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Complete Audio/Tuner Kits Radio/Audio/Communications Modules

We have various RC ICs. including NE544NE5044, and two new ones from OKI

KB4445 4 channel dig.prop. FM TX IC. 30mW out (amplifyable) -£2.30 incKB4446 4/5 ch. dig. prop FM RX IC. Suits KB4445 or RCME cyst. £2.65.KB4445/6 pair: E4.75. New 8 page data -sheet 35 + SAE. More RC ICs in list

More features and facilities, thanksto DC switching and control design

revievving the most comprehensive audio preamplifier yet DC switching of 7 inputs, plustwo tape in/outs 2 low pass, 2 high pass active filters, genuine volum- 'ated loudness, ldf3channel matching, with DC volume, balance, bass and treble controls. qable for bus/remotecontrol, tape dubbing, switched monitor etc. 1313d13 S/N+, THD -75dB .x better. Pluggable PUequalization boards, tone control override. Price for comtete unit about £149 no VAT.

SemiconductorsRadio/Communications ICs

CA3089ECA3189EHA1137WHA11225HA12412KB4420TBA120SKt34406

5L1610SL1611SL1612SL 1613SL1620S1.1623SL 1624SL1625

2,112.531.952.472.811.951.15090

1.841.841 842 172.502.803.772.50

HA1197CA3123ETDA1072TBA651TDA1090TDA 1220TDA1083TDA1062

SL1626 2.80SL 1630 1.86SL1640 2.17SL1641 2.17SL6600 4.31SL6640 3.16SL6690 3.68MC1496 1.44

1.611.613.092.533511.612.242.24

SD6000TDA4420MC1330PMC1350PK84412KB4413KB4417MC3357P

4.312.591.381.382.242.242.533.16

FOR COMPLETE LISTINGSSEE OUR NEW PRICELIST

VARICAP DIODESA section from our PL.BA102 0.35 16'.1 ratio AM tuning88204 0.41 KV1215 9v triple 2.9388105 0.41 KV1211 9v dual 2.0188109 0.31 KV1225 25v triple 116MVAM2 1.93 88212 9v dual 2.25

POWER MOSFETS 100W PA's made simpleince pioneering t 1 W comp ementary OSFET technique Hitachi have developed a range

of output devices and drivers that ought to revolutionise opinions and attitudes towards thedesign of all L F amplification systems. We have a new 48 page application note (£1.50 inc) andcomplete sets of parts, modules and now the new complete PA system (see above).2SK133 120v N-ch 100W MOSFET £6.33 2SJ48 Pch complement £6.332SK135 160v N-ch 100W MOSFET £7.29 2SJ50 Pch complement £7.39PA1016 Kit for 100W MOSFET PA less Heatsink £16.10. £23 inc heatsink/bkt)

ULTRA

VW.

I t 9519

Mk III FM Tuner series Carriage for Mk III tuner £3 inc

The Mark III series FM tuner has been updated, and now includes acentre zero tuning meter as standard. The instruction manual has beenmeticulously revised, enabling easy assembly by constructors of variouslevels of experience a preview copy may be purchased for £1.00.Mark III A series 'Reference series' tuner modules £171.35 inc.Mark Ill B senet 'Hyperfi' modules, with switched

IF BW, pilot cancel decoder £198.95 inc.A matching synthesise, unit will be made available later this year, and can beretrofitted to either version. All versions include digital frequency readout/clock,VU deviation meters, 6 preset stations, 10 turn pot manual tuning, toroidal PSU,output level adjustment, 110/240v AC input. Full alignment service available.

Power Amplifier Style and performance with a real'belt and braces' PSU design.

After a couple of preview comments. it seems that many of you are waiting to hearabout the matching HMOSFET power amplifier for the Mk III tuner. Well, it's outat last - complete with twin toroidal PSUs for comfortable 80W RMS per channel,over 100W peak, but limited by thermal shutdown of the HMOS. 10W -100W logLED output peak indicator, DC offset protection and switch -on pause relay. AC orDC input coupling, direct or relay protected output terminals. The works.Only one version of this item. Cornplete kit £178.25 inc. Carr. £5.

Preamplifier

LOW NOISE PU PREAMPLIFIERThe HA12017 is the last word in PU preamps, and general low noise audio design.It is an SIL IC, with 86dB S/N in RIAA configuration, 10v RMS output capability,0.002% typ THD at 10v RMS output (imagine the overload margin !!). It comfort-ably supercedes discrete circuit designs in terms of price/performance, and takesthe art beyond the TDA1042's capabilities. (Replaces HA14571 £1.80 each . oran RIAA applications PCB with two ICs for E5.75. Complete with Rs&Cs £9.95.

Radio Con trol ICs

CMOS, LPSNTTL, TTL, MPUListings in the new iricelist.

Coming SoonSSB transceiver system : 10kHz to 1000MHz !!

Most CMOS Is available in lowvolume also L PSN. Standardlinears and TTL OK.

Things like ICM721613, ICL8038, 8080A, 6800P, 2708, NE555,NE556, etcContain yourselves, RF fans i Not yet ready fora full launch until autumn but reviewed here

A modular VLF to UHF SSB TX FIX system at last. With the correct first miner, the basic PCBcovers 10kM, to 1000MHz using LO fed from eat source (Our 2 IC Mullard synth for instance)and RF PA for TX OP 0 2uV basic sensitivity in HE Typ cost for HF synth SSB RX will beless than 1200 Add an RF PA for full TRX for another £50 See one in our foyer, and marvel.

Please send anSAE with allenquiries.Phone orders byACCESS butminimum E5Callers welcome

LW -MW -SW -SW DC tuned and switched91072 All switching of bands by a single

pin to grid. Varicap tuned, with LOoutput for synth. MW/LW versionor MW/LW plus 1 or 2 SW bandsMW/LW: E15.58 +1SW £16.73

VHF TunerheadsEuropes largest stock range for broadcast andcommunications. Probably also the world's -details in the catalogues and PL. Specials arealso supplied in the region 30-220MHz.

Pilot Cancel PLL Stereo decodersAgain. Europe's widest range of stereo decodersincluding pilot cancel PLL types. The pic showsthe 944378 pilot cancel including post decoder26/38kHz filtering and muting preamp output

Switched bandwidth FM IF strips

944378 2I-26 45

Broadcast FM IF strips for all occasions, including the new 911225 with diodeswitched narrow filter option, ultra linear phase ceramic filters, 84dB S/N, and0.04% THD (40kHz deviation). Plus usual things like AGC, AFC, der. mute, levelmeter drive. £23.95 (supplied in screen can with 0.1 edge connection system)Also the 7230 hyperfi series - as the 911225, but with slope controlled AFC thatoper3tes in conjunction with signal level and an extra IF amp stage for DXing.

Various digital frequency displaysThe World's largest range of receiver DFMs is nowjoined by the DFM7 (shown) - and L shaped versionof the DFM3 with remote display mount connectorpossibility . 1kHz SW resolution with 455kHz or10.7MHz offsets, 100Hz res up to 3.9999MHz, andVHF to 299.99 MHz in 10kHz steps £41.75

Components

Crystal Filters Most popular types are availableex stock, and in quantity

10.7MHz 25kHz Channel spacing 8pole12hkHz2.4kHz SSBMonolithic dual roofing filter

34.5MHz 1.3dB loss, 80dB stopband HFfirst filter in synth. RX

RC XTALS FM pairs (no splits)AM pairs ..

USB/LSB Xtals for 10 7SSB filter

Piezo Sounders

E16.67£17.82E19.78E2.30

£36.80E3.74£3.57£2.88 ea

The most efficient warning so -ratters yet

The latest thing in electro-acoustic efficiency. 1mA of drive fromCMOS will give an SPL of 83dB 10v RMS drive from CMOS uses3mA for 100dB SPL at 4.8kHz (88dB at 1.65kHz)The data sheets shows various drive circuits, and give fullspecifications with regard to broadband responses and powerconsumption etc. 1 off 44p inc. 100 off 28.75p (25p ex vat)

Keyboard switches and capsFrom the world's most widely used switchmanufacturers - ALPS come the biggest andbest range of keyswitches, and data entry key-board switches. The SCM81101 is shown here,with the KT5 2 -part cap (with clear top, to enableeasy fitting of your chosen legend. Other types areavailable with built in LED. 900 mounting etc.SCM81101 17p, K T5 - 16p - or 29p/pair

LCD CLOCKSLCD DVM

Clocks use 1.5vat 15uA only.DVM 9v/1mA

CM161 7mm LCD 12/24hr, alarms etc £11.44 eachCM172. 13mm, 12hr, alarms,timer etc E14.32 eachCM174: 13mm, 12hr, min/sec stopwatch £14.32 eaDVM 176: ICM7106 based LCD 3Y2digit E22.36 each

switch

12.5

WHAT's NEW at AMBITNEW PRICELIST/SHORTFORM:-28 pages, FOC with AS SAE pse

Bigger pant than ourrecent one page listand vastly extended

If you still need convincing to invest Li 60 in the cats, be mean and get this first.

POWER MOSFET APPLICATIONSHANDBOOK b HITACHI :

£1.50 each or freewith pairs of HMOSand the PA1018

Everything you should know about HMOSF ET devices theory and applications

ambit so chomp. so please phone anr1 cheer or Pout.

CATALOGUES 6 ea . all three for CI 60 CINO PS EASE Commerchol MA terms on appircatronPRICES SHOWN CHARGEC VAT Goods am offered sob,. to wariabrh. sorer, soh*.POST/PACKAGE NOW Me

INTERNATIONAL

200 north Seruice Rood, Brentwood, EssexTELEPHONE (STD 0277) 230909 TELEX 995194 AMBIT G POSTCODE CM14 4SG

Pans 1-3AMBITcatalogues60p ea, orE1.60 thelot.

2_

AUGUST 1980Vol. 2 No.10

Editor: Ron Harris B.ScAssistant Editor: Rick Maybury.

Project Editor: Keith BrindleyArt Director: Diego Rincon ats

playing away in your car p.1 1

a steady hand with her around? p.41

works wonders for trannies p.29

Technical Artists: Paul Edwards, Tony Strakas

Advertisement Department: GroupAdvertisement Manager: Christopher Surgenor;

Advertisement Manager: Steve Howe;Advertisement Representative: Roy Perryment,

Editorial Assistant: Tina Boylan

Managing Director: T J. Connell.

PROJECTSEQUITONE CAR EQUALISER 21Very simple project to give your car some tone!RADIO TIMER 29

41

49

57

62

PCB FOIL PATTERNS 73The other side of our projects!

Inexpensive way to turn your trannie off!PASS THE LOOP GAMEEasy way to raise funds - and a few laughs!MOVEMENT ALARMOut -smart the snoopers for a couple of quidGAZTEC GAS DETECTORA clever way of being nosey.OP -AMP CHECKERCheap and efficient tester.

FEATURESIN CAR ENTERTAINMENT 11What to buy and why.BUILDING SITE 26New series of hints on construction projects.CRIMSON AMPLIFIER REVIEW 32Home build hi-fi - how good?WHAT'S IN A NAME? 35New series to take the mystery out of jargon.READER SURVEY 37Help us to help you . . please?

CLEVER DICK 46Your chance to air your views.MICROPROCESSORS ARE EASY! 53Chit Chat explains the ever present MPU.BREAKER -ONE -FOUR 65CB news, views and personalities.

NEWS & INFOHobby next month, 17: Specials from Modmags, 18: ETI next month, 3647: Binders, 47: HE Book Service, 61: CB offer! 71: Hobby prints, 72.

Subscriptions,

Hobby Electronics is normallypublished on the second Friday ofthe month prior to the cover date.

Hobby Electronics, 145 Charing CrossRoad, London WC2H OEE, 01-4371002.Published by Modmags Ltd.Distributed by Argus Distribution Ltd,12-18 Paul St., London EC2A 4JS.Printed by QB Ltd, Colchester

Copyright: All material in this publica-tion is subject to world-wide copyrightprotection. Permission to reproduceprinted circuit board patterns commer-cially or marketing kits of the projectsmust be sought from the Publisher. Allreasonable care is taken in the prepara-tion of the magazine to ensure accuracy.but Modmags cannot be held responsible for it legally.

Copyright 1980Modmags Ltd

ABC

Hobby Electronics, August 1980 3

4

Simply ahead ...POWER AMPLIFIERSILP Power Amplifiers areencapsulated withinheatsinks designed tomeet total heatdissipation needs. Theyare rugged and made tolast a lifetime. Advancedcircuitry ensures theirsuitability for use with thefinest loudspeakers, pick-ups, tuners, etc. usingdigital or analogue soundsources.

0 10

005

0 02

00

F 1KHzLOAD 8110N ALLEXCEPT HY400 AT 4 CI

START OF WAVE /FORM CLIPPING

/

-2'

2 5 10 20 50 100 250OUTPUT POWER -WATTS R S

ModelOutputPowerR.M.S.

Dis-tortionTypicalat 1KHz

MinimumSignal/NoiseRatio

PowerSupplyVoltage

Sizein mm

Weightin gins

Price +V .A.T.

HY30 15 Winto 8 El

0.02% 100 dB -20 -0- +20 105x50x25 155 £6.34+ 950

HY50 30 Winto 8 S-2

0.02%100 dB

-25 -0- +25 105x50x25 155 £7.24+ c 1 o9

HY120 60 Winto 8 El

0.01% 100 dB -35 -0- +35 114x50435 575 £15.20. £228

HY200 120 Winto 8 S-2

0.01% 100 dB 45 -0. +45 114x 50x 85 575 £18.44+ £2 77

HY400 240 Winto 4 E2

0.01% 100 dB -45 -0. +45 114x 100x85 1 15Kg £27.68+ E4 15

ILP PRE -AMPS ARE

COMPATIBLE WITH ALL

ILP POWER AMPS AND PSUs

POWER SUPPLY UNITS

Load impedance - all models 4 n - aoInput sensitivity - all me is 500 mVInput impedance - all models 100K clFrequency response - all models 10Hz - 45 KHz - 3dB

ILP Power Supply Units with transformers made in ourown factory are designed specifically for use with ILPpower amplifiers and are in two basic forms - one withcircuit panel mounted on conventionally styledlaminated transformer, for smaller PSU's - in the other,for larger PSU's, ILPtoroidal transformers are used whichaie half the size and weight of laminated equivalents, aremore efficient and have greatly reduced radiation.

PSU 30 + 15V at 100mA to drive up to 12 x HY6 or 6x HY66 f 4.50 + £0.68 VAT

THE FOLLOWING WILL ALSO DRIVE ILP PRE -AMPSPSU 36 for 1 or 2 HY 30's f8.10+ £1.22 VATPSU 50 for 1 or 2 HY 50's f 8.10 + C1.22 VATPSU60 with toroidal transformer for

1 1-0/ 120 f 9.75 + f 1.46 VATPSU 70 with toroidal transformer for 1 or

2 HY120's f13.61+ E2.04 VATPSU 90 with toroidal transformer for

1 HY200 f 13.61+ f 2.04 VATPSU 180 with toroidal transformer for

1 HY400 or 2 x HY200 [23.02+ £3.45 VAT

AVAILABLE ALSO FROM WATFORD ELECTRONICS, MARSHALLS AND CERTAIN OTHER SELECTED STOCKISTS.

Hobby Electronics, August 1980

this time with twonew pre -amps

TAPE IN)

TAPEc)

AUX )

RAD )--1

MAGIj HY6

GND

MONITORSWITCH

11--

VOLUME100K ORLI-

SOURCESWITCH

BASS 10K LIN

; HY6 2

I L P POWER/ AMPLIFIER

to otherchannel

SCHEMATIC BLOCK DIAGRAMOF HY6 PRE -AMP, WITHSTEREO CONNECTION SHOWN

I L P POWERSUPPLY UNIT

0

HY6 mono HY66 stereoWhen ILP add a new design to their audio -module range, there have to be veryspecial reasons for doing so. You expect even better results. We have achievedthis with two new pre -amplifiers - HY6 for mono operation, HY66Ifor stereo.We have simplified connections, and improved performance figures all round.Our new pre -amps are short-circuit and polarity protected; mounting boardsare available to simplify construction.Sizes - HY6 - 45 x 20 x 40 mm iHY66 90 x 20 x 40 mm Active Tone Controlcircuits provide ± 12dB cut and boost. Inputs Sensitivity - Mag PU - 3mV:Mic - selectable 1 -12mV All others 100mV Tape 0/P 100mV.Main 0/P - 500rnV: Frequency response - D C to 100KHz - 3dB

HY6 mono

£5.60+ VAT 84p

H Y665t1£10.60

VAT 4:1..Y:3

Connectors includedB6 Mounting Board78p + 1 2p VATB6 6 Mounting Board99p + 15p VAT

* ALL U.K.

II LOW DISTORTION - Typically 0.005%

S/N RATIO - Typically 90 dB Map. P.U.- 58 dB I.

III HIGH OVERLOAD FACTOR -38 dB on Map. P.U.

In LATEST DESIGN HIGH QUALITY CONNECTORS.

REQUIRE ONLY POTS,SWITCHES, PLUGS AND SOCKETS.

COMPATIBLE WITH ALL ILP POWER AMPS AND PSUs.

1111 NEEDS ONLY UNREGULATED POWER SUPPLY ±15V to ±50V.,

ORDERS DESPATCHED POST PAIDHOW TO ORDER, USING FREEPOST SYSTEM rSimply fill in order coupon with payment orcredit card instructions. Post to address asbelow but do not stamp envelope - we paypostage on allletters sent to us by readers of

12this journal.

RIP 1

ELECTRONICS LTD. 1

FREEPOST 4 Graham Bell House, Roper Close, ICanterbury, Kent CT2 7EP.Telephone10227154778 Telex 965780

NO QUIBBLE

5 YEAR GUARANTEE

7 DAY DESPATCH ONALL ORDERS

BRITISH DESIGN ANDMANUFACTURE

FREEPOST SERVICE

see below

Please supply

Total purchase price E

I enclose Cheque 0 Postal Orders E International Money Order 0

Please debit my Access/Barclaycard Account No.

NAME

ADDRESS

Signature HE

MI ENV MIN MN MI IOW


Monitor

Fast Frigate?We thought that you would liketo see this picture of the RoyalNavy's first water -jet propelledhydrofoil, not because it is par-ticularly amazing in itself butbecause of its name. Now waitfor it, this vessel goes under theawe-inspiring title of HMSSpeedy, can you believe it?

HMS Speedy, now don'tlaugh, has a top speed of 45

knots, it's just crammed full ofthe latest minicomputer gubbins(supplied by Perkins Elmer at acost of £75,000) to evaluate thevessels performance during thesea trials. Ultimately it is hopedHMS Speedy will carry out fish-ery protection duties aroundour coastline. We can't get overthe feeling that HMS Speedysounds like one of those littlepedal boats seen at resorts upand down the country.

Breadboard '80Diaries at the ready, this years,bigger -and -better -than -everBreadboard Exhibition is goingto be held at the Royal Horticul-tural Hall, London SW1 bet-ween the 26th and 30th of

November. This year it will bestay open one late night (Thurs-day 27th) and for the first timeever it will be open on the Sun-day. Look out for more news onBreadboard in the next coupleof months.

Desert Island TapesOnce in a while somebody has agood idea, you know the sort ofthing, cat's eyes, TV games,suspender belts; we could go onbut we would run out of spacein which to tell you all about theSony Stowaway. Unfortun-ately the way publishing worksthis review will be somewhat

old hat by the time you read it,nevertheless, what we're aboutto tell you should serve toemphasise that you cannot live afull and fruitful life without oneof these machines.

For the uninitiated theStowaway is a portable stereocassette player. There are nospeakers, just a pair of amazingMDR 3 stereo headphones.These use a mixture based oncobalt for the magnets, take itfrom us, we've had several pairsof MDR 3s in the office for thepast six months, they are thebest headphones this side of£100. (Actually they cost under£20 on their own). Sony havecoupled them up to a miniaturetape player, it looks somethinglike those dictating machines, itcertainly doesn't sound likeone. It's impossible to describethe sensation when yourfavourite music is blastingthrough your head in genuinehi-fi quality from a little boxabout the size of a couple ofpackets of fags, our only adviceis to get along to your nearestSony dealer, try them for fiveminutes. We guarantee that ifyou've got £99 to spare you'llemerge with a Stowaway inyour pocket. Beware, peopletend to give you strange lookswhen you walk down the streetsinging to yourself.

Moon MadnessYou've all heard how people aresupposed to be affected by thefull moon, madness,werewolves etc. It just so hap-pens one of the more respect-able American universities havejust published a report thatclaims a significant number of

computer 'crashes' (failures orbreakdowns) occur during theperiod of the full moon. It's agood thing the Apollo astro-nauts went to the moon duringthe day or all sorts of thingscould have gone wrong.Actually the ill-fated Apollo 13mission set off at night, was it afull moon?

Energy OverheadsA company called Clyde Sur-veys has been flitting aroundthe country, flying over largefactories and making measure-ments to determine heat wast-age. Aerial surveys like this relyon Infra -Red scanning techni-ques, variations as small as 0.2°C can be detected over the tem-perature range of -10° to 40°Clyde Surveys claim theirequipment is so sensitive thatthey can measure dissipationfrom a one inch pipe buriedunderground at a height of 500metres (the aircraft that is!). The

airborne electronics are cent-ered around the EMI SE700 in-strumentation recorder, outputsfrom the Infra -Red cameras arestored as analogue signals onfive of the SE700s seven chan-nels. Once all the informationhas been gathered it is takenback to their laboratory for ana-lysis. Having your factory sur-veyed is not cheap, around£3,500 for a single site but thenone large company can lose thismuch money in terms of energyloss in a single week. For furtherinformation on Clyde Surveys orthe SE700 contact SE Labs(EMI) Ltd, Spur Road, Feltham,Middx.

ErrataYes, we have got egg on ourfaces, the Egg Timer (June HE)had a little!!! problem with thecircuit diagram. Somewheredown the line a couple of com-ponents got left off. If you built

the circuit from the PCB andOverlay diagrams there shouldbe no problems so for those ofyou that are using your ownlayout we have the correcteddiagram below.

1.122f11


WATFORD ELECTRONICS35 CARDIFF ROAD, WATFORD, HERTS., ENGLAND

MAIL ORDER, CALLERS WELCOME. Tel. Watford 40588/9

ALL DEVICES BRAND NEW, FULL SPEC. AND FULLY GUARANTEED. ORDERSDESPATCHED BY RETURN OF POST. TERMS OF BUSINESS: CASH /CHEQUE/P.Os OR BANKERS DRAFT WITH ORDER. GOVERNMENT AND EDUCATIONALINSTITUTIONS' OFFICIAL ORDERS ACCEPTED. TRADE AND EXPORT INQUIRYWELCOME. P&P ADD 40p TO ALL ORDERS UNDER E10. OVERSEAS ORDERSPOSTAGE AT COST, AIR /SURFACE. ACCESS ORDERS WELCOME.

VATExport ardor. no VAT. Applicable to U.K. Customer. only. Unless started othenviee.eNpesos are oxclusive of VAT. Maas* odd 15% to all prices.

We mock thousands more items. It pays to visit us. We ere obtained behind Watford FombeN Onsund.Nearest Underground/BR Station: Watford High Street. Open Monthly to Saturday. Ample Free CarParking specs available.

POLYESTER CAPACITORS. Axial lead type400V: 1 riF, 1n5. 2n2. 393, 4n7, 6n8, 104 I5n 9p; 18n 10p; 22n, 33n 11p; 479 G8n 14p; 100n 17p;150n, 220n 24p; 330n, 470n 41p; 680n 52p; 1.F 64p; 2.2 82p; 4,7 85p.160V: 39,F, 100n, 150n, 220n 11p; 330n, 470n 19p; 680n, 1,F 22p; 1,5, 2,2 32p; 4,7F 36p.1000V: 10nF, 15n 20p; 22n 22p; 47n 26p; 100n 38p; 470n 153p; 1 s F 175p.

POLYESTER RADIAL LEAD CAPACITORS: 250V:10n. 159, 22n. 27n 59; 33n, 47n, 68n. 100n 7p; 150n 10p; 220n,

330n 13p; 470n 17p; 680n 19p; 1,F 22p; 1.5 30p; 2.2 34p; 4,47 409.

GAS & SMOKE DETECTORSTO 5E112 or 813 415pSocket for above 35p

ELECTROLYTIC CAPACITORS: And lead type (Values are in eF). 500V: 10 50p; 47 78p; 250V. 100 65p;63V: 0 47, 1 0. 1 5. 2.2. 2 5. 3.3. 4.7, 6.8, 8. 10, 8p; 15, 22, 47, 32. 50 12p; 63. 100. 27p; 50V; 50.100, 220, 25p; 470, 32p 1000. 60p; 40V: 22, 33, 10p; 100. 12p; 2200, 3300. 869; 4700. 98p; 351/:33, 10p; 330, 470. 32p; 26V: 10. 22, 47, 100, 8p; 160. 220. 250. 15p; 470. 25p; 640, 1000. 35p;1500. 40p; 2200, 48p; 3300. 7Tp; 4700 65p; 16V: 10, 47. 68. 7p; 100, 125, 6p; 220. 330. 14p; 470,20p; 1000. 1500, 30p; 2200. 36p.TAG -END TYPE: 454V: 100,F 180p; 70V: 4700, 165p; MV: 3300 98p; 2500 90p; 50V: 3300 135p;220019p; 40V: 4700130p; 400092p; 30093p; 250065p; 220085p; 20004-2000 120p; 30V: 4700110p; 25V: 15,000 I95p, 6400120p; 4700100p; 3300115p; 2200110p.

TANTALUM BEAD CAPACITORS35V: 0.1,: 0.22, 0.33. 0.47: 0.68,1.0,) 2.2,. 3.3,6 4.7, 25V: 10. 20V:6,8; 16V: 42; 4,7. 10. 20p. 16V:22.: 30p; 47; 100 68p, 22080p. 10V:15,, 22e, 33. 2Sp. 100 40p. 6V. 47s68. 100 32p. 3V: 100 23p.

POTENTIOMETERS: Rotary. Carbon,Track 0 25W Log & 0 5W Lin5000, 160 & 2611 (Linear only) SingleGang 211p560.2M0 Single Gang 219560.2M0 Single Gang Dr P Switch 614p560 -2M0 Double Gang Sip

MYLAR FILM CAPACITORS100V: 0401. 0402 0-005 0-010 590-015, 0-02 0-04. 0-05, 0-056.F 7p

50V) 0.474F 12p

MINIATURE TYPE TRIMMERS2 5.6pF, 3-10pF, 10.40pF 2895-25pF, 5-45pF, 60pF 88pF 35p

SLIDER POTENTIOMETERS0.25W log and linear values 60mm560-50060 single gang 70p1060.50060 dual gang 809Self Stick Graduated Flews 33p

COMPRESSION TRIMMERS3-40p F.10-80pF 25)190pF100-500pF 45p 1250pF

33p58p

POLYSTYRENE CAPACITORS:10pF to InF Bp; 1 5nF to 10nF 109

PRESET POTENTIOMETERSVertical & Hortiontal0 1W 500 -5M1.) Miniature0.25W 1000 -3 3M0 horn.0-25W 2000 -4 ?MO vert

7p10910p

SILVER MICA (Values in pF) 3-3. 4-7.6-8. 10. 12. 18, 22. 33. 47, 50. 68, 75.82, 85, 100. 120, 150, 180 11p each.220, 250, 270, 300, 330, 360, 390,600. 820 16p each; 1000, 1200, 1800,2200 26p each.

CERAMIC CAPACITORS 50V: 0-54Fto 1 OnF 4p; 22n to 47n Bp. 100n 7p

RESISTORS - Cd,170. Film, HighStability. Low Noise, Miniature Tolerance5%

RANGE VAL 1)99 100+SAW 21)2-4M7 E24 2p 1p1/2W 2c/2 -4M7 E12 2p 1p1W 202-10M E 1 2 5p 4p2%Metal Film 100)1M Bp 4p1%Metal Film 516/.1M Bp Sp

.100+ price applies to Resistors of eachvalue not mixed

EURO BREADBOARD £5.20.S-Oec 350p T. Dec 400pUGec 'A 465p U -Dec B 699p

VOLTAGE REGULATORS1A T03 ve

55 7805 1459 7905 220912V 7812 145p 7912 220p)5V 7815 145p18V 7818 145p

IA 10220 Plastic Casing\ 5V 7805 110p 7905

12V 7812 110p 791215V 7815 110p 791518V 7818 60p 791824V 7824 60p 7924

6596596Sp659659

100.1.A 7092 Plastic Casing5V 78105 30p 79L05 6596V 78162 3098V 78182 30p

12V 78L12 30p 79L12 65915V 78L15 30p 79L15

CA3085 95p TM3236 62591.513000 170p LM 325N 240pLM305H 140p (M3265 240pLM3096 1359 LM 327 270pLM317K 3509 LM /23 39p

1

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We stock parts for mostof the projects in this

megezine.

50p95p

150p595p6509

ACCESSJust phone your orderthrough. We deal withthe reel (but min. E10

pose).

OPTOELECTRONICSLEDs plus clipsTIL209 Red 13711211 Grn 17TI1212 Yet 182" Red 152" Vol Gm 18

Square LEDs 30ORP12 63255777 45

SFH205 98TIL32 58TIL78 707 Segment DisplaysTIL321 C.4 .5" 115TIL322 C.0 .5" 115DL704 CCth 3" 99DL707C.A..3" 99.3'' Green CA 150'D1747 C.A.6" 180F50357 120MAN3640 17510 Sag Bargraph 226LCD 31/2 Dign 875

SWITCHESMEC, Black body,Red. Gm, Blue. Yel.TopsSRL Latching 125SRM Momentary 125TOGGLE 2A 250VSPST 32DPDT 444 Pole on/oft 54

SUB -MIN TOGGLESP changeover 59SPIT on/ off 54DPDT 6 tags 70DPDT c/o( 79DPDT Biased 115

SLIDE 250V:IA DPDT 1414 DP c/off 15ViA DPDT 134 pole c/over 24

SWITCHES Miniature NonLock rigPush to Make 15 Push Break 25ROCKER: SPIT on/off 10A/250V 30ROCKER: IlluminVed (white) Chrome bezelLights when 00 3A 240V soROTARY: (ADJUSTABLE STO I 1 pole/2-12way. 2p/2-6 way. 3p/2-4 way. p/ 2-3 way 43

. ROTARY: Mains 250V AC 4 Amp 50

DIL SOCKETS (Low Profile -T xas) 8 pin 10p:14 pin 12p; 16 pin 13p; 18 pinlep; 20 pin 22924 pin 30p; 28 pin 35p; 40 pin 40p.

JACKSONS VARIABLE CAPACITORSDielectric 0 2 365pF with slow100 /300pF 2059 motion Drive 450p500pF 2509 00208/176 395p6 1 Ball Drive 00 208/ 176 with45116DAF 1459 slowDtal Drive 4103 motion drive 410p6 1/36 1 775p C804.59F 10 15Drum 54mm 599 25 50pF 250p0-1 365pF 3259 100. 150pF 335900-2 365pF 395p 'l 36310pF 7259

00 3s25pF 550p

DENCO COILS'OP' VALVE TYPERange 1 to 5 131Rd.. TI Wht. 10696-7 B Y R 9591.5 Green 13097' type 1 to 5. AlRd. Wht. VI 128pB9A Valve Holder

359RDT2 1209

RFC 5 chokes 120pRFC 7 (19mH)

133p13. 14, 15; 16, 17

110p18/1.6 116p18/465 1329TOC 1 110pMW5FR 112pMW/ LW SFR 134p

VEROBOARD 0.1 01s 01s(copper clad) (plain)

21/2 it 3'4" 669 59p 34P21/245" 75p 699 39p374 x 344" 75p 759 -3346 5" 86p 929 63p21/2 x17" 240p 202p 125p3'4 x 17" 296p 260p 178p47A x 17" 387p - 2809Pkt of 36pins 20p DIP Board 326pSpot face cutter 107p va Board 144p

141;;:er"ntool 147p Veroblock 350p

DIODES

BA1(10 10BY126 12BY127 12CR033 158049 460447 1

0A70 1

0A79 1

0A81 1

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04900A910A95OA20004202N9141491654001/2144003N4004/554006/7N4148N5401/2 1

55403/4 20S44 2

34/100V 1

3A/4004 2034/6004 2734/1000V 30

We stock awide selectionof ElectronicBooks andMagazines

ZENERSRange 257 to39V 40091141

Bp eachRange 3V3 to33V. 1 3W

159 each

NOISEZ5J 11109

BRIDGERECTIFIERS(plastic case) p1A/50V 201A/100V 221A/200V 251A/400V 2914/6005 342A/50V 3524 100V 44

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40636 13040673 9,


MITRADMITRAD QUARTZ L.C.D.s AT THEIR BEST MITRAD

GENTS MEMORY CALENDAR ALARMCHRONO

A really successful watch incor-porating all the latest techno-logy.

Hours, mins, secs, weekdayand snooze alarm indication onconstant display.

A further two optional dis-play modes are available, one

* being the calendar and month,

GENT'S MULTI -MELODY CHIME ALARMCHRONOGRAPH

"'Latest technology"' constant dis-play of hours, minutes andseconds; weekday date and month,

mode indicationwith and chimedisplay. A musical alarm is built inand can be set to any time within24 hours; once activated playingthe tune "Oh Suzanna". Two 7.1CDRONfurther alarm systems are incorpo-!

which can be increased or de-creased to give the appropriatemonth of the year.

A 1 / 106th second chrono-graph with split and lap mode

rated in this outstanding watch: (i)24 -hour alarm; (ii) count downalarm. The watch can be set tochime on every full hour. A1 /100th second chronograph

.. .

Ap

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facilities are built into the watchwith a 12 -hour capacity.111111=11tA 21 -hour alarm with a 10-

A minute snooze function is alsof -L rk standard to this watch. A

LM''' -'1,*- further feature is the backlight-......,,,......, . o. and fully adjustable stainless... steel bracelet.

*STAR VALUE

£19.95

with split and lap mode facilities is in eameamostandard, the watch function mayalso be switched off. An excellentfeature is the mineral glass face.This watch also has a battery hatch,backlight and infinitely adjustablestainless steel strap.

Value at £19.95

This month's special offer on the above two shut-off coming in attractive FREE wallet. REMEMBER - ABSO-LUTEL FREE with every one of the above watches ordered thiswatches_ a FREE credit card calculator currently being retailed particular month.

at £7.95. 8 digits, square root, full memory, per cent keys, plus auto.

GENT'S SOLAR ALARMThe slimmest Chrono Solar Alarmin the World. Only 7mm thick.This watch has a genuine solarpanel. You can take the battery outand the watch will still function as

I

normal. Battery hatch. Mineral'4 1

glass. vir.....porririb1

LADIES' COCKTAIL

Elegance and style for the ladywith the discerning taste. Ingold or silver finish withmatching bracelet. Constantdisplay of hours and mins. withmonth, date, secs., auto.

Constant display of Hours, Mins. -...,ZEONand Secs. with Date Flag. Optional

display of Hours, Mins. and Date.The alarm can be set to any timewithin a 24 -hour period and isactuated for a full 60 seconds.The chrono runs to a 1/10th Secwith a maximum capacity of 24hours. Lap Time and Freeze Facil-ities are available.Dual timing facilities are readilyavailable.Back Light. Fully adjustable OFFERED AT £19.95stainless -steel strap.This watch is available in gold orsilver.

calendar and back -light.

VERY SPECIAL£10.50

CREDIT CARD HOLDERSPlace your order over the phone and get your new time -piecedespatched same day. 24 -hour ansaphone service.

MITRAD THE UNRIVALLED RANGE MITRADWe are able yet again to offer you the above watches plus acomplete quartz watch range. All at unrivalled prices. Just lookat the following points:(i) 48 -hour despatch guaranteed on both retail and trade

orders.(ii) Full instructions and 12 month manufacturers guaran-

tee.(iii) Our own free back-up service.(iv) 10 -day full money refund if not completely satisfied.(v) Free felt presentation case with each watch.

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* FULL COLOUR CATALOGUE NOW AVAILABLE *Write or phone for your free copy. Trade lists onapplication.Earn £E£s selling watches to all your friends. P/P peritem 85p which includes insurance. Cheques or P.O.smade payable to Mitrad and sent to (Dept. HE)), 68-70High Street, Kettering, Northants NN16 8SY.

Telephone: (0536) 522024

8 Hobby Electronics, August 1980

080-MSMTOTF$

456e

CAIENO

Calendar Calc

MonitorNews from the Electronics World

You've all seen calculators withcalendars before, now haven'tyou? Well, Casio, well knownmanufacturers of calculatorshave just announced the HR 1010 digit, LCD display etc, etcprinter calc with calendarfacility. Should you wish toknow the days of the week forany month between the years1901 (January) to 2099 (De-cember) then this is whatyou've been waiting for. Thishighly useful feature comes in abox only 88 x 168 x 40millimeters. The battery life is asyou expect something in excessof 200 years (well, 5000 hours,but who's counting) or 8800lines of print should you wish.

Price for this box of tricks is avery reasonable £36 (or less)and should be reaching theshops about now. Just for therecord Casio live at 28 ScruttonStreet, London EC2A 4TY.

Kitted OutIn electronics shops up anddown the country there will beappearing a selection of smallplastic bags, each bearing thename Hobbikit. These little bagscome in twenty varieties andcontain all the parts necessaryto build anything from a Smokeand Gas Detector to a Modeltrain speed controller. If thename Hobbikit is unfamiliarthen you'll be relieved to knowthat they come from Vero Elec-tronics, suppliers of electronic

hardware for nearly twentyyears.

Each kit comes completewith all the components, a glassfibre PCB, drilled, masked andprinted with the componentlegend. At the time of going topress we're not sure of the pricebut informed sources reckonthey'll start at around £5.00 forthe simple kits. If you're localshop has yet to stock them thencontact Vero, at Vero Elec-tronics Ltd, Industrial Estate,Chandlers Ford, Eastleigh,Hants S05 3ZR.

Video VariationsIf you are still pondering as towhether your life is incompletewithout a video tape recorderthen here's another one to con-sider.

This one comes from Mitsu-bishi and uses the well triedVHS format. Firstly, the import-ant bit, it will retail at around£698 (inc VAT), this places itsquarely in the mid- to upper -price bracket, so what do youget for close on 700 quid? Howabout a full function infra -redremote control, picture searchmode (seven times normalspeed), slow motion (half -speed) and freeze frame. Stillwith us? Then how does thissound, a seven-day timer withoptions to record up to six pro-

grammes of varying length onany channel. If the HS300(that's what to ask for whenparting with the readies) is foryou then you'll be glad to know

that a cabinet with tape storagecan be yours for as little as £51.Mitsubishi are awaiting yourcall at: Mitsubishi Electric (UK)Ltd, Otterspool Way, Watford,Herts WD2 8LD.

Book ReviewsThree for your approval thismonth, the first two are fromthe Babani stable and comefrom the pens of two very wellknown gentlemen.

First away is called ElectronicHousehold Projects. (R. A. Pen -fold, ISBN 0 900162 91 0,£1.75, BP71). This book is averitable mine of informationfor anyone even vaguely inter-ested in gadgetery. Everythingfrom a doorbuzzer to a simpleultrasonic remote system,you're bound to find somethingof interest here. Our only critic-ism is the lack of constructionaldetails, many of these circuitsare ideal beginners projects butunless you are familiar with PCBdesign or stnpboard layout it'sall a bit tricky. Well worthlooking at though, not forabsolute beginners.

Our second Babani book isentitled A MicroprocessorPrimer. (E. A. Parr, ISBN 0900162 92 0, £1.75, BP72).Confused by computers, mixedup over micros? Worry no more,of all the 'undersyand micro-processor in three easy lessons'books, this one comes closest topainlessly explaining these littledevils to a complete layman.

Last, but definitely not leastis an extremely attractive bookentitled Test Ger Projects.(Terry Dixon, ISBN 0 33326396 0, £3.95). This really is adelight to read, clearly written,beautifully illustrated and aboveall, full of really well designedprojects. All the projects haveaccompanying stripboardlayouts and could quite easily beput together by even the mostinexperienced constructor.Virtually every piece of test gearyou'll ever need, except ofcourse an oscilloscope, is to befound here. Don't let the priceput you off, it's well worth it.

Catalogue CornerTwo of the largest componentretailers have just announcednew catalogues, or to be fair,new versions of their previousofferings. Both Stevenson andBi-Pak's new catalogues werejust a touch too late to make itinto our catalogue survey in theJune issue, but you may restassured that both are well up tostandard. Prices are both veryreasonable and both contain auseful amount of additional dataon semiconductors. The ad-dresses for both companies canbe found elsewhere in thisissue.

9

CAMBRIDGELEARNINGENTERPRISES

SelfInstruction

CoursesMicrocomputers are comingwave! Learn to program.Millions of jobs are threatened butmillions will be created. LearnBASIC - the language of the small com-puter and the most easy -to -learn com-puter language in widespread use. Teachyourself with a course which takes youfrom complete ignorance step-by-step toreal proficiency, with a unique style ofgraded hints. In 60 straightforwardlessons you will learn the five essentials ofprogramming: problem definition,flowcharting, coding the program,debugging, and clear documentationBOOK 1 Computers and what they do well; READ, DATA, PRINT, powers, brackets,variable names; LET; errors; coding simple programs. BOOK 2 High and low level languages;flowcharting; functions; REM and documentation; INPUT, IF.... THEN, GO TO; limitations ofcomputers, problem definition. BOOK 3 Compilers and interpreters; loops, FOR.... NEXT,RESTORE; debugging; arrays; bubble sorting; TAB BOOK 4 Advanced BASIC; subroutines;strings; files; complex programming; examples; glossary.

ride the -r

I//ComputerProgrammingin Basic ICPEII

f9.00

Also THE BASIC HANDBOOK (BHB) £11.50 An encyclopaedicguide to the major BASIC dialects. A must if you use other peoples'programs

and: ALGORITHM WRITER'S GUIDE (AWG) £4.00 Communicateby flow chart! Learn to use Yes/ No questions for: procedures, systemdesign, safety, legislation etc.

Understand DigitalElectronicsWritten for the student or enthusiast, thiscourse is packed with information,diagrams, and questions designed to leadyou step-by-step through numbersystems and Boolean algebra tomemories, counters, and simplearithmetic circuits; and finally to anunderstanding of the design and opera-tion of calculators and computersBOOK 1 Decimal Octal, hexadecimal, and binary number systems and conversion betweennumber systems; negative numbers; complementary systems. BOOK 2 OR and AND func-tions; multiple'inpur gates; truth tables; De Morgan's Laws; canonical forms; logic conventions; Karnaugh mapping; three -state and wired logic. BOOK 3 Ha/f, full, serial, and paralleladders; subtraction; processors and ALU's; multiplication and division. BOOK 4 flip flops;shift registers; asynchronous, synchronous, ring, Johnson, and exclusive -OR feedbackcounters; ROMS and RAMS. BOOK 5 Structure of calculators; keyboard encoding;decoding display -data; register systems; control unit; PROM; address de -coding. BOOK 6CPU; memory organisation character representation; program storage; address modes; in-put/output systems; program interrupts; interrupt priorities: programming, assemblers: com-puters; executive programs: operating systems.

Design ofDigitalSystems(DDS) (12.50

DIGITAL COMPUTER LOGIC Et ELECTRONICS. IDCLI £7.00A course covering the material in italics above, but at a slower pace.14 vols)GUARANTEE - No risk to you. If you are not completely satisfied your moneywill be refunded without question, on return of the books in good condition.

PLEASE SEND ME: -CPB 1£9.00)BHB (£11.50)AWG 1f4.00)DDS (£12.50)DCL (E7.00)FOUR WAYS TO PAY:11 A U.K. cheque or a U.K. postal order INot Eire or overseas)21 A bank draft, in sterling on a London bank (available at any major bank)31 Please charge my Access/ M.Ch 0 Barclay/ TrustC / Visa 0 Am. Exp.0 Diners041 Or phone us with these credit card details - 0480 67446 lansaphonel 24 hour service.

Quantity

Card No SignedTHESE PRICES COVER THE COST OF SURFACE MAIL WORLDWIDE. AIRMAIL:Eur, N.Af, Mid.E. add % to price of books: Jpn. Aus. N.Z. Pcfc add %: elsewhereadd Vi

Name

Address

U.K. Delivery: up to 21 days (or send 50p for 1st cl.p.)

Cambridge Learning Enterprises, Unit 83 Rivermill Site, FREEPOST, St. Ives, Huntingdon,

Combs PE17 4BR England.

Proprietors: Drayridge Ltd., address as above, Reg. in Eng. No. 1328762

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e cnquerhiBe it career, hobby or interest, like it or not

the Silicon Chip will revolutionise every humanactivity over the next ten years.

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UR,10 Hobby Electronics, August 1980

ICE or to give it its full name, In CarEntertainment, is one of the biggestgrowth markets for hi-fi manufacturers.Terry Bentley looks at some of the mostrecent additions to the market and aglimpse of what's to come.

In CarEntertainment'IN -CAR ENTERTAINMENT': notwhat goes on with seats reclined insecluded parking lots but the popularname, godawful as it is, for a sector ofthe audio market worth an estimated£38 million last year in the UK alone.Big business is what we're talkingabout, and a highly competitive one atthat.

As in most areas of commerce, thechallenge of competition has led to aconstant struggle among manufac-turers to get one technical jump aheadof rivals whilst pegging prices withinacceptable limits. The result has beenrelatively rapid assimilation of newtechnology, particularly in the elec-tronics field, but a degree of conser-vatism, varying between companies,mainly motivated by good old-fashioned market forces - i.e. howstrong an influence the desire of thepunters for the latest gadgetry has ontheir willingness to open their wallets.

UKICERight now the ICE field in thiscountry is going through sometraumas, as are just about all areas ofindustry falling largely into the'luxury' bracket. World economictrends and domestic policies mean.tough times ahead in Britain, and lessmoney available for spending onnon -essentials, including frivolitieslike car radios and tape players.Things are going to get a hell of a lotworse before they ever get any better,


and there are already strong signs ofstagnation in sales.

Don't let's get too despondent,though; assuming you still have alittle cash left in your pocket, there is agood side to the apparently gloomystate of affairs. Car audio equipmentmakers have actually been reducingprices of current models amid theraging inflation we all know and hate,in an attempt to shift stocks before therot sets in for real. In terms of actualpurchasing power, you can currentlyget extremely good value. Youhaven't been able to get such a gooddeal for your week's wages for a longwhile, and you probably never willagain . .

In the longer term, there's everyreason to expect general develop-ments to carry on as before. Once the

-novelty of the recession wears off,those that have it will start spendingmoney on luxuries again, and it'slikely that recent trends give a goodindication of the direction in which theICE market will move once the ball isrolling once more.

Some figures . . . . as of last year,around 55% of the 14 million -oddcars in Britain were fitted with somesort of audio equipment. Combinationradio/tape units accounted for maybe6%, while 40% had radios. 1 2% hadtape players; obviously there was acertain amount of overlap in thosefigures - i.e. some vehicles hadseparate radios and tape machines. Inthe separate radio sector, 90% of sets

were AM only, but 37% of combina-tion units had both AM and FM radiocapability. 80% of car audio equip-ment sold in Britain last year wasimported.

Current TrendsTrends? Over the past few years therehave been very strong moves towardscombined radio/tape units FM radio.Technical improvements havebrought these two together, asmanufacturers have become capableof packing an increasing numbers offacilities into the standardised casedimensions. Progress has been start-lingly fast. Initially it was difficult tocram all the possible features ofseparate units into one small packageand.... it was rare to find a pushbuttonradio tuning along with a cassettedeck and virtually unheard-of to findall the works together - i.e. auto -reverse cassette, pushbutton FM +2AM radio with IAC, muting and de-cent output. Today, from the middleof the market upwards, the former isthe rule rather than the exception,while the latter list of features is by nomeans unusual.

If increasingly sophisticated com-binations made to fit DIN -sized dash-board apertures have been one side ofthe story, even more complexseparate component systems havemade up the other. Where space isnot restricted, it's now possible toinstall systems of near domestic hi-fistandard, with all the associated

11

A cassette power booster, this one comes fromPioneer, you can expect up to 120 watts from this model!

refinements. Power amplifiers withupwards of 50 watts RMS per chan-nel, tape decks with Dolby noisereduction and switchable equalisationfor metal /Cr02 tapes, five- or six -bandgraphic eqialisers and multi -elementspeaker systems are all now availablefrom a wide range of manufacturers.Performance levels are very high. Ofcourse it's arguable that it's not worthgoing to such bother in as acousticallypoor an environment as the inside of amotor vehicle anyway, but if you wantit and can afford it, it's easy now tospend a thousand pounds on a caraudio system.

There's a third trend, which formsa kind of bridge between the othertwo. This is to use 'booster' amplifierunits, often in conjunction withgraphic equalisers, to give 'ordinary'low -output units the power to drivebetter speakers at acceptable distor-tion levels. You still have the inherentdisadvantages of the compactmachinery - typically poorerfrequency response and wow /flutterfigures, along with the lack of Dolbyand so on - but the advantages overthe 'straight' 4 or 5W per channel ofthe basic unit are considerable, and atleast you can improve and upgradeyour system step by step instead ofspending a fortune all at once.

Just recently, there's also been atendency to raise power outputs of thebest in -dash units to more sensiblelevels, 20 watts or so per channel. Atthe same time, these are being packedwith more features (even Dolby), soperhaps the gaps between separatesand combinations are closing up.

Digital DashboardsThe magic word 'digital' has recentlycrept into many current up-marketcombinations. Some of these havelittle to offer over long-establishedelectro-mechanical designs, but anumber exploit digital techniqueseffectively by offering more stationpreselections, light -action pushbut-tons and precise electronic frequencydisplays, among other things. Phase -

locked loop frequency synthesis offersvery accurate and stable radio tuning.

The higher output powers of the'new generation' units and the betterbooster amplifiers come from usingbridge amplifiers, which can doublethe voltage across the speaker andhence develop four times the usualpower. Techniques like this have beenknown for some time, but only latelyhave they been put into integratedcircuit form so that they can be cram-med into the small space available in acar radio casing.

Future DevelopmentsGoing off at a tangent, an area of ICEdue for more publicity soon is trafficinformation broadcasting. For sometime now, the Bosch-devel6ped ALIsystem has been under trial in WestGermany and other areas on the Con-tinent. Public testing in this country ofthe BBC's alternative CAR FAX systemwill, it may be hoped, soon establishwhich is the more useful and lead tofull-scale introduction of one or otherof the rival concepts.

Briefly, CARFAX will utilise a net-work of medium wave transmittersbroadcasting traffic messages over an8 minute repetition sequence withingiven areas. Reception will be bymeans of an extra, fixed -tune receiver,either integrated with other audioequipment or in the form of a bolt -onaddition, which can be switched intooperation when the user wants to hearthe messages.

Of course, whichever traffic infor-mation system is adopted, the successand popularity of the scheme willdepend entirely on timing and contentof the messages. It's not difficult toimagine a few bolt -on devices beingtorn off and hurled through carwindows as irate motorists are givengems like 'you are now joining a tenmile queue.' The Transport and RoadResearch Laboratory is co-ordinatingwork on aspects such as this.

Station programme identification('SPI)' is another likely development.SPI systems are based on FM trans-

missions with a digitally encoded pilotsign, used in conjunction withreceivers that can have decoders anddisplays of several different levels ofcomplexity. Initially the receiverwould identify the station, transmitterrand programme type for any signal it,.was tuned in to - e.g. 'Radio 4,Wrotham, News.' Subsequent refine-ments could include automatic searchfunctions, so that it would seek out aprogramme of the desired naturewhen the user keyed in a request for'News,' 'Classical Music,' 'Rock,''Commercial Garbage' or whatever.At least one proposed system alongsuch lines is undergoing broadcastcompatibility trials by the BBC.

Further development could bringthrough a facility akin to Teletext, butfor safety reasons this would probablybe restricted for in -vehicle use. Simi-lar systems will probably evolvearound AM radio, though these arelikely to be more limited in scope.

Several AM stereo radio transmis-sion methods have recently beentested in America, and there is somescope for something along the samelines in Britain. For various reasonsFM reception is still patchy in manyparts of the country, and AM stereowould be a reasonable compromisemethod of improving facilities for lis-teners in poorly -served FM areas.

On the recorded sound side,several alternatives to the normalcassette tape have been propounded.The ludicrously bulky eight -track car-tridge has been dead for some time (if,indeed, it was ever alive on this side ofthe Atlantic) but other, smaller than'compact' cassette, tape systemscannot be ruled out although theypresent severe mechanical problems.A 4 inch audio disc has been pro-posed by one manufacturer, whiledigital storage of whole programmesin small, interchangeable solid statedevices such as read-only memories isanother strong possibility.

ConclusionsThere are plenty of exciting ideas inthe pipeline but most of these arenecessarily vague at present. What isfor sure is that in the immediate futurecar audio manufacturers will go onsqueezing more functions and greaterpower outputs into existing case di-mensions - both the in -dash sizesand the bigger component units.Pricewise, now is a good time to buybut constantly improving technologymeans that there's always a betterproduct just around the corner. Buynow or wait - it's your choice.


Car Audio - Who,What & WhereWhat follows is a listing of some of themakes available in this country and a briefdescription of whatever seems newest ormost interesting in each of their ranges.Prices include VAT, rounded to the nearestpound.

AlpineThus Japanese make has built its reputationon a range of in -dash sets of high quality butconservative design. Latest of these is theCM923, a combination unit with a sixpushbutton MW/ LW/FM stereo radio andauto -stop tape section. It has IAC-type FMnoise suppression, auto -muting, manualmono/stereo switching and costs around£168.

Alpine also produce a selection of muchmore sophisticated 'component' units, in-cluding the 7307 tape deck /tuner, 3000and 3003 graphic equalisers and 3002 50watts per channel power amplifier. Listed

Blaupunkt

This Bosch brand is well known as anup-market champion but also makes quitecompetitively priced sets for mere mortals.

ClarionA top Japanese make that has only in the past

year or so become well-known on the UK scene,this firm has an extensive range of DIN -sizeddash -mounting tape and combination units, plusthe '6 -Series' selection of high -quality separatecomponents and various boosters, equalisers.speakers, etc. Clarion are among the frontrunners in application of advanced technologyand their more up -range in -dash sets, in parti-cular, have some very interesting features.

The recently introduced PE -957 is currentlythe top combination unit and it possesses anumber of impressive attributes. It is amicroprocessor -based device, which comes intwo parts a DIN -fitting tape deck/tuner and a'black box' containing the amplifier and much ofthe sophisticated electronic circuitry. The tapesection is very compact, yet has auto -reverseand unusually good wow and flutter figures. Theradio has pushbuttons for MW, LW and four FMpreselections, with stereo reception on FM. Ithas auto -seeking a digital frequency displaywhich will also tell you the time when required,and a 'loudness' button for emphasis of high andlow frequencies at low volume settings. So farso good . . . .

Now for the really tricky bits. Instead of thephase -lock loop (PLL) synthesis in the electronictuner that most leading manufacturers nowemploy, Clarion use a voltage synthesiser sys-tem which, they claim, gives the capability forfiner and more accurate frequency selection.

In Car Entertainment

along with the 'separates' range is the 7206which is actually a very high -quality inte-grated combination unit. It has, amongvarious other refinements, CrO, / FeCrswitching and Dolby on its tape deck,separate treble and bass controls, a goodAM /FM MPX radio, plus a 20W per chan-nel output with pretty good distortion cha-

For example, the Coburg and Paris com-bination units are both currently selling for£172; both have MW/ LW/FM stereoradios but the former has a more sophisti-cated, six pushbutton radio section while

There is inter -station muting and automaticfrequency control on FM reception - but AFC isalso, most unusually, available on MW AM. Thereis a good active noise reduction system alongIAC lines (Clarion call theirs 'CZ11, DX/localswitching on AM, stereo/mono switchover andwhat Clarion term 'SASC' ('signal -actuatedstereo control'). This last facility is a circuit thatresponds to changing quality of FM stereoreception by continuously variable attenuationof channel separation according to fieldstrength; it also cuts out extraneous high -frequency noise. Only a couple of othermanufacturers have comparable systems as yetbut the improvement over straight on/off stereoswitching has to be heard to be believed: it mustbe the way to go. Cost of all this clever stuff islisted at £366, but it's possible to find the setdiscounted down to around £260.

Talking of 'hearing to believe', I took theopportunity to try out a PE -957 during the

racteristics. Price of this piece is £259.There are high -quality speakers to matchthe component range.

Alpine's distributors in the UK, AutocarElectrical, also handles the prestige Beckerrange from Germany, along with theAmerican Jensen speakers, aerials fromHirschmann and Facet accessories.

the latter has a superior tape deck withauto -reverse and a switchable 'db' noise -reduction circuit.

Blaupunkt continue to shoot for themoon, on the other hand, with sets like theBerlin 8000, which they don't mind calling'the most expensive in the world' at £750.Among the features of this unit are agoose -neck mounted remote tuner controlpanel placing seven pre -selection touch -buttons, volume control, self -seek controland on/off switch close to the steeringwheel and the driver's fingertips; Dolby,Cr02 switching, auto -reverse and stereorecording facility on the tape deck;automatic volume level adjustment whichreacts according to noise level inside thecar; output of a claimed 18W into each offour channels.

preparation of this article. The chance to checkin practice the functioning of the variousalluring facilities was too good to miss. I amhappy to report that in virtually every respectthe set lived up to its promise. Radio perfor-mance was altogether excellent, while the tapedeck did everything that could be expected of it.Some tape hiss was audible but only Dolby -equipped competitors could be expected to dobetter (and there are hardly any of those outsidethe specialised 'separates' sphere - certainlynone with such an array of other worthwhilefeatures). Facilities found most effective anduseful included the tape auto -reverse. and onradio the auto -search and SASC.

Speakers used for the test were Clarion'sconcentric twin element GS -509E model. Thesewere rated very highly. with adequate, well-defined bass response. full mid -range andunusually sharp, clear treble. At a list price ofabout £50 a pair, they seem very good value.


TONE F M 88 92 98 104W 560 II 750 1000 1600

L 1,0V 200 260 300

FULL AUTO STOP

.4-4/1 100.11ir

1

MHzkHzkHz

FM

Hitachi

Hitachi were first on the UK market with a'digital' combination unit, the CSK501, andthis is still among the best available. With amicroprocessor memory, its tuner storessix pre -selections on MW, LW and FM, willself -seek all or stereo only signals as well asbe manually tuned, and has all the by -nowusual attributes like IAC, inter -stationmuting, local/DX sensitivity switching onAM, and so on; it also matches automati-cally to any aerial. It has a straightforwardbut reliable tape section, and sells for £215.

Latest development from Hitachi is"ASLC" - automatic sound level control -which, like Bosch's system, governs radioor tape volume in relation to ambient noiselevel. It's currently available built-in to onecombination unit, the CSK303X, and as anadd-on device in the form of the DU16, ataround £40. k will also be offered in abooster amp package later this year.

Pioneer

Another make with a very high reputationfor quality, Pioneer have a big range fea-turing some very sophisticated equipment,both combinations and separate com-ponents. Top combination unit is the K E-2300, which has the usual three bands butuse of electronics for a synthesiser varactortuner, 15 -station pre -selection and a 32 -element LED analogue tuning scale ratherthan a digital frequency display. It has theirversion of IAC ('PNS') and also featurestheir equivalent of Philips continuous FMmode variation - Pioneer call it 'ARC'(automatic reception control), and it'sswitchable. The cassette deck has no frills,but its performance is second to none in itsclass. Current price of the 2300 is around£213.

On the separate component front, Pion-eer have more units with more good pointsthan there's room to describe here. In termsof performance and specifications, they are

probably unsurpassed in the car audioworld. Their speakers are also held to beamong the best, and there's a huge range ofthem.

MinikitsMinikits Electronics sell one model only,and it's a bit of an anomaly among the restof the sets I've described. Called the 'Har-vard Autosport De Luxe', it's a pretty basicJapanese unit with MW/ FM stereo radioand auto -stop tape deck with lockable FFbut no fast rewind. FM suppressionis by ceramic filters - there's no activeinterference rejection - and the tuningscale is also the cassette door.Output is about 4-5w per channel RMS.

Why have I bothered to mention it? Well,it has one very big thing in its favour: price.It costs just £45 plus £1.40 p&p, and thatincludes speakers! What can you say?Minikits' address is 88 Hainault Road,Leytonstone, London, E11 1E H.

National Panasonic

Another good Japanese make with well -priced combinations and component units,National are in the process of introducingseveral new models. There's a digital unit,the CQ-863, with auto -seek, frequencysynthesiser tuner and all the other goodthings a microprocessor or two can bringfor £200; there's also a more ordinary-looking unit with a claimed 20w poweroutput, the 673, which sells at £166. Realnews, though, is the 973. This digital unithas all the works on the radio section (PLLFS tuner, 15 station pre-set, auto -seek,etc., etc.), plus a cassette deck with auto -reverse, Dolby, CrO, equalisation; LEDsignal level meter, loudness -compensationand four-way balance. It works with achoice of power amps, and no price is yetavailable as I write.

PUSH RADIOPULL BALANCE


In Car EntertainmentMotorola

One of the long-established 'big names',Motorola have a quality separate com-ponent range, including power amps,graphic equalisers and some very goodspeakers. They also produce sensiblypriced combination units, which haverecently been restyled and reduced in price.The best of them, the 708, has a three -bandradio including FM stereo, six pushbuttons,each of which can be set to select a stationon MW, LW or FM, and a good, straight-forward auto -eject tape deck. It now sellsfor £167.

Philips

Philips were the company that started thewhole cassette thing off; they were alsothe first with IAC. Perhaps it's not toosurprising, then, that their combinationunits are still among the best of the lot interms of actual, as against theoretical,performance. The AC880 has LW / MW /FM stereo radio with 'tumolock' six -stationbutton selection, plus a good tape deckwith electronic speed control; the 890 issimilar but has digital frequency display.Both have what Philips call SDS /SDRcircuitry on radio as well as the more usualAFC and IAC. This means that as you movethrough areas of varying FM signalstrength, stereo separation and high -frequency response are continuously andimperceptibly modified to give the opti-mum sound. In practice, both this and theirFM noise rejection (IAC) work better thananybody else's alternatives.

There is no Philips separate componentrange at present, but there are some goodSpeakers, and boosters, equalisers and soforth.

Radiomobile

An English make with a good reputation forquality and reliability, Radiomobile have arelatively conservative range of in -dashunits. Their 409 model has a manually -tuned three -band radio with stereo FM, andan auto -reverse cassette deck, while theirnew 420 unit has Dolby on its tape side butonly two AM bands on its six pushbuttonradio.

OFF' VOLUMEpWI BALANCE

0 TONE

SYNTNES1ZEii

0 BANG

NAIR CLOCK

Voxson

Just for a change, an Italian make. Allmodels are compact units, some designedto be 'extractable' for security when

leaving the vehicle. Top model is the Indi-anapolis combination, which has a 16 sta-tion (MW & FM) memory, thanks to a chipmanufactured by Fairchild; there's one-upmanship for you. The tape section isrelatively ordinary. Price is around £252.

Sanyo

Yet another Japanese brand with a selec-tion of in -dash and component units, Sanyoare soon to launch a number of new models.At present their most interesting 'normal'sets include the FT4400M, a MW /FMdigital display combination unit, and theFT4687ME, which has three wavebandsand auto -reverse tape section.

Among the 'big guns' is the FT-DT10,which has a high -frequency filter switch. Ithas FM radio only. The matching poweramp has a claimed power output of 20Wper channel.

Sharp

Sharp are one-up on most of their competi-tors in that their prices always seem to beexceptionally keen. Their range is purelyin -dash stuff - no fancy separate com-ponents - but the units perform well.

Most interesting new model is theRG6600E. This is a microprocessor -controlled set with five station memory foreach of its three wavebands, PLL synthes-ised tuner, FM noise suppression and whatSharp call 'ASTS' (automatic stereo tuningsystem), which is another gradual stereo/mono FM signal regulator along Philips/Pioneer lines and a similarly great improve-ment over the conventional 'on -off'switching. The set also has DX /localswitching on AM, built-in loudness circuit,FM muting, etc,

Boosters, speakers, etc. are available. HE


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HobbyElectronicsTHE SEPTEMBER ISSUE WILL BE ON SALE AUGUST ir

Into Digital ElectronicsThis is it. The beginners series you've been waiting for. Theone that begins at the beginning, goes on until it reaches theend, then stops! The beginning here is the absolute basics ofdigital circuitry - nothing assumed - and the end ismicrocomputing! Written by Ian Sinclair, by now wellestablished as the country's leading author in this field it isnot to be missed. If you've always wanted to know, but weretoo confused to ask - this is your series!

Full Spec. Phaser For £12?Incredible but true! This is an amazing unit in every way. Itcan be built in an evening, is very simple to construct andcost less than £12 to put together. Compare that with the£60 or so a commercial unit would cost you. Performance isas good as anything in the shops at five times the price too,so no worries there. Another Hobby scoop this - don't missit.

Teletext TextbookAt last! How many times in the past have you wonderedwhen someone would finally take the mystery out of teletextonce and for all with a clear, easily comprehended explana-tion of Ceefax, Oracle, Prestel and the rest?

Well, wonder no longer. Next month HE does exactly that.Who else would anyway? Had ye no faith? Read Hobby nextmonth for this important screening!

Reaction TesterWell, I suppose it had to come didn't it? After all those linesof pretty little lights, someone just had to go and produce asimple, inexpensive way of sending out reaction timesaccurate to 1 / 1 000th of a second. And of course thatsomeone had to be HE! Pick up a copy as fast as you can elseyou'll never know how quick on the draw you really are!

Power Supply, Touch Switch, Darkroom Timer andAudio MixerSays it all really, doesn't it? Except that all these arebrilliantly realised as Hobby Electronics projects next month- which means they can all be built easily and quickly byanyone who can hold a soldering iron straight!


NE WS HEADLINES 101NEWS IN DETAIL 102-119NEWS FLASH 150NEWS INDEX 190NEWSREEL 199

FINANCE HEADLINES 120FINANCIAL NEWS 121-139

SPORT HEADLINES 140SPORT PAGES . .141-159

FOOD (JIDE 161FARMING

- 168

FOR THE DEAF169

TV,'RAOIO 171-4TV CHOICE 177TOMORROW 179

WEATHER/ TRAVELINDEX ....180

FULL INDEXA F 193G -0 194P-2195

TRAHSATLANT C YACHT RACE LEADERS 191

P666 CEEFAX experiment

ENHANCED TELETEXT SYSTEMS

An

Enhanced

TELETEXTsystem willallow pagesto include

with aqualityLimitedonly bythe displaydevice.

The items mentioned here are those planned but unforeseencircumstances may affect the actual contents.

17

SPECIALSFROMMODMAGSMark your envelopes 'Specials' andwith your cheque or postal order to:Modmags (Sales Office) Ltd,145 Charing Cross Road,London WC2H OEE.

Ell CIRCUITSBooks I & 2.Each volume contains over 150 circuits, mainlydrawn from the best of our Tech -Tips. The circuits areindexed for rapid selection and an additional sectionis included which gives transistor specs, and plenty ofother useful data. Sales of this publication have beenphenomenal - hardly surprising when the circuitscost under I p each!£1.50 + 25p P&P each.

electronicstoniorriuk- ThP

send it, together

ET1

.CIRCUITS

No1

Sego Cue Isaac,

ELECTRONICS TOMORROWComprised entirely of new material, the editioncovers such diverse topics as Star Wars and Hi-Fi!The magazine contains projects for everyone - noneof which have appeared in ETI - and a look at thefuture of MPUs, audio, calculators and video. Howcan you not read it?

75p + 25p P&P.TOP PROJECTSBook 1 + 2: £2.50 + 25p P&P.Master mixer, 100W guitar amp., low power laser,printmeter, transistor tester, mixer preamp., logicprobe, Ni-Cad charger, loudhailer, 'scope callibrator,electronic ignition, car theft alarm, turn indicatorcancellor, brake light warning, LM3800 circuits,temperature alarm, aerial matcher, UHF -TV preamp.,metal locator, four input mixer, IC power supply,rumble filter, IC tester, ignition timing light, 50Wstereo amp. and many more.Book 3: SOLD OUT! Book 4: £1.00 + 25pP&P. Book 5: £1.00 + 25p P&P. Book 6:£1.00 + 25p P&P.

TOP PROJECTSBook 7: E1.25 + 25p P&P.ER II loudspeaker, CCD phaser, 3 -channel tonecontrol, bass enhancer, continuity tester, benchsupply, LCD digital multimeter, digital frequencymeter, wide range oscillator, ETI wet, egg timer,house alarm, porch light, torch finder, light dimmer,1B metal locater, electronic bongos. puzzle of thedrunken sailor, race track, ultrasonic switch, tic-tacradio, rev counter, Transcendent 2000, spirit level.

ELECTRONICS - IT'S EASYThis very successful beginners' series hasnow been reprinted in one volume. The bookcovers just about every aspect of electronictheory and is ideal for anyone just startingout in this fascinating hobby.

£3.60 + 25p P&P each

INTO ELECTRONICS PLUSThe complete series of Ian Sinclair's series IntoElectronics Plus a selection of some of the mostpopular and informative articles from HE. Everythingfrom Home Computing to making your own PCBs.El +25p P&P.

BARGAINCORNER

Show us that you could have purchased forless within one month of your purchase andwe will refund the difference!

MULTIMETERS: DT 1314 Asuperb 38range meter.

1.111.1.1.01T Special featuresinclude 50K0 /VDC move-ment, 10 ampDC Scale, res-istance up to100 MW 2ranges for tes-ting batteries.long extraflexleads, batteriesincluded.Usually sold for£35. FORLIMITEDPERIOD £25 +70p post.

DT1004 20KO/VDC move-ment, 16 rangesand off position,mirror scale, pro-tected move-ment, battery in-cluded. Usuallysold for £16, ourprice £12 + 70ppost.

CAR AUDIO:

New Model Stereo C to/RadioM.W., stereo FM and stereo cassette player. 8Watts per channel, fast forward and autostop,includes fitting kit and FREE SPEAKERS. Soldelsewhere for up to £85 (believe it or not). Ourprice £45 + £1.40 post. (For negative earthcars only). End of line clearanceLW /MW stereo cassetteplayers. 8 watts per channel.Fast forward and autostop,usually sold for between £45and £65. Limited number at£34 + £1.20 post. (Fornegative earth only). Manualcar radios 5 watts, includesfitting kit and speaker. Neg. orpos. earth. £9 + £1.20 post.

METALDETECTORS:

Induction BalanceModel. Highly sensitivemodel with speaker andmeter, 7 -inch search headand telescopic stem. Usuallysold for £39.95. Our price'£24.50 + £1 20 post. BFO Model Due toimporter clearing stocks wecan offer this standard modelfor the incredible price of£11.50 + £1.20 post.All goods guaranteed one year. 10 day moneyback offer on all undamaged goods. Goodsex -stock at time of going to press. Send S.A.E.for details

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TOP GEAR

V

Sound, like anything else you putin your car, should be top -rate. ClarionCar Hi-Fi is. Just check out thesecomponents.

First, the power amps. Left andright channels are separate to eliminateinterference. And they push out a hefty25 watts each. With a minimum ofdistortion.

Next comes the Stereo Control Amp. It not onlyhas bass and treble controls but also midrange.A loudness button levels up and adjusts lows andhighs that can't be appreciated at low volume.There's also a mic socket and volume knob. And theAUX socket will take anything from a radio/cassetteto an electric guitar.

The MW/FM tuner has pushbutton control and'self-seeking' station selection. There's built-in noisereduction on FM plus a CZ1 circuit to cut noise fromoutside sources.

Our cassette is also packed with featuresincluding Dolby, a selector for normal or CrO, tapes,auto reverse and a tape protection mechanism.

As for speakers, we suggest our GS -501 highpower 3 -way system for the kind of sound youthought you left at home.

And finally, if you want total sound control, getyourself a GE -501 5 -band graphic equalizer.


BMW by courtesy ofBMW Park Lane Ltd

Sound like a lot of equipment? You'll find itsurprisingly small. Unlike the sound.

Why not sound us out about Clarion Hi-FiComponent Car Stereo. Just fill in the coupon andmail it today.

4) ClarioHigh Speed Hi-Fi

Norse Audio Systems Ltd . ,111110

Unit B. Dorcan Industrial Estate ...orFaraday Road. Dorcan.Swindon SN3 5HQ I NameTel: (0793124081/2/3 #

Address

11vOP'ALI

n # Pleasesend me

colour leafleton the Clarion

G -series ComponentCar Stereo

I

I

II--------- IN MI NI INI im MN MN

19

OOOOO

000 000 0 00 000 000OOOOOO 000 000

000 000000000

000 0000400 0410

SOO SOOOOOOOO 0.0 000

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000 000 OOOOOOO

111::

0.0OOOOOO 000 000 000 000

000 0.0 000 .00 000

0.0 .00 000 000 000 0001000 000

000 000 000 0.0 000 000 0.0 *OS

OOOOOO 000 00. 000

GERM. DIODES200 Mixed Diodes mainly Germ.0A81.91.1N34 60 GC61 62 etc.Case DO -7 Coded and uncoded You to testValue all the way!o No SJ127 £1 per Pak.

SIL. DIODES200 Mixed Diodes - mainly SILICON case DO -7,0A200 202 General purpose 200mA marked andseceded you to sod and test OutstandingValue!

0 Na 02128 £1 per pak

AUDIO AMPLIFIER5 watt Audio Amplifier Module

Special Clearance Offero No AL2o £2.50

HEADPHONES

BC108 FALLOUTS

OOOOOO 000 000 000

Manufacturers out of spec. on volts or gain orneither Metal 1018 case - You test

0 No. SJ124 50 for £1

DIODES300 154148 Type uncoded Silicon Diodes.

Case DO -35 you to test.0 No. SJ129 £1 per Pak

Silicon Fast SwitchNPN like 2N 7062N2369 You select bytest!

0 No. SJ125 50 for £1

000

000 000 000000OOOOOO 000 S00000

0.0 0.0 0000OOOOOO 0. 00000. 000

4100 000

OOOOOO 000 000

NPNBD131. TO-126-NPN. Untested

o No. SJ84 25 for £1

SCRs1066 SCRs 5 Amp ALL good untested forvolt good yield 400+.

0 No. SJ130 10 for £1

OOOOOO 0000..

IC SOCKET PAKS

S J 3 6 1 4 6 p i n Sj41 c 12 p,SJ37 12 14 pin SJ42 5 24 pinSJ38 11 16 pin SJ43 4 28 pinSJ39 8 18 pin SJ44 3 40 pinSJ40 7 20 pin

ALL AT ONLY £1 EACH

AERIALS

GERM. TRANSISTORS

NEW Improved Lightweight Stereo Headphonesincluding double headband and padded earcups

Impedance .ohms Frequency 30-1800HZALL Black

0 No. 885 £4

As above but with coiled lead and rotary volumecontrols

0 No 884 £7

HEADPHONE ACCESSORIES7 metre Headphone Extension Lead

0 No. 136. £1.50.

HEADPHONE JUNCTION BOXGives facility for using Stereo Headphones withamplifiers and radiogrammes which do not have

a headphone outlet. TO CLEAR!0 No 881 £1.20 each.

ANTEX

Antex X25 Iron 25 watt soldering iron OURSUPER SALE PRICE, Great reduction

0 No. 1931 £4.00.ST3 Iron Stand Suitable for above OURSale Price

0 No. 1939 £1.25 each.

METERS23mm Level Meter Special Sale Price.

0 No 1320 £1.00.40mm V U Meter OUR SPECIAL PRICE

0 No 1321 £1.50.

PLUGS & SOCKETSSet of 4 1 -metre Colour coiled leads with phonoplug ends ideal for audio and test use.0 O ding Value

0 No SJ122 £1.00 per Pak1 mm Plugs & Sockets in Red & black

0 No. SJ123 5 prS. £1.00

CAPACITORSSJ11 150 Capacitors "-rued lopes end values

£0.50SJ12 60 Electrolitics all sorts mixed £0.50SJ13 40 Polyester polystyrene capacitors mixed

£0.50SJ14. 50 C280 type capacitors mixed £1.00SJ15 40 High quality electrolitics 100-470mfd

£1.0SJ16 40 Low volts electrolitics mixed values up

£0.50

TRANSFORMERS

MINIATURE MAINS Primary 240v.No Secondary

2021 6v,0 -6v 100mA2022 9v 0 9v 100mA

2035

f0.75£0.75£0.95£5.50

The last of the Geimanium PNP0071,71.75 etc Mullard Black Glass Type Youtest (5 could cost you that!)

0 No SJ126 50 pcs £1

GERM. POWER TRANS.AD1490C26 AD140 £0.50 eachAD1420C29 2N3614 £0.65 each

FM Indoor Tape Ribbon Aerial0.No. 107 40p each

HI-FI CAR AERIAL4 -section fully retractable and locking.

SPECIAL PRICE0 No 109 £1.40 each

VERO PLASTIC CASEComplete with lid and fixing screws. Finishedwhite. Size: 72mm x 50rnm x 25min

0 No 173 35p each

STEREO 30Complete 7 watt per channel Stereo AmplifierBoard includes amps, pre -amp, power supply,front panel, knobs, etc. PLUS transformer andreal Teak Cabinet for that professional finish,

SPECIAL SALE PRICESAVING £5!

OUR PRICE £25

BI-PAK'S OPTO BARGAIN OF THE YEARValued at over £10 - Normal Re-tail - We offer you a pack of 25 Optodevices to include LED's Large andSmall in Red, Green, Yellow and Clear.7 Segment Displays both CommonCathode and Common Anode PLUSbubble type displays - like DL -33.Photo Transistors - similar to OCP71and Photo Detectors - like MEL11-12.This whole pack of 25 devices will costyou just £4.00!And we guarantee your moneyback if you are not completelysatisfied.

FULL data etc. included0 No. SJ120. z

SILICON TRANS.SJ25. 100 Silicon NPN transistors all perfect and

coded mixed types with data and equivalentsheet no rejects £2.50

SJ26. 100 Silicon PNP transistors all perfect andcoded - mixed types and cases, data andequivalent sheet £2.50

SJ27. 50 Assorted pieces of SCR's, diodes andrectifiers incl. stud types, all perfect no re-jects, fully coded data Intl £2.50

TTUSSJ28. 20 TTL74 series gates - assorted 7401-

7450 £1.00SJ53. Mammoth IC Pak Approx. 200 pcs

assorted fallout integrated circuits includinglogic 74 series Linear audio and DTI manycoded devices but some unmarked you toidentify £1.00

PRECISION VOMMULTITESTER

20 ,000ohins volts DC Com-plete with test leads and In-structions

OUR SPECIALOFFER PRICE£11.00 each

Use your Barclay or AccessCard,

0 No 1323.

VOLTAGE REGULATORSCast 10220

Positive NegativeuA7805 £0.65 uA7905uA7812 £0.65 uA7912uA7815 £0.65 uA7915uA7818 £0.65 uA7918uA7824 £0.65 uA7924

TEXAS NPN

£0.70£0.70£0.70£0.70£0.70

Texas NPN silicon transistors, metal canperfect and coded.2S503-BC108, TO -18

O No. SJ29 50 off £2.50100 off £4. 1,000 off £35

AUDIO ACCESSORIESSJ75, FM coax cable plain copper conductioncellular polythene insulated and plain copperbraided PVC sheath impedance 75ohms

£0.10 per metreSJ76. 1 Board containing 2 x 5pin DIN sockets180' 02-2pin DIN loudspeaker sockets £0.30.SJ77 A 5pin DIN 180 chassis normal socket inclDPDT Switch £0.20.

DISC CERAMIC CAP100 Disc Ceramic CAP. Mixed values coverinncomplete range 3PF-4,700PF SUPER VALUE

0 No. SJ121 £1.00.

SWITCHESPush -to -make 6mm panel mounond

0 No. SJ131 5 for £0.50Push -to -break as above

0 No SJ'32 4 for £0.50

LED

2nd Quality Paks1507 10 Assorted colours and sizes £0.65S122 10.125 RED £0.50S123 10.2 RED 0000 £0-50

LED CLIPS1508 125..125 5 for £0.101508 2..2 5for£0.12

NPN TRANSISTORS

RESISTORSSJ1. 200 Resistors mixed values £0.50SJ2 200 Carbon resistors 1.4.1,1 watt preformed

OOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOO £0.50SJ3. 100 1/8 watt miniature resistors mixedvalues £0.50

SJ4. 60 '/2 watt resistors mixed values .. £0.50SJ5 50 1-2 watt resistors mixed pot values

£0.50SJ7 30 2 -10 watt wirewound resistors inured

£0.50

CASSETTESSUPER VALUE

And AGREAT SAVING!!!

C120 Dindy CassettesLow noise astoundingvalue and sound OlNo

ST32

10 for £3.50

IMPAK

SJ68 30 ZTX300 type transistors NPN pm -formed for P C Board colour coded Blue allperfect £1.00

SJ70 25 BC107 NPN TO106 case perfect tran-sistors Green Spot £1.00

SJ71 25 BC177 PNP TO106 case perfect Iran.sistors code C1395 £1.00

SJ72 4 253055 silicon power NPN transistors303 £1.00

POTENTIOMETERS16173. 15 Assorted Pots £0.50SJ54. 20 Assorted Slider Pots £1.00SJ56. 10 100K Lin Slider Pots 40mm OOOO f0.5016186. 25 Pre-sets Assorted £0.50SJ49 8 Dual gang carbon pots log and lie mixedvalues....f1.00SJ50. 20 Assorted slider knobs chrome black

£1.00

MISCELLANEOUSSJ20. 2 Large trot clips 25A rated ideal for

battery chargers etc £0.30SJ21. Large 71.2" Mains Neon Tester - screw

driver chrome finish £0.85SJ22. Small pocket size Mains Neon Testy,

screwdriver £0.55SJ23. Siemens 220v AC relay DPDT' contacts

10amp rating housed in plastic case £1.00SJ24. Black PVC tape 15/81 15mm x 25m - strong

tape for electrical and household use£0.35 per roll

ODDMENTS16170. 50 metres asst. colours single strand wire

£0.5016187. 30 metres stranded wire mixed colours

£0.5016178. 5 Main slider switches assorted £0.50SJ76. 1 Board containing 2 x 5 -pin, DIN sockets

180 & 2 x 2 -pin, DIN loudspeaker sockets£0.30

METAL SLIDERS

Metal Case Dual Slider Pots' 45mm travel£0.25 each£0.25 each£0.10 each

KNOBSSJ62 5 15mnt chrome knobs standard push fit

£0.50SJ63 Instrument knob black winged 129 x

20mml with pointer. 1'4" standard screw fit£0.15

SJ64 Instrument knob black silver aluminiumtop 117 x 15mml. 1,4" standard screw fit £0.12

Send your orders to DEPT 11 E, 8, BI-PAK PO BOX 6 WARE HERTS.SHOP AT: 3 BALDOCK ST. WARE HERTS.TERMS: CASH WITH ORDER, SAME DAY DESPATCH, ACCESS.BARCLAYCARD ALSO ACCEPTED. TEL: (0920) 3182. GIRO 3887006ADD 15% VAT AND 50p PER ORDER POSTAGE AND PACKING


EquitoneHE comes up with a project to enable you to equalize your car sound system,designed to match the HE CAR BOOSTER in last month's issue.

THE HE CAR BOOSTER is withoutdoubt a very good project. 18 wattsRMS per channel stereo music in acar gives a reasonably (?) acceptablelevel of sound. The basic unit doeshowever suffer from one slightdrawback, of necessity it relies on theexisting tone control of the musicsource. Car radios and cassetteplayers tend to feature a singletreble -cut tone control, which hardlyallows the listener to match hispersonal preference of tone in withthe listening environment of his carcockpit.

The HE CAR EQUITONE CONTROLgives you this facility with theminimum of fuss, controlling thelevel of bass, middle and treblefrequences with three fully adjustablepots. Because it has three mastercontrols rather than just the normal 2channel (bass and treble) type, theunit does justify the term soundequalizer, hence the name EQUITONE.Matching the absolute simplicity ofthe BOOSTER, our design for theEQUITONE Control uses only 29


components total and fits onto a PCBonly 85 x 50 millimetres. It connectsin between the sound source ie carradio and cassette player, and thebooster amplifier so coupling it up isno problem. Because of its passivenature it (magically) needs no powersupply whatsoever, just two audioconnections at the I /P and two at the0/P.

ConstructionDue to the passive, rather than activetone control networks involved in theEQITONE, there are absolutely nosemiconductors in the circuit. Thissimplifies construction somewhatand enables a small neat PCB to beused. This holds all componentsincluding the pots. The potsobviously need to be of the PCmounting type and a suitable sourceis noted in BUYLIN ES.

The potentiometers give an extrabonus in that when they are bolted tothe front panel of whatever case youuse, they automatically hold Flhecircuit board perpendicular,eliminating the need to bolt it to thechassis of the case. The board ispurpose -designed to fit easily into(yes, you've guessed it) a SINK BOX,to match last month's CARBOOSTER in appearance. The samelength ie 100mm is ideal, althoughthe enterprising builder may wish tofit the two BOOSTER Amps and anEQUITONE Control board in thesame case (length 1 50mm). If youfind that the output volume of thebooster has dropped slightly with theinsertion of Equitone, don'tworry. Reducing the value of R1 inthe amplifier circuit from 2M7 to(say) 1 M8 will give you any extragain that is required, once again toperforate your eardrums.

21

=How It Works= INPUTThe HE CAR EQUITONE Control basicallyconsists of 6 similar tone control stages ie 3per channel, 1 bass, 1 mid -range and 1 treble.

These days it's usual to make tone controlstages 'active' (if you consult the schematicsof most pre -amplifier circuits yoti will prob-ably find that the tone controls are present inthe feedback loop of an amplifying stage).The main advantage of 'active' control is thatthere is no insertion loss ie no "volume" islost. This was the first method we considered.

It soon became apparent that there was noneed for it to be active. After all, we have allthe "volume" we need from the output of thecar cassette player. The alternative - pass-ive controls, need far fewer components andtherefore a smaller, neater circuit evolved.They are much less complicated in construc-tion and design, acting only as simple ACvoltage dividers, cutting the signal at parti-cular frequencies, hence the insertion loss.

EARTH

INPUTS

Above. Layout diagram for the Equitone,the neatness of this board is mainly due tothe use of PCB mounting pots.

Right. Inside the 'Sink Box' cage theEquitone makes the ideal partner for lastmonth's stereo booster.

BuylinesOnce again we have used the SINK BOXfrom West Hyde Developments, to housethis project. It makes for an exceptionallyneat and tidy appearance which is justabout destruction proof - ideal for the car.

The PC mounting pots, as far as weknow, are available only from Electrovalue.

The estimated cost of all parts excludingthe case and PCB is about the £,8 mark.

22

C110u

RVla100kLOGBASS

0110k

C2j15n

R41k0

Te'5100n

RV2a100kLOGMIDDLE

10n

R210k

cs

Figure 1. Circuit diagram of the Equitone,simplicity is the name of the game.

OUTPUTS

135

150

RV3a100kLOGTREBLE

Equitone

150n

0310k

R611,0

°OUTPUT

NOTES.DIAGRAM SHOWS ONE CHANNELONLY. OTHER CHANNEL COMPONENTSARE PREFIXED 2

=Parts List=RESISTORS (all ,/.1W, 5%RI, 2, 3, 21, 21, 23 10kR4, 5, 6, 24, 25, 26 lk

POTENTIOMETERSRV1, 2, 3, 100k dual log

printed circuitmounting

CAPACITORSCI, 21C2, 22C3, 23C4, 24C5, 25C6, 26C7, 27

10u 16V electrolytic15n polycarnbonate10n polyester

150n polyester100n polycarbonate470n polycarbonate22n polyester

MISCELLANEOUS178??MM Sink Box4 x Phono Sockets3 x Knobs


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Pet 8kPet 16K

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Swiss watches are the finestin the world. Nowyou canseewhy.Swiss watch manufacturers have always been famous for theirquality, their design and their style.

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BULER MULTI -FUNCTION DUAL TIMEALARM CHRONO WITH COUNT -DOWN

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There are 34 different functions in 5 separate modes ofoperation (Time 1: Time 2: Stop -watch: Alarm; Count -down) andamazingly all 5 modes can be operated independently and atthe same time.

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ELECTRONICS & TIME CENTRES

47 High Street, Daventry, Northants.Hobby Electronics, August 1980

Buler dual time multi -function alarm chronowith count -down.Special Metac price.

L2495Time' Hours, mins secs. day and date ././///Time 1 Automatic viewing of time.

day and date.

Time 1.12 24 hour AM PM display. VTime 1 24 hour alarm i../Time 1. Day of week English. i.-2""

Time 1 Day of week in French and Germanas well 1/ V

Hourly chimes.

Time 2 -Hours. mins. secs day and date. VV.,//Time 2 Automatic viewing of time.

day and date v"'

Time 2 12 24 hour AM PM display VTime 2 24 hoar alarm 1. ---

Time 2 Duo of week in English. Frenchend GeT man Z/Z

Chronograph Measioin2 lip to 12 hourse,

VChronograph Moosunng up to 24 hoe r i

ii ,ec. VChrnnnornoh sic:, iap timing modes V

i. ro 1 , ',notes V2 i, hour . 59 nons V

Numb, 6

Nbo.t, 8

Sh.,, ,.. 7mm

13/4 years

most batteryretailers

,...---

,..---

99ft

Seiko alarm chrono. L42.95Lowest retail shop price.

Tune 1. Hours. mins. secs, day and date. VV i/y/VTime 1 Automatic viewing of time,

day and date.V

Time 1 12. 24 hour AM/PM display

Time 1.24 hour alarm. VTime 1. Day of week in English.

Time 1. Day of week in French and Germanas well

Hourly chimes

Time 2 Hours. mins. secs. day nd date.

Time 2 Automatic viewing of tone.day and date.

Time 212 24 hour AM PM display.

Time 2.24 hour alarm

Time 2 Day of week in English. Frenchano German.

Chronograph. Measuring up to 12 hoursit /, i,ec. yr/

Chronograph. Measuring up to 24 hour,in / sec

Chronograph Split lap timing modes io---

Countido n timer up to 100 minutes. yr/

Count down timer op2 ' hours59 mins.

Number of digit 10

Number of symbols 7

Slimness 8mm

Battery life 2 years

Battery ay addbiiity Seiko dealeronly

Stainless steel construction VQuartz mineral crystal lens VWater resistant to a depth of Yes. but not

specified

Metac 24 -hour Despatch Centre.47 High Street, Daventry, Northants.Please send me Buler watches at £24.95 plus75p&p. I enclose chegue/P0 for

Barclaycard/ Access No.

Please Complete

Name

Address.

Name

Address

HE 8

25

Building SiteWelcome to Building Site, the new feature where HE's Project Editor - Keith Brindley -takes a look at the month's projects with the accent on construction techniques.

WHEN I was asked to write a monthlyfeature in HE, I immediately jumpedat the chance of discussing the prac-tical problems and difficulties whichmight arise in the construction of theprojects in the issue. Having built theprojects myself I suppose I am in thebest position to take a more detailedlook at them and to pass on anyrelevant information not normallygiven in the project section but whichmay be of help to you.

Speaking of projects in this generalway provides a useful introduction tothose contained in this issue. Thereare six this month, three are con-structed on Printed Circuit Board andthree on veroboard. The veroboardprojects are all constructed onstandard sized, 10 x 24 holes 0.1"matrix veroboard. These boards, ofcourse, are fairly cheap and readilyavailable. There can't be many elec-tronics enthusiasts who haven't usedveroboard, but for those of you thathave missed out, or are just a littlerusty, I will quickly run over thebasics.

Veroboard essentially consists ofpredrilled circuit board available withholes on either o.1" or 0.1 5" matrix.Photograph 1 shows a sample of 0.1"matrix board with its copper tracksjoining all the holes in lines, horizon-tally.

The Good, The Bad And

When building a project which isdesigned for veroboard, the first jobto be done is the cutting of the trackwhere indicated in the diagrams of theunderside of the board, usually givenin the project section. The places to"cut" are shown by large black circlesin the track. There is a special tool forthe job but you can use a drill, (about1/8" - holding it in your hand). Seephotograph 4. Gently twist the drill ortool on to the hole where the break isshown, until a good clean hole in thecopper track is formed. Check that noswarf or loose copper bridges acrossto nearby tracks. Photograph 2 shows

0-t

Photo 1. A piece of veroboard of the sizeand type used in many of our projects -10x24 holes on a 0.1" matrix.

0

0000

If=

0

Photo 2. The track break on the left is agood one. However, that on the right is not- note how a loose piece of copper isbridging across to the adjacent track.

Photo 3. Mount the component, in this casea resistor, close to the board, preventingany future short sircuits between it andother component leads which may be closeby.

a good and a bad break - make sureyou know the difference.

Neatly Does ItNext, the components are inserted.

Generally speaking, the lowest heightcomponents should be put in first(both with veroboard and PCBs) e.g.resistors, wire links, etc. It is normallyadvisable to leave all semiconductorstill last as they tend to be easilydamaged by excessive heat.

Insert one component at a time.Before soldering check that the com-ponents are mounted close to theboard (photo 3), and that the endresult is neat and tidy without anycomponent leads shorting together.

Ready To Go

Underneath the board two otherpotential hazards can be avoided bytrimming the protruding leads usingside cutters (as in photo 5) as close tothe solder joint as you can, preventingany future short circuits and checkingthat there are no solder bridges acrossadjacent tracks.

After all this, you should have aworking veroboard project, un-doubtedly something to be proud of.Perhaps, next time you will have theconfidence to have a go at a projectconstructed on PCB - it may be oneof the three featured in this issue. Forinstance, Gaztec, the gas detectingalarm, should pose no real construc-tional problems. However, do takecare when handling CMOS integratedcircuits - leave them until the veryend before insertion and never holdthem by the pins.

Sound AdviceThe HE Equitone is of course the

complementary tone control to theCar Booster featured in last month'sissue. Neither the Booster nor theEquitone are too difficult to build,deliberately so. You will be rewardedwith a cheap yet good quality soundsystem for the car cassette/radiowhich, believe me, is loud. There isnothing too critical in the constructionof this project, except perhaps the use


Photo 4. Using the cutting tool to break a track in the correct places.Alternatively a small drill bit held in the hand can be used.

of the printed circuit mounting poten-tiometers. Ordinary pots could ofcourse be used but those specified cutdown the interwiring involved to no-thing.

Last But Not Least

Uur last project this month is 'PassThe Loop.' HE's updated version ofthe old game which used an alarmbell, battery and wire, although oursis much evolved from the original and

RESISTORS

0 - BLACK1 - BROWN2 - RED3 - ORANGE4 - YELLOW5 - GREEN6 - BLUE7 - VIOLET8 - GREY9 - WHITE

Photo 5. Use a good quality pair of side cutters to snip thecomponent leads off as close to the solder joint as possible.

quite a bit more entertaining. This oneis going to be a real winner at fetesand fairs. We haJe used CMOS chipsagain so care will be needed at the ICinsertion stage. Interwiring betweenthe PCB and the various controls,leads, wires etc, is fairly complex andso we have tried to help you with clearconnection diagrams. We fitted ourcomplete unit into a case but you can,if required, put yours onto a largerbaseboard to enable the shaped wireto be much longer and bigger.

The Resistor CodeFinally, we have shown below the

conventional resistor colour codescheme and a table of preferredvalues and corresponding tolerances.If you dabble in the hobby for anylength of time you are almost certainto pick up the code - it is not toodifficult to learn (being basically thecolours of the rainbow) but we areincluding for the benefit of new en-trants into the electronics world (orsimply the lazy regulars!). HE

The Resistor Colour Code

READING THE RESISTOR CODEResistors are coded with coloured bandsto ease the problem of marking suchsmall components.The numbers corresponding to the tencolours used and the values per positionare shown above.

For example, 180 000 ohms is codedwith the first digit brown, then grey andfinally yellow. The fourth band indicatesthe tolerance that the value has withrespect to the stated value. For example,silver indicates 10% tolerance meaningthe 180 000 ohms could vary between180 000 ±18 000 i.e. 162 000 to198 000.

These tolerance may seem to reflectpoor manufacture but in most circuitsthey are, in fact, quite satisfactory.

FIRST DIGITSECOND DIGITNUMBER OF ZEROS FOLLOWINGTOLERANCE - RED 2%

GOLD 5%SILVER 10%NO BAND 20%

Relaxing the tolerance enables the makerto sell them more cheaply.

PREFERRED VALUESIf the maker tried to produce and sellevery value of resistance that,exists therewould be chaos and the costs would begreatly increased. The actual values made,therefore, are limited to a range calledthe preferred values. These are listed inthe table at right.

The values may seem illogical at firstsight, but this is not so. They stem fromthe fact that the tolerance extremesof a value reach the extremes of adjacentvalues, thereby covering the whole rangewithout overlap. Values normallyavailable stop in the megohm decade.

Tolerance

±5% ±10% ±20%

1.0

1.1

1.2

1.51.61.82.0

2.22.42.73.0

3.33.63.94.3

4.75.15.66.2

6.87.58.29.1

1.0

1.2

1.5

1.8

2.2

2.7

3.3

3.9

4.7

5.6

1.0

1.5

2.2

3.3

4.7

6.8 6.8


Freepost B FREEPOST ON ORDERS ACCESSi Birmingham.

VAT INCLUSIVE PRICES 612.1

B19 1BR is ADD 30p P&P CHEQUEELECTRONICS 021.233.2400 24 HR PHONE ANSWERING SERVICE

ALL PRICES IN PENCE EACH UNLESS OTHERWISE STATED

CAPACITORSElectrolytic Axial Loads-10% to MO% Tol.

V Lc le

4113.13

10

15723347es

100150

' 220330470680

100015002200

9

13

21

253542

26

10

23303039

Graaf Ca.Cop 016 AF 4V etc

40 83

9

911

13

2630323959

31

3840

54

P.C.B. Component,

Delo P.O. Blue In, Slow Or.. 98 P. 33PC

Miniature Low Mal® Order Codene, Anial, 41% Tot., 2e3V DC W 9 Cap 424

Ceram. Plate, Radial, Lt. 0, 100V DC Al 9 Cop 631Comento Plata, Radial, Mod 8, 100V DC W 9. Cap 630Caren. Plete, Rad,. 01911 K, 630 DC Wi4g. Cap 629

Value424 622 632 830 434 629

27 8pF

1.21.5

112.22.733

4.7586.851

101215

182227333947

566881

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20202020202020202020202020202025252525

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101215

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22273339

292931

31

424550

9

Polymter Radial Leeds Order Code

Domed Tam 0250/352 StyleMoulded Ty., 10.1.. PRER

Ai 362 360 o911

0010015 150022 .220033 .330047 41

.00613 es01 1.0.015 1.5022 2.2033047

Cap 352Cap 360

Vol.362 360

7 9

B 109 11

11

14

1721

3035

Tantalum Reed Order Code20% TM Cae PR AF Vol%AF

0.220.47

2.1

1022

V el.c. 10

16

34

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1215

2228

26 35

2228

12

28

RESISTORSCarbon Film, Fixed0.250. 524 Values 1150-100, Tol. 1each 100/100 (Mult 10/Valuel Res RD,0.5W. 012 V.1.1100-407, 10% To, 3.c. 150/100 W. 10/Veluel Re, u00'/4

VaIus

Metal Film, Fixed0.5W, E24 Values, 501.1M, 2% Tot.2.50, 012 Values, IO0775, 5% Tel

8 eocrt16 each

Order Code

400/100 (Mud 10/1e10e1 R6119630800/10011.11 10/Velua I Res 0052

Val.Metal Olan, Flood050.5240.1*...114-331.1, 5% Tot. 16 earn 800/100 Ildult 10/VP.I Res VR37

value

Skeleton Presets, MiniMure0.19. 53 vow, t0011-im, 1,n. yeicsi Mount,0.19, 03 Voluw, 1006 -IM, Lon. Hororonvol Mountong

Skeleton Presets, Standard0.39, E3 V.1ues, 10011.407, Lon. Vertmer Mounung0.309, 03 Value., 10011-4147, Lon. Homontal Mounting

Potentiometer, Rotary0.50. E3 Velum, 1K-202 Lon0.259, 53 Values, 487.362 Log.

Potentiometer, Slider0.5W. E3 Velum, 210.4701, Litt0.166, E3 Vaues. 180. IMO Log.

8 Mon Preset V13 Mon Preset H

velus

Std Preset VStd Prep. H

Val.

39 Ro Pot Lon39 Flo 007 Log

Va1.

45 SI Pot Lon45 SI Poi Log

vol.

OM 0 S 6.811.01HEF4200 22 11010044

HEF4001 22 0E1.46HE.002 22 HEF4047HEF4006 119 liEF4049HEF4007 22 11.0050HEF4008 . 1..001HEF4011 22 H8.002HEF/012 22 HEM.HEF4013 57 H EF4066

HEM. 105 0E04067

HLF4015 100 8.40688004016 67 H.40698E84017 100 HEF4070

8E84010 100 LI EF4371

8E84019 58 8E840728E84020 112 81740728E8.21 107 HFF4075

0E7.22 103 0E140767E1.23 22 0410077HEF4021 7u 11E84078

HEF4025 22 8E84081

11E84026 244 EE4082

H684027 57 1.84086HEF4028 89 1.810868E41029 113 HE0493HEF30 58 8E84094H01100300031 250 0E14104

61E4036 138 8E81002HEF4040 107 HEF4005

HEE.. NEF4508o6E4002 83 HEF4610

HEF.. . HEF4611

105

133

10957

S7

87

90

62475

22

22

2223

23

23

3

30

22

2323

23

8000

19

208114

714

230

135

157

1..51211.15148E81515NEF0516HEF4317HEF4518

045191.845201.84521OEF452811.4522NEF0620HEF40.39

HEF0665HEF4636HF4657

E465HEF472411.18097HEF480981.8.1068L840160MEF4010141384016281.40163HEF00174HEF.173HEF40192HEF40193

HEF40494EF40196

1311

313374127

478118

69

118

235124

150

630138194

98

98

122

214113

92

8

1.149

149

109

149

149

14

149

149

149

74LS74.2074450174450274850374.04744506

44508744.74.10741511

7.012744012

41314 74

744010 2674.20 19

744021 26741522 2674/320 357.030 19

741332 27

704533 35

74.7 35

744. 35

744.0 27

74.. 60

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744582974408674E5567.9044092

7013937045965741.6013107.4510974131127445113741311474.125744512074E3132744313674.13B74451397445.744S1547.516674.1667.5.77.01587061.744310174E5162

74E516374.16474401707.5173

10600

395,767682

12641

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7.52.74402617.52667.52727402827.52907.02.74.298741536.57403.74433677440365

91

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2440374 173

7410375 117

7445378 156745306 66

7413390 1967915393 1967440395 2077440490

Plessey I/C's440 331445 182

L610 245L612 245620 369621 369

L622 910624 342

L630640

L68016101611161216211626163016401.1

L864051.629

231409245177177177239157177

106206270475

LINEARCA3046 84

093080E 77

093130E 99CA31406 48CA31896 293LA.301AN 3411,396 781031306 10415138145 19811039005 75NIC3403P 156NE531 131

NE5361 259NE5555 18665565 66665660 171

6E6706 486NE5716 505R1,4138 14613211205 88104,1022 713TDA103413 2391,1381CP 84',OWN 156121174106 2012/9741CT 47UR 746C6 39

SEMICONDUCTORS09140400104002WONN4007N414805402

2164623696164662926G63053

03055 55N3055ull ISB Tett 9563.2 15563702 93704

5 1637055 2937735 2638197 1038209 1039044 165457

15 16545931 4067321 A016173 AD16213 13010719 BC..

6010806C1098C1091113C1090BCI48BC158130177

10297

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1111

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29

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0181360 1860000101 3604910028 1180C35 105T1P31 A OB

110324 51

1,41C142CT1179551,3055TIS43

7676756036

40000 407-C33132086/62 X79 Voltage 9

VoltageRegulators.0091341K1 1190472306 421297130500 781.781CU 7.1.01781510 78110791241/ 979791500 97

12,81.05CS 38LIAILI ICS 38

OPTO ELECTRONICSLight Emitting Diodes, Individual

125- 1300001 R. 16Green 113

yellow 10an, Mountong Clop to ot 3

15rnm/ OM 16Green 18yellow 20

Panel Mount62 Chp to snot 5

C0954C099500997503 Cl o

COT,.COT.COY954E05 C.

Photorest1to.0.12 9503P131 95

Photot.n11110.01071 220131.15 19501.29 195

Photocouplar0001310 165

Plank Boxes - Boss Industrial Mould ngsMawed Illoa and Close Fon, Fianged LoABS Box. Brene Suakee, PM Lid In Or 0.

Order Code4112 45e2 031 W Cone 611912003 OR

115011190 D50 131 Case 131102005 ORL1906110 060 223 Cele 810320013 ORP lestic Boxes with Motel LidsRecalled op BoxABS BeecTC/Vol Bran Bud., In OrangeInun 410monourn Top Pens! Formbed Gr.

185056 029 112L11 671 041 150L16 W9111 D63 216

D owast BoxesOlocest Box end Glonped L.Murnankurn 80. and Lus on Natural Fon.

L113.53 DllL1521.12 6350L1916113 D61

114216334

Order Cod.Cm. 81144003 ORCam 4111914004 ORCam 81.4006 OR

Order CodeCase 61.51703 NACase 131145005 NACam 8105006 NA

SWITCHESMiniature Toggle - 140neywellSPOTSPOT C/OffSPOT Dou Ise Boas To CentreSPOT Songle Boas ro CentreSPOT Boas

OPOT°PDT C/OffOPOT Double Boas To CentreOPDT Sonde 8. To CentreDPDT Boas

Miniature Paull -C & KSP Pum To Mahe, MomentarySP Pu n , Sreek Moment.,

Order Code

67 00 84101181 SW 134.101190 SW 84104190 SW84105184 522821106199 SW 842011

111 SW 842021123 SW 847041123 SW 842051116 SW 842061

62 SW 853162 SW 8533

D.I.L. Socket.8 Pon Low Profile Socket Ton

14 in Low Prufore Socket Ton16 Pon Low Profol Socket Ton

12 011107614 OIL SKT 1416 COL SKT 16

MAINS TRANSFORMERSSecondeces may be connecter,' series orApp. to goye v.. voltage rangerom...0.220. 240,

6VA - Clamp Type Constroctoon 236 each

Appro. 18% Regulation F C 54, H36, W35

64.012, 0-4.512 Second..000, 0-612012V, 0-12V0.1512, 0.15V02012,03012

Order Cod*

Trans 6VA 45

20VA - Cow, Type ,nstructoon 3130.ca

Approx. 16% Reguletoon F C 70, 748

Oa 5V OA SV Secondaries0-6V. 06,0120,0-1700150,0.150011.512, 017.506200,0-200

120150200

Trens 1004 4560

110150175

200

VERO ELECTRONICS PRODUCTS2.5" or 5" .1" 1,1101 vsumowd 71

3.75" n 5' .1" pot. vemumrd 7976' s .1' 0.tch Varob.. 15/ 85/Pack3.7, 5' .1" pot. Nam Bos. 68582"

pit0-0 DIP Board 135

Spot 5404 Cutler 107Pon Ineartion T.1 for 040 type Ron 1,OS Pons .040 11001 44/0oc4SS Pons 040 1100/ 44/PeckVerowore Kot 2.wore 15-cornbl 454/KotVenom,. Corn. 1251 109/PeckVerowore Wort 121 109/Pack

200.210692200-21072020021076010611078H100.110840203-210134203-21015F20021087E200210178200 71341020021339F200-11340G

Mmtsinks

mdondor. Tome for 1 105 50°C/6 17

TT... 100166 10 ,C/W 28tonInclual Type for 1 9 10 2.C. SS

Indwoduel Type for 1 . TO126 Ittcm 26Indwodual Type for 1 .10210 1 7°C Mt 26

Smk SFSink 1,2Sink TV3Sink TVOSink TVS

G.M.T. ELECTRONICS KITS.

FULL TELETEXT KIT(Free-standing unit- no internal connection to T.V.)

TELETEXT DECODER + REMOTE CONTROL KIT(For wiring into existing television)

PAL ENCODER/MODULATOR KIT

DOPPLER RADAR ALARM KIT

F. E.T. POWER AMPLIFIER OUTPUT MODULE KIT

ONE AMP POWER SUPPLY MODULE KIT - FIVE VOLTS

ONE AMP POWER SUPPLY MODULE KIT - TWELVE VOLTS

MODEL INERTIA CONTROLLER MK I - SLOT RACER

MODEL INERTIA CONTROLLER MK II - TRAIN (HAND UNIT)

MODEL INERTIA CONTROLLER MK III - TRAIN (CONSOLE UNIT)

099-90

E135-90

22-90

£ 44-90

E. 27-50

6-00

£ 7-50

£ 30-00

£ 25-00

E. 25-00

PUBLIC ADDRESS EQUIPMENT

A55 20W AC/12vDC MOBILE AMPLIFIER 69-00

A56 50W AC/12vDC AMPLIFIER £117-30

A70 175W AC/24vDC PROFESSIONAL AMPLIFIER E276-00

L78 20W WEATHERPROOF HORN SPEAKER, 8 OHM & LINE 41-40

L83 16W MEGAPHONE (SEPARATE MICROPHONE) £ 69-00

L110 40W CABINET SPEAKER 8 OR 16 OHMS (SPECIFY WHICH)(c/w block 'vynide' covering, metal corners and overall cover) £ 89-70

M21 UNI-DIRECTIONAL ELECTRET CONDENSOR MIKE, 600 OHM £ 19-32

M30 BALL WINDSHIELD DYNAMIC CARDOID MIKE, 600/50K OHM 28-98

M104 SIX CHANNEL STEREO MIXER AND PRE -AMPLIFIER(accepts high and low imp mikes, and has RIAA input) E. 62-10

M124 FLOOR TYPE MICROPHONE STAND, EXTENDS TO 60" K 14-49


RadioTimerThis inexpensive littleproject will turn your plainordinary transistor radiointo a bedside radiocomplete with 'sleep'facility.

THIS SIMPLE AND inexpensive littleproject is designed to make itpossible for you to reach the land ofdreams more easily, whatever theoutside world may do to prevent you:It will convert your simple little-trannie- into a true bedside radio,which lulls you to sleep with musicand then switches itself off topreserve those expensive batteries.

Six pre-set timing periods areprovided on the unit, from fiveminutes to thirty, but if you need toextend this 'How It Works' willprovide you with the information youneed. Longer times are possible withthis device, since the ICM 7555 IC(integrated circuit) we have used is aCMOS version of the ubiquitous555 timer chip, having twoadvantages over the latter: -(i) it consumes far less current inoperation(ii) it has the ability to work withlarger values of resistance as a timingcomponent.

F8R1M2 8M2

R38M2

R48M2

How it WorksICI is used in the standard 555 monostablemultivibrator configuration. Cl is thetiming capacitor. It's essential that a highstability type should be chosen if the unit isto function properly. Ideally it should be atantalum bead capacitor as these havecloser tolerances and lower leakage cur-rents than ordinary electrolytic capacitors.The timing resistance is formed by which-ever of the resistors (RI and R6) areswitched into circuit using SW1. The out-put pulse length of ICI is nominally 1.1CR,giving and output pulse duration of about300 seconds (five minutes) with one resis-tor, 600 seconds (10 minutes) with tworesistors, and so on. Of course, these timeswill not be exact due to the tolerances ofthe timing components and ICI itself, butthey will be close enough for this applica-

tion. ICI is triggered by taking pin 2 low bymomentarily operating SW3. The output atpin 3 then goes high for the time set usingSWI, biasing Q1 into conduction via cur-rent limiting resistor R7. Power is thenapplied to the radio which forms the col-lector load for Ql. At the end of the timingperiod the output returns to the low state,switching off both Q1 and the radio. Poweris still applied to the timer circuit at the endof the timing period, but as it has a currentconsumption of only about 70 uA underthese conditions the life of the battery willnot be much reduced even if the unit is leftswitched on almost continuously. SW2enables the unit to be bypassed and theradio to be operated normally. SW4 is anordinary on/off switch.

0-

SVV1

R58M2

NOTE:IC1 IS 755501 IS 2N2219 OR 2N3053

R68M2

Ti33u

IC1

R7100k

R83k3

+OUTPUT

IC2 0 -100n

01

SW3 +9VON/OFF

SW2OVERRIDE

Figure 1. The circuit diagram of the Radio Timer. Note how the resistor chain R1-6 is connected in series with the switch SW1.

OV


From this photograph you can see how we use a battery connector to power the radio.

ConstructionWe assembled our prototype onveroboard, but there is no reasonwhy you could not use a PCB for theproject. This might be a good placeto try your first design, as actualboard layout should not provecritical. If you use a PCB the timingresistors we fixed to the switch couldeasily be accommodated, with aresultant 'cleaning -up' of the case!

Before assembling on Veroboard,make sure you have cut the tracks atthe locations shown in the diagram(Fig. 2). If you don't neither the timer

Parts List-RESISTORS (All 1/4W 5%)

RI -6R7R8

8M2100k3k3

CAPACITORSCl 33u 10V tantalumC2 100n polyester

SEMICONDUCTORSICI 7555QI 2N2219 or 2N3053

MISCELLANEOUSSW1 1 pole, 6 -way

rotary switchSW2,3 single -pole, single -throw

toggle switchPB1 push -to -make, release -

to break switch10 x 24 hole, 0.1" veroboardCase to suitPP3 battery and 2 x connectors.

BuylinesWe cannot foresee any problems in obtainingthe components for this project. Theapproximate cost for all components shouldnot be any more than about £5.

nor the 7555 will operate -probably ever again!

Solder in the links and wiring pinsfirst, as these are least susceptible toheat damage, followed by theresistors and capacitors. Be carefultoo with the copper tracksthemselves, if you overheat thesethey will lift from the board andprobably snap in the proces Fit thetransistor and IC last of all andpreferably use a holder for the IC.

Check that you have the IC andtantalum capacitors orientedcorrectly before soldering in too, lookfor the indent or spot next to pin 1and the lead markings respectively. Ifyou follow the diagrams all will bewell. HE

A 0 0 0 0

8 0

C 0D

F 0

G 0

14 00

7

The resistors fitted to the switchshould be aligned as neatly aspossible, taking care that the leadsfrom these components do not toucheach other. Check that when youclose up the case the resistors do nottouch the metalwork thereby shortingthem out completely. Soundsobvious but it's easily done weassure you - ask our technicians.

Choice of case is not all thatcritical, by the way, so if you can fitin the board, hardware and battery -it will do nicely.

Constructive UseConnecting up the Timer is easy.Just fit the radio into the battery clipprovided - noting that the TimersClip is wired in reverse to normalpractise so that it will fit thecorresponding clip on the radio. Youshould choose this clip to fit the typeof battery in the radio.

Switch on, set the time you wantand press 'Start'. The unit will nowturn the radio off after the selectedperiod has elapsed. Sweet dreams.

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0o 4:4 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0

o 0 0 0 0 0 0 o 0 o 0 0 0 0 0 0 0. 0 0 0 0 0 0. 0 0 0 0 0 0 0 0 0 o000000000 0 0 0 0 0 0 0 0 0 o0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 2 3 4 5 9 1 I 9 10 11 12 13 14 15 16 I> 19 19 20 21 22 23 24

Fig. 2. Above. The underside of the boardshowing break pointsFig. 3. Below. Connection details andveroboard layout

8 9 10 11 12 13 14 15 16

0 0 0 0 0 0 0 0 0" IC1

I

O

O

O

SW2OVER IDE

SW3ON/OFF

V

OV


VMOS POWERFETSVN67AF (15W, 2A, T0202) 75p, 10+70pVN1OKM (1W, 1/2A, T092) 55p, 10+50p

BD512 (P-chan. 10W, 11/2A, T0202/3) 85p 10+80pHeat clips, T0202 12p, T092 8p, VN/VM Design Cat. 20p

O

0

CA3080E 70pCA3140E 38pLM3900 43pMC3401 30pTL081 29pTL082 55p2102 80p4011B 17p709 15p710 25p733 50p741 18p78L05/12 29p

HI-FI ON TWO CHIPSHA12017 (Preamp 0.001% distor-tion 83dB S,N in phono application)99pHA1370 (Poweramp 20 watts in80. 0.02% distortion (typ) 195pBoth with data and circuits.

POWERFET AMPLIFIER semicon-ductor sets. High power designsoffering very low distortions.'80 watt 11THD 0.008%1 £8.75.120 watt (1THD 0004%1 £16.65

(with circuits)`into 80 tat all powers and all

audio frequencies

J. W. RIMMER

SCOPE TRACE DOUBLER P.C.B.Built C W shift, than. select, cho-prate controls and instructions. use-ful display from DC to 10MH7. Runsfrom 9V battery £9.95

VCA High quality design offers attenuation from 0dB to 90dB. S N90dB. THD 0.01%, B.W. DC to100KHz. Complete components setand circuit £2.50

P&P 30p Mail orders to 148Quarry Street, Liverpool L256HQ. Tel 051 428 2651.

Technical enquiries to 367 Green Lanes, London N4 1DY. Tel 01-800 6667

OHIO SCIENTIFIC Superboard 2 Assembled50Hr model E169.95 15% vat post free.Colourboard 2 (the new colour version of Superboard2) E205 15% vatSpecial otter If bought with super board orcolourboerd these items are at the reducedprice shown first.Also sold separately at the bracketed prices.

Add 15% vat Modulator and power supplykit £7.95 (El 11 4K extra ram £20 (024)Case E23 (0261 Cassette recorder EISiE151 Colour conversion board E45 (045)SINCLAIR PRODUCTS New 10MHz scope E145.pfm200 £51.95, case E2.07, adaptor E4.20,connector kit £13.95. Microvision tv £89, adaptor£6.88. pdm35 E34.23, adaptor £4.20, case 02.07.dm350 £76.70, dm450 0102.17, dm235 £55.55,rechargeable bans Ell, adaptor E4.20. case E9,enterprise prog calculator + accessories £19.95.TG105 £87. Bench Frequency Counter £150.COMPUTER GAMES chess champion 6 E49.95.Chess challenger 7 E75. New sensory chess chal-lenger 8 £109.Atari videocomputer E129. Cartridges £14.95.COMPONENTS 1N4148 0.9p. 1N4002 3.1p.741 18p. bc182, bc184, bc212, bc214 bc5485.5p. Resistors 1/2W 5% E12 IOR to 10M 1p, 0.8pfor 50-, of one value 16V electrolytics 0 5, 1, 2. 510, 22m1 Sp, 100mf 7p, 1000m1 11p. 1 lb FeCIE1.50. Palo pen 84p. 40 sq ins pcb 45p. Poly.styrene capacitors E 12 63V 10 to 1000013p, 1 n2 to10n 4p. Ceramic capacitors 50V E6 22pf to 47n 2p.Zeners 400rnW E24 2v7 to 33v 7p.

TV GAMES AY -3-8500 + kit E10.21. AY -3-8600+ kit £14.98. Stunt cycle chip + kit E14.09. Colourgenerator kit £9.05.TRANSFORMERS 6-0-6V 10Orna 80p. 1 ViaE2.60. 9.0-9V 75rna 80p, la E2.40, 2a E3.94.1 2-0-1 2V I 0Orna 98p, 10 E2.80.IC AUDIO AMPS with pcb JC12 SW 02.08. JC20IOW 03.54.B ATTERY ELIMINATORS 3 -way NMI 6 / 71/2 /9t30Orna E3.14. 100ma radio type with press -studs9v 03.77.9+9v E4.99. Car convertor 12v inputoutput 41/2/6/71/2/9v 800ma £2.76.B ATTERY ELIMINATOR KITS 10Orna radio typeswith press -studs 41/2v E1.49, Sie £1.49. 9v £1.49,41/2+41/2v £1.92, 6+6v E1.92, 9+9v E1.92.Stabilized 8 -way types 3 /41/2 / 8/ 71/2 /9 / 12 , 15 /18v 10Orna £2.60. tAmp £6.50. stabilized powerkits 2.18v 100ma £2.60, 1-30v IA E6.75, 1-30v2A E12.10. 12v car convenor 6/71/2/ 9v 1A 01.35.T -DEC AND CSC BREADBOARDS s-dec E3.79,t-dec £4.59, u-deca £4.69, u-decb £7.16, exp4b£2.64, exp300 £6.61, exp350 £3.62, exp325£1.84.BI-PAK AUDIO MODULES s450 £27.90. ALSO£5.62. pa100 E19.24. spm80 £5.26. brn t80£6.06. stereo 30 E23.94. A130A £4.53.

SWANLEY ELECTRONICSDept. HE, 32 Geldeol Rd.. Swenley, Kent.Post 35p extra. Prices include VAT unless statedOfficial and overseas orders welcome. Lists 27p postfree. Mail order only

13EiRSTIESVf.. %LEA k 4W 1144 131k011,40)S

ink RIZO Stt kly 2.kiSWhk..)61t4C1c,...

WOO' NA 9f.,140?

a.,19

If WORA'ED ENE - VKI,ett-S0010JOM -116

OcE 1-4C ROOC

ate ;ie.stamp/Oe,a-irth,e//5CPR 1 - THE ADVANCED PRE -AMPLIFIER. The best pre -amplifier in the U.K. Thesuperiority of the CPR 1 is probably in the disc stage. The overload margin is a superb 40bB, thistogether with the high slewing rate ensures clean top, even with high output cartridges trackingheavily modulated records. Common -mode distortion is eliminated by an unusual design. R.I.A.A

accurate to 1613 signal to noise ratio is 70dB relative to 3.5mV, distortion <005% at 30dBoverload 20kHz.Following the stage us the flat gain /balance stage to bring tape, tuner, etc. up to power ampSignal to noise ratio 86dB, slew -rate 3V/ uS, T.H.D. 20Hz - 20kHz< 008% at any level. F.E.Tmuting. No controls are fined. There is no provision for tone controls. CPR 1 size is 138 x 80 x20mm. Supply to be -.,- 15 volts.

MC 1 - PRE -PRE -AMPLIFIER. Suitable for nearly all moving -coil cartridges. Send for details.

X02 X03 - ACTIVE CROSSOVERS. X02 - two way, X03 - three way. Slope 24dB /octave.Crossover points set to order within 10%

REG 1 - POWER SUPPLY. The regulator module. REG 1 provides 15-0-15v to power the CPA1 and MC 1 It can be used with any of our power amp supplies or our small transformer TR 6 Thepower amp kit will accommodate it.

ee NEW ISSUE 5 0.

POWER AMPLIFIERS. Our new issue 5 power amplifier modules have automatic shut -downthat will not allow serious overloads for more than 0.1 sec - thus vastly increasing reliability atelevated temperatures. Other improvements to the circuitry have improved the subjective qualitieswhich keeps CRIMSON even further ahead of the field.

POWER SUPPLIES. We produce suitable power supplies which use our superb TOROIDALtransformers only 50mm high with a 120.240 primary and single bolt fixing (includescapacitors/bridge rectifier)

PRE -AMP KITThis includes all metalwork pots, knobs, etc to make a complete pre -amp with the CPR I (5) module ifrequired

All prices shown are U.K only and include V A.T and post. C.O.D. 90p extra 0100 limit. Export is noproblem, please write for specific quote Send large S A E. or 3 International Reply Coupons for detailedinformation

POWER AMPLIFIER KIT. The kit includes all metalwork. heatsinks and hardware to house any !woof ouramp modules plus a power supply. It is contemporarily styled and its quality is consistent with that of ourother products. Comprehensive instructions and full backup services enable a novice to build it withconfidence in a few hours.

POWER AMPLIFIER MODULESCE 608 021.00CE 1004 024.50CE 1008 027.50CE 1704 E35.00CE 1708 035.00

HEATSINKSLight duty, 50mm. 2 Cr VV E1.70Medium power. 100mm. 1 4 C/W

E2.70Disco/group 150mrn 1.1 C /W

E3.50Fan mounted on two drilled 100mmheatsinks2 x 4 C/W 65 max when used withtwo 170Wmodules E36.00

THERMAL CUT-OFF, 70C E1.90TOROIDAL POWER SUPPLIESCPS I for 2x CE 608 or CE 1004

E19.50CPS3 for 2x CE 1004 or 1/2 x CE1008 E23.50CPS6 for 1/ 2 CE 1 704 or I/ 2 CE1708 E30.00

POWER AMP KIT

PRE -AMP KIT

PRE -AMPSThese are available in two versions - one uses standardcomponents, and the other (the SI. uses MO resistorswhere necessary and tantalum capacitors

CPR IMC1CPR 15MC IS

ACTIVE CROSSOVERX02X03

POWER SUPPLY

REGI £9.30 IRS E2.50

BRIDGE DRIVER, BD1Obtain up to 340W using, 2,170W amps and this moduleBD1 E7.25

E38.60

£39.60

E34.00£28.00£44.50037.50

£19.00E28.35

U K - Please allow up to 21 days for delivery'Write for free literature or send 50p for application /users

manual

Crimson Elektrikla STAMFORD STREET, LEICESTER LE1 6NL.

Tel. (0533) 553508


Kit ReviewThe ultimate amplifier kit? We think this month's offering from Crimson will makeyou think twice about buying that flashy oriental box of tricks.

CRIMSON ELEKTRIK kits are nowavailable over-the-counter and thecompany has just announced a newgeneration of power modules, so nowis a good time to have a look at whatthey offer. Crimson sell a range ofpre -assembled PCB modules for usein hi-fi and other quality sound sys-tems. They sell 'Hardware Kits' so youcan build up the modules you haveselected into a preamp or power amplooking like those pictured above.

The modules in the Hobby Elec-tronics system are CPR 1S preampboard, two CE608 power amp boards(each 60W, 8 ohms), and the CPS1and REG 1 power supply boards. The'S' suffix on the preamp board indi-cates that tantalum capacitors andmetal -oxide resistors have been usedwhere applicable.

The Crimson Elektrik advertise-ment in Electronics Today Internatio-nal gives details of the other modules.Briefly, they offer 100W and 1 70Wpower amps (4 or 8 ohms) and apre -amp for use with a moving -coilcartridge (this fits into the case on thefour unused PCB pillars shown inPhoto Two).

The KitWe do not recommend our readers tobuild hi-fi amplifiers from scratch(unless they are experts at workingwith high -power transistors and audiocircuitry). The Crimson amplifier,however is suitable because the kitcomes with all the difficult bits pre -assembled. (Not that it's a piece ofcake, though. You need to have hadsome project -building experience toput this kit together.) This is an ex-pensive top-quality amplifier, so itshould be built with care.

FeaturesThe amplifier is low on front -panelfeatures, but behind the simple exter-ior lies a sophisticated amplifier. Thespec is superb. The preamp's discinput stage boasts a 40dB overloadmargin - at 30dB overload there'sless than 0.005% distortion at

20kHz. Signal / noise ratio of thestage is 70dB. THD over the range20Hz to 20kHz is less than 0.008%through the preamp. FET muting pro-tects your loudspeakers when youswitch the power on.

The power amplifier specs are:THD typically 0.01 %, TID negligible,slew -rate limit 25V/us, signal/noiseratio 110dB, and frequency response10Hz-35kHz -3dB. The distortionnormally introduced by fuses in thespeaker leads can be avoided - fusesare not needed with the series '5'amplifiers (except to protect low -power speakers from high powerwhen the volume control is abused).

Crimson call their protection sys-tem an 'Intelligent Sensing Circuit'.The ISC does not trigger on transients(or clipping) - inferior protectioncircuits do and thereby distort thesignal. The ISC monitors both voltageand current and, should a fault arise inthe load circuit, virtually instant-aneously (0.1s) the amplifier is putinto standby mode with the load dis-connected. Unless you fit a quick -reset switch (handy in discos) the ampwill stay shut -down for about aminute. Using the ISC you can shortout the speakers when the amp isturned up full without damage.

The high power and high specsidentify Crimson equipment asaudiophile material. The medium-fienthusiast will be bewildered by whatlooks like an absence of tone controls.That's because there are no tone con-trols. If you don't understand why,join the club - I gave up trying tounderstand audiophiles years ago.

The Preamp KitThe preamp kit consists of all the bitsshown in Photo One, plus the mattblack steel case and two leaflets. TheApplication Notes (12 pages of pho-tocopied typescript) tell any buyer ofthe CPR 1 how to make it work; theAssembly Instructions (61/2 pages) tellyou how to use the Hardware Kit.

The Hardware Kit isn't cheap(E38.07 - use your local shop forthe pots, switches, sockets, and wire,and make your own case, and you'dsave a few pounds) - but it is good.You are assured of a neat finish and nohassle, so for domestic Hi-Fi it's worthit. The components supplied are alltop quality; most come in RadioSpares packing. Good componentsare fun to use - everything clicks intoplace and the thrill of watching goldturn to silver as you solder the mains


Kit Review

leads to the switch is an experience noamateur constructor will forget (whycan't all components have gold-platedtags?).

Minor problems encountered wereone threadless nut (identified as suchonly after five minutes of digital con-tortion with long -nosed pliers andscrewdriver), a patch of bad photoco-pying (a marginal note explaining howthe phono sockets supplied were dif-ferent to those in the instructions,resulting in the application of a bit ofcreative thought to figure out what todo), and the omission of (more likelymy misplacement of) insulatedsleeving from the wire pack. The pet-tiness of these quibbles is my way ofsaying how easy it was to build. Onlysomeone unfamiliar with the basicfunction and construction of simplecomponents would have trouble. (Forexample, I doubt that a raw beginnercould make the RS 6 -way switch intoa 4 -way switch using these instruc-tions and no further help.)

The Power Amplifier KitPhoto Three shows all the com-ponents that fit into the power ampcase. There is less wire than in PhotoOne: correspondingly this kit takes

less time to build (six hours if you'reslow, three if you rush). The AssemblyInstructions (8 pages) and largeWiring Diagram make the job easy.

I made notes when the corn-penents supplied didn't live up to theexpectations of the instructions. Therewas no room for washers on some ofthe heatsink bolts, and I'm pretty surethe mains plug and socket suppliedwere different from the ones writtenabout. Anyone who has ever built aHobby Electronics project will realisethat if that's all I can find wrong withthe instructions then Crimson havedone a good job. There's always roomfor improvement. Step 26 refers to adiagram (which you use to decidewhich rectifier you are using). Thiswould be better located alongsideStep 26 so you don't have to spendtime deciding which diagram onwhich bit of paper you are supposedto be looking at.

Like the preamp, the poweramplifier can be built by anyonefamiliar with components and sol-dering. I'm pleased that Crimsondidn't pitch their instructions at theman in the street. I've built kits thatsaid things like "Find socket S7. Takeapart as shown in Fig. 32. Fix intohole HS7 as shown in Fig. 33, takingcare to make sure that the conductoris insulated from the back panel."'When building kits like that I have atendency to ignore the instructionsaltogether and build directly from thewiring diagram. But there's alwayssomething important you miss, so youhave to read the tedious instructionsanyway!

Testing the amplifier is simple -all you need is a multimeter. Thepower supply is tested before power iswired to the amplifier boards. Onenice touch is that Crimson give you a560 ohm resistor which you use todischarge the power supply capaci-tors after testing. Testing the corn-

plete unit is a matter of measuring thevoltage at the speaker sockets. For meit identified one dodgy joint in thepower supply - one of those multipleconnections where a 25W solderingiron is really inadequate.

The Final AnalysisTo be honest, I knew Crimson weregood before I built this kit. I had heardthe amplifier demonstrated at a hi-fishop and I know people who use theirmodules in PA applications. My eX-pectations - both of the kit and theamplifier -when -built - were plea-santly fulfilled. The only drawback isthe price, you have to be prepared toinvest in a hi-fi system costing over£500 if you are to do justice to theamp.

I haven't commented on theappearance of the equipment.Hopefully this will be apparent fromthe photographs. The use of a toroidalmains transformer (only 50mm high)means a low -profile design can beaccommodated. All the controls areon the front panel of the preamp, sothe power amp can be hidden away. Idoubt, however, that anyone wouldwant to - the black slab with heat -sinks across the front would take prideof place in any HE reader's home.

Crimson kits and modules areretailed by Marshalls and can bebought across the counter in London,Glasgow and Bristol, and from BadgerSound Services in Lytham and DownHifi in Bangor. The prices of themodules described here are: CPR1S£40.87, REG1 £6.90, CE608£19.52 each, CPS1 £16.56, PreampHardware Kit £38.07, Power AmpHardware Kit £35.03.

If you cannot get the kit to workproperly Crimson will get it going foryou for a small charge (typically £10,at worst around £25, including returnpostage). Crimson Elektrik are at 1AStamford Street, Leicester, LE 1 6NL.

HE


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What's In a NameThis month we start a new series. Rick Maybury tries to cut his way through the jungleof Jargon - we start with the differences between Electricity and Electronics.FOR THE NEXT FEW months, as anongoing situation, we are going totake a systemised, time -phased,functional investigation into the incr-edible world of jargonese, acronymsand abbreviations.

If you understood that paragraphthen you are probably one ofthose people that persist in talking inwhat amounts to a foreign language- technical jargon. I suppose to acomplete outsider even Hobby Elec-tronics (HE to its friends) can appeardaunting so, to everyone who hascomplained about our useage of suchconfusing terms as CMOS and LEDOpto Isolator we dedicate this series.

Misleading MedicsBefore we dive in at the deep end it'sprobably a good idea to look at someof the reasons why everyone frompoliticians to postmen surround them-selves in incomprehensible (unlessyou happen to be one) jargon.

The first, and still one of the mostprolific users of jargon must be themedical profession. The actual rea-sons for using such terms as 'acetyl-salicyic acid' (aspirin) or even a do-uble convoluted femural contusion (Imade that one up) was to protect theprofession from outside (usuallyamateurish) involvement. Of coursethis is a gross simplification but if youhad just spent seven or more yearsstudying all manner of human ail-ments you wouldn't want every Tom,Dick or Harry running around curingthemselves - or worse! You'd be outof a job pretty quickly. Now before we

get hundreds of letters from membersof the medical profession com-plaining, see if you can decipher adoctor's prescription.

The most recent addition to thejargon game is our old friend thecomputer. During the last 10 years,with the advent of cheap micro-processors, volumes of (mostly un-necessary) jargon have been writtento protect those in the know, fromletting the general public - you andme, in on all the 'fun'. After allknowledge can be a dangerous thing.Sadly it is far too late to changethings, anyone seriously interested incomputing has to learn the seeminglyendless lists of terms and assortednonsense before they can even look aPET (that's an acronym for PersonalElectronic Transactor) squarely in theASCII keyboard. (American StandardCode for Information Interchange, seewhat we mean?)

I suppose all this sounds rather likethrowing stones in glasshouses, sinceelectronics, because of the diversity ofdisciplines it encompasses, mustcome pretty high on the list ofoffenders. The only difference bet-ween us and the medical profession isthat we are actively encouraging youto dabble.

Electronics vs ElectricityTo start the series off we are going tolook at the word Electronics and howit's different from its older brother,electricity.

Here is the instant HE Jargon Generator, ifyou are at a loss at parties, confounded bycomputer nuts or simply out to impress theboss then take note of these words. Tobuild up an impressive phrase all you haveto do is select a word from each column andstring it together. For instance you couldsay to someone: "I was involved on a Col 1,5, Col 2, 1, Col 3, 7," there's not much onecan say to you after that, try it some time.

JARGON GENERATOR

Looking through the various dic-tionaries and knowledgeable tomesthat litter the HE office it's easy to seethat there is no clear cut definition ofelectronics. So, I have taken the bestbits from the various definitions toproduce the following. I think you'llagree it comes as close as possible.

First ElectricityThe study of the low of large currentsin metal conductors. By large wemean 'comparatively' large. Very few'electrical' systems operate with cur-rents less than 0.5 amps.

Now ElectronicsThe science and study dealing withthe motion, emission and behaviour ofelectrons, especially in a vacuum, gas,specialised conductor or semiconduc-tor and ctntrolling the motion of elec-trons within environments.

Down To EarthBrought to its simplest form elec-tricity looks at electrons flowingthrough conductors and the effects ithas in those circuits. Electronics goesone stage further and attempts tocontrol the electrons by passing themthrough substances or materials (notnecessarily conductors in the truesense), as well as metal conductors.

So now you know, next month wewill be looking at some of the termswe use to describe how electronsbehave themselves. HE

Column 1 Column 2 Column 30. Integrated 0. Management 0. Options1. Total 1 . Organizational 1. Flexibility2. Systematized 2. Monitored 2. Capability3. Parallel 3. Reciprocal 3. Mobility4. Functional 4. Digital 4. Programming5. Responsive 5. Logic 5. Concept6. Optical 6. Transitional 6. Time phase7. Synchronized 7. Incremental 7. Projection8. Compatible 8. Third generation 8. Hardware9. Balanced 9. Policy 9. Contingency


NEWS

ETI NEXT M NTHVocoder

Now you can make your own synthesiser or guitar or even your cat speak or singto you. This design uses 14 channels and has all the goodies like LED PPM meters,slew rate control, voiced/unvoiced detector and very versatile internal excita-tion! What more could you ask for? The ETI Vocoder's got the lot.

TV Sound AmplifierYou've read the book and seen the film. Now hear the TV version AS IT REALLYIS! Yes folks true glorious hi-fi sound from your telly! Broadcast sound is of an in-credibly high standard and TV sound circuits are of an incredibly LOW standard.What a waste.

Improve your viewing and give your ears a treat by playing Crossroads in highfidelity. No messy wiring into the set either, its all self contained - completewith monitor amp - and is easily constructed.

SurvivalThe time interval is getting shorter and the ladder higher. Your opponent has turn-ed up the skill level to maximum - one tiny slip and you're gonna hit the bottomand hard. Can you make it to the top? Can you survive? Good game, Good game!

Very Low Level Circuit Design

An absorbing article on the obstacles to be overcome at signal levels of a fewmicrovolts and less. How do you minimise noise problems, when the amplitudeof the noise is comparable to the amplitude of the signal? How about obtaining adecent gain without increasing hum pickup? An unusual and intriguing subjectwell explained.

Digital Test MeterIf we told you that next month we are running what is probably the ultimatedigital meter project would you believe us? Probably not - but try anyway,because its true! You name it, this box will measure it - accurately. Frequency,voltage, resistance, current etc etc. It has an LCD display and costs a lot less tobuild than you think.

Articles mentioned herein are in an advanced state of preparation. However, circumstances may dictate changes to the final contents.


HElp us to help YouHobby Electronics needs your help. We are continually striving tobring you the most informative and most enjoyable electronicsmagazine around. We know that there are a large number of ourreaders out there, on the other side of this printer's ink, who neverwrite in to us and who have never filled in a magazine survey - evenours!

The highest response we had to a survey such as this was around10% of the total readership, which although staggeringly good innormal terms still means that only one in ten Hobby readers fedhis/her opinions into our receptive ears. Nine out of ten, therefore, areseeing the magazine that number ten wants!

This time PLEASE pick up your pens, pencils, quills - anything youlike, and let's hear from more of you. We want to produce themagazine that you want to read, and the best way to help us do that isto spare us five minutes and fill in the form overleaf. No bribes, noinducements - just a better HE!

HOBBY ELECTRONICS SURVEY

MODMAGS LTD

145 CHARING CROSS ROAD

LONDON WC2


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DO MAGAZINE REMOTE CONTROLes PROJECTS MAKE

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How many times have you considered building a remote control protect but were put off by the dozens ofICs, special coils, lenses and other hard to get components, not to mention the need fora well equipped lab.to set the unit up? T.K.ELECTRONICS have changed all that, Three ICs can build a sophisticated systemthat requires only a capacitor and resistor to set the clock frequency (which can drift up to 20% withoutaffecting performance) Control radios. Hi.fi (including bass, treble and volume), lighting, toys, garagedoors. etc Still not convinced? Then look at the prices,

i, - -- -2', - --;-.K II'

, ".kr71.1116,,.. 1 'I and3

Momenta

Outputsre0..u2

puts) £1.40ML928 16 -channel Receiver (4 Latched binary outputs)

LD271 IR Er -inning Diode 36p £1.40SFH2O5 Photodiode Detector 95p Data sheets (per device) 5p

SLAB° IC Pulse E7.40 These !Cs can also be used with ultrasonic and radioAmplifiSL490 Keyboard Cont

errolled Encoder/Transmitter links, depending on range, cost and speed of operation

52.40 For more details, why not give us a ring - we will bepleased to advise you.

If you do not require a sophisticated multi -channel remote control, we have developed a simple. a single -channel ON /OFF infra red transmitter and receiver The transmitter unit comes complete with a

Ot P4 hand held and requires a PP3 (9V) battery. The receiver includes a mac capable of switching up to500W at 240V a c and comprises a preamplifier, bistable latch and a mains power supply. making the unit01 completHy self -contained The small sire of the receiver enables the unit to be -built into" all kinds olequipment from lamps to tape recorders. The minimum range is 20 feet

ONLY E12.00 (Order as RC500K)

I -I D1.304 Red 0 3" c c pin compantile with L704 70p

I 1D1307 Red 0 3" c a pin compDL 707 70p

DL847 Red 08" Pin comp DL7411 c c El.S001720 Red 0 "cc8 (pin comp 01 7501 E1.9001.727 Dual 0 5" c a Red (1.50

D.V.M. THERMOMETER KIT

Based on the ICE 7106. This

.....

Standardprimaries100mA secondaries6-o-sv9.0-9V

12-0-12V

-.---1ipl.

LELii.. 0 1'. Red 9p. 1" Green 12p0 1" Yellow 12p0 2" Red 9p

mains 0 2" Green 12p240V a.c 0 2" Yellow 12p

0.2" clips 3p80p Rectangular Red ley85p Rectangular Green 20p90p Rectangular Yellow 21p

tkit contains a PCB, resistors.presets, capacitors. diodes. ICand 0 5" liquid crystal displayComponents are also includedto enable the basic DVM kit tobe rnodified to a Digital The,mometer using single diodeas M e sensor Requires a 3mA9V supply (PP3 batterY)

E20.75

TOUCH CONTROL LIGHTING KITS

These KITS replace light switches and control upto 300 Watts of lighting. No rewiring, fit plasterdepth boxes, insulated touchplates Easy to followInstructions.TD3OOK TOUCHOIMMER. Smote touchplatewith alternate action Brief touch switches lamp onand off, longer touch dims or brightens lampsNeon lamp helps find the the dark.

MINI KITSswitch in

E6.50TDE /K Enonsion 101 for TD3OOK for 2 -way

These kits form useful subsystems which may beincorporated into larger designs or used alone. Kitsinclude PCB, short instructions and all corn-ponents.MK1 TEMPERATURE CONTROLLER/THERMOSTATUses LM3911 IC to sense temperature (80`Cmax) and mac to switch heater

switching. etc. El AOT50300K TOUCHSWITCH & DIMMERSingle touchplate, small knob controls brightness

E5.50TSA300K TIME DELAY TOUCHSWITCHTurns off atter preset delay (2 secs to 31/2 mint )

£4.30L0300K Conventional Lightdimmer £2.90

INTEGRATED CIRCUITS TRIACS

SN76477 Complex Sound Generator £2.52TBA800 5VV Audio Amp 58p784810AS 7W Audio Amp 85pTDA1024 Zero Voltage Switch E1.20TDA2020 20W Audio Amp £2.85ZN1034E Timer E1.80All ICs supplied with data sheetsData Sheets only 5p each device

SPECIAL

orders must be received

10 x8pin sockets 65p10 x 14pin sockets E1.0010x 16pin sockets E1.1510X 18pin sockets E1.40100 x Soldercon pins 40p

400V Plastic Case (Texas)3A 49p 16A 80PBA 58o 20A 165p

12A 85p 25A 190p6A with trigger 80pBA isolated tab 65p

Diac 18p0

by 30 7 8010 x 555 El .6010x741 E1.6025x 0.2" Red Leds E1.50ORP12 50p2N3055 40p

500W(3,20 1KW E3.50.MK2 SOLID STATE RELAY INTEGRATED CIRCUITSIdeal for switching motors, lights, heaters. etc.from logic. Optoisolated with zero voltageswitching. Supplied without Mac Select therequired Mac from our range. E2.60MK3 BAR/DOT DISPLAYDisplays an analogue voltage on a linear 10-element LED display as a bar or single dot. Ideal forthermometers, level indicators, etc. May beslacked to obtain 20 to 100 element displays.Requires 5-20V supply £4.76MK4 PROPORTIONAL TEMPERATURECONTROLLERBased on the TDA1024 Zero voltage switch. thiskit may be wired to form a 'burst fire- powercontroller or a 'proportional temperature"1201.11,0fler enabling the temperature of an uncles-ure to be maintained to within 0.5''C1.5KW E6.25 3KW £8.85MK5 MAINS TIMERBased on the ZN13E for IG this kit will switcha mains load on (or off) for a preset time from 20minutes to 35 hours. Longer or shorter periodsmay be realised by minor component changesMaximum load 1KW £4.50

555 Timer 21p741 Op. Amp 19pAY -5-1 224 Clock E2.80

AY -5-1230/2 Clock/Timer E4.50AY -3- 1270 Thermometer E9.20ICL7106 DVM ( LCD drive) E7.00LNI377 Dual 2 W Amp £1.45LM379S Dual 6W Amp E3.50LM380 2W Audio Amp 80pLM382 Dual/low noise Prearnp E1.00LM386 250mW low voltage Amp 75pLM1830 Fluid Level Detector El .50LAA 2907 f -v Converter (8 pin) E1.40LM2917 f -v Convener (14 pin) Et O0L M3909 LED Flasher/0/ Oscillator 55pLM3911 Thermometer E1.20LM3914 Dot / Bar Driver E2.10MM74C911 4 digit display controller £6.50MM74C915 7 segment -BCD converter 95pMM 74C926 4 digit counter with 7 seg.o/ p

E4.50S566B Touchdimmer E2.5059263 Touchswitch 16 -way E4.85

ALL COMPONENTS ARE BRAND NEW AND TO SPECIFICATION. ADD VAT ATCURRENT RATE TO ABOVE PRICES. 40p P&P MAIL ORDER - CALLERS WELCOMEBY APPOINTMENT

TK Electronics fi.i.ill'f;111 (H.E.), 106 STUDLEY GRANGE ROAD (

LONDON W7 2LX. TEL. 01-579 9794

AL.---7t- 1 1==

EX -STOCK FROM US

u r BELT DRIVEN5J Li TURNTABLEWITH STEREO MAGNETIC

AUDIO TECHNICACARTRIDGE

LIST PRICE OVER £50J.V.C. Turntable supplied com-plete with Audio Technica ATIOstereo magnetic cartridge. Beltdriven

'S' shaped tone arm.Modern designFull size 12- platter.Calibrated counter balanceweight (0-3 grins).Anti -skate (bias) device.Size - x 153a- (approx)

AT ONLYLIMITEDSTOCKS £25.99PLUS VAT E3.89 Post (2 50

GECHIGH

QUALITY STEREO10+ 10 watt AMPLIFIERWITH AM/FM STEREO TUNER

IDEAL FOR THE HOMEA cancelled export orderbrings you this offerfrom the world-famous firm of G.E.C.AM/FM stereo Tuner AmplifierReady built. Comprising of a tuner pre -amp. board and

separate power supply 'power amp board withwiring diagram.

Rotary Controls: Tuning. on. off volume, balancetreble bass. Stereo Beacon indicator.

Push-button Controls. Mono. Tape. Disc. A F C

F.M. (VHF). LW. MW. SW.

Power Output: 7 watts EMS per channel. al betterthan 21° THO into 8 ohms. 10 walls speech andmusic.

Frequency Response: 60Hz-2010Iz within t 3dB.Tape Sensitivity: Output - typically 150 me. Input -

300 my for rated output.Disc Sensitivity: 100 my [ceramic cartridge)Radio: FM (VHF) 87.5MHz-108MHz.Long Wave 145101z-2651(HzMedium Wave 5201(Hz I 6201(HzShort Wave 5.13KHz-16MHz.Size: Tuner - 2' iin. a 15in 7' an. Power Amp - 2in.

a 7. rin, x Can.

LOWPRICEOFFER

Limited stocksSuperb ValueDon't delayorder one today

ON/DOFF BALANCE. TREBLE. BASS. MONO TAPE Phono AFC FM LW MW SW Tuning.

Volume

Fully Guaranteed Ex --Stock

SUITABLESPEAKERSIN CABINETS

CAR STEREO CASSETTE MECHANISM* Front loading 12 volt transistorised* Speed & Voltage control* Ex -equipment - Tested 0 K* Takes standard C60 cassette

ONLY £7.50INC VA rPOST 80p

ONLY

PAIR £19.95 POST £19.9510 WATTS INC 1250 Par VAT [2 99

VAT CARRIAGE [2 SO

5+5 Watt Car Stereo Amplifier made for Motorola* WITH pre -amplifier and M. & Long wave assembly.* Supplied as two built and tested units.* R.F. and I.F. stereo preamplifier and radio 4 x 2 x I".* 5+5 watt stereo amplifier 0/14 volt 4 x 2 x 1"* Complete with circuit, data and connection diagrams.* Limited quantity available. ex -stock.

rmoiouuC:oWoet

Phone (01) 723 1008/9404 Edgware Road, London W2, England I.E.D.

HENRYS

BRAND NEWOnly £5+ VAT

VAT

Post 50p

BRAND NEW

ONLY £5+ VAT

NANO NEW

PRO M25 Professional capacitor boom -arm microphone by Eagle.A graceful 60 cm boom -arm capacitor studio microphone using a cardinal capsule. A highstandard of finish lor invision use and yet robust enough to withstand long periods betweenmaintenance. Supplied complete with I red and I black windshield and 6 metres of twinscreened cable terminating at the microphone end in an X LA connector.Impedance: 600 ohms ploating1 Response: 20-18.000 Hz. Sensitivity: - 70 dBV.Cable: 6 metres two conductor shielded. Connector: XLR 3-11C. Battery type: HP7.

LIST PRICEt

OUR PRICE£19.95

tin VATPOST f 1 50


Pass The LoopAll the fun of the fair with this easy to construct, cheap to build project from HE.Amuse your friends and annoy your neighbours, or raise funds with the HE Pass theLoop.CAN you remember the old gamewhere the aim was to pass a loop ofwire slowly along an intricate shapeof stiff wire without the twotouching? If they did touch, an alarmbell rang, indicating that the playerhad lost.

Well, that was too simple for us.We wanted something that was a bitmore up to date and moredemanding of the finersensory motor skills. So ourdesigners set to work and eventuallyhit upon this solution to the problem- an all solid state circuit whichproduces audible and visiblewarnings of game won, game lost,and loop contact conditions. If thatisn't enough we have also includedtimer circuitry so that the player cancompete against the clock, therebyincreasing the fun quotient.

Four common CMOS ICs form theheart of the game, all fitting neatlyonto our purpose -designed printedcircuit board. These ICs generate allthe functions of the device, such astiming visible warnings via LEDS,and audible tones. Three differenttones are produced to indicate to theplayer whether he has won, lost or hitthe wire.

Transistor Q1 amplifies thegenerated frequencies to power asmall loudspeaker so that the PCB isself-contained and in most cases thisis sufficient. But, if you want muchmore volume then the low leveloutput can be used to drive anotheramplifier.

ConstructionUse IC sockets to mount the ICs butas they are CMOS remember to leavethe ICs until the very end beforeinsertion. Follow the overlay carefullyputting all other components andlinks in. Carefully check thatelectrolytic capacitors, diodes and thetransistor are the correct way round.

Next make all off -boardconnections to the loop, wire, phonosockets (see later) and loudspeakeretc., and then when you are sure thatall is O.K. you can insert the ICs. If


you have never dealt with CMOSchips before then be careful! Theywill be supplied either in conductivefoam or in a small plastic holder andit is advisable not to take the chipsout of this until the very last minute.

Do not touch any of the pins!CMOS is susceptible to staticelectricity and can be easilydamaged. Hold the ICs carefully by

the ends and fit them into theirholders, without bending any pinsunderneath. This is quite a fiddly jobso take your time and get it right.

The end pieces can be made usingcommon or garden phono socketswithout their cover cap, thusproviding the necessary isolationbetween the centre and outsideconnections. Screw or glue the

41

0LOOP

0START

FINISH

OWIRE

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NOTE:1C18,3 ARE 40011C2&4 ARE 4011D1-5 ARE 104148LED1812 ARE 0.2T RED LEDOS IS BCI82L

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C24u7

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R11681,

3 12

Ilc,.10n

All components should be easily obtainablefrom your local stockists, however if youhave problems most of the larger mail ordercompanies advertising with us should bewilling to help.

Although any case into which the circuitcan be used the particular one in our proto-type is noted in the Parts List.

As a rough guide to the cost of components(not including the case or PCB) we estimatethe price to be around E10.

phono sockets (one for each end,start and finish) into a baseboardthick enough to hold the plugs butstill thin enough to make adequateelectrical connections underneath(see Fig 3). The wire to be formed ispushed into the sockets' centres andjoined from the underneath of onesocket to the circuit board - we usedan old wire coat hanger. The outsidesof the sockets are also wired to thePCB. See the connection diagramsfor details. The loop can literally be asimple loop of wire connected at oneend to the board.

42

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IC >246

CS2u2

D3

R132211 R14

100k

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TOOUTPUT

'Figure 1. The circuit diagram of the Pass the Loop game.

How it WorksIC1 forms a monostable multivibratorwhich is triggered into its timing periodwhen the loop is disconnected from itsstarting position. RVI presents the timingperiod during which the monostable is oni.e. the play -time.

If this timing period lapses without theloop reaching the finish position thenIC3-1C3d, a second timer with a period ofabout 4 seconds, is triggered. The outputfrom this enables the lose indicator LED1and the astable multivibrator formed byIC4c and IC4d. This provides a visual andaudible indication that the player has lost.

If, however, the loop reaches the finishposition in time then the lose indicators are

disabled and a similar block of circuitry(1C3b-1C3c and IC4a-IC4b) indicates the"game won" condition by illuminatingLED2 and producing a different tone.

Any time the loop touches the wire theastable formed by IC2B and IC2c is enabledand an audible signal indicates a hit. Thiscan, by using SWI, automatically triggerthe lose indication or not, depending onwhether or not you want to simply add upthe number of hits per go.

Ql forms a simple amplifier to power asmall speaker. Alternatively an externalamplifier can be used to provide a muchlouder sound level by connecting it to thelow level output.


Above. The HE Pass the Loop game in use.

Figure 2. The overlay of the printed circuitboard (the foil pattern is on page 73). Allconnections should be more or less self-explanatory.

TO THELOOP

START

FINISH

TO THEWIRE

q

S W1

Pass The Loop

Figure 3. The connections between the printed circuit board, the loop and the bentwire, shown in greater detail to aid clarity. The edge of the circuit board showncorresponds to the left hand edge of the overlay shown in figure 2 below. A wire coathanger can be used for the loop and the bent wire.

PB1 LED1RESET K A

K ALED2

8Aq 3HLOW LEVEL

OUTPUTOV

+9V

SPEAKER 64R

Parts ListRESISTORS (all 1/4W, 5%)

RI, 2, 5, 10, 12,14, 17R3, 15, 19R4, 6, 16R7R8R9, 13, 18R11R20R21R22

100kIMO1k21M8

470k22k68k

6k8150k

lkO

POTENTIOMETERS

RV1 4M7 Miniature Horizon-tal Preset

CAPACITORSCl, 3, 6, 8, 10 lOn polyesterC2, 7 4u7 10V electrolyticC4 100n polyesterC5 282 10V electrolyticC9 10u 10V tantalum

SEMICONDUCTORS

ICI, 3, 4001 (Quad 2 -input NORgates)

IC2, 4 4011 (Quad 2 -inputNAND gates)

DI -5 1N4148LED!, 2 0.2 in LEDS (Red for

"LOSE" Green for "WIN"BC182L NPN TransistorQ1

MISCELLANEOUS

PB1SW1, 264 ohm2 x phono socketsPP3 battery clipVerocase type - 202-21-34J

Push button switchSPST Toggle switchminiature loudspeaker


Beasties1.31< \/oU To

OUR nlaJCowIRKEk qAyei.SCoklq_SPohllet.1-1!!

_.............---

Multitester1.000 opr

AC roe, 0-15-150-500-1000OC rella 0-15_130-500-10n11 mai o I me 150 ,e

Fie,star,re 0-25K does -1001( seasOw 90 x a NAN

Multitester20.000 pew

AC rella 0-10-50-100-250500-1000

DC nib 0-05-5-25-15-2511500-1000

DC corrist 0-50 as06es 250 ma

REstslsocs 0-30 sll..--."'"_n ."--3 ese Ass

5.95 :

DeLlimis -20 la .63esors 127 c 90 c Kee

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Please add 3111p PP Please acid 309 PPper unit order es per unit order aserr 2 err 7

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ARROW& UDIO vl ENTRE at ci(MAIL ORDER DEPT.) "A

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A subscription to HE costs just £9.00 fortwelve issues, that includes post and packingUK and overseas (surface mail only). Forairmail rates please write to us for details.

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225p375p

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100p140p450p300p100p2013p750p8600340p

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VAT RATE: Please ldclt,,VAT at1 5% on total order value.Access and Barclaycard acceptedPlease send SAE for list

OPTO-ELECTRONICS2N5777 45pOCP71 130908912 90pOPTO-ISOLATORS11074 130,MCT26 100pMC52400 190pLEDS0.125"TIL32 75pTIL209 Red 13pTIL211 Gr 20pTIL212 Ye 25p111216 Red 18pDISPLAYS3015F 200pDL704 140pDL707 lied 140p

707 Gr 140pDL747 Red 225p

747 Gr 225pEND357 120pEND500 120pEND507 120pMAN3640 175pMAN4640 2013p

BREADBOARDS6%9350 3.6 x 2 1(Up to 3 x 14 pin ICs)EXP650 3 6 x 2.4(Up to 1 x 40 pm IC)099300 6 x 2 1

(Up to 6 x 14 pin ICs)159600 6 x 2 4(0p to 1 x40 OP OCH

IC TEST CLIPS14 pin E2.8016 pm 12.75

ORP60ORP61TIL78

111111TIL112711116

1(1220 Red111222 Gr111_228 RaiRectangularLEDs (R. G. Y)

NSB5881111311111312/ 3TIL321 / 21113307750/60

DRIVERS96389370UDN6118UDN6184

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70p

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lap18p22p

30p

570p600p110p130p140p200p

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TRANSISTORS

AC I 26 25pAC127 / 8 20pAC I 76 25pAC187 / 8 25pAF I 16 500AD 149 710p

AD1 61/ 2 460AU 107 2000BC107 /8 110B C 109 1 1pBC117 20pBC147 / 8 9pBC149 100BC157/ 8 10pBC1 59 110BC169C 12pBC I 72 12pBC177/ 8 17pBC179 18pBC182/3 10pBC184 11pB C 187 30p80212/ 3 llpBC214 12pBC237 15pBC327 160BC337 16pBC338 16pBC461 36p80477/83008C51 6. 7 50pBC 547B 16pBC 548C 9pBC54 9C 18pBC 5578 16pBC559C 180BCY70 180BCY71 / 2 22p80131, 2 50p60135 / 5 54pBD 139 58pBD 140 60pBD I 89 600BD232 95pBD233 75pBD235 85p80241 70p80242 70pFIDY56 2000BF200 32pBF244B 35pB F2566 700BF257 / 8 32pBF259 36p

30p50p50p5,01,50p50p32p501,

MPSUO6 63pMPSUO7 909M PSU45 90pMPSU65 78pOC28 130p0035 130p11929A 40pTIP29C 55p

61039 25pBER40 25pBER41 25p6E1379 25pBFR80 25p8E881 25pBFX29 30pBFX30 34pBFX84/5 40pBFX86/ 7 30pBFX88 30pBFVVIO 90pBEYSO 30pBEY51 2 30pBEY56 33p13FY90 90pBRY39 45pBSX19/ 20 20pBU104 225p64105 190p0 U 108 250pBU109 225pBU205 200pBU208 200pBU406 145pE300 50pE308 50pE310 50pMJ2501 225pMJ2955 800MJ3001 225pMJE340 50pMJE2955 100pMJE3055 700MPF102 46pMPF103/ 4 40pMPF105 6 40pMPS6531 50pMPS6534 50pMPS406MPS417MPSA13MPSA20MPS442MPSA43MPSA56MPS470

MEMORIES2102-21 120p21078 500p2111-2 225p2112-2 300112114 300p211421 500p4027-3 375p4044 90M,4116 500p5101 510p6810 325p745201 350p82516 325pROM / PROMs71301 7001,745188 225p745287 350074S387 350p745470 6501,745471 650p745571 650p82S137 750p93427 400p93436 650p93446 650p93448 90013CPU.1600 1200p1802CE 650p26504 2000p6502 1000p6800 700p6802 1250p6809 2500080804 550p80854 1400p1NS8060 1000pZ80 E10Z804 1150pEPROMS1702A 500p2708 600p2716(+551 E12SUPPORT DEVICES3242 800p3245 450p6532 100006820 500p6821 500p6845 2500p6850 500p8205 320p8212 225p8216 225p8224 400p8228 525p8251 55018253 1200i08255 550p8257 1100p8259 14009280P102804P10 8000Z80CTC 650pMC14411 1100pMC14412 1100p

TI P304 48pTIP30C 60pTIP314 58pTIP31C 62pTIP32A 689TIP32C 82pTIP334 90pTIP33C 114pTIP344 115pTIP34C 160pTIP35A 225p11935C 290pTIP364 270pTIP36C 3409

.TIP414 65pTIP41C 78pTIP424 70p119420 82pTIP54 160pTIP( 20 120pTIP122 130p119142 130p119147 130pT1P2955 78pTIP4055 70p71543 34pTIS93 30pZTX108 12p23X300 13pZTX500 159775502 18pZTX504 300204574 250p2N696 35p20697 25p25698 4.5p207064 20p207084 20p20918 45p20930 18p201131, 2 20p201613 25p201711 251:2N2102 70p202160 350p2022194 30p2N2222A 30p2023694 20p252484 30p202646 45p202904/5 301,2929064 30p2029074 30p202926 911

2N3053 30p203054 1150

DARTAY -3-1015P 9009AY -5-1013P 400p9.16402 500P,TMS6011NC 4000

CHARACTERGENERATORS3257ADC 990pMCM6576 112110-32513 U C 600pR0-3-2513 LC 7013p507452624N 800p

KEYBOARDENCODERAY -5-2376 900p

2N3055 489 40364253442 1400253553 2460253565 300253584 2500253643 / 4 48p2N3702/3 12p253704 / 5 12p2N3706/7 14p253708/9 12p253773 300p25 3819 25p25 3820 90p253823 70p253866 90p25-102 700p251,903/4 18p253905 / 6 20p2514037 86p254058/9 12p254060 12p254061 / 2 18p2N4123/4 27p254125/6 27p254401/3 27p2N4427 900254871 60p255087 27p2N5089 27p255172 27p255179 90p255191 900255194 90p2N5245 400255296 )6p255401 SOp255457/8 40p2N5459 40p25 5460 80p25 5485 44p2N5875 260025 6027 450256107 66p25 6247 190025 6254 130p25 6290 86p25 6292 85p2501172 160p3N128 120p35 140 100p3N141 110p3N201 11003N204 100p40290 290p40360 40p40361 / 2 75p

404134040940410404114059440595406734084140871/2

120p70plipSOP

300p121101201:

75p90,p90,p

10A 400V 200p25A 400V 4000

ZENERS2 7V -33V40OrnW1W

9p1 5p

DIODESBY I 27

BYX36-3000A470A8104E15

04900A910A950A2000A20215 914

1N91615414B154001 /2154003/41540051N4006/ 71N5401 /3155464 / 7

.6920

12p20p

9p15p15p9p

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Op606p7p

14p19p

Op

TRIALSPLASTIC3A 4004 60p3A 500V 6506A 4004 70p6A 500V 881,844001. 75p8A 500V. 95p124 400V 85p12A 5005 105p164 400V 110p16A 5005 130,,T2800D 130p

HEAT SINKSFor 10220 Volt-age Reds. andTransestors 22pFor T05 120

BRIDGERECTIFIERS14 50V 18p14 1005 20p1A 400V 25p14 600V 30p2A 50V 30p2A 100V 35p2A 400V 45p3A 200V 60p3A 600V 72p4A 100V 85p4A 4001 100p6A 50V 190p6A 103V 100p6A 400V 120p

THYRISTORS14 50V 40p14400V 65p3A 400V 901184 600V 140p12A 400V 160p16A 100V 180p16A 400V 180p16A 600V 220p51106 110pC106D 45pMCR101 369203525 120p204444 140p2N5060 34p255064 40,

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8 pr 259 18 pn 500 24 pn 70p14 pin 26p 20 pon 669 28 ion 80916 pn 45p 22 pn 70p 40 pm 100p

WIRE WRAP SOCKETS BY TEXAS8 po 30p 18 pm 70p 24 pan 80p

14 pm 40p 20 pen 7Sp 28 pin 110016 pin SSP 22 pn 800 40 pm 140p

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(A 265p'(Neese add 50p p&p chargeto PI oohed ' above our nor -n...1 P&P charge)

SUBMINIATURESWITCHESToggleSPST 60pSPDT 85pDPDT 70pDPOT ocenve of& 05pPush to make 159Break 25pPush latchng SPCO

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RESISTORS HighStab 5% 612Carnal Film

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VEROBOARlitDIP Breadboard4 15 x 6 15 3009(Suitable for 20 x 14 pin or16 x 16 pin DIL IC -s) DIPBreadboard as above with tracksfor 31 way connector 375pV-0 Boards for ICs 115p(No track cutting)

CONNECTOR PLUGS31 way Plug 110p31 way Socket 11005-100 Busboard 1200p

EDGESOARD CONNECTORS 0.166" PITCHx 10 bey ISEP 2 22 wey 135p

2 a 15 coy 1009 2 x 25 wey 160p2,18 way 120p

COUNTERS74C925740928ICM721613ICM72174ZN 10406

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A

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P5102 12 x 14 DIL ICs66.30 98103 24, 14 DIL ICs

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SPECIAL OFFERS (subject to stocks)555 £187100 7805741 £16/100 78122114L-3 E4.00 79052708 (450 ns) £5.25 79122708 (650 ns) £4.00 2114E 450 ns2716 (plus 5V only) £12.004116 (200 ns) E28, 8 P&P + VAT Extra

16 KEY KEYPAD(Reed Switches)UHF Modulator 6kAfirUHF Modulator 8M HrReed Switches (12VA)LOGIC PROBESOPERTESTER 6505MICROTEST 808TMK 500Pocket mulerneter

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£5/10£5/10£6/10C6/10£24/8

0 1 0 1,5, Pkt of 100 pins SOp(col:1PP, Et, Spot lace cutter 88p4..,8P 4.:° Pm insertion tool 118pV.,11 1 Vero Wiring Pen:Li'1..1° '-'1.

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TECHNOMATIC LTD.17 BURNLEY ROAD, LONDON NW10(2 minutes Doll's Hill tube station) (ample street parking)Tel: 01-452 1500/01-450 6597 Telex: 922801

45

Clever DickHave you ever heard of an Ultrasonicrecord player? How about an Ironand Constantan thermocouple? Bud-ding inventors and creeping Wor-thingites, they're all here in thismonth's episode of Clever Dick.

YOU AT THE BACK THERE, sit up andpay attention. Clever Dick is about towax lyrical on a subject that is neverfar from our wallets - Inflation.

Inflation is particularly nasty stuff,you can't smell it or hear it but bygolly you can feel it. Being unable topredict prices from month to monthwas the main reason we dropped the''approximate cost" from our project'Buylines'. But, as we have discov-ered from countless letters (like theone from Martin Ayub below) many ofyou would like to see its return.

Dear CD,Recently, while wearily thumbing

through an ex -friend's copy of a certain'electronics mag' (not HE or ETI -that's why he's an ex -friend), I dis-covered that alongside each projectwas an estimated price. This struckme as a good idea, one which HEand / or ETI should take up(?). Perhapsyou could include it with 'Buylines'.

Martin Ayub, Hants

PS I'm not scrounging for a Binder,but

OK, you win. From now on we'll in-clude an approximate cost of eachproject in the Buylines but don'tblame us if the ravages of inflation get.to it first. One of the reasons wedropped it from the early issues of HEwas the letters of complaint. Few ofyou seemed able to match our prices.We will base our approximate costs onthe catalogue prices of the 'big three'mail order companies. If you buy your,components from the radio shop'round the corner' then expect to paymore.

We're always glad to hear sugges-tions on how to improve the mag,after all HE is meant for you. Here's agood one from John Pepper, de -

finitely not to be sneezed at. (Sorryabout that John, couldn't resist it.)

Dear CD,How about having a page or so

reserved for our own circuits or evenmodifications to your circuits? I have acouple of circuits that I have designedand are ready for you to see.

John PepperWinchester

Actually John, we've never discou-raged anyone from sending us ideasor suggestions (that's what this pageis for). If you have a circuit, modifica-tion or any suggestion that you thinkis worth sharing then we would beonly too happy to see it. If the res-ponse is big enough then maybe we'llhand over some space to you.Remember though, the ideas must beyour own and not pinched from an -'other book or magazine, look forwardto hearing from you.

Gary Lowe must need patches for hisknees, rarely have we read such acreeping letter.

Dear DC (Oops, I mean CD),Is it possible to acquire a list of the

numbers and functions of ICs. Ihave at least 50 that I have scrounged(being a creep) or de -soldered from oldboards. I haven't the slightest ideawhat they do. The same applies totransistors, my local componentsshop (31/2 miles away) does not have alist or a very good supply of transis-tors.

Changing the subject to CB, I wasglad to see another petition in theJune issue, I am busily getting it filledin (creep, creep). I would just like toand that even though I cannot reallyafford it, I never miss my monthlyinstallment of that wonderful, sophis-

cumc.Dcs,

/1,'1, 7/

ticated, fantastic and even excellentelectro mag HE (creep creep).

Gary LoweWorthing.

PS I think I deserve a Binder with allthat creeping.

Yes, you do deserve a Binder butunfortunately we've dished out thismonths quota. Keep up the goodwork. Another letter like thatand you may well get one.Now, to your main problem(apart from creeping), we pub-lished a two part Data Supple-ment in the November and Decemberissues, sadly both those issues areeither sold out or are about to do so.The only other source of data that iseither free or cheap are mail-ordercatalogues. Two that we recommendcome from Watford Electronics and ofcourse Maplin. If you have a few quidto spare then invest in a copy ofTowers International TransistorSelector, published by Foulsham for£.9.50. ICs are a little tricky, we use anAmerican book(s) called D.A.T.A.,again, they're not cheap but just onelook will tell you why. They aredistributed in this country by RowseMuir Ltd, their address is: IndexHouse, Ascot, Berks SL5 7EU. Whydon't you persuade your local com-ponents shop to invest in a set?

Do you remember Mr Wagstaff andthe Thermocouple question in theJune edition? Here's a reply from A.G. Lorimer.

Dear Clever Dick,In the June edition of HE you made

mention of a thermocouple in yourreply to F. G. Wagstaff's letter. How-ever, you suggest the use of Platinumand Rhodium as the metals for use inthe thermocouple. Using sufficient ofthese metals to power a radio is'


unlikely to improve the bank balanceand so might I suggest the use of ironand constantan (much more likely tocheer the bank manager). At 100'C aniron constantan thermocouple will

produce an EMF of 5 millivolts or so. Anumber of these devices could easilybe connected in series (not forgettingthe need fora cold junction in betweeneach hot one).

Although this arrangement will notprovide enough current to power theaverage tranny, it should certainly beadequate to drive a ZN 414 AM radio.

A. G. LorimerClydebank

We naturally assumed all HE readerswere incredibly rich just like our-selves. Oh well, if you want tocheapen the whole affair, go ahead.

Here's a good question.

Dear Dick,Could you please describe the prin-

ciples of a tone control. How can it beconnected between the amp andspeaker? Finally, HE is a mag ofsuperb quality, keep it up. Thanks.

L. JonesTorquay.

In its most basic form a tone control isa filter that will permit only a selectedband of frequencies to pass throughan audio system. Your request for acircuit to fit between the output of theamplifier and the speaker is a littleimpractical. Although a crossovernetwork is a kind of tone control it isdesigned to operate at high powerlevels. Almost without exception thetone control network is sited betweenthe pre -amplifier and power amplifier,or alternatively, forms an integral partof the pre -amp. Have a look at theEquitone circuit this month for a goodidea of a simple passive tone controlnetwork.

Although the Equitone seems tocontradict the general rule it does infact use the existing power amplifieras a pre -amp and feeds its output intoa power amplifier. In any case theEquitone will operate quite happilyafter a conventional pre -amp.

If you're looking for something alittle more advanced then you coulddo worse than consider the 5080pre -amp /tone control published inthe May issue.

Lastly, a letter from a budding inven-tor, take it away Adrian.

Dear Dick,Please could you tell me whether

the following device has ever beenpatented. My idea is basically toreplace the stylus in a record player.Instead of the stylus there would be asmall ultrasonic 'microscope' workingrather like a TV camera. Instead ofproducing a picture there would be aprocessor unit converting the outputinto sound. I would like this informa-tion as I intend entering this idea in acompetition.

Adrian HallasMidlothian

To our rather uncertain knowledgenobody has ever thought of usingultrasonics to replace gramophoneneedles (stylus if you're state-of-the-art!). This sounds like an excellentidea as it would completely eliminaterecord wear. If you are successfulthen drop us a line, we would be morethan happy to publish it as a project.We are however a little dubious as tothe practicality of such an inventionbut then they said man would neverfly. Watch this space for comments.Some bright spark is bound to write inand tell us it was invented 50 yearsago. HE

Shown here are all of the back issues currently available.Each issue costs just £1,(that includes post and packing).

The latest addition to our stocks is the March issue.Features include:AutomotiveElectronics,PETting it Together and the second part of Ian Sinclair's new seriesInto Electronics Construction.The projects include:The 5080 modular amplifiersystem,PSU module for the 5080,Short Wave Radio and a novel Touch Switch.For details of other issues see our main Index in the January issue.HOBBYPRINTS for this and all back issues are still available.For order codes andinformation on how to use HOBBYPRINTS see the ad.in this issue.

Please send me the following issues.

NumbersI enclose cheque/PO for £

Name.

Address

BACKNUMBERS DEPARTMENT:HOBBY ELECTRONICS. 145 CharingCross Road,London WC2H OEE.


STEVENSONElectronic Components

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0.1251n. 0.2in.Red TIL209 TIL220 10p it:LIGreen TIL211 TIL221 160Yellow TIL213 TIL223 16P YrClips 3p 3pDISPLAYSDL704 0.3in CC 1300DL707 0.3in CA 1300END500 0.5in CA 100p

-.A

TRANSISTORS

AC127 250AC128 25pAD161 40pAD162 40pBC107 10pBC108 10pBC109 10pBC147 9pBC178 16pBC182 10pBC1B2L 10pBC184 10pBC184L 10pBC212 10pBC212L 10pBC214 10pBC214L 10P

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3p5p

140

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741 18p747 70p748 40p7106 850pCA3046 700CA3080 75pCA3130 100pCA3140 60pLF347 170pLF351 45pLF353 90pLF356 95pLM301A 30pLM318 85p'

LM324 52pLM339 55PLM348 100pLM377 170pLM378 230pLM380 80pLM381 140pLM382 120pLM386 900LM387 1200LM1458 40pLM1830 180pLM3900 60pLM3909 72pLM3911 120pLM3914 320pLM3915320p

MM57160 650pNE531 140pNE555 23pNE556 60pNE567 120pRC4136 100pSN76477 230pTBA800 80pTBA81O 110pTDA1022 6300TL081 45pT L082 85pTL084 125pXR2206 390PZN414 80pZN425E 475p

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%w resistors. 10 of each value 4.7ohm to 1 Mohma total of 650 resistors. 530p each.'6w resistors. 10 of each value 4.7ohm to 1 Mohma total of 650 resistors. 875p each.Presets. Pack of 5 of each value from 100ohrns to1 Megohm. a total of 65 presets. 390p each.LED's. Pack containing 10 of each colour LED0.2 size. Total of 30 Led's * clips. 450p each.Zeners. Pack of 5 of each value from 2U7 to 33VA total of 130 zeners. 880p each.

CMOS

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4072408140824085409340954510451145184520452745284532454345834585

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100p90p

110p1650100P125P1700

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SIRS Low ProfileTexas

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SWITCHESTOGGLEStandard SPST 40p DPDT 55pMiniature SPOT 80p DPDT 90pSubminiature SPST 65p DPDT 85P

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Movement AlarmAre you picking up good vibrations? Here's something for the bad ones.Alarm your would be snoopers with this 'nifty little gadget.'

DO YOU SUSPECT that people arelooking in your drawers? If so, thenthis project is for you. The HEmovement alarm will catch themred-handed.

The circuit really is quite simpleand should pose no problems to theaspiring amateur. A thyristor'slatching action is used to hold thealarm on until the whole circuit isturned off by disconnection from itsbattery supply. Thyristor operationmeans that the device can beinterfaced directly to a low voltagealarm, e.g. a piezoelectric buzzer (orsimilar), or if you really want to raisethe roof, then a mains powered alarmcan be used. In this case it is safest touse the thyristor to latch a relay on,which in turn switches the alarm.Although this may seem a somewhatlengthy process, it is preferable todirectly operating the mains devicevia the thyristor - things can gobadly wrong unless the builder isexperienced. Dare we say, a shockingtime could be had by all.

-How it Works-The title 'Movement Alarm' is a slightmisnomer really. The device doesn'tactually pick up movement but sound. Thesound of a drawer opening will tend to be ofa fairly low frequency, so the main part ofthe device is a microphone followed by alow-pass pre -amplifier. Q1 and Q2 form thepre -amplifier which cuts off frequenciesabove about 2kHz. A low frequency soundpicked up by the crystal insert is thereforeamplified and triggers the thyristor THY I.RVI adjusts for varied levels of gain toallow for a range of microphones and soundlevels.

As the supply is DC the thyristor latchesand holds the alarm or relay in its activatedposition until the supply is turned off.

Diodes DI and D2 give an AND functionat the gate of the thyristor, thus disabling ituntil both anodes are at positive potential.fransistor Q3 forms a simple time delaycircuit holding the emitter of Q3 low for aperiod of about 10 seconds after switch on.During this time it doesn't matter whatsound is picked up and amplified by thepre -amplifier, the thrysistor cannot beturned on due to the DI and D2 AND gate.


C2100u

041ci10u

81 R26k8 100k

RV1220k

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13680p

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C4 02 IS BC212L100u THY1 C1060

0182 ARE IN4148OV

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Figure 1. Circuit diagram of the HE Movement Alarm, ensure the thyristor THY1 isconnected the right way round.

R715k

89470k

+9V

TO ALARMOR RELAY

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THY,

Now the smart ones amongst ourreaders (and you must be smart to bereading HE) will at this point be onestep ahead of us and thinking tothemselves - won't the alarm betriggered as the drawer is shut by theowner? Well, due to a disabling timedelay of about 10 seconds -no! With typical HE efficiency we've

R81k0

thought of everything, haven't we?All joking apart, this Veroboard

project really is quite a novelty beingso simple, easy to build and yet sosensitive. A preset resistor caters fordifferent sound levels, microphonesand personal taste, while batteryoperation can mean absoluteportability.

49

Movement Alarm

1 3 4 5 6 7 1 9 10 11 12 13 14 15 III 17 11 19 20 21 22 23 24

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0 0 0 0 0

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Figure 2. Connection detals and vesboard layout of the HE Movement Alarm. The crystal insert cay be of any convenient type, refer toBuilding Site on page 26 to find out about versboard construction before you begin this project.

Parts ListRESISTORS (All 1/4W, 5%)RIR2, 6R3, 7R4, 5,8R9

POTENTIOMETERS

RV1 220k Miniature horizontalpreset

6k8100k

15k_lk

470k

CAPACITORSC 1 10u 16V electrolyticC2, 4 100u 16V printed circuit mounting

electrolyticC3, 680p polystyreneSEMICONDUCTORSQ1,3 BC182L NPN transistorQ2 BC212L PNP transistorTHY 1 C106D ThyristorD1,2 IN4148 DiodeMISCELLANEOUS10 x 24 hole Veroboard, 0.1 inch.Crystal microphone insert.6 V Relay or solid state buzzer.PP3 battery clip.Case to suit

BuylinesThe crystal microphone insert and solidstate buzzer can be obtained from most ofthe usual mail order companies should youhave difficulties obtaining them locally.

None of the parts should be at all difficultto find.

All components excluding case shouldbe available for around E7.

tykrrLE C06111116M13'N

4101N11,W CORIPVTER

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o o o 0 0 00000oo0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0o o outoo 0 0 000 00000 to 000 o o to 00000 0 ooo0 0 o

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0owoooito 0 o 0 0 0 0 0 oo2 3 4 5 5 7 6 5 10 11 12 13 14 15 16 17 15 111 20 21 22 23 24

Above. Veroboard layout, the large blackcircles show breaks in the copper tracks.The smaller dots show the position of thecomponents.Below. The completed Movement Alarmshown with its case.

HEMovement

Alarm

ConstructionThere's not a lot to be said really.Veroboard is an easy method ofjoining all the component leadstogether in the right places. That is aslong as you insert the components inthe right holes and that you solderthem in carefully without joiningadjacent copper strips. Alsoremember to cut the strips in thecorrect places.

Of course, neatness is the key, tryto keep all components close to theboard, in this way short circuits areminimised.

Finally, connect your battery andgo. The circuit is quite simple andshould work first time. HE


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MicrosAre Easy!In this month's Chit -Chat, Ron Harrispulls the shrouds of mystery away fromMPUs to reveal just another component!

MICROPROCESSOR is a word youwill find difficult to avoid these days.Home computing is a rapidly expan-ding hobby and any self-respectingoffice or school has to be equippedwith a computer - of whatever size -or risk a trip to Coventry.

The aim of this article is to explainwhat a microprocessor - MPU forshort - is, and how it fits into amicrocomputer system. Next monthIan Sinclair will be weighing in with amajor new beginners' series called

-Into Digital Electronics" which willbe starting with basics and leadingyou simply and logically (ouch!) intothe mystical world of the MPU.

The most difficult thing to compre-hend in the field of computing is thejargon its disciples throw around sofreely. Once you understand it, ofcourse, it's as clear as day - but howdo you get started?

Well, this is as good a place as any,so . .

Above: a close up of the main PCB of the Tangerine Microtan 65 computer system. TheMPU here is the largest of the ICs, to the right of the picture. Most of the other chips arememory. The full Tangerine system is seen in the heading photo.

Logical GatewaysAn MPU is nothing more than an

adaptable integrated circuit which can'impersonate' any one of a set ofdifferent types of logic circuit whentold to do so. The instructions for whatit is supposed to look like to the sur-rounding circuitry, at any given mo-ment, comes from the program sup-plied by the user. This program is keptin the computer system's memory,without which the MPU is totally use-less.

An instruction is passed to theMPU as a 'pattern' of voltages on itspins. These voltages are at one of twolevels, HIGH or LOW.

A typical MPU uses eight voltagesto understand its instructions and anyspecific pattern will be called a"byte'", or "instruction word".Manufacturers publish a list of thesepatterns, and what they mean to theMPU, calling it an "instruction set'

Exactly what the MPU can pretendto be is built in by the manufacturerand will vary a little from IC to IC, butwe can look at some of the morecommon varieties.

What To Be Or Not To BeThe first and most common func-

tion is an AND gate. When in thisguise, an MPU monitors two voltagesto see if they are both high, and pro-duces an output only when they are.

This can be closely compared to,say, a person's decision to take a drinkof water from a cup on a table. Twoconditions exist - the first is whetherthe person is thirsty or not, and the


Voltage A Voltage B Output?Low Low NoLow High NoHigh Low NoHigh High Yes

DUAL INPUT MULTIPLE INPUT

Above: the symbol used for an AND gate incircuit diagrams. Two inputs are standardand four such gates would comprise one IC.Above that is the output, or truth, table forsuch a circuit.

second is whether the cup actuallyhas water in it. Only if both conditionsare satisfied will the drinking actionoccur.

For example, an MPU controlling aburglar alarm might have to decidewhether a door was open or not, aswell as whether or not the alarm hadbeen set. If the answer to both is YESit can ring the alarm bell.

A second type of logic gate is theOR circuit. Again this does exactlywhat its name implies, and if wereturn to our two voltages, an output

be obtained if one OR the other ofthese is high, i.e.

Voltage A Voltage B Output?Low Low NoLow High YesHigh Low YesHigh High Yes

Above: truth table and circuit symbol for anOR gate. As with the AND gate, ICs arereadily available containing four dual -inputcircuits in one package.

If the program has told the MPU inour mythical burglar alarm to look atthings as an OR gate now, if either adoor OR a window is open, the bellswill ring. It would be useful as asecond inspection, perhaps after ithas checked to see if the alarm isswitched on.

With proper program control theMPU could first check out the circuitas an AND gate, then move on to anOR consideration if all is well - andgo back again if it isn't! Repetitive buthighly accurate.

Branching OutThis brings us to consider a third

ability, that of being able to carry out atask, depending on certain conditionsbeing met. Making the MPU run backaround a set of actions until they aremet, is called a "loop- and is a veryuseful program trick.

MPUs can only handle one job at atime and so they are by nature slowerthan a handful of ICs all dedicated tobeing AND or OR gates permanently.Slower, but infinitely more flexible.

If the job requirement changes, allthe MPU needs is a new program. Thededicated ICs would all need rewiring,i.e. a complete circuit rebuild!

In order to carry out the programinstructions the micro "(MPU)"needs some help. It needs a system towork in. The block diagram belowshows one such (simplified) system.

The keyboard and VDU (VisualDisplay Unit) are there solely so thatthe user can give the MPU instruc-tions and be sure that it has correctlyunderstood them. If the program isalready in the memory, they are notneeded at all!

This 'memory' is for storing bits ofinformation that the MPU will need tocomplete its tasks, i.e. data and pro-gram. It can be of two types - RAM(Random Access Memory), whichgenerally loses the information whenswitched off, and ROM (Read OnlyMemory) which is not alterable by theuser and contains things such as pro -

TIMINGLOGIC

gram language and a monitor, which'checks up' on the MPU in the courseof its duties. The information in theROM remains intact regardless ofwhether or not power is applied to thesystem.

Memory size is normally quoted inkilobytes i.e. 8K is eight kilobytes ofinformation storage. This means thatapproximately eight thousand'patterns' of voltages can beremembered by the machine. A verylong program!

Clocking In And OutAll parts of the system have to work

together at the same rate, not only toprovide the MPU with information atthe precise moment it is required, butalso that the MPU can supply anoutput at the right time. Information- in the form of voltages - has to beshifted around the system with per-fect timing, and this timing is set bythe system clock. This must be highlyaccurate and very fast. A normalspeed of operation would be around 2MHz, or two million changes persecond. The MPU might thus alter itsmode of working this many times in asecond.

The interface is simply to allow thevoltage changes occurring at theMPU to affect the world outside thebox and at its simplest could be abasic relay, switched by the MPU. Inthe burglar alarm, for example, this

MPU CHIP

02

:DAT

URAM

VIDEOLOGIC

VDU

,--ROME!

BUFFERS

JJ

PROGRAM'INSTRUCTION

KEYBOARD

CONTROL DATA

OUTSIDE WORLDAbove: a typical computer system in simplified block diagram form. The ROM (Read OnlyMemory) and RAM (Random Access Memory) is there to allow the MPU to storeinformation - either programs or data - for later use when it needs it. The programinstructions can come from memory, or direct from the keyboard. Information is presentedto the outside world as voltages , either data or control.


Above: the end result. This particular computer is a Zenith Z89, which uses two MPUs - oneis there just to make the keyboard more efficient and easier to use. Printer interface isbuilt-in too.

Chit -Chatmight power the bell when told to doso by the micro.

This output adaptor is needed be-cause the voltage levels in the systemare too small and change too rapidlyto do much work outside. The MPUneeds to be sheltered, or buffered,from the big bad world! About themost common adaptor would be usedto enable the MPU to control a printerand the interface for this could bequite a complex circuit in itself.

SummaryNot much to it after all, is there? An

MPU is simply a flexible work toolwhich can be adapted to do manydifferent jobs by its controlling pro-gram. In order to work at all it needs amemory to store information andsome sort of adaptor between it andthe real world.

One final point I have to make, canwe at HE at least, not refer to MPUs as'the silicon chip' PLEASE? Of coursethey ARE produced on silicon but soare most other ICs. The equivalentwould be to start calling all cars'Fords'. HE

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Gas DetectorProtect your floating or mobile home from a big bang with the HE Gaztec gasmonitor. A device to warn you of the presence of combustible gas, whichincorporates a low voltage indication to warn you of a poor battery condition

THE INITIAL AIM of the project wasfor an alarm to operate when theamount of cooking gas in theatmosphere increases past apredetermined level. Obviously thismakes the device suitable for use inboats or caravans to detect if thelevel of gas (due to leakage) isreaching combustion proportions.However, propane, butane, naturaland town gas will all trigger thealarm before their danger levels areexceeded so the HE Gaztec is notrestricted only to use in boats andcaravans.

The power requirement of thedevice is minimal, 1 2VDC thusallowing its use in a boat or caravan(car battery). To ensure utmost safetythe device emits a warning when thebattery voltage drops below 11 volts,at which time the owner knows it'stime to recharge the battery.

Use is made of a special gassensing transducer. Inside the unitis a heated filament. The voltageacross this filament varies with thelevel of combustible gas in theatmosphere. Modern instrumentationand transducer measuringtechniques are utilised to detectwhen the level of gas increasestowards danger proportion and totrigger a loud piercing alarm.

The HE Gaztec is a potentiallife-saver using four common ICs andone transistor in a simple yetingenious circuit (mounted on onePCB) which fits neatly into a readilyavailable plastic moulded case.Without doubt, the HE Gaztec is thebest gas detecting project to appearon the hobbyist scene.

ConstructionWith our PCB design construction it'seasy. Start by cutting out the part ofthe board which is to fit round youralarm device. The size of the cut-outdepends on the actual size of thealarm which you use, but thesemi -oval shape seen on the PCBlayout defines the maximum area

HE

This good looking piece of electronic wizardry could end up saving your life one day.The metallic "nose" at the top is the gas sensor and the round black object underneathit is the solid state alarm.

which can be cut out withoutpossibly affecting the circuit itself.

Next, all resistors, capacitors andIC sockets should be fitted followedby ICI, Q1 and the diodes. Allconnections to and from the boardare best made at this stage. Makesure that the connections to the gassensing transducer are correct - thisis most important!

Finally, fit the remaining ICs intotheir sockets being careful not todamage IC3 and 4 by staticdischarge as you handle them.

Setting up is not difficult. Turn thepreset RV1 rully anticlockwise.Connect your HE Gaztec to the 1 2Vbattery. Slowly turn the presetclockwise until the alarm sounds.Push the "clear" pushbutton and thealarm should stop. Turn the presetjust a fraction anticlockwise - thedevice is now set.

You can test the under -voltagewarning by running the unit from a9V battery. Approximately every 40seconds the alarm should sound,only for an instant.

SIDE VIEW OFGAS SENSORSHOWING SECTION

UNDERNEATHVIEW

COMPENSATINGELEMENT

SENSINGELEMENT

The heart of Gaztec, the gas sensor itself,which is glued to the lid of the case with itsleads protruding through.

A word of warning - do not testyour detector, by holding the sensorin a continuous flow of gas such asthat from a cigarette lighter. Theheated element can easily burn out inthese conditions.


STABLEVOLTAGE

zi]GAS

SENSOR

SENSORCOMPARATOR

0-C)+12V

BATTERY

BATTERYCOMPARATOR

BISTABLELATCH

ASTABLE(1 pulse

every 40 secs)

Fig. 1. A comprehensive system diagram of HE Gaytec, showing all important parts ofthe circuit as blocks. By referring to the How it Works section and the circuit diagramon page 59 along with this, the mode of operation should be easily understood.

Fig. 2. Below. The overlay of the printedcircuit board whose foil pattern can befound on page 73. The oval shape at thebottom of the overlay should be cut outfirst, before any components are inserted.Make sure that all integrated circuits areinserted correctly.

2tc< -

0 -I<

+12V

OV

BuylinesA complete list of all components, bar thecase, is obtainable from Technomatic, whoadvertise with us, at the very reasonableprice of E17.

The case is model CM5 125K from OKMachine -Tool (UK) Ltd, Dutton Lane,Eastleigh, Hants.

HE OV8 DEIECIOL1

0

TOP B1

IMPLE

TRANSISTORSWITCH

ALARM

-Parts ListRESISTORS(all NW 5% except where stated)

R1,2 10kR3 8k2R4 12R 1/2 wattR5,7,8 lkR6,11,12,

15,17 100kR9 479kRIO 33M High ohmic thick film

resistorR13,16 4k7R14 3k3

POTENTIOMETERS

RV1 10k Miniature horizontalpreset

CAPACITORS

C I 220uC2 100nC3 2u2C4 220n

16V electrolyticpolyesterpolycarbonatepolyester

SEMICONDUCTORS

ICI 7805 5 V voltage regulator1 Amp

IC2 741 Op AmpIC3 3130 Mos-fet Op -AmpIC4 4001 Quad, -2-input NOR

gatesQ1 TIP121 Darlington transistorDI IN4001 1 Amp diodeD2,3 IN4148 Diode

MISCELLANEOUS

Gas Sensor see BuylinesPB I Push -to -make,

momentary action12 V Solid State alarmCase to suit - see Buylines


° 0101+12V

0

Gas Detector

Cl220u

ICI

R210k

C2100n

R412RAW

OR160

RIO33M D2

-1~44E.RI1100k 03

0-ANV-10+-6

C3 62u2

GAS SENSOR

571k0

L__

Fig. 3. The circuit diagram or schematic of the Graytec gas detector.

-How it Works-Taking a look at the block diagram of Fig 1the HE Gaztec assumes a somewhat frien-dlier appearance. By cross referring fromthe schematic to the block diagram thecircuit should be easily understood. The gassensing transducer has a stable voltage ofexactly 3 volts applied across it derivedfrom ICI, a voltage regulator and droppingresistor R4.

The voltage at the output of the sensor iscompared with a portion of a stable voltage(from the preset RV1) by an op ampcircuit called (remarkably) a comparator.When gas is in the surrounding atmospherethe voltage at the output of the sensorincreases causing the output of the compa-rator to jump to a high position. Thistriggers a bistable latch formed by IC4 aand b, which in turn holds transistor switchQ1 on until the "clear" button is pressed.

Q1 can also be turned on by the astableformed around IC4c and d, so that it is onfor approximately 200mS every 40 secs.This astable can be disabled or enabled, i.e.stopped or started, simply by the output ofIC2, another comparator, which comparesthe junction of RI and R3, a voltage divider,with the stable voltage from IC 1. Wheneverthe voltage at the junction falls below 5volts (the voltage of the regulator) then theastable is turned on. Therefore, a lowvoltage from the battery causes the alarmto be sounded but so as not to drain anymore current from the battery thannecessary, it is sounded regularly every sooften. This also differentiates from a de-tection of gas.

R9470k

RI34k7

R143k3

NOTE:ICI IS 7805IC2 IS 741IC3 IS 3130IC4 IS 40010115 1N4148D2& 3 ARE 1N400101 IS TIP121GAS SENSOR; SEE BUYLINESALARM IS 12V AUDIBLE WARNING DEVICE

C4ion

CS220n

I

PB1CLEAR

ALARM


WEST HYDE CASES FOR H.E. PROJECTSPower Supply Unit (May 1979) Order Code SWF 222LDigibell Project (May 1979) Order Code MIN 020 +020A

Baby Alarm (July 1979) Order Code BOC 440Scalextric Lap Counter (January 1 980) Order Code BOC 670

Crosshatch Generator (January 1980) Order Code SAM 003System 5080A Amplifier Module (March 1980) Order Code ACE 100K

System 5080A Power Supply (March 1980) Order Code MD4 01KHobby Corn (April 1980) Order Code PR B CTB1

PLEASE SEND FOR OUR FREE

80 -PAGE CATALOGUE & PRICE LIST

System 5080 Pre -Amp (May 1980). Order Code Ace 300KL.C.D. Clock (May 1980) Order Code BOC 706B

Car Power Booster. (June 1980) Order Code ACE 100K

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FirestiltANTENNAS

I

MODEL KW2 £14.402' 5/8 + wave 3dB gain. Fire-power rating - 100AM watts,200 SSB.


MODEL KW4 £16.704' 5/8 + wave 6dB gain. Fire-power rating - 400AM watts.800 SSB.


MODEL KW7 £20.157' 3/4 + wave 6dB gain. Fire-power rating - 700AM watts,1400 SSB. + Base/Cable. 27MHz = 120 Channel PlusTunable to 10 Meters.

UNTIL C.B.IS LEGALISED WEDO NOT SUPPLY RIGS.

C.57414110440.

REBEL 500£10.95

We stock a very large selec-tion of CB Accessories. Ifwhat you require is not instock we will gladly order.DV27DX275/8 HELICAL WHIPSFULLY DISGUISEDANTENNAEBASE STATION ANTEN-NAESTARDUSTER ETC.SWR METERSPOWER METERSPOWER SUPPLIESSLIDE MOUNTSSUPPRESSION KITSMAGIC MIKESPOWER MIKESANTENNAE MATCHERSSPLITTER BOXES C.B. BOOKSBig Dummy's Guide £2.75CB Lingo Bible £2.75Best Book on CB £3.95CB Yearbook 1980 £2.25+ 25p per book p&p

Citizen Band, Antennas and Accessoriesfor Marine, RV, Truck, Auto, Van

Motorcycles . . . Mobile and Indoor/Outdoor Base Applications

10-4 Good Buddies

Come to us for yourCar Spares - Accessories - Customizing Equipment

TEL: CHERTSEY (STD 09328) 62556229 CHERTSEY ROAD

ADDLESTONE, SURREY


Books from the HE Book Service28 Tested Transistor Project

£1.55Richard Torrens. The projectscan be split down into simplebuilding blocks which can berecombined for ideas of yourown.

Electronic Projects for Be-ginners £1.65F. G. Rayer. Divided into 'NoSoldering Projects,' Radio andAudio Frequency, Power Sup-plies and Miscellaneous.

Practical Electronic Calcula-tions and Formulae . £2.55F. A. Wilson. A valuablereference for the home andlaboratory, containing all themost frequently used, andsome of the less well-knownelectronic formulae and calcu-lations.

Popular Electronic Projects£1.75

R. A. Penfold. A collection ofthe most popular types ofcircuits and projects usingmodern, inexpensive and freelyavailable components.

POPULAR ELECTRONICSBOOKSSinclair, I. R., IntroducingElectronic Systems . . £1.95Sinclair, I. R., IntroducingAmateur Electronics . £1.65Sinclair, I. R., Electronic FaultDiagnosis £3.55Sinclair, I. R., Repairing PocketTransistor Radios . . . £2.60Sinclair, I. R., Oscilloscope InUse £3.10Sinclair, I. R., UnderstandingElectronic Components £4.20Sinclair, I. R., UnderstandingElectronic Circuits . . £4.20Kitchen, H. T., Handtools ForElectronic Workshop . £2.95Kitchen, H. T., Electronic TestEquipment £5.20Capel, V., How To Build Elec-tronic Kits £2.35Darr, J., How to test almosteverything electronic . £3.70Brown, R. M., How to readelectronic circuit diagrams

£5.60

AUDIOEarl, J., Audio TechniciansBench Manual £3.70Earl, J., Pickups and LoudSpeakers £3.70Earl. J., Tuners and Amplifiers

£3.20Earl. J., Cassette TapeRecorders £5.40Earl. J., ABC of Hi-Fi £4.35Capel, V., Microphones In Ac-tion £3.15

Digital IC Equivalents andPin Connections .. . £2.85Adrian Michaels. Covers mostpopular types and gives detailsof packaging, families, func-tions, country of origin andmanufacturer.

Radio Stations Guide £1.75B. Babani and M. Jay. An inva-luable aid to everyone with aradio receiver helping them toobtain maximum entertain-ment, value and enjoymentfrom their set.

IC 555 Project £2.05E. A. Parr. Circuits are given forthe car, model railways, alarmsand noise makers. Also coversthe related devices 556, 558and 559.

Second Book of CMOS ICProjects £1.80R. A. Penfold. Following in thesuccess of the original CMOSprojects book we present thesecond volume covering allaspects of CMOS technologyfrom multivibrators to trig-gering devices.

Electronic Security Devices£1.75

R. A. Penfold. Full of construc-tional circuits covering the mostbasic security systems to theUltrasonic and Doppler Shiftsystems

How To Build Your OwnSolid State Oscilloscope

£1.80F. G. Rayer. The book containsconcise practical instructions sothat even an inexperiencedhobbyist can construct a fairlysophisticated instrument withthe minimum of difficulty andexpense.

50 FET (Field Effect Transis-tor) Project £1.55F. G. Rayer. Contains some-thing of interest for every classof enthusiast. Short Wave Lis-tener, Radio Amateur, Experi-menter or audio devotee.

Linear IC Equivalents andPin Connections .. . £3.10Adrian Michaels. Gives mostessential data for popular de-vices.

Essential Theory for theElectronics Hobbyist £1.55G. T. Rubaroe gives the hob-byist a background knowledgetailored to meet his specificneeds.

Beginners Guide to BuildingElectronic Projects . £1.55R. A. Penfold. Covers com-ponent identification, tools,soldering, constructionalmethods and examples ofsimple projects are given.

50 Projects using IC CA3130£1.25

R. A. Penfold. Describes audioprojects, RF project, TestEquipment, Household andmiscellaneous circuits.

50 Circuits Using 7400Series ICs £1.65R. N. Soar. The author hasmanaged to compile no lessthan 50 interesting and usefulcircuits using this range of de-vices, covering many differentaspects of electronics.

Capel, V., Improving Your Hi-Fi£3.65

Capel, V., Creative Tape Record-ing £4.20Hellyer, H. W., Tape Recorders

£4.45Sinclair, I. R., Audio AmplifiersFor Home Construction £2.85

RADIO CONTROLDrake, J., Radio ControlledHelicopter Models . . £4.20Jeffries, C. R., Radio ControlFor Model Yachts . . . £3.85Safford, E. L., Radio ControlManual £2.60

COOKBOOKSTracton, K., BASIC Cookbook

£4.10Lancaster, D., TTL Cookbook

£7.00Lancaster, D., RTL Cookbook

£4.65Lancaster, D., CMOS Cookbook

£8.20Jong, W., IC Op Amp Cook-book £10.00Lancaster, D., T.V. TypewriterCookbook £7.75Lancaster, D., Cheap VideoCookbook £7.00Jong, W., IC Timer Cookbook

£7.50Lancaster, D., Incredible SecretMoney Machine (a how to cookbook for setting up your com-puter or technical business)

£4.95

QUESTIONS AND ANSWERSSIMPLE AND CONCISEANSWERS TO MANY QUES-TIONS WHICH PUZZLE THEBEGINNER.Coker, A. J., Q & A On ElectricMotors £1.90Hellyer, H., Q & A On Radiosand T.V. £1.90Hibberd, R., Q & A On Inte-grated Circuits £1.90Jackson, K., Q & A On Elec-tricity £1.90Brown, C., Q & A On Hi-Fi

£1.90Brown, C., Q & A On Transis-tors £1.90Brown, C., Q & A On Elec-tronics £1.90Reddihough, J., Q & A On Col-our T.V. £1.90Miller, H., Q & A On ElectricWiring £1.90

CONSTRUCTOR GUIDESGraham, P., Simple CircuitBuilding £2.70Colwell, M., Electronic Dia-grams £2.70Colwell, M., Electronic Com-ponents £2.70Colwell, M., Printed CircuitAssembly £2.70Ainslee, A., Practical ElectronicProject Building . . £2.70Colwell, M., Project Planningand Building £2.70

BEGINNER'S GUIDESinclair, I. R., Beginner's GuideTo Tape Recording . . £3.45

Sinclair, I. R., Beginner's GuideTo Integrated Circuits . £3.45Sinclair, I. R., Beginner's GuideTo Audio £3.45King, G. J., Beginner's GuideTo Radio £3.45King, G. J., Beginner's GuideTo Television £3.45King, G. J., Beginner's GuideTo Colour T.V. £3.45Guilou, F., Beginner's Guide ToElectric Wiring £3.45

PROJECT BOOKSMarston, R.M., 110 CosmosDigital IC Projects For TheHome Constructor . . . £3.95Marston, R. M., 110 WaveForm Projects For The HomeConstructor £3.95Marston, R. M., 110 Op AmpProjects For The Home Con-structor £3.95Marston, R. M., 110 Semicon-ductor Projects For The HomeConstructor £3.95Marston, R. M., 110Thyristor/SCR Projects For TheHome Constructor . . . £3.95Marston, R. M., 110 ElectronicAlarm Projects For The HomeConstructor £3.95Marston, R. M., 1 10 IntegratedCircuits Projects For The HomeConstructor £3.95Marston, R. M., 20 Solid StateProjects For The Car andGarage £3.20Marston, R. M., 20 Solid StateProjects For The Home £3.20

Note that all prices include postage and packing. Please make cheques, etc. payable to Hobby Electronics Book Service (in sterling onlyplease) and send to:Hobby Electronics Book ServiceModmags Ltd * Prices may be subject to change without notice.145 Charing Cross RoadLondon WC2H OEE


Op Amp CheckerConstruct your own vital test equipment with HE. An ideal first-time project whichwill be handy for many years to come.

The HE Op Amp Checker is a usefuldevice designed to give easy andquick checking of IC operationalamplifiers having the standard 8 pinDIL (Dual in line) package and pinconnection layout (or TO -99 typeswith their leadouts formed into an 8pin DIL configuration). The op amp isinserted into a DIL socket situated onthe lid of the case and if it is workingan LED indicator flashes on and offwhen a "push to test" switch isoperated. However, if the op amp isfaulty in any way the LED remainseither on or off, giving an instantcheck on the op amp's state.

The device is simple to constructand use and is very cheap, as it reliestotally on the operation of the ICunder test rather than any activecomponents of its own. A handful ofresistors, capacitors and an LED formthe circuit which is constructed onveroboards. However, you could tryyour hand at designing and makingyour own P.C.B. if you wish, as thecircuit is quite a simple one.

00 0 000 00000000 00 0 00500005000000000500000000 0 0 0. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

I 411 oooo 0000000000 00000000 0 00000000 00 0000800 0 0 000 000 0000 000 0 00 0 0 5 0 0000000000000000000000000000000000 0 00 00 00 0 00 0000 0000 0000 00000000 0000 0000050 01 2 3 4 5 6 7 9 9 10 11 12 13 14 15 15 17 18 19 20 21 2223 24

Figure 1. The underside of the boardshowing "break" points.

Figure 2. Board layout and wiring connec-tions of the Op Amp Checker.

A

8

00§81004

C2

00 000 0000000 000HOLDER

c2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

'moo 0 0 0 0 0 0 0 0 0 0 000

R1

A2 R1

1qp.

0K

ConstructionAs far as construction of the circuititself is concerned there is nothingunusual. The veroboard layout isuncluttered and neat, and buildersshould find no problems to hold themback. If you are not too sure aboutthe use of veroboard then take a lookat Building Site on page 26

However, our prototype has arather novel method to interface withthe outside world. We have used awire -wrap socket to "piggy -back -with the IC socket mounted on theveroboard. The wire -wrapping socketis mounted on the top of the case -after 8 small holes have been drilledin the case to allow the eight wirewrap tags to go through! Pushing theveroboard up onto the wire -wrap tagsconveniently mounts the board aswell as making tne ncessaryconnections between the op ampunder test and the rest of the circuit.


P81PUSH TO TEST

Cl100n

R1100k S 120k

R21k0

C2io.

R3

ICUNDER

7 TEST6

R4120k

LED1

R51k0

C310u

Figure 3. The circuit diagram of the Op Amp Checker.

Figure 4 shows the method of construction using a wire wrapping socket to provideconnections between the IC under test and the board.

R615k

R71k0

+9V

--How it Works=The device being tested is connected up as anon -inverting amplifier, with the non -inverting (+) input biased by R3 and R4. RIand R2 are a negative feedback networkgiving a closed loop voltage gain of 101 times(closed loop voltage gain equals RI plus R2divided by R2). The open loop voltage gain ofan op amp is the gain without any feedbackapplied - this is generally of the order of100,000, a value much too high to be of anyuse. Applying negative feedback reduces thisto a reasonable value - the closed loopvoltage gain. LED 1 is the LED indicator andis connected to the output of the op amp viacurrent limiting resistor R5. The LED willswitch on when the output of the test deviceis in the low state, and off when it is high.

R6 and R7 attenuate the output voltage ofthe amplifier, giving a nominal sixteenfoldreduction in the output signal amplitude. C3couples the output from the attenuator to thenon -inverting input of the test device, pro-viding some positive feedback. If the testdevice is functioning properly, the voltagegain its provides will considerably more thancompensate for the losses through the atte-nuator, and the circuit will oscillate at afrequency of a few Hertz when SW1 isoperated and power is supplied to the circuit.The repeated changes in the state of theoutput will cause LED 1 to flash on and off,indicating that the op amp is working cor-rectly. Of course, a dud device would almostcertainly fail to provide any significant vol-tage gain, and its output would then remainin a fixed state.

ORDINARY8 -PIN SOCKET

-Ve0

WI REWRAPPING8 -PIN SOCKET

VEROBOARD

Figure 4 shows this in detail. Becareful that you get the veroboardthe right way round i.e. pin 1 of thewire -wrap socket going to pin 1 ofthe normal IC socket. Mount PB 1,the test push button and LED 1, theindicator LED into the front panel.

All that remains is to connect yourbattery and find an op amp thatneeds testing! HE

Parts List-RESISTORS (all 1/4W, 5%)

RIR2, 5, 7R3, 4R6

100kIkO120k15k

CAPACITORS

CI 100n polyesterC2, 3 10u 10V electrolytic

SEMICONDUCTORS

LED I 0.2" Red LED

MISCELLANEOUS

10 strips x 24 hole 0.1" veroboardPB1 - push to make switch8 pin IC socket8 pin wire wrapping socketCase to suitPP3 battery and clip

BuylinesYour local stockist should have all partswhich we specify, except possibly the wire -wrapping socket, but most of the mail-ordercompanies who advertise with us may beable to help.

The approximate, parts only (ie no case)cost is £2.50.


CBANTENNAS AND ACCESSORIES

- ... CB andCB

monitor antennasAccessories

r---

ANTENNASfirestik' Citizen Band Fibreglass Antennas and Accessories

Watch for the new film"SMOKEY AND THE BANDIT II"

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r

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ELECTRONICS PHASORS, ANTENNAS, LEADS AND NUMEROUS OTHERACCESSORIES.

-,

,I,Asr

dimMicrophones, Power Supplies, SWR Meters, Linear Amplifiers, Preamplifiers,

40 Antennas, Frequency Counters etc., etc

TELEX® MICROPHONES AND HEADSETS.,

AND MICROPHONESTURNER® ANTENNAS

dm CB MOBILE AND BASE STATION ANTENNAS

K40 SPEECH PROCESSORS AND BASE LOAD ANTENNAS

WE ARE UK DISTRIBUTORS FOR THE MANUFACTURERS LISTED ABOVE AS WELL ASMANY OTHER COMPANIES. WE BUY DIRECT FROM THEM WITHOUT ANY MIDDLEMENSO THE PRICES WE CAN OFFER ON THEIR PRODUCTS ARE SOME OF THE BEST IN THECOUNTRY AND THEIR RANGE IS VAST. COME AND SEE US IT MAKES SENSE!

**SEND £1 FOR A COMPREHENSIVE CATALOGUE 1k-*

---4---103 High Street, Shepperton,

WNTJO I Middlesex TW17 9BL, England.

Tel:Ltd. Walton -on -Thames (STD 09322) 48145

COMMUNICATIONS EQUIPMENT DISTRIBUTORS

UK UK RETAIL OUTLETS IN SELECTEDAREAS STILL BEING SOUGHT

**UNTIL RIGS BECOME LEGALWE ARE UNABLE TO SUPPLYTHEM **


BreakerOneFourSend any news, comments or information you may have to:Breaker One Four, Hobby Electronics, 145 Charing CrossRoad, London WC2H OEE.

All quiet on the CB front, no news is good news - or is it. Rick Maybury looks at thelatest happenings on the CB and Open Channel scene

INCREDIBLE, that's the only work that adequatelydescribes the response to our National Directory ofHandles. Over twelve thousand of you have submittedyour handle. Our problem is that it's absolutely impos-sible for us to include it as a free supplement. Before yougo shouring 'foul' consider this, if we use the smallestpractical type size we can get around 150 names perpage, it doesn't take a degree in mathematics to workout that we'll need around 60 pages of HE to take themall. I don't think that would go down too well with ourprinters.

Our aim now is to produce the Directory as a 'Special'in its own right. To make it really worthwhile we're goingto include a couple of features and general informationon the CB scene in this country. Compiling the list hasproved something of a headache so we're using one ofour office computers to sort out the names alphabeticallyand allocate each handle a number. Obviously all this isgoing to take time, we anticipate publication aroundSeptember, hopefully we'll be announcing the date andcover price next month.

Open Channel

Still no news on the arrival of Open Channel, variousrumours are flying around for another announcement,January 1st, '81 is the most popular so far. The GreenPaper discussion document has yet to appear, it maywell be available by the time you read this. You can makesure of your copy by pestering your local HMSO (HerMajesty's Stationery Office) or by writing to the Rt HonWilliam Whitelaw (usual address, Houses of Parliament,Whitehall, London SW1), he should be able to tell youwhen. While you're at it you may like to tell Mr Whitelawhow distressed you are at having to wait for so long, you

could also impress upon him that the Government islosing an awful lot of money through not collectinglicense fees, VAT etc.

Trafalgar Demo

As luck would have it the Trafalgar Square Demonstra-tion will have been and gone by the time you read this (afull picture report next month of course), at the time ofwriting it looks set to be the biggest so far. Doubtlessthere will be other demonstrations in the comingmonths. Time and again people have asked us why wedo not give more warning of these events (the usualexcuse for not turning up), all we can do is relayinformation, the constraints of a monthly publicationdemand that we know at least two months before theevent if we're to give it a mention. So club organisers andcampaign leaders please note, we're only too happy togive your event a mention but let us know in good timeThe same goes for clubs, it's no good phoning us upand complaining that a club we mentioned in one of ourdirectories no longer exists, if you don't tell us about ithow are we supposed to know?

Breadboard 80

Most of our regular readers will know of the annualBreadboard Exhibition held in London in November, wellthis year it has fallen on Modmags (us) to organise theshow. Last year our theme was the amazing Hebot robot,this year we hope to make CB the focal point of theproceedings. Already we have some of our regular CBadvertisers booked for space, a couple of stands are stillfree so if you run a shop, club or any other CB organisa-


C.B. SCOTLANDScotland's first suppliers of C.B

Accessories bring you:-Aerials

Meters

In fact you name it

We stock it

But sorry, no rigsSmokey Bear says negatory

We are also TANDY dealers for the'Radio Shack' range of accessories.

VICTOR MORRIS(Audio Visual) Ltd.340 Argyle Street

Glasgow041-221 8958

That's a big 10-4

Suppliers of Quality CB Antennasand Accessories

OPEN 7 DAYS A WEEK

79 Far Gosford StreetCoventry

Telephone: (0203) 29567

All leading brands in stock

H.M.P., HY-GAIN TELEXFIRESTIK, MURA, TURNER

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rCB EquipmentSpecialists

the U.K's leading CBequipment supplier..!

All types of antennae - disguise, tri-band, DV27, DX27, B27, T27, dipoles, twins - every possible type/position of mount. We'reapproved distributors for antenna specialists. We also sell burners (50-1000 watts), pre -amps, SWR meters, mikes, testequipment, suppression gear, plus, connectors, books, etc. In fact, anything to do with CB EXCEPT RIGS. Special pledge - wewill match or beat any genuine price anywhere in the UK.Mail order expressed by Red Star, all goods returnable if not satisfied.Phone your requirements, quoting your Access or Barclaycard number for immediate despatch. We'll help with any problems,by phone if at all possible.

Our new address is: 10-21 breakers72-74 Queen's Road, Hersham, Walton -on -Thames

Tel. Walton -on -Thames 47395


tion and you want to get your name down for standspace then write to or phone Peter Freebey at our usualnumber for details. The show will be held at the RoyalHorticultural Hall between the 26th and 30th ofNovember. It will stay open late on the Thursday andopen for the first time ever on the following Sunday.

Club CallThe club scene is livening up at last, the Ten -Four Club inparticular has been undergoing some dramatic changes.After a number of internal disagreements the club haselected a new committee and a very good job they aredoing too! At the beginning of June the club entered afloat in the Waltham Forest Carnival (North East London)and as you can see from the photographs considerableimagination went into the design of the float. In fact theytook third prize in their class and collected a tidy sum forlocal charities in their 'Big Rig' collection boxes. Eventslike these are superb publicity for the campaign, indeedthe 10-4 Club attracted a number of new members andsome favourable 'write-ups' in the local press. If anyother clubs are organising similar events then we wouldbe only too happy to send along some of our 'LegaliseCB' Baloons to decorate your float or stand.

Above, the 10.4 Club's float, how about the rig above the driverscab - big enough?Below. The carnival underway, the collection boxes raised a feweyebrows.


Here's this month's selection of club addresses.10-4 CLUBSecretary Ian LeslieBM/ 10.4London WC1.

Meetings every other Tuesday (1st July, 1 5th July etc)at the 'Essex Arms' Forest Road, \Aialthamstow and lastWednesday each month at the 'Kings Oak', High Beech,Loughton (for formal club meetings), all are welcome.EDINBURGH CB RADIO CLUBSecretary: Jim Martin22 Ross Gardens,Edinburgh, EH9 3BR.

OPEN CHANNEL CB CLUB, PRESTON AND DISTRICT(Formerly Preston CB Club)Chairman: F. W. McKeownSecretary: S. J. Battersby (Address below)17 Coronation Street,Blackburn, BB1 6BS.'HART OF ENGLAND CB CLUBSecretary: Mrs S. K. Wilson58 Clarendon Road,Hinckley,Leicestershire.

Please note that the Weymouth CB Club has beendissolved. Anyone in the Weymouth area starting a clubmight like to drop us a line.The UBA ESSEX has been renamed the ESSEX CBCLUB, the address is still the same as the one given inthe June issue.

MonitorBet you've seen the Monitor Offer on page 71, if youhaven't sent your order in yet then why not? For theridiculously low price of just £11.50 (including VAT andeverything) you'll get a superb Short Wave converterand believe us, it's just about the best one you can buyunder £50. Look no further, you can buy with con-fidence as this offer is being run in conjunction withgenial Glyn Hall of Wintjoy Ltd, well, what are youwaiting for?

Still on the subject of Glyn Hall, he's our CBVIP thismonth, don't miss it for a real rags -to -riches story. Youmay be interested to know that for the price of an SAE

Two new catalogues available from WintJoy.

67

ORDER CB receivers at E14 99 eachCarnage El 00 per Item

FORMVATTotalclosed

"SKYWAVE"FOR

COMMUNICATIONANTENNAS BY H.M.P.

ANTENNASArestik' s s4.64,aea,ta

ALSO:C.B.-V.H.F. AMATEUR ANDTEST GEAR ACCESSORIES

COMPONENTS AND SURPLUS

Telephone: Bournemouth 30208073 Curzon Road, Boscombe

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CALLERS WELCOME

THE #1 WIRE WOUNDAND MOST COPIED

ANTENNA IN THE WORLD!

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AND ACCESSORIES.

Call or write for full information

WINTJOY LTD.103 HIGH STREET, SHEPPERTON

MIDDX. TW17 9BLTel. Walton -on -Thames (STD

09322) 48145

C.B. AERIAL EVERYTHING BUT RIGS PLUGS SWR METERS

C11)ttuning

(--D

ey0 G* toe o

STEREO

= 0 =;7; MOBILE STEREOcO

Dept. HE, 360 York Road, London, SW18Telephone 01-870 7362

Free fitting on all units purchased from us

WE ARE SOUTH LONDON'S IN CARENTERTAINMENT SPECIALISTS.

0rn

03

WHATEVER YOUR AUDIO PROB-LEMS ARE, COME TO US AND 2WE'LL CURE THEM. T

-4

30-4C) fT1

* Come and have a cup of coffee while we fityour stereo

* Wide range of fitting kits ands aerials *

BASE ANTENNAE RAIN CAPS MICROPHONES CB SUPPRESSORS

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CZ.ItUit'Bt CB RADIO RECEIVERS

LISTEN TO CB ON YOUR CARRADIO FOR ONLY £14.99 + VAT"Listen for speed traps and accident warningsand learn the lingo(Hear all 40 channels on your medium wave dial)

SIMPLE TO FIT:

INSTANT Please supply NameAddress

Tel no

Goods despatched within 7 days (subject to availability) (orders accepted on plain paper)

FULLY LEGAL

minimr momflUIV MIN= MI d MEd

M1/11/ %' MAIL141 SNARGATE STREET, DOVER (0304) 207043 or 202183


W4ihe'll send you one of his excellent Shakespear orAntenna Specialists catalogues, they make very interes-ting reading. Before we leave Glyn altogether have alook at the picture of the 'un-Tenna', (below) thiscunning little black box will convert your existing caraerial into a genuine Short Wave aerial, only one simpleadjustment to make for a perfect SWR, what more canwe say?

The 'Un-Tenna' car aerial converter

GLYN HALL

React UKOur last item this month concerns the efforst of IvanFrancis. He's a Canadian Gentleman over here for a fewweeks. He represents REACT organisation, they are thepeople who voluntarily monitor channel 9 for emergen-cies in the States. Under the REACT Charter we couldn'tstart an official monitoring service until we have a legalsystem, however, Ivan has managed to start a clubcalled REACT UK Supporters Club. If anyone is inter-ested in finding out more about the benefits of REACT ora similar type of emergency monitoring system then youcan either contact Ivan direct at:28 The Coots,Bristol, BS14 8LH.or get in touch with any of the regional organisers listedbelow:London - David HughesMidlands - Keith TownsendNorth East - Les CarrolScotland - Keith Townsend

The REACT Club have already been in touch with theRed Cross and St John's Ambulance so as soon as wehave a legal system there should be someone there 24hours a day able to assist in emergencies. Now isn't thatwhat CB is all about? See you next month.

Stay lucky . .

CB VIP

I was born 18 years ago, at the age of 17, in Salisbury,Rhodesia. I lived there until 1966 after doing a spellwith Rhodesian Air Force during the Emergency Call-upjust after U.D.I.

In July of that year whilst working for de Beers, in thediamond fields on the Skeleton Coast of South WestAfrica, I became interested in two way radio, which wasmy only contact with the outside world as my camp was250 miles in the Namib Desert. My callsign was ZSR 72and during this spell I was lucky (?) enough to get a blow

by blow account of the Six Day War which was relayedby Israeli Hams.

When I returned to Rhodesia in 1969 I seemed tospend most of my time in and out of the Air Force as thewar in Rhodesia was starting to "hot up". In betweenfighting I was quality Control technician with a factorymanufacturing motor vehicles.

April, 1971 saw me once again on the move, thistime to Europe to seek my fortune. After dabblingaround in the Motor Industry I decided to study Com-puter Technology and in November of '76 I graduated. Ijoined a small electronics manufacturer as Assistant R &D Engineer and worked my way up to Works Managerleaving them in July '79 to go it alone, although at thistime I wasn't too sure whether to do CB accessoriestotally or diversify. I had a position as a consultant to afairly large organisation available to me but after a fewforay's on to the Continent found the CB market to be agrowing industry.

On my return to the UK I contacted Bill Taylor to see ifI could obtain backing for my idea. He had the foresightto realise the potential of the CB market and inNovember 1979, Wintjoy Limited was born. The aim ofthe company was to obtain goods direct from thefactories in the USA, Europe and Asia rather than buyingfrom middlemen and several franchises have been set upwith top manufacturers. Though I believe that it is toolate to stop 27MHz due to the sheer numbers alreadyillegally operating, the manufacturers represented byWintjoy have said they will manufacture for anyfrequency named.

May we at Wintjoy wish HE and BOF all the best andlook forward to the day when BOF becomes a Magazinein it's own right, which it surely deserves.Glyn Hall,WINTJOY LIMITED.


CB MOBILE ANTEritifl SERIES

% POWER WAVE ANTENNAThe Rebel 500 CB mobile antenna series is, elec-tronically speaking, an engineered %'s wave

conductor length in a constant mode helical wind-

ing. This produces a power wave with a currentfield similar to a full conductor length non -loaded

antenna. Spaced winding keeps energy forces

away from the metal ground plane, preventing field

effect and flux lines from absorbing power. Voltage

at the field point is at a minimum, preventing loss

of power through leakage and stray currents. The

power goes where you need it...into the antenna(not into the vehicle body)!

% wave performance Fits any standard 3/8" 24thread mount

Power rated at 500 Available in black, white,watts or bright orange

Continuous loaded for w 48" straight or 72"continuing power tapered whips

Power wave of full length non -loaded antenna

The Rebel 500 antennas..they refuse to behave liketame antennas!

Power wave of center loaded orlump wound antenna

Power wave of constant modehelical wound antenna the

Rebel 500

WNTJOYLtd.

103 High Street, Shepperton,Middlesex TW17 9BL, England,

Tel:

Walton -on -Thames (STD 09322) 48145

RADIOACCESSORIES

The Largest distributors of CB accessories in the UK.WIS

Come and see the biggest andbest selection of CB radio

accessories ANTENNAS

including:- byHY-GAINSIRTELA.S.HMP

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SUPRESSION EQUIPMENTPLUS MUCH MUCH MORE

10% discount onpresentation of this ad

UM 1111111Mura Electronics (UK) Ltd ,

Blackpool. A. D S. Electronics, 16 Warbeck Drive (Nth.Shore) Blackpool. Tel. 02353 572 2/0253 21173; Edin-burgh. Cunom Equip., 131 Fountain Bridge. Edinburgh E113.Tel. 031-229 8830; Stoke-on-Trent. HSBC. 27 Hope Street,Henley, Stoke-on-Trertt. Tel. 0782 27 815; Wigan. Car RadioWigan, 80 Darlington Street East, Wigan, Lancs. Tel. 094243101. Spans 'n" Repairs, 79 Far Gosford Street, Coventry(0203) 29567. Sonic Sounds Audio, 248/256 TottenhamCourt Ront, W.1.01-637 1908.

79 Church Road, Hendon, London. N.W.4Tel. 01-203 5277/8

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;1)

Very Special OfferCB MONITOR CB MONITOR CB MONITOR CB MONITOR CB MONITOR CB MONITOR

LEGAL CB, right, that's got your attention,now we can tell you all about this month's 'fil:s-IVery Special Offer. I 0

ets 01For just £11.50 (all inclusive) you can be ..the proud owner of one of these ELENCO # %II(no rubbish 'ere mate!) CB Monitor/Con- # 1-- Iverters. Just slip the plug from your exist- # , cik .. a

ing car aerial into the appropriate socket, i ,o .... >1plug the lead from the unit into your car e e- :Iradio aerial socket and connect the black c.,pe,

wire up to +12 volts and you're ready to go. .--.. 3,1The eight transistor circuit has now ,, ,use 1731

converted your AM car radio into a narrow- e ..- fiband Short Wave receiver. It will tune over ., ..

the entire 40 channels used by CB networks .;1/40 ... Fli.worldwide. Thrill to the sound of Italians /- 445 . zi

cursing each other, listen to the Americans / ,,,z) ......

.../on the 'skip' in the evenings, all sorts of , c.,0 A11..'interesting' transmissions may be heard! e <,>e, ...... .. wilThe ELENCO is one of the best converters e ... .." Elon the market, even has a switchable noise .. ." ,

0blanker built in to cut out the irritating back- . , -.I."

ground hiss. I z'Well, what are you waiting for? Fill in the c.t. ,

aaicoupon today. 04z, i

iz e,, tiModmags (Sales Office) Ltd. I \e' ac`

V- : ..145 Charing Cross Road, London WC2H OEE A__ t.iiiNom so .. m mi Ell A= En IIIMI = m mu m swim no m EN mi MEI MN mow

YOUR NEAREST INTERNATIONAL

The

MOON-FANTOM

Mobile Moonraker

DEALERS REQUIRED

C.B.i SUPPLIERSOLE AGENTS FOR:-

Avanti's`Astro-FantornGoes WhereNo CBAntennaHas GoneBefore!

arm

From the AVANTIResearch laboratoriescomes a sleek. 22.lull 1/2 wave antenna.so unique that Itmounts on glass.0ansmots throughglass and receivesthrough glass yetrequires no groundingto metal as doconventional 1/4 waveantennas. No holes todrill ..no clamps. clips

,`;;;;":?",:r"Io

.they":L,0a's finish, Noponched cables to runin through doors.sendows or trunk Nomore leaks. TheAstro Fantorn Is ahandsome. low profileantenna that providesthe ultornate onconvenience!

Replace yourpresentantennawith anew Avant'

AVANTI ANTENNAS MOBILE & HOME BASE =,..-SOMMERKAMP AMATEUR & MARINE RADIOSSTALKER RANGEC.T.E. POWER SUPPLY UNITS, ALL ACCESSORIES & AERIALS.

A NewDirection inFiberglassAntenna Whips!From Avanti

TheAvantiSkinnyStick.

MOBILE MOOMRAMERAVIS, M

ASTRO CANTO*.AV TOO

MOONRAKER 4Form 21033D 12/13 Greenpark Road, Bray, Co. Wicklow, Ireland.Tel: 860077, 868727, Telex: El. 31539Northern Ireland Office: DunDonald 2941

"WHILST WE CANNOT SELL RIGS TOTHE U.K. AT THE MOMENT, WHY NOTSEND FOR DETAILS OF OUR RANGE IN PREPARATION FOR LEGISLATION"

T.V.E.S. LT


HOBBYPRINTS

If you have never used HOBBYPRINTS before,then you don't know what you've been missing.HOBBYPRINTS are an etch -resistant rub -downtransfer. Just place the appropriate HOBBY -PRINT over a clean piece of copper clad PCBmaterial and rub. It's as simple as that. Oncethe design has been transferred, immerse theboard into the Ferric Chloride. 15 minutes lateryou will be rewarded with a perfect PCBprepared from our original artwork, so you canhave no worries about making a mistake. Bythe way, HOBBYPRINTS are ideal for makingPCBs by Ultra -Violet exposure.

.4)

HOBBYPRINTSHEETS AREAVAILABLE FORISSUES FROMNOV. 78 RIGHT UPTO THIS ONE.ALL SHEETS COST£1.20 ALLINCLUSIVE OFPOST ANDPACKING ANDVAT.ORDER BY SHEETLETTER ANDISSUE MONTH(SEE BELOW).

ISSUESHEET REF.

Nov. 78 ADec. 78 B

ISSUESHEET

Sept. 79Oct. 79

REF.

Jan. 79 C Nov. 79 MFeb. 79 Dec. 79 NMar. 79 E Jan. 80 0Apr. 79 F Feb. 80 PMay 79 G Mar. 80 QJun. 79 H Apr. 80 RJul. 79 May 80 SAug. 79 Jun. 80T

10!For your HOBBYPRINT refer to the chart aboveand send your cheque or postal order to:HOBBYPRINTS,Modmags Sales Office,Hobby Electronics,145 Charing Cross Road,London WC2H OEE.


PCB Foil PatternsFor the benefit of our confusedreaders who have been rushingaround, frantically turning overpages, trying to find the foil patternsfor the projects they are wanting tobuild - here they are!

We have collected all the tracklayouts or foil patterns (call them whatyou will) together on one page tomake things easier.

Figure 1. The foil pattern for the HE Gaytec

7.1

HE CAR onE-1

604 <00?

Es*

"Ard.

CH. pr.. 8 j3j

Fig 2. The foil pattern for HE Pass the Loop


Fig 3. Equitance foil pattern.73

%*7-Trt

i3 Amp 250V

CLASSIFIED INFORMATION

Semi -Display: -1 -3 insertions - £4.50 per single column centimetre4-11 insertions - £4.00 per s.c.c.

12 insertions - £3.50 per s.c.c.Classified: -18 pence per word (minimum 25 words)Box number on application (Personal ads only)

MODULES. Mullard LP1164 AM/FM I.F.Unused, guaranteed £1.50 P.P. C.W.O.B.A. screws, hardware, loudspeakers,components. Manufacturers clearance.S.A.E. lists: Tennex Limited, Stock Road,Southend, Essex.

RACK ISSUES! Hobby and Electronicsmagazines. Bought/sold/exchanged. Staterequirements and request quotation.Denstone Educational Publications, 1 Water -foot Avenue, Southport PR8 3TE.

£5 OSCILLOSCOPE. Standard Junk BoxComponents plus approx. another £5 (totalcomponents approx. £12). This unit plugsinto TV Aerial socket and converts TV toOscilloscope. Circuit and plans £3. Kerr, 27.Coles Road, Milton, Cambridge, CB4 4BL.

Security and Surveillance distributorrequires additional specialised manufac-turers and products. Serious replies only.Forward details to - Box No. 115, HobbyElectronics, 145 Charing Cross Road,London WC2H OEG.

CHEAPER THAN A VISIT TO THE PIC-TURES. Latest top quality films prerecordedon videocassettes from only £6. Full detail!from G.T. Technical Video Library (10a HE)119 Oxford Street, London W1R 1PA.

All mixed. 200 components £4. 50 transis-tors 95p. 100 diodes 85p. 10 switches 95p.Lists 15p. - Sole Electronics (HE), 37Stanley Street, Ormskirk, Lancs. L39 2DH.

Upgrade your projects with Hi -Stab metalfilm resistors. One -hundred mixed value andwattage (mostly 0.25w) £1.20 inc. p.&p. -Jackson, 37 Knott Lane, Gee Cross, Hyde,Cheshire.

WEBB ELECTRONICS41 Winwick St

WARRINGTON. Tel 54174

LED's2" Round

Square

LED's .2" onlyRedYellowGreenWhite (Red when lit)White (Green when lit)

7.5p10.5p10.5p7.5p7.5p

Red 7.5pYellow 10.5pGreen 10.5p

CLIPS FOR ALL LED's 3p each

TOGGLE SPST (on -off) 52pSPDT Ion -on) 60p

SWITCHES SPDT (blased-on) 64pSPOT (centre 001 67pSPDT (centre off biased one way) 68pSPDT (centre off biased both ways) 69pDouble -pole version of above switches

(not on -off) add 18pMISULDED FLAT TOGGLES IN

FIVE COLOURS: Red, black, white, yellow.' SAE for full list of switches

Add VAT at current rate.P&P add 50p. Orders over ES P&P free

ALL ADVERTISEMENTS IN THIS SECTION MUST BE PRE -PAID.Closing date: 2nd Friday in month preceding publication.

Advertisements are accepted subject to the terms and conditonsprinted on the advertisement rate card (available on request).

TOP QUALITY PRE-RECORDED VIDEO-CASSETTES, the latest films, free lists. Fromhalf recommended price. Write now for de-tails, AUSHE, 76 Church Street, Larkhall,Lanarkshire.

INTRODUCTION TO MICROPROCES-SORS. A beginners book £2.30. PopularElectronic Projects £1.45. Single IC Projects£1.50. 28 Tested Transistor Projects £1.25.Add 35p p&p. - Educational Data & Techni-cal Services, 59 Station Road, Cogenhoe,Northampton NN7 1 LU.

CB ACCESSORIES in Leeds. PhoneHoward after 6pm for Mic's, Ant's, Speakers,Plugs & SWR Meters. Strictly no rigs untillegal. Leeds (0532).686960.

INGENIOUS GAMES to distract andtantalize -and to construct. Three originaldesigns by me in kit form, pocket sizedwith a top quality finish to grace yourcoffee table and decieve your friends.From £4.25. Send SAE for details to H. S.Houston, 12 Harlech Avenue, Leeds 11,Yorkshire.

ADVERTISERS' INDEXAJD 55 VICTOR MORRIS 66AMBIT INTERNATIONAL 2 MURA ELECTRONICS 70ARROW AUDIO CENTRE 44 NIC MODELS 23BI-PAK SEMICONDUCTORS 20 T. POWELL 56BK ELECTRONICS 24 POWERTRAN 75BRNS 10 PRECISION PETITE 24S & R BREWSTER 16 J. W. RIMMER 31

CAMBRIDGE LEARNING 10 SKYWAVE 68CB CITY LTD. 51 SPARES 'N' REPAIRS 66CLARION 18 & 19 SRU AUTOS 60CRIMSON ELECKTRIK 31 S. N. STEVENSON 48CSC 23 & 48 STEVE'S ELECTRONICS 44EDA 56 SWANLEY ELECTRONICS 31

FIRESTIK ANTENNAS 24 SYMBOLYKA 66GMT ELECTRONICS 28 TECHNOMATIC 45HENRY'S RADIO 40 TEMPUS 52HI -TECH 34 TK. ELECTRONICS 40ILP 4 & 5 TVES LTD. 71

MAPLIN 76 VERO 51MARSHALLS 16 WATFORD ELECTRONICS 7

METAC 25 WEST HYDE DEVELOPMENTS 60MIDLAND TRADING 8 WHEELS DOVER 68MINIKITS 16 & 18 WINTJOY LTD. 64, 68 & 70MOBILE STEREO 68

PRINTEDCIRCUITS

and

HARDWAREComprehensive range Constructors Hardwareand accessories

Selected range of popular componentsFull range of HE printed circuit boardsnormally ex -stock, same day despatch atcompetitive pricesP C Boards to individual designsResist -coated epoxy glass laminate for thed i y man with full processing instructions (nounusual chemicals required)

Alfac range of etch resist transfers and otherdrawing materials for p c boards.

Send 15p for catalogue.

RAMAR CONSTRUCTORSERVICES

MAS011115 ROADSTRATFORD-ON-AVONWARWICKS, Tel. 4879

BARGAINS FOR THE ELEC-TRONIC HANDYMAN

BRANDED L.E.D. DIGITALALARM CLOCKS

(1)

Returned to ServiceDepartment withinguarantee period. (2)

1. With alarm repeat. S.R.S.P. of Et 7.00. Offered at£3.95, inc. VAT, or 3 for £9.95, inc. VAT.

2. With luxury lamp and repeat alarm. S.P.S.P.E31.00. Offered at E7.95 inc. VAT each, or 3 for£19.95 inc. VAT.

These will be sold as received from our customers withthe existing fault(s) and without guarantee.

U.K. onlyDiscounts available on large bulk purchase.

PRESCOTT CLOCK & WATCH CO.LTD.

PRESCOTT HOUSE, HUMBER ROAD, LONDONNW2 6ER


PRICE STABILITY: Order with confidence. Irrespective of any price changes wewill honour all prices in this advertisement until September 30, 1980, if thismonth's advertisement is mentioned with your order. Errors and VAT ratechanges excluded.EXPORT ORDERS: No VAT. Postage charged at actual cost plus 11 handlingand documentation.U.K. ORDERS: Subject to 15% surcharge for VAT. No charge is made for car-riage, or at current rate if changed.SECURICOR DELIVERY: For this optional service (U.K. mainland only) add12.50 (VAT inclusive) per kit.SALES COUNTER: If you prefer to collect kit from the factory, call at SalesCounter. Open 9 a.m. - 12 noon - 1 - 4.30 p.m. Monday -Thursday.

ehromatheque 5000

Off ON

ETI 5 CHANNEL LIGHTING EFFECTS SYSTEM

OVIIROADeltronsatheque 8000

LIM I UM 2 3AUTO LIVID .011 SPIRO D. , A

- I q4, tI

MERMANETI 5 CHANNEL UGHTING EFFECTS SYSTEM

Panel size 19.0" a 3.5". Depth 7.3"This versatile system featured as a constructional article in ELECTRONICS TODAY INTERNATIONAL has 5 frequency channels with indivi-dual level controls on each channel Control of the lights is comprehensive to say the least You can run the unit as a straightforward sound -

to -light or have it strobe all the lights at a speed dependent upon music level or front panel control or use the internal digital circuitry whichproduces some superb random and sequencing effects Each channel handles up to 500W and as the kit is a single board design wiring isminimal and construction very straightforward

Kit includes fully finished metalwork, fibreglass PCB controls, wire, etc - Complete right down to the last nut and bolt,

MUSIC EFFECTS DEVICE AS FEATURED INELECTRONICS TODAY INTERNATIONALThe BLACK HGLE designed by Tim Orr, is a powerful new musical effects device for processing both natural and electronicinstruments, offering genuine VIBRATO (pitch modulation) and a CHORUS mode which gives a "spacey" feel to the sound achievedby delaying the input signal and mixing it back with the original. Notches (HOLES), introduced in the frequency response, move upand down as the time delay is modulated by the chorus sweep generator. An optional double chorus mode allows exciting antiphraseeffects to be added. The device is floor standing with foot switch controls, LED effect selection indicators, has a variable sensitivityinput, has high signal/ noise ratio obtained by an audio compander and is mains powered - no batteries to change! Like all our kitseverything is provided including a highly superior, rugged steel, beautifully finished enclosure.

COMPLETE KIT ONLY £49.80 + VAT (SINGLE DELAY LINE SYSTEM)De Luxe version (dual delay line s stem) also available for £59.80 + VAT.

MANY MORE KITS!including synthesizers, computer, hi-fi amps, tuners, etc.

in our FREE CATALOGUE

UM* UVTLS

COMPLETE KITONLY

£49.50 VAT

POWERTRAN

MPA 21111 100 Watt Mixer -Amplifier

.55INTERNATIONAI

0VOLUME MDOU MILE MK0 ON

NNI.1/ N. .1/ N " 0 N. V/ N. 1/ e N." I .., II , 'N.del

e

if...,,A. j4i.. . ... ..

MPA 2n : os: 7 : 7 0 : 7 ip : 7 7 ft ,0 . .,. ,11.

POWERTRAN I * 0 0 0 0 so i

LOW MGM

Panel size 19.0" x 3.5". Depth 7.3"

Featured as a constructional article in ETI. the MPA 200 is an exceptionally low priced - but professionally finished - general purposehigh power amplifier It features adaptable input mixer which accepts a wider range of sources such as microphone. guitar. etc There arewide range tone controls and a master volume control Mechanically the MPA 200 is simplicity itself with minimal wiring needed makingconstruction very straightforward.

The kit includes fully finished metalwork, fibreglass PCBs, control, wire. etc - complete down to the last nut and bolt

OUR CATALOGUE IS FREE! WRITE OR PHONE NOW!

COMPLETE KITONLY

£49.90 + VAT

POWERTRAN ELECTRONICSPORTWAY INDUSTRIAL ESTATE ANDOVER

ANDOVER, HANTS SP10 3MM (STD 0264) 64455

STEP INTO A NEW WORLD nr,01,WHEN YOU DISCOVER II H IIIat11)11.11111

For beginners or professionals, the Maplin catalogue will help you

find just about everything you need for your project.

Over 5,000 of the most useful components - from resistors tomicroprocessors - clearly described and illustrated.

Send the coupon for your copyand STEP UP TO

MAPLIN SERVICENOW

Post this coupon now for your copyof our 1979-80 catalogue price 70p.Please send me a copy of your 280 pagecatalogue i enclose 70p (plus 46p p&p).If I am not completely satisfied I may return thecatalogue to you and have my money refunded.If you live outside the U.K. send £1 .35 or tenInternational Reply Coupons. I enclose £1.16.

ADDRESS

HE780

maim rnELECTRONIC SUPPLIES LTDAll mail to:-P.O. Box 3, Rayleigh, Essex SSE 8LR.Telephone: Southend (0702) 554155.Shop: 284 London Road, Westcliff-on-Sea, Essex. (Closed on Monday).Telephone: Southend (0702) 554000.

c,, Catalogue now available in all branches of WHSMITHO Price £1.00

in car entertainment ectr nics · ambit so chomp. so please phone anr1 cheer or pout. catalogues 6...

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