voltmeter, timer, ohm- 
meter, etc. 

Send lOp for full list of field effect translator* and 
other top au«UtV transistors available at bargain 
prices. 

REDHAWK SALES LIMITED 
45 Station Road, Berrarda Cross, Bucks. 
Mall Order only 



TV'S COLOUR TV'S 

Reaervlced, perfect working order, repoltshed. 

ISin. DECCA «» 

191n. GEC a02S £115 

19ln. THORN 20W £«* 

ISln. DECCA ««S 

ISin. RBM PHILIPS £130 

25in. THORN 2000 £135 

One month comprehensive written guarantee. 

These are cash and collect prices. Delivery 
quotations by phone 

MONO UHF 

Fabulous TVs. No rubbish, from good source. 
RepoHshed cabinets. Many working. Recent irano 
alstorised models. Inct.: 

BUSH TV t4*U. TV IBS. TV 171 

PHILIPS style 70 and 210 

PYE & ECKO 868 chassis 

THORN 9S0. 1400, SEC Concorde from 
£12 aach 

Valve UHF models Inc.: 

BUSH push-button, THORNE (SO. 

SO BELL, 1000, etc. from £5 

U.H.F. TUNERS 

For FERGUSON 850, 900 chassis but adaptable 
for most DfSTD chassis £2-50 each, cwo oostage 
Included. Send s.a.e. for lists of tubes, tvs, valves, 
etc. For England: 

TRADE DISPOSALS, 1043 Leeds Road, 
Bradford. Tel. Bradford 665670 
For Scotland: 

TRADE DISPOSALS, Unit S, Peacock Cross 
INDUSTRIAL ESTATE, 32 Bumbank Road, 
Hamilton. Tel. Hamilton 29511/2 



COMPONENTS GALORE. Pack of 500 
mixed components manufacturers sur- 
plus plus once used. Pack includes 
resistors, capacitors, transistors, 
diodes, I.C., gang, pots, etc. Tremen- 
dous value. Send £1 + 10p P & P 
C.W.O. to Caledonian Components, 
Fosterton Firs, Strathore Road, 
Thornton, Fife. 

TRANSISTOR AMPLIFIER 80p- Vol/ 
Tone Control Panel 75p. 465 K/CS IF 
Panel 75p. Wavechange-OSC Panel 75p. 
LW-MW Rod Aerial 25p. Colour Tele- 
vision. Croma Panels £3-50. IF Panels 
£3.00. EHT Tripler Panel £108. Con- 
trol Panel ON/OFF + Vol /Brightness 
Controls £1'00. Archer, 9 Pine Grove, 
Maidstone, Kent. 



VALVE LIST 

ALL VALVES FULLY TESTED 

One valve postage 3p. Over 5 valves 
postage paid. 



DY86-37 

EB91 

ECC62 

EC CSS 

ECLS0 

EFB0 

EF1B3 

EF18+ 

EH90 

PCB6 

PCBS 

PC900 

PCCB4 

PCC183 

PCC805 



12iP 
ISp 
ISp 
20p 
7+P 
7ip 
Dp 
tOp 
ISp 
£0p 
23 p 
10p 
5p 
7ip 
ISp 



PCF80 


Sp 


PCF86 


15p 


PCF80S 


25p 


PCL82 


12+P 


PCL83 


12fp 


PCL84 


12JP 


PCL8S 


»p 


PCL8B 


17+p 


PFL200 


25p 


PL36 


20p 


PL50* 


20p 


PY8O0 


12tP 


PY801 


25p 


U191 


17+P 


U2S 


lOp 



6F23 
6/30L2 
30 F5 
30FLI 
30PLI 
30PL1 3 



ISp 

15p 
10p 
20p 

20p 

nip 



MANY MORE 

AVAILABLE 

S. & W. 

ELECTRONICS 

114 Burnley 

Road 

Raw ten stall 

Rossendale 

Lanes. 



ELEVEN BAND RADIO. SW1-4 (4-30 
MHz). Marine. LW, MYV, FM. PB 
(76-86). Aircraft (108-136). PB (148-174). 
Battery/Mains. BFO. AGC. Squelch 
Control. Output: 1'3W. 15in x 10in x 
SUin, £66. Eight Band Model, with 
BFO. £42. Four Band, MW. FM. Air- 
craft. PB. £15. SAE. Full Lists. Lang- 
tons Radio, High Street, ROCESTER, 
Staffordshire, Tel. 388. 



SPECIAL INTRODUCTORY OFFER OF 

BRAND NEW & MARKED COMPONENTS 

ALL PHICES INCLUDE V.A.T. 
TRANSISTORS: 6CI07B, BCI08A,'B/C. BCI09B 
Call atB4p; 8YF50/5I I4p; 2N3055 38p. DIODES: 
1N4I48 4jp; IN9I4 4+p. CARBON FILM RE- 
SISTORS: ±W S% ip each. 30p/S0 anv mi« 
(220-2 2M) El 2. 

UNMARKED BARGAIN PAKS: These tran- 
sistors have been properly tested and are guaranteed 
to have the specified hfe spreads. Pak of S, 
Plastic BCI08A Me 125-240, ISpr Pak o( 5. Plastic 
BCI09B hfe 240-500, ISp; Pak of 5. Plastic BCI79A 
hfe 124-240, 25f>: Pak of 4, BFYSI 50p; Pak of 4. 
2N697 20p. DIODES: Pak of S OA200 20p; Pak 
of 12 1N4I4B 20p. . _ 

C W.O. P. & P. lOp. on orders betow £4. Overseas 
at cost. S.A.E. for lists. Mail Order only. Money 
back if not satisfied. 

ADFONIC (Oept. PW>, 18 YEW LANE 
ASHLEY, NEW MILTON, HANTS BH2S5BA 



FISREGLASS PRINTED CIRCUIT BOARD 

A-Vsi SINGLE— 5p per 12 so. Ins. 50p sq. It. 
DOUBLE— Bp oer 12 sa. ins. 70p sq. g 
ANY SIZE CUT, NO EXTRA CHARGE 
ND VAT REQUIRED 
P. arid P. Up up to 1 sq. tt. 
25p up to 4 sq. tt 
57p up to 18 sq. II 
BRB 
17, SOUTHBRECK RISE 
WORKSOP 
NOTTS SB0 2U P 



|R ROSLESS SERVICES 



GUARANTEED SEMICONDUCTORS 
FAST SERVICE— LOW PRICES 



AC12B 13b BFX84 E7p i ZENER 

\CV17 13p BFXftO 34p DIODES 

M3158 13p USXaO 18p | 400m W S% 

JIU107 Bp 'iNOSO 22p ; M tn 33 volts 

BC10B 9p 8N11OT 27 » ie D each 

AF114 18p 2N17U 28p * 

AF115 18p -JNiPn-l 38p | T H:l " ° -« 

HCY71 35n 2S'370H flp I 18p each. 

ALSO CAPACITATORS KECTIFIERfi. ETC, 



PRICES 



INCLUDE 



VAT 



CASH .W.O - P.P. I6p TO 

ROSLESS SERVICES 
PARNDON HALL - HAMSTEL ROAD 
HARLOW - ESSEX 



UNUSED RESISTORS and Capacitors 
250 of each. Including high stabs and 
electrolytics. Only £1-50. Trade en- 
quiries invited. G76 Foxhall Koad, 
Ipswich, Suffolk. 

COMPONENTS AND HARDWARE, 

new and used, for P.W. circuits. S.A.E. 
for list. David Coulam, Tathwell. 
Louth, Lines. 



TUNBRIDGE WELLS, Components 
from Teleservice, 108 Camden Road, 

Tunbridge Wells, Kent. Telephone 
31803. 



Miscellaneous 



"AT LAST YOU CAN TRANSMIT AND 
FORGET ABOUT LICENCE EXAMINATIONS" 

because this Ministry approved transmitter/receiver 
kit does not uie R.F. Your transmissions will be 
virtual 1/ SECRET tinea they won't be heard by 
conventional means. Actually it'* TWO KITS IN 
ONE becaute you get the printed-cireuit boardi 
and components i'or both the transmitter AND 
receiver. You're foing to find this project REALLY 
FUN-TO-BUILD with the EASY-TO-FOLLOW 
instructions. An extremely flexible design with 
quite an AMAZING RANGE— has obvious appli- 
cations for SCHOOL PROIECTS, LANGUAGE 
LABORATORIES. SCOUT CAMPS, etc. 

GET YOURS! SEND £5B0 (inc. VAT) NOW 
'(S.A.6. for details)' 'MAIL ORDER ONLY ' 

TO: 'BOFFIN PROJECTS* 

DEPT. KW2OI0 

4 CUNLiFFE ROAD 

STONELEIGH, EWELL, SURREY 



380 



Darned 

Electronic 

Wizardry 

by Dewfron (vat e « ra ). 

Famous Kits. e.g. waa-waa. complete 
kit £2'il*ir Fuzz kit- £1-75. auto 
rhythm modules P & P 20p mln. 
Ring Modulator modules £8 and 
whole rang* of synthesiser modules, 
musical novelties. etc. Catalogue 15p 
from D.K.1V. Ltd., !*>J Kingwood 
Koad. Frrmlnwn, Dorset. 



BEDFORD ELECTRONICS 



2 Grove Place, Bedford 
Bedford 51961 

YOUR LOCAL 
COMPONENTS SUPPLIER 






BUILD IT hi a DEWBOX quality 
cabinet. 2in x 2 l ?in x any length. 
Il.E.W. Ltd., Ringwood Road, FERN- 
DOWN, Dorset. S.A.E. for leaflet. Write 
now — Right now. 



ALUMINIUM SHEET to individual 
sizes or in standard packs, 3p stamp 
for details. Ramar Constructor Ser- 
vices, 23 Shelbourne Road, Stratford 
on Avon, Warwicks. 



Remember the R & E "MEMORY"* 
Invented 1971 

You i-an leave ><>ur Delect. it la K edit K 

Now Modified using latest I C Solid State 
Technology (74IC's or LSI Chip) 

:t Ufretjita, 4iriafffj numerous aarailBaifjoaM Baby Alam 
Burglar R reorder/Alarm, UFO All-night MaattOH 
Micmloijie Multi'pnn> *e System Circuits 75p. Numerous 
ulhrr systems, (drtocOtm), Hw, PrarJtctloaSi re 1,00b 
t'KOx at. Banbury. Details ami 1.W -.'ml *\F, ■ dp 
In'tmi'ialili' vitili .ir-k-r). 

R & E Publications 
Highlands, Need ham Market, Suffolk 



GLASS FIBRE P.C. BOARD. Large 
supplies available. ',,in single sided 
one ounce copper 2p per 3 sq. inches 
(under 1 foot). 75p per sq. ft. <over 
I foot). \,in double sided one ounce 
copper lp per sq. inch (under 1 ft.). 
£1 per sq. ft. (over 1 foot). Please add 
lOp per sq. foot postage and packing. 
"We can cut to your size at lp per cut. 
Solid State Lighting, The Firs, Small- 
worth Lane, Garboldisham, Diss, Nor- 
folk. 



CONSTRUCTION AIDS — Screws, nuts, 
spacers etc., in small quantities. Alu- 
minium panels punched to spec, or 
plain sheet supplied. Fascia panels 
etched aluminium to individual re- 
quirements. Printed circuit boards- 
masters, negatives and boards, one-off 
or small numbers. Send 6p for list. 
Ramar Constructor Services, 29 Shel- 
bourne Rd., Stratford on Avon, 
Warwks. 



EXPERIMENTERS! Hundreds of un- 
usual items cheap. 1973 catalogue 5p. 
Grimsby Electronics, 64 Tennyson Road, 
Cleethorpes, Lines. (Mail Order Only). 



GM4AGG— The West of Scotland 
Amateur Radio Society, meets on Fri- 
day evenings at 8. Everyone welcome. 
81 Virginia Street, Glasgow or Tel: 
Cumbernauld 26922. 



AERIAL BOOSTERS— £3 25 

Wt make- three types of Aerial Boosters: B45- 
UHF 625, BIZ-VHF 405, B11-VHF RADIO 

VALVE BARGAINS 

ANY 5— 50 p. 10-75P, 50— £3-30 — 
ECC32, ECLBO, EB91, EBF89, EF80, EFB5, EF1B3, 
EF1B4. EYB6, PCC84. PCCB6, PCC18B, PC97, 
PCFflO, PCF88, PCFBOS, PCF808. PCLB2. PCL83, 
PCL84. PCL85, PFLZO0. PL36, PLB1. PL504, PY33, 
PVB2. PV800, PY801, 30L1S. 

19" UHF/VHF (BBC 2) £6 00 

Thorn-850 of Pye, with est of spars valvei 
Carriage £2 00 (Untested). 

100 MIXED RESISTORS— 65p 

r to 2 watt— 10 otima to above 1m-ohm« (our 
choice) 114 mixed Capacitors up to 5O0MFD — 
£110 Com choice). 

BARGAINS PARTS 

Transistor UHF Tuners— £2 00, 500 K -ohms V/C 
with Switch— ttp. 50 mined Tuner Valves— £2-2S. 
Brand New Transistor* 3F115, BF173, BC171, 
BC153. 8C135, BC113. BCtn, BC115, BA102. 
BA129. All 10P each. 

Alt prices Include V. A.T. p. ft p. lip per order 
Money back guarantee, S.A.E. for leaflets. 

ELECTRONIC MAILORDER 

(BURY) LTD. 

62 Bridge St., Ramsbottom, Bury, 

Lanes. Tel. Rams 3034 



SINGLE CHANNEL. 

SOUND-TO-LIGHT 
CONVERTER 




WITH LIGHT DIMMER 
Max. toad 2k W. al 250v. A.C. 

Price include* ready built anil tested module, 
edge connector/mounting bracket, dimmer 
potentiometer, audio sensitivity potentiometer, 
full connecting data. Pries £7 90 inc. VAT 

EXTRA FACILITIES. Push-button lor Manual 
Pulsing 25p extra. Photocell for turning on the 
lights ae the ambient light decreases, 75n extra. 

3 CHANNEL FILTER UNIT 

When used with three tingle channel modules 
this unit filters the sound into base, middle and 
top frequencies enabling three coloured light 
displays to be shown. Independent Htnaltivity 
controls on each channel. Heady built aud tested. 
Price £J» Inc. VAT 

OIL WHEEL PROJECTOR 

Build your own 
using our 

MULTI- 
COLOURED OIL 
WHEEL AND MOTOR 
KIT 




(at 



!>n 



mounting 
Slide Projec 



Kit euutaina; 



it 6* dia. or -I* dla. OIL WHEEL (please state 

size required trhen ordering. 
ie Hi-iiiable Miniature tnajna motor. 
It Full instructions, 

For Professional Discotheque use or borne enjoy merit. 
Price £7 15 inc. VAT 

ELECTRONIC COMPONENTS 
BARGAIN COMPONENT PACKS 
Pack No. 

1 500 Carbon resist or*, t, {, 1, 2 watt. 

3 100 lileetrolytie Oondensera 

3 2«i0 Ceramic, Polystyrene, Silver Mica etc. 

condensers. 
a 250 Polyester, Polycarbonate, Paj>er. etc, 

condensers. 
6 25 Potentiometer*, assorted. 

6 250 High-stab, 1%, S%, 5% resistors, 

7 50 Assorted Tagstrips. 

B lib n-t. Assorted Hate, boltn, washers, spacers, 
etc. 

9 25 Assorted switches, rotary, lever, micro, toggle, 

etc. 

10 SO Preset Potentiometers. 

ALL COMPONENTS NEW AND UNUSEO. 

£1 + ZSp p.p. par pack, £5 for S packs p, Its* 

CT. ELECTRONICS 

Mail Order. Retail Shop, Components— 

26? Acton Lane, LONDON, W4 50G 0t.JM.S275 

Warehouse, Test Equipment. Surplus Goods — 
10-14 Beaurnont Road, LONDON, Wt 

Audio Accessor/ Shop, Components — 

17 Turnham Green Terrace, LONDON, W4 



I 



D.I.Y, TECHNICAL BOOKS 

RADIO RECEIVER SERVICING GUIDE .. £190 

101 EASY HAM RADIO PROJECTS £150 

101 EASY AUDIO PROJECTS .. £1-48 

RAPID T.V. REPAIR (224 op) .. £130 

ELECTRONIC GAMES AND TOYS YOU CAN BUILD .. .. £1-40 

PAL RECEIVER SERVICING GUIDE (2a0 pp) £3 50 

BASIC ELECTRICITY <5 VOLUMES. 630 pp. BOO ILLUS.t £S 10 

ELECTRONIC DESIGNERS HANDBOOK £3-48 

BASIC ELECTRONICS (6 VOLUMES, 674 pp. 700 ILLUS.) £5-10 

ELECTRICITY. ELECTRONICS MADE SIMPLE .. Each 95p 

RADIO HANDBOOK (896 PO) ■■ £6-50 

1-2-3-4- SERVICING STEREO AMPLIFIERS (240 pp) £2-50 

MAKING & REPAIRING TRANSISTOR RADIOS. ADVANCED 

RADIO CONTROL, EASY WAYS TO SERVICE RADIO RE- 
CEIVERS, BEGINNERS GUIDE TO T.V. REPAIR, PRACTICAL 

HAM RADIO PROJECTS, HI - Ft PROJECTS FOR THE 

HOBBYIST .. .. .. Each £1 00 

HOW TO BUILD SPEAKER ENCLOSURES £150 

HI - Fl STEREO SERVICING GUIDE, 99 ELECTRONIC PROJECTS, 

99 WAYS TO IMPROVE YOUR HI - Fl Each £150 

ELECTRONICS FOR THE BEGINNER. T.V. SERVICING MADE 

EASY, 101 OUES. & ANSWERS ABOUT AM, FM 4 SSB Each £1-75 

HOW TO REPAIR SMALL APPLIANCES £1-20 

ADD 10% FOR POSTAGE AND PACKING 
WHEEL <PWJ), 41 A ADELAIDE GROVE. LONDON. WI2 



Clif 440V K.M.S. Block 
fUiF 440V B.M.B. 51" X I 
e-Hiif'-JSOV Folyeuter 
8/iH 300 V A.C. Block 
10mF 250V B.H.8, Block 



160 
1-50 
31 
ISO 
160 



ELECTROLYTIC CAPACITORS /xK/V 2000/50, 2500/GO. 6000/50, 10000/50, 12500/50 
All at 50b each, post paid. 6000 ill', 70V 4i" X 21" fi5p. 

SPECIAL OFFER ERIE DIM! CERAMIC CAPACITORS. OlpK 600V. 10 off 20p. 
100 OD fl. 600 on £4. 1000 0(1 £0. 

PAPER/ BLOCS/ MOTOR-ST ART CAPACITORS: 
£ 

IpiF 350V AC SO 

1 5pP 300V it.M.a. Block 010 

2iiF 2800V D.C. Block 1-75 

3fiP 100V A.C. Polyester 0-30 

3-5fiF 2S0V A.C. al" X If 0-35 

4fiF 250V A.C. 21" x If 40 

20jlf Z76V R.M.t) r>{ 
FLESSEY VIBRATORS. Type 1214 SOp 

SDBMINIATDRE PLTJfJ-IN CRYSTALS FOR RADIO CONTROL. WtOSSMH* and 
27-025MH2. 70p each. 

Add 10% V.A.T. 

ELEKON ENTERPRISES 

224a St Paul's Road, Highbury Corner, London N.I 



15(iK 2-5kV U.C. Block Ptolc**oh 3 60 
1" SI BO 



38t 



G. F. MILWARD 369 Alum Rock Road, : ningham B8 3DR. 



Tel. 021-327 2339 



TRANSISTORS 
Output Transistors 

BD112' 

OC36 

B0 145 



Small Signal N.P.N. 

BC 108 

BC 109 
BF194.. 



is P 
sop 

Mp 



Transmitting Types 
BFR64 
BKY 89A 
BLY B3A 



Field Effect Transistors 

BFW 52/13/14 



Micro-miniature N.P.N. 
BFS18R 
LDA 400/403/450/452 



10p 
10p 



Infra-rea Transmitters 

CQY1IA « 

CQY12A - »><* 



Light-sensitive Trans, 

OCP70 



NEWI NEW! NEW! NEW! 

An aerosol spray providing a convenient means of producing any number orcoples of a 
printed circuit both simply and Quickly. 

Method: Spray copper laminate board with light sensitive spray. Cover wUh trans- 
parent film i upon which circuit has been drawn. Fjpose to tight. (No need to use 
ultra-violet.) Spray with developer, rinse and etch In normal manner. 



Light sensitive aerosol spray SJn 

Developer and Etchant ■- •• ■• alp 



Microwave Varactor Diodes 

BXY 27/28/3a;3S/36(37;38(39/«/41 



Microwave Detector 
CAY 10 



Microwave Mixer 
CL 7331 






Microwave Gunn Effect Oscillator 

CL8370 ., . . , .. 

CLB380 

CL8390 

CL 8470 



Microwave Tunnel Diodes 

AEY13 

AEY16 



£5 
£10 



R.F. Transistors 
BF180 .. 
BF194.. 
AF124.. 



ZOp 
10p 

aop 



Complementary Drivers, 2 watts (per 
matched pair) 30p. a pair. 

NTEGRATEO CIRCUITS 

TBA 500 Luminance I.C. ■ - 

T8A 510 Chrominance I.C. 

FED' 

7400 

7401 



7410 
7420 
7440 
7453 
7470 
7472 
7473 
7474 
74S2 
7483 
7490 
7491 
7492 
7493 
7495 
HOB 
5404 



£1 
£1 
£1 

iin 

Up 
llfl 

I2S 

lie 
up 

Zip 

24 

32f 



Developei 

NEWER THAN NEWI 1 ! 
Fttwe Glass Board pre-trealed with tlght- 
iitive lacquer enabling you to produce 
;ttitotype printed circuits within five 

100mm M P 

100mm 66P 

200mm .£1-32 

22 p 
44p 

sap 



plus 
postage 



.ites. 
■ im ' 



Ti^im x 100mm 

lClmm x 150mm 

V 'mm x 200mm 

-. ppr.clad Fibre Board 

bn x 6tn 

•. .-pper-clad Epoxy Resin Board 

B x Bin 



25p 



9S; 
5bp 

V 

S-. 
6; 

11 



MULLARO POLYESTER 
CAPACITORS 

500.000 in STOCK!!! 

001 uf OOtBfif 0056jif '015fif 

0012nf -0022(if OIKl 033//! 

•OOlSuf 0027^1 -0t2(if 082M 

So dozen; 7Sp-100; £5-1,000; £4<H0,00O 

■gu.f -IB^f '22M1 *39nf -68uf 

v c dozen; £1-100; £8-50-1,000; £59-10,000 



2+in r. 1 in x 0-15in , 
3jin x 2^in X 0-15in 
3iln x 3jin X 0-15in 
5in x 2 tin X 0-15in 
5in X 3iin x 0-15ln 



VERO BOARD 

8p 
16P 
20p 

20p 
21 p 

17ln x 2Jln x 15in 55p 

17in x 3iin x 0-ISin 74p 

3iin x 2±in x 0-1ln 21p 

3Jin x 3 ; jin x 0-Hn 24p 

Sin x 2|ln * 1ln 23p 

Sin x 3iin k 0-lin .. .. .. 2Bp 

Spot Face Cutter 38p. Pin Insert Tool 48p. 
Terminal Pins (0-1 or 0-15) 38 for 16p. 
Special Offer Pack consisting of 5 2yln x 
1ln boards and a Spot Face Cutter— SOp. 
"ODDS 4 ENDS"-1» sq in. 



ERIE MONOLITHIC CERAMIC 
CAPACITORS 

Ipeach: 20p dozen; £1-75 per 100 

i0pi eapf seopf 

ISpt 100pl 620pt 

22pl 150pl 630pf 

33pl 220pl 1 .OOOpf 

39pl 330pl 

47pf 470p( 



/»-* 



MO {.if WATT RESISTORS I (f%«4 

^Hmic !#> ' 

100 DIODES 



in -""RB CI 



SO Sw. 
V6RO 



POSTAGE 15p 



i PACK No. 1 POSTAGE 15p 



uj-li *-lfcCfcS 



| PACK No. 3 



~1 



20 ASSORTED UNUSED 
MARKED, TESTED 
TRANSISTORS 
BC108 ETC. 



100 RESISTORS 
100 CERAMIC 
CAPACITORS 
100 POLYSTYRENE 

CAPACITORS 

POSTAGE lip 1 PA 



£1 



£1 



100 RESISTORS 
100 CERAMIC 

CAPACITORS 

SO MULLARO POLYESTER 
CAPACITORS 



POSTAGE Up 



PACK No. 4 



POSTAGE 15p 



£1 



1 TRANSISTORISED 
SIGNAL TRACER KIT 
1 TRANSISTORISED 
SIGNAL INJECTOR KIT 



POSTAGE »P 



I COMPUTER PANELS 
CONTAINING MASSES OF 
DIODES, TRANSISTORS, 
INDUCTORS, RESISTORS 

A CAPACITORS^ 

POSTAGE 2Sp : PACK No. 7 



£1 



£1 



100 RESISTORS 
100 CAPACITORS 
(ASSORTED TYPES) 



POSTAGE lip 



rpACK No. 8 



POSTAGE (MINIMUM) 15P PER ORDER 



ALL GOODS PLUS 10% V.A.T. 



HARDWARE— Screws, nuts, washers 
and other useful items in small quan- 
tities. Sheet aluminium to individual 
requirements, punched/drilled. Send 
6p for list. Ramar Constructor Services, 
29 Shelbourne Rd. Stratford-on-Avon, 
Warwks. 



LADDERS 24» a ft £9-80. Carr 80p. 
(Please add 10% V.A.T.tO total order). 
Leaflet. Home Sales Ladder Centre, 
(WLS) Haldane, Halesfleld (1) North, 
Telford, Salop. Tel: 0952 586644. 



CIRCUIT DIAGRAMS 

R1155, B. F.L.N. R1392, R1475, B40, 52 Rx, R220, all 66p ea. R4187 Rx set of 
circs, etc. £1-10. R107 Rx 88p. R209 Rx circ 4 notes £1*21, R210 £M0, 
R216 £1 .10, CR100 £M0, 19 set 88p, 31 set 88p, 88 set 88p, Wavemeter D 
No, 2 £1-10 CT38 66p, Sip, Gens TF144G Wp, TF801 a 88p, Scope 13A 66p. 
CT316 (00518) 66p, Cossor 1035 Mk 1, 2 &. 3 all 66p ea. 1049 Mk 3a 66p, 
Scope CT52/84 with notes £1-32. CDS13-2 3 shts £1-65, CD1014-2 3 shts 
£1 -65, Rx3873 6flp, Snd CRT26 66p. 

AMERICAN types ARR-2 55p, Rxlnd/APN-9 55p, AR88D 4 AR88LF £1-10 
ea, Tx/Rx BC634/5 88p, USM-24 £1-65.TS-34 88p, OS-8 66p, Dumont 208 
66 p, TS-382 88 p, TS-413 £1 -65, RX36738 6p, Ind CRT26 66p. 



The above prices inc. post and VAT charges, where available values are 
supplied. Full manuals available on some of above, SAE with enquiry, 



A. H. SUPPLIES 

57 Main Road Sheffield S9 5HL 
Telephone 444278 (0742) 



GETTING BORED WITH 
ELECTRONICS 

Some thing, are repetitive, once you have built 
an attabte multivibrator: they tend to get 
borirti — tried a 555 timer! It worki in mono or 
ascable model for long or short pulses («>P)- 
How about building a radio tuner for your 
record player, the ZN4I4 chip makes this 
simple ft 1. 101. LED.f We have a fantastic 
choice— LED lamp.— TIL209 or HP448Q, 4 for 
£1 SO for £10; large lamps (HP4B80). J5peach, 
50 'for £15. RED and GREEN LEDs £1 per pair. 
LED display.— TIL302 (or similar) £1.50 each, 
T1L3I2 (similar to MAM4> ""<*—'' "V 1 ™ 
quantity. T1L360 6 digit package £15 DL34 four 
digit package £10. DL61 (»(V) ttJO 
Phosphor diode dlnplayi DC 1 or DG 1 2 £1 each, 
CLOCKS CLOCKS CLOCKS CLOCKS 
Bvwood is now foremost in the LSI clock crip 
market (who else has four different clock chip, 
in itoek with two more on orderf). MM53 I — 
the original— £11 • 50, MK50I7AN with alarm 
and riefi o contro I. £ 1 5 • 50, M KS0 1 7A A w, th 
glarm or MK50I7BB with calendar, either of 
these two is offered with a PCB, socket »nd 
suitable displjyi (4 DGIli) at £14. 
Don't get bored, If none of the above fa«JT«« 
you how about liquid crystal displays, DVM 
chips, etc! This technology, i» here to stay, 
Bywood have got it or can get it— give ui a try. 
VAT. All price, above EXCLUDE VAT. add 10% 
P. & P, Please add lOp pott and packing. 
You can have dock data iheei. for a S.A.E. or 
our 1973 catalogue {Ind l.»ue) (or lip, (And 
we htvn't even mentioned our calculator, yet — 
but they ire In the catalogue). 
You may phone uu for help on 0-M2-A17S7; . and 
you can u.e your ACCESS card for phorie.or 
per.onal purehaic-— Service from Bywoool 

BYUODD 

ELECTRONICS 

181 EBBERNS ROAD, HEM EL 

HEMPSTEAD, HERTS. 0442 6J7S7 






382 



STEREO IC DECODER 

HIGH PERFORMANCE PHASE LOCKED LOOP 
{as in 'W.W.' Jury '72) 
MOTOROLA MC1310P EX STOCK DELIVERY 

SPECIFICATION:— Sec-station: 40dB 50Hi-15KHi. Distortion' 0-3%. UP level: 
560m V rms. 0,'P level: 485mV rms per channel. Input Impedance: 50k Q. Power 
requirements: 8-12V at 16mA. 

Will drive up to 75mA stereo "on" lamp or LED, 



KIT COMPRISES FIBREGLASS PCB 

(printed and tinned), Resistors, I.C, Capacitors, 
Preset Potm. &. Instructions. 



ONLY 

£3-40 



WHY PAY 
MORE! 

post tree. 



ONLY 

29p piusp.i 



LIGHT EMITTING DIODE 'Red) 
Suitable as stereo "on" Indicator, For above 
with panel mounting clip and instructions 

MCT310P only £2 77 plus p.p. 6p 
NOTE:— As the supplier of the first MC1310P decoder kit, of which we have 
sold literally thousands, our customers can benefit from our wide experience, 
V.A.T. :— From April 1st add V.A.T. at the standard rate to all prices. 

Fi-Comp Electronics 

BURTON ROAD, EGGINTON, DERBY, DE6 6GY 



' Mil 

| If you have difficulty in obtaining j 

I PRACTICAL I 

f WIRELESS | 

m Please place a regular order with your newsagent or m 

jj send 1 year's subscription (£2-65) to: — 

3 Subscription Department, 5 

1 Practical Wireless, j| 

| Tower House, Southampton Street, | 

| London, WC2E9QX 1 

VaHnouKauirjinuDiHiaiaisiDi. iiui!]i!iii;i;]ii^!:iiiiiaimigniiniqjnwstBBUii!&nBiuii 7 ■' s ^iiiiiI 



FELSTEAD ELECTRONICS (PW7I) 

LONGLEY LANE. GATLEY, CHEADLE, CHES. SK8 4EE 

Selection Tram our List, sent free for stamped addressed envelope, (Free oversea*, ami 
with all orders on recjoest). Caih with order only— No C.O.D. or Caller wrvice. Chareea 
(3tln, 7p) in brackets after all item* apply tt> «,B. and Hire only. HegM orders under SOp 
jihi- ..-liiirECH unacceptable. 8.A.B. please tor eimnlrleK or cannot be replied tn. Overseas, 
ineludine Eire and Channel Tsles, orders less W«'„ nil price!! rx-lnw, which include V.A.T. 
RECORDING TAPE: Finest qitaiitv'vnlue British Mylar available: STAN'DAUD B" 600ft. 
40p . 03' 900ft. 55p: 7' 1200ft. 82pf LOXtS PLAY 5* 900ft. 55p: 51' 1300ft. BSp: ?' lSOOIt. 
£1*<% (Charges for 5* and 5J". sincks Dp. two to four fn each; five and over 33pthe lot. 
For T. one or two lip each reel. ,1, 4 an d 3 r eels 33p the lot. 6 reels anil over 39p the lot.) 
Other sizes and nwimntrn in list. CASSETTES. T»n tyi«-t, Both in Library Oases, CtiO 33p, 
C90 48p, C120 7Bp. Deluxe Types: CW> 55p. C90 73p. OWO 89p. (Charges tor both types, 
under 5, Sp each. !i for 17' p. All rjuantities oi-er S, 28p the lot.) 

CARTRIDGES all with standard flttings and stylil. Stereo-compatible Mono CP91/8C 
98p; STEREO BP98 £1-36, Sti-r*" Ceramic OPM £175, [All at 7p each.) Comparative* 
shown in List, with more tvpes inc. Sonotane OTAItC, Stereo Ceramic Diamond fl-70 
(7pl DIAMOND STYLIT: simile tip tvpes: Acqs GF.T7, GP59, CPSS/iiT. GP71, B3R 
TCS/Ll'/ST: CQLLARQ O.P. and 1K.-231. GARRARD GC2. GCS, GCS10, GCE12, 
ROSETTE BK40. O.P. and T. PHILIPS 3301 OOflO, 30H6, 3302. 3,104). 3010/12/13/16, 
BOSOTOVE 19T/'JiiTALLAT3epeach[7p). SAPPHIRE I6p (7pl DIAMOND DOUBLE 
TIP TFRN'OVEH TVPES GS sup. on other side). For ACOS GP73, (SPftl (for iwtritteea 
OPB3, GP94 etc.) GP91SC (for stereo compat. types) 01*104 BSH ST4 (ST3, BT5). ST9 
(STS). STI2'14/15. SOSOTOSK 8TA. OTA, STATIC. PHILIPS 330(1 3310, 3224, 3228/39 
C-P2K0 GARRARD CCM2I, and 22. GCS23, GK82S and 96, GCM21T and 22T, CCM24T 
GCS23. GK32ST and 26T. GCM31. GCS36. QOBW, GCS3B. KS40A. K841B ETC. ALL 
AT eSp (7p). SAPPHIRE 32d i7pi. DODBLE DIAMOND STYLH: woe dia ST/LP tip eaeb 
side: no 78) All types £1-35 <7p>, SAPPHIRE DOCBLE ST/LP, TIPPED 32p (7p). 
DIAMOHD STYLII GOLDRISG REPLACEMERTS: ':»O0, G800H & f'fcSfl. £2 S5 each, 
C.800E. £3-75 (SB each). PICK-UP WIRE: super thin flex screened, sheathed. TWIN 7p 
per yard, 4-corc 13p per vanl (either up to fi vds. 7p). Over, charges paid. MICROPHONES: 
CRYSTAL: LAPEL IV", clip/hand, lead 3'Oinni Jack pine 39p (Up). CM'jn Cream Plastl 
hand 5Sp (9p); "MIC 43". Carved metal hand t'rip £110 ( I lp) ALL with lea. Is. DYNAMIC: 
Eicetlent Mike, SOK CI, only 3J" Inns, black, 'chrome. s» itched, lead wilt) 2-ft and 3'fl ram 
jack plmrsil. 37(8p). Cardial BaK,HK/eWQ built in volume cnatrol. im/nrf switch, special 
20ft lead, the best valne anywhere at £8 60 (33p): Tnl-dir mesh ball MK/SOOQ jack pin* 
cable, adaptor, £5 38 *33p): Omni-dir. Ball mesh. 6(!K. cable adaptor, jack pine, £4 29 
(33p eachi. SPEAKERS: Very popol-ir 12" ROUND, fitted tweeter, 3, 8 or 15 ohms 
(state which) £208 (33p) or pair for stereo £4-65, charpen paid. SMALL 21". 3 fi. 8 £1 or 
84 fi (state which) 41p (9p). More "ncakers in Lint. HEADPHONES: HiRh resistance 
2000 CI adjustable £110 (lip). EARPIECES: with, lead and min. 2 Omni or 3 Srnni (state 
which) jack phut. ntAOSBTIC 13p. CRYSTAL (3'Smm plug only) 28p (up to fi for 9p 
aiiT size). SOLDERING IRON: Slim, modern. British hiuh speed. H\", all part? replaceable, 
hlch-.st qualitv. lullv euaranteed £1 29 (llpl- TRANSFORMERS: Bob-nita 11 x II x 
llmta. OUTPCT (3vl [or OC72,ete.) 18p or DRI%"ER 17p(Lp to 19 for 7p). CORNECTINO 
WIRE: Packs ot S coils, each coil 5 vds. Assts. crds. SOLID CORE 18p (7p). FLEXIBLE 
COKE 18p [By). RETRACTABLE FLEXIBLE LEADS (CURLIES) with phono plrnr each 
end, or phono pbiir one end, phono socket at the other (state which) 8ft , 3up: 12ft, 53p 
(cllhcr 7p). VIBRATORS: 12v/4 pin non-synch 12IIID4, 2J" ex. pins, 33p. SAME but 
31" ex. pins. DBA, 181n. 19v/7 pin svneh. (12Slti) Bl* ex. pins, 72p (Op any type). 
MAINS BATTERY ELIMINATORS: Two models, tioth 240v A.C. Input. Suit most radios 
and cassette recordern/players with front switch, pilot lights, mains and output leads 
Model SO, 3. 6, 71 and 9v 400mA. stabilised with multi-output adaptor £5 50 (35j>) 
Model S.R. ha- a.ldi(Ional I'2v output and is 500mA £800 (35p). 

OV^R LIST (see beading) has added to the above Items Cartridge and Stylii Comparison 
Special Son-repeatable Offers, Aerials, Dials. Transistors, Miilll-Leads, Plugs, Socket 
ol many typ-s, Speakers, Vol. Controls, Multi-testers, Mike Inserts, Neons. Indicators 
BTEREO "Headphones, Pocket Berewd river Testers, Tel. Pick-ups, Wire, Cable, etc., etc. 



INDEX TO ADVERTISERS 



A.H. Supplies 324, 332 

ArJFonic ... 380 

Antex Ltd 293 

Arrow Electronics 367 

Audionic 380 

B.R.B 380 

B.H. Com portent Factors Ltd, ... 292 

Baines. R 378 

Baker Loudspeakers Ltd. ... ... 292 

Bedford Electronics ... ... ... 381 

Bencley Acoustic Corporation Ltd. ... 344 

Bernard, Gerald 352 

B.I.E.T ", ...306, Cover iti 

Bi-Pak Semiconductors ... 301, 302, 303 

Bi-Pre-Pak Ltd. .: 363 

Boffin Projects 380 

British National Radio and Electronic 

School 288, 343 

Broadway Electronics ... ... ... 344 

Bull, j, (Electrical) Ltd 359 

By wood Electronics ... ... ... 382 

C.C.I.L Ltd 306 

C.T. Electronics 381 

Caranna, C. ... ... ... ... 378 

Chiltmead Ltd 348 

Chromasonic Electronics ... ... 347 

Colomor Electronics Ltd 360 

Comet High-Fid el icy Discount Ware- 
houses 308. 309 

Control Data Institute 360 

D.E.W. Ltd 381 

Dabar Electronic Products ... ... 364 

Denco (Claeton) Ltd 378 

Discosound ... ... ... ... 30S 

Douglas Electronic Industries Ltd. ... 373 

Eleetrokit 292 

Electronic Mail Order 381 

Electronic Design Associates 344 

Electrospares ... ... ... ... 372 

Electrovatue ... ... ... ... 323 

Elekon Enterprises 381 

EWins Electronic Musical Instruments 372 



Felstead Electronics 
Fi-Comp Electronics 
Francis, J.J. Ltd 

Galleon Trading 
Gladstone Radio 
Green weld Electronics 



383 
383 
298 

379 
352 
372 



HAC Shortwave Products 328 

Harrow College of Technology and Art 379 

Harverson Surplus Co. Ltd. ... ... 375 

Heath (Gloucester) Ltd. 304 

Henry's Radio Ltd. ... Cover ii, 355 

Home Radio (Components) Ltd. ... 310 

I.C.S 352 

I.L.P. (Electronics) Ltd. 295 

Imhof 324 

Integrex Ltd 300 

Jef Electronics ... ... ... 380 

Jermnyn Industries ... ... ... 299 

Johns Radio 294 

Johnson (Radio) 379 

K.V.A. Electronics 328 

Kensington Supplies 378 

Keytronics ... ... ... ... 294 

Lasky's Radio Ltd 306 

Lewis Radio ... ... ... ... 348 

Linear Products Ltd. ... 294 

London Computer Operators Training 

Centre ... ... ... ... 292 

London Electronic College 379 

MagtorLtd 294 

Mapl in Electronic Supplies 298 

Marco Trading Ltd. ... ... ... 379 

Milward, G.F 382 

Mir.ikits Electronics 360 

Morse 378 

Multicore Solders Ltd 304 

Mullard Ltd ... 365 



Padgetts Radio Store ... 
Partridge Electronics Ltd. 

Piccadilly 

Pern bridge College 
Phonosonics 



... 304 
... 364 
Cover iv 
... 324 
... 352 



R.D.I. Ltd 379 

R.E. Publications ... 381 

R.S. Components ... ... ... 378 

Radio Component Specialists ... ... 351 

Radio Book Service 378 

Radio Exchange Co, Ltd. ... ... 327 

Radio & T.V. Components (Acton) Ltd. 



Radio Society of Great Britain 

Readers Radio 

Redhawk Sales 

Riversdale Electronics Ltd. 
Rossless Services 
RSC (Hi-Fi Centres) Ltd. 
R.S.T. Vaive Mail Order Co, .. 

S. & W. Electronics 

Saxon Entertainments 

Semicon Index Ltd. 

Sinclair Radionics Ltd 

Smith. G.W. & Co, Ltd. 368, 

Surplectronics 

Swanley Electronics 

Tele radio Co. Ltd. 

Thaeker, A.H. & Sons Ltd. 

Tidman Mat) Order 

Trade Aids 

Trade Disposals 

Tram pus Electronix 

Trannics ... 

Tuac Ltd. 

West London Direct Supplies 
Weyrad (Electronics) Ltd. 

Wheel 

Wilmslow Audio 

Xeroza Radio 

York Electronics 

Z. & I. Aero Services 



296. 297 
... 374 
... 348 
... 380 
... 364 
... 380 

290,291 
... 374 

... 380 
... 311 
... 378 
376. 377 
369, 370, 371 
... 310 
... 328 

... 379 

... 300 

... 378 

... 373 

... 380 

... 380 
307 

... 373 

... 373 

... 306 
... 381 
300, 328 

... 344 

... 310 

... 384 



383 



Head Oftkt and Warthout* 
4a WESTBOURNE GROVE 
LONDON W2 SSF 
Til: 737 SMI /J J 



Z & I AERO SERVICES LTD. 

Pltaie Mnd all cor mpondence and Mall-Ordart to Head Office 

When landing- eaih with ord«r, pl«aj* include I2±np in I for poieaja and handling 

MINIMUM CHARGE ISnp, No COD. orden accepted 

Plewe note that the valval offered below art not nece«aril)r of U.K. origin 



Retail Shop 

0S TOTTENHAM COURT ROAD 

LONDON WI 

Tel: 580 8403 

Open all day Saturday 



OA'J 


0.40 


OA3 


0.48 


OB9 


0.40 


OBI 


0.70 


OC3 


0.40 


ODS 


0.40 


iB3i/r 


0.45 

o.es 


1L4 


1F.4 


0,60 


IRS 


0.45 


1B4 


0.10 


IBS 


0.80 


1T4 


0.80 


III* 


0.40 


\vt 


0.78 


IV2 


0.88 


1X3 It 


0.88 


9D21 


0.40 


SA4 


0.48 


8A8 


0,78 


IB4 


0.40 


SV4 


0.70 



SAS7U 0.85 
BATfi 0.88 
6ATJ6 0.80 
8AV8 0.40 
5AWBA 0.88 

en as o.es 

6BE8 0.88 
8BF8 0.88 
3BH6 0.78 
8BJ6 0.88 
6BK7A 0.78 
6BN6 0.48 



8BN8 
SBQS 



0,80 
O.ES 



0.48 

0.88 



6R4GY 0.75 

6U4U 0.40 

EV4U 0.80 

erSUT 0.48 

523 0.75 

EZ4U 0.48 

5/30L-J 0.80 

8AB4 0.48 

6AF4A 0.80 

8 AG 5 0.25 

6A07 0.48 

6 AH 6 0.80 

6AJ8 0.S0 

8AK0 0.40 

8AK6 0.80 

SALS 0.43 

SALS 0.22 

SAMS 0.87 

8AQS 0.42 

6AQ6 0.70 

BARS 0.88 

BARS 0.65 

SABS 0.80 



8BR8 0.75 

6B37 1.88 

8I1WS 0.80 

8BW7 0.00 

8BX8 O.ES 

6C4 

bcsot o.es 

BCBfl 0.4Q 
BCDtHiA 

1.80 

ecu? o.eo 

Bt'Lfi 0.80 

ecus oso 

BCW4 0.70 

6CYS O.50 

6CY7 0.75 

cr»3 0.88 

6L>Ci: 0.80 

ours o.eo 

8DQ6U 0.75 

ADS4 1.26 

6KAS 0.6S 

8EH7 0.30 

BEJ7 0.36 

SEWS 0.70 

8F1 0.76 

6F5 0.76 

fiFfii. 0.4S 

8F11 0.60 



8F13 
6FI4 
6F]B 
6F1B 

6F23 
6F24 
ef'JS 
BF26 
8F2B 



0.60 
0.70 
0.65 
0,80 
0.80 
0.80 
1.00 
0.8G 
0.70 



60K6 0,80 

8J4 0.80 

6JSUT 0.40 

6JS 0.80 

SJ7 0.48 

c,K-in o.eo 

6KM1T 0.75 

SK7 0.43 

6K8<! 0.46 

8K25 0.76 

SLStiT 0.58 I 

fil.7 0.46 

8L18 0.50 * 

6LD20 0.60 ! 

6N7(;T 0.66 ' 

eru o.es 



10D1 

10D2 

10F1 

10F9 

10F1S 

10L1 



0.88 
0.55 I 
0.76 I 
0.88 
0,80 
0.80 



Rrtt Quality Fully Guaranteed 



0.50 
0.46 
0.45 
0.60 



i sba; 

I 6HU' 

88K 

63L7(iT0.45 

68K7OT0.46 

I 6SQ7 0.50 

' 68 K7 0.60 

6T8 0.88 

8U4UT 0.70 

el'SU 76 

6UBA 0.48 

eviiCT 0.46 

! 8X4 0.40 

| 6XSUT 0.45 

6X8 0.85 

6 Yiili O.liO 

I 7Y4 0.75 

| 9BWH 0.70 

. 10CU 0.60 



1OLDU0.70 

10P13 0.75 

12ABB 0.70 

12AC8 0.80 

I2AE6 0.80 

12AL5 0.65 

12AQS 0.60 

12AT4 0.40 

12 AT 7 0.40 

12AU4 0.46 

]2A!T 0,88 

12AV6 0.46 

12AVT 0.70 

ISAX7 0.88 

12AY7 0.76 

12B4A 0.88 

12BA6 0.46 

12BA7 0.60 

12BKB 0.50 

I2BH7 0.60 

12BY7 0.85 

13E1 3.00 

12K0 100 
12K7OT0.50 
12Q7«T0.4S 

1BBR7 0.50 
!0P1 




■RAND 



EK9B 0.40 

EF97 0.66 

EF03 0.75 

EF183 0.30 

EF184 0.85 

EF804 1.28 

EK90 0.88 



ELECTRONIC VALVES 



20L1 
20F1 

20F4 
20 F5 
25C6 



0.60 

1.10 I 
0.50 l 

1.10 

1.20 

c.eu 



toci' 


1.10 ■ 


30C18 


0.8O ] 


30F8 


1.00 1 


S0FL1 


0.80 


30FL12 1.10 


3QFL14 0.80 


301.1 


0.40 


3DL15 


0.05 


30L17 


0.85 


80F13 


1.00 


30P19 


0.95 


30PL1 


0.95 


30FL13 1.10 


30PL14 1.25 


35 A3 


0.80 


35 A 5 


0.75 


35B5 


0.86 


36C5 


0.80 


351>5 


0.76 



£.40 
1.60 
0.78 
£.40 
0.60 
4,00 
0.36 
0.70 
1.75 
1.60 



'6L6UT0.60 
■J5Z4'- 0.36 
75ZBUT0.76 

30 a 5 o.eo 

30AK3 0.40 
30CJ 0.80 
30C13 1.00 



TRANSISTORS 

OWK08 0.16 1 AC128 0. 



0.15 
0.16 
0.80 
0.70 
0.10 
0.15 
O.ES 
0,80 
0,20 
0.80 
0.25 
0.25 
1.25 



O.EO 
0.20 
0.25 
O.ES 
0.26 
0.E6 



0.76 
0.76 
0.80 
0.26 
0.20 
0.20 



2N696 
2N897 

2N6S» 

3N70S 

2N706 

3K70B 

2N75J 

2N929 

2N080 

fit! 9*7 

BN1131 

2N1132 

BN1184 

2M1302 0.17 

3N1303 0.17 

ON 1304 

2N1808 

2N1308 

OS 1807 

3S1B0S 

2S1S09 

3N1613 0.17 

2S1711 0.E0 

2S17B8 

2N2147 

3N2180 

3N2217 

as 22 IS 

2N2219 

2S23S9A 0.16 

2N2477 0.66 

2N2848 

2S3905 

2S2923 

2N2924 
2S2926 

2NS053 

2N3054 

2S308S 

2S313S 

2X3134 

2SS391 

2N3392 

2N3393 

2S3394 

2N339S 

•i N 3402 

2N3403 

2S3404 

2S3414 

2S3415 

3S341T 

2X3702 

2S370J 

2N3704 

as 37 07 

2 N 3709 

2N3710 

3N3H19 

2 N 3906 

2S702 



2B746 
ACUS 
A0125 
AU126 
AC127 



0.40 
0.25 
0.12 
0.18 
0.10 
O.EO 
0.60 

o.eo 

0.25 
0.25 
0.17 
0.17 
0.15 
0.16 
0.20 
0.16 
0.16 
0.32 
O.EO 
0.15 
0.26 
0.10 
.0.10 
0.18 
0.12 
0.10 
0.10 
0.35 
0.26 
0.60 
0.25 
0.16 
0.30 
0.20 
0.17 



AC128 

AC1S2 

AC163 

AC164 

AC157 

AC169 

AC176 

AC1B7 

AC 188 

ACT17 

ACY16 

ACY19 

ACY20 

ACY21 

ACY22 

AD 140 

AD149 

AD161 

AD182 

ADZ11 

ADZ 12 

AF114 

AF115 

AF118 

AF117 

AF11S 

AF12S 

AF127 

AF180 

AF1S1 

AF1B6 

AF239 

AFZ11 

AFZ12 

A9Y28 

A8Y27 

ABY2S 

ABY2B 

ABY54 

A8Z13 

ABZ16 

AB217 

A821B 

ABZ20 

ABZ21 

AUY10 

I5C10T 

BC108 

DO 109 

BC113 

BC11B 

BC134 

BC147 

BCI48 

J1C149 

BC1S2 

BC15S 

BC175 

BC1S6 

UCY30 

BCY31 

BCY33 

BCY34 

BOY73 

BC7.10 

BUZU 



0.18 

0.36 

0.20 

0.16 

0.17 

0.10 

0.17 

0.25 

0.25 

0.26 

0.20 

0.25 

0.20 

O.EO 

0.10 

0.60 

0.46 

0.86 

0.86 

1.2S 

1.25 

0.17 

0.17 

0.17 

0.1T 

0.80 

0.20 

0.E0 

0.85 

0.35 

0.40 

0.86 

0.46 

1.00 

0.25 

0.80 

0.26 

0.80 

0.26 

0.70 

0.70 

0.75 

0.75 

O.ES 

0.40 

100 

0.10 

0.10 

0.10 

0.10 

0.80 

0.20 

0.10 

0.10 

0.12 

0.16 

0.15 

0.20 

0.25 

0.26 

0.30 

0.25 

0.30 

0.16 

0.80 

0.40 



BD121 


0.66 


BD123 


0.80 


BD124 


0.80 


BD131 


0.75 


BD132 


O.S0 


BF116 


0.20 


BF167 


0.18 


BF173 


0.20 


BF179 


0.80 


BF1S0 


0.80 


BFI81 


0.80 


BF184 


0.20 


BF185 


0.20 


BF194 


0.14 


BF195 


0.14 


BFI96 


0.12 


BF197 


o.ie 


BF200 


0.85 


BFW87 


0.25 


BFW8S 


0.20 


BFW89 


o.eo 


BFW91 


0.20 


BFXBS 


0.20 


BFY17 


0.40 


BFY19 


0.26 


BFY50 


0.20 


BFY51 


0.20 


BFYB2 


0.20 


BBY28 


0.17 


B8Y27 


0.15 


BSTS8 


0.17 


B9YB5 


0.20 


BBY93A 


0.12 


OC16 


0.50 


OC23 


0.60 


OC2S 


0.80 


UC24 


0.60 


OC25 


0.35 


OC26 


0.28 


OC29 


0.60 


OC35 


0.60 


OC36 


0.45 


OC42 


0.20 


OC44 


0.15 


OC45 


0.12 


OC70 


0.10 


OC71 


0.12 


OC72 


0.12 


OC73 


0.30 


OC75 


0.16 


OC76 


0.15 


OC78 


0.26 


OC781) 


0.20 


OC81 


0.20 


OC81D 


0.20 


OCB3 


0.20 


OCI39 


0.80 


OC140 


0.36 


OC141 


0.60 


OC170 


0.28 


OC171 


0.28 


oejoo 


0.80 


OC201 


0.60 


OC202 


0.85 


OC203 


0.40 


OC204 


0.40 



35L6UT0.75 
30 W4 0.40 
3523 0.75 
3524a 0.40 

3BZ5OT0.70 
50 AG 0.80 
SOBS 0.70 
50C5 0.60 
50CD6(J1.£0 
S0EH5 0.65 
60LBGT 0.80 
85A2 0.55 



90AI. 

90 A V 

90C1 

90CV 

807 

S13 

866 A 

5642 

6080 

6146 

8146 B 2.50 

6360 1.26 

6939 

7199 

TS86 

7S9S 

A99W 220 

A21 0.60 

A231 

CBLI 

CBL31 1.00 

CY1 0.60 

CY31 0.50 

DAF9S 0.50 

DF9B 0.60 

DK92 0.70 

DK96 0.60 

DL9S 0.66 

DM70 0.60 

DM180 0.68 

DYS1 0.5S 



2.25 

0.85 
1.50 
1.60 



0.66 
0.90 



DYS'i 0.35 
DYS7 0.88 
DY802 0.37 
E80F 1.35 
E88CC 0,70 
R180F 1.00 
E810F 2-90 

■iimmuli 

EAF42 0.80 

EBC33 0.80 
KBC41 0.B6 
EBCS1 0.33 
EBF80 0.40 
EBF83 0.40 
EBF89 0.32 
EBL31 1-60 
EC53 0.50 



I EC80 

| ECB6 

ECSS 

EC90 

EC93 

, EC93 



2.65 
0.80 
0.60 
0,35 

0.46 
0.80 



KCC6S 0.40 
KCC89 0.50 
ECC91 0.30 
ECC189 0.65 
ECCB07 1.00 
EOF60 0.36 
ECF83 0.36 
BCFSMUa 
ECH42 0.75 
ECHS1 0.20 
ECBS3 0.45 
ECHS4 0.45 
ECL80 0.60 
ECL81 0.50 
ECL83 0.86 
ECLB3 0.70 
ECL84 0.65 
ECLB5 0.56 
ECLS6 0.40 
ECLl^OO 

3-20 
EF37A 1.00 
EF40 0.60 



EL34 
EL30 
EL41 
F.L81 

EL83 

KI.il 
EL85 



0.50 
0.60 
0.76 
0.56 
0.60 
025 
0.43 



ELS 6 O.40 

EL90 0.42 

EL3B0 1.15 

EL832 1,50 

ELL80 0.88 

EM 71 0.80 

EU80 0.46 

EM93 0.50 

EMB4 0,85 

EM 85 1.00 



EM87 

EN91 

I EYSt 



0.70 
0.40 
0.40 



EY83 0.66 
EYBB 0.40 



: EZ40 
EZ41 
EZB0 
EZ81 



ECC35 1.00 

KCC40 0.70 

ECG81 0.40 

EOCS3 0.88 

ECC83 0.33 

ECC84 0.30 



I EF41 
i EF43 
EFS0 
EF86 
EFBS 
EFB9 
EF91 
EF02 



0.65 
0.70 
0.30 
0.35 
0.30 
0.28 
0.37 
0.35 



0.50 
0.76 
0.28 

0.20 



GT1C 3.00 

GYS01 0.70 

GZ30 0.46 

UZ31 0.40 

GZ32 0.60 

GZ34 0.60 
ITABC800,58 



JIK90 0.50 
KT6B 2.35 
KT77 100 
KT8S 2 26 
S7B 160 
PABC800.4O 
PC86 0.60 
PC 88 0.60 
PC9U 0.60 
PC97 0.60 
PC900 0.48 
FCC84 0.40 
PCCS6 0.40 
PCCS8 0.55 
PCC89 0.55 
PCCSB9 0.60 
PCCS05 0.85 
PCC806 0.85 
FCF80 0.30 
PCFS3 0.36 
PCFS4 0.60 
PC FSB 0.80 
PCF87 110 
FCF801 0,60 
FCF802 0.50 
FCF80S0.90 
PCF8080.75 
, FCF808 0.90 
PCH20O0.70 
FCLSt 0.5O 
I PCW2 0.85 
| rC.L83 0.65 
1 PCL84 0.45 
FCX88 0.45 
PCLB3 1.26 
FCL200 0.75 
PCILSOO 1.10 
PCLB01 0.95 
PCT.80S 0.60 
FDSOO 1.30 
PF86 0.70 
FFB1B 1.00 

pFiaooe.es 



PI.33 0.4O t 

PL 3 6 0.65 

PL81 0,60 

FLS2 0.46 

PL83 0.46 

PL84 0.40 | 

FL302 0.95 I 

PLS04 0.75 

PL50B 0.80 

FLS09 1.10 

PMOl 1.00 I 

PL802 0'85 

FMS4 0.60 

PY31 0.36 

PY33 0.83 

PT80 0,40 



FY81 

FYS 2 
FY83 



0.30 
0.35 
0.88 



FYB8 0.40 
PY500 1.00 
PY800 0.47 
FY801 0.50 
PZ30 0.S8 
QQVOS-fl 

E.E5 
QQVO3-10 

1.25 
TT21 8.80 
TT22 4.00 
U18 20 0.75 
U25 0.85 



U404 0.70 

i;soi o^« 

UABC80 

0.40 
TAF41 0.70 
IIAF43 0.80 
VB41 065 
UBC41 0.66 
LIBC81 0.48 
UBF80 0.40 
UBFB9 0.40 
UBL1 0.70 
UBL21 0.70 
UC92 0.46 
I'CCSS 0.46 
UCF80 0.70 
UCH21 0.80 
UCH43 0.70 
UCB81 0.40 
UCLS1 0.60 
XJGL82 0.35 
1JCLS1 0.85 
UF9 0,86 



U26 
U3) 
V31 
U63 
1176 
U78 

inoi 

C201 
U281 
D282 
L-301 
U403 



0.86 

0.70 
6.60 
0.40 
0.40 
0.40 
0.75 
0.60 
0.65 
0.66 
0.55 
0.70 



CF11 
UF41 
0F43 
UF4S 
UFSO 
UFS5 
l'F89 

rm 

ULS4 



0.60 
0.66 
0.85 
0.85 
1.36 
0.40 
4 40 
065 
0.43 



UM84 0.80 
CT1S 0.80 



UY11 
UY41 

UY83 

UY85 

W72B 

XC12 

Y63 

2759 



1.00 
0.46 

0.50 
0.40 
0.75 
60 
075 
3.80 



28 043 4.50 
ZB058 7.00 
ZS03XJ 1.85 




MULTIMETERS MADE IN USSR 

Prices of these exceptionally well made Instruments range 
from £4-95 to £10-50. Please write for Illustrated catalogue. 



SYNCHROSCOPE TYPE C1-5 




Matic in rsan 



3- in lulw fitted wilti telescopic viewing boot I, giving 
bright dltplay in full daylight. Seciltlvity ]0mV/mra 
(narrow band) to SOmV/iwn (wide band). 
Bandwidth 10 cja — 10 me/s. Triggered iweep pre-»et 
at 1-2-S-10-30-IOO-300-1000-3000 >i»ec per utroite. 
Free -running time ba»e 20 o/s to 200!tc/» with built-in 
crvotat calibrator providing timing marks at 00..2-1-S- 
20-100 u sea. 

Amptituda calibrator dlreclly calibrated lit VOW, 
Input attenuator 1-10-100. 
Power suppliei 127/230v AC. 
PRICE 28900. Packing and carriage £1-50. 



Series BZX61 1-watt ZENEB Diodei 
Available In: 7 S-8-2-ll-l5^16-34-27-30-38-S6-82-68 
volts. 80-8 each. 

"" DIODES 





0'26 


OA81 


007 




0-12 


OAB0 


07 




0-18 


oAse 


015 


OA10 


(1-20 


OA80 


007 




COB 


OA91 " 


007 


OA70 


007 


OA9S 


07 


OA79 


C-07 


OA200 


007 


MINIATURE SILK 


:ON HALF-WAVE 




WIRE-ENDED 


RECTIFIERS 




IN 4003 


100 p.l.v. 


1A 


0-07 

009 


IN4004 


400 p.i.v. 


1A 


1X4008 


800 p.l.v. 


1A 




IN 53911 


1000 p.i.v. 


1-5A 


025 


1.S540* 


1OO0 p.i.v. 


3-OA 




BY101 


450 p.l.v. 


11A 




BYIOO 


BOO p.l.v. 


11A 




BY127 


1250 pJ.v. 


1A 




DD00O 


60 p.I.v. 


500mA 




UDOOli 


400 p.l.v. 


SOOmA 




DDOSa 


H00 p.l.v. 


500mA 


0-88 



VALUE ADDED TAX 

THE ABOVE PRICES DO HOT IKCLTJDE V.A.T. WHE» 
REMITTIMO CASH WITH ORDERS PLEASE ADD 
10% O* THE VALUE OP GOODS WCL™!^ PO S TA?S 
AHD HAHDLIRB. AB 80MR OF THB ITB1U STILL 
CONTAW THE PR0P0BTIOH OP P^9JS** E TAX, 
BESPECTTVE AMOtTJiT WILL BR BgyPlDKD. 



384 



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