Wireless October 1985 85P
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Wireless October 1985 85p 68000 computer board Memory expansion Switched -mode power supply Multi-standard digital terminal Australia AS 3.30 Spain Pts. 370.00 Denmark DKr. 38.00 Switzerland SFr. 8.00 Germany DM 7.00 Singapore MS 7.00 Holland DPI. 9.00 U.S.A. S 4.00 Italy. L 4200 www.americanradiohistory.com DUAL TRACE THE ANSWER TEKOSCILLOSCOPES BY ANY MEASURE Now! Tek quality and expert advice are just a free phone call away... Our National Order Desk line gets you fast delivery of the industry's leading value/ performance portables... and technical advice from experts! The 60MHz 2213A, 2215A and the 100MHz 2235 and 2236 These UK offer unprecedented reliability anufactured 'scopes are and affordability, plus the obtainable through the industry's first 3 year warranty National Order Desk. Call us on labour and parts, CRT to order or obtain literature, included. or to talk to our expert on All 2200 series scopes scope applications. have the bandwidth for digital ..talk circuits and sensitivity for low signal analogue measurement. The sweep speeds for fast logic families, and delayed sweep for to Pete fast, accurate timing Dial 100 and ask for measurement. The top of the range 2236 combines a Freefone Tek- scope counter/timer/DMM with the Tektronix UK Ltd scope to provide fast, easy Fourth Avenue, Globe Park, measurements for voltage, Marlow, Bucks SL7 1YD Tel: (06284) 6000 resistance and temperature. Telex: 847277 & 847378 The Company reserves the right to modify designs, speci'ications and change prices without notice. Tektronix (:I)MMI1Fflll.If 1.IIItNI.1 CIRCLE 1 FOR FURTHER INFORMATION www.americanradiohistory.com Editor ELECTRONICS PHILIP DARRINGTON Deputy Editor GEOFFREY SHORTER, B.Sc. 01-661 8639 Technical Editor MARTIN ECCLES over 70 years inindependent electronics publishing01-661 8638 Projects Editor October 1985RICHARD LAMBLEY 01-661 3039 OR 8637 News Editor HURHUOVolume 91 number 1596 DAVID SCOBIE 01-6618632 MN MINIUM Mlift Nair Mb idMME =NI Drawing Office ROGER GOODMAN 01-6618690 Multistandard digital terminal unit Case study in interface design 58 BETTY PALMER by J. Walker 21 by A. Ray Implementing a digital filter with a How the Syscon 6 interface was developed Advertisement Manager microprocessor leads to simple hardware for using Commodore peripherals with a BOB NIBBS, A.C.I.I. for this programmable modem. BBC computer. 01-661 3130 MICHAEL DOWNING 01-661 8640 The tale of the long -tail pair - part 2 Switched -mode power supply ASHLEY WALLIS by F.J. Lidgey 27 by K.L. Smith 61 01-661 8641 Further applications ranging from analogue Last part of the instructional series on log/exp circuits, multipliers and dividers, power supplies is a practical design for a Northern and Midland Sales to fast logic gates. 13A, 14V switcher. BASIL McGOWAN 021-356 4838 Group Classified Manager BRIAN DURRANT Half -megabyte memory for SC84 35 Call cost calculator 69 01-661 3033 by J.H. Adams by S.A. Cameron Assistant Classified Manager 'Silicon disc' with 256k or 512k of dynamic How the software works and how to reprogram the instrument. MIKE RATCLIFFE memory uses novel refresh technique. 01-661 8161 Classified Supervisor i IAN FAUX The future - what it could hold Digital polyphonic keyboard -2 73 01-6613033 by R.E. Young 45 by D.G. Greaves Production Where Britain's hidden strengths exist, Digipoly's t.t.l. processor circuit and BRIAN BANNISTER where they are being suppressed, and how microcode program. (Make-up and copy) they could be brought to the surface. 01-661 8648 Current issue price 85p, back issues (if available) £1.06, at Retail and Trade Counter, Units 1 & 2, Bankside Industrial 68000 evaluation kit 51 Electronic mailbox Centre, Hopton Street, London SE1. by R.F. Coates by M. Allard 77 Available on microfilm; please contact The £100 Kaycomp is Bob Coates 68000 Construction tips and line interface circuits editor. board for engineers, students, and complete this description of an electronic By post, current issue £1.30, back issues message system. (if available) £1.40, order and payments to enthusiasts. EEP Sundry Sales Dept. , Quadrant House, The Quadrant, Sutton, Surrey SM2 5AS. Tel.: 01-661 3378. Editorial & Advertising offices: Quadrant House, The Quadrant, Sutton, iMil , 4110 ill. M.M.Ikal, Surrey SM2 5AD. Telephones: Editorial 01-661 3614. News commentary 4 Feedback - - Advertising 01-661 3130. Swings and swings Electromagnetic paradox 18 Telex: 892084 BISPRS G (EEP) Molecular beam epitaxy Energy transfer *vies I Facsimile: 01-661 2071 (Groups II & III) Optical communication a Beeline (300 baud): 01-661 8978 Spark hazards (Type EWVV to start, NNNN to end). Eftpos comes to High Street Valve preamplifier 68000 computer boar d Subscription rates: 1 year £15 UK and News in brief Relatively interesting £19 outside UK. Student rates: 1 year £10 UK and £12.70 Circuit ideas outside UK. Humidity control 40 Distribution: Quadrant House, The Communications 9 Quadrant, Sutton, Surrey SM2 5AS. commentary Add-on current dumping - Telephone 01-661 3248. RS232 to Centronics British research Mummy expansion Subscriptions: Oakfield House, Interference agro Frequency meter Switebod.mode power supply Perrymount Road, Haywards Heath, Preventing reverse charging Multlstandunl digital tomtits! Sussex RH16 3DH. telephone: 04444 Amateur radio Five -decade op -amp oscillator 59188. Please notify a change of address. NSC800 runs Z80 software USA: $49.40 surface mail, $102.60 airmail. Business Press International Phil Brooker's cover shows (USA). Subscriptions Office, 205 E. 42nd Report New products 81 Bob Coates' 68000 board Street, NY 10017. Television at Montreux; 14 934MHz c.b. transceiver which links to hundreds of USA mailing agents: Expediters of the Satellite broadcasting, Multitasking 6809 with STE bus peripheral cards in the outside Printed World Ltd, 527 Madison Avenue, high definition and the future of Automatic i.c. tester world through its G64 Suite 1217, New York, NY 10022, 2nd class terrestrial tv Control expansion for BBC Micro postage paid at New York. interface. © Business Press International Ltd 1985. ISBN 0043 6062. Trio, quality PMR AOR, monitoring equipment. & surveillance. TK801S ÁR2002 of the ÁR2001 with Now from TRIO. the eagerly awaited range of high quality. purpose designed, VHF and The NEW ÁR2002 from AOR combines the well known performance are an easier to use press bottom key board, UHF mobile radio transceivers improved operating features. Improvements stepping by knob as well as Built with uncompromising quality in mind. these fully synthesisaed transceivers use a the addition of a signal strength meter, up/down frequency remote control on the canpletely diecast backbone chassis for reliability and ease of use. Up to 32 channels are push button, a headphones lack on the front panel and a socket for 1300 MHz has also been included. held in PROM and frequency changes or additions can be carried but without delay to the rear panel. An additional frequency range from 800 to frequency monitoring/measurement Selective customer. General off air monitoring Spot Detection of unwanted transmis- The transceivers will handle all current frequency allocations including UHF community multi frequency analysis Spectrum surveillance . morel repeater channels and. plug in CTCSS modules allow 5 minute installation time with no sions (Bug hunting and much and from 800 to 1300 MHz, in wiring necessary- Frequency coverage is continuous Pram 25 to 550 MHz of AM. FM (wide'). 5r FM (narrow). CTCâ6 encoder/decoder units are available with 3; lose DIP swdch programming, or selectable increments of 5, 12 5. or 25 KHz, and modes spacing A further facility is the ability PROM programming when you wish to allocate different tones on different channels. Any mode can be used at any frequency or channel limits with to law or low to high searching Ifyou deal in radiotelephones, the TRIO range is designed for you Remove your installa- to search between two user programmed high keyboard entry and recall Each mem- tion and service headaches by contacting the sole distributor right now for further details Twenty memory channels are provided. with easy without any restrictions. The memo- You will not he disappointed ory channel stores frequency and mode information' ries can be recalled manually. or may be automatically scanned in sequence for unat- tended monitoring AR2002. monitor receiver £326.09 plus vat. LOWE ELECTRONICS LIMITED Chesterfield Road. Matlock, Derbyshire DE4 5LE -Ihlephonet 0629 2817, 2430, 4057, 4995 Thlex: 377482 CIRCLE 49 FOR FURTHER DETAILS. 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