Silicon ChipMarket Centre - April 1990 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: Myths and microwave ovens
  4. Feature: Servicing Your Microwave Oven by Leo Simpson
  5. Vintage Radio: Finding receivers from the 1920s by John Hill
  6. Project: Relative Field Strength Meter by Ralph Holland
  7. Project: Build A VOX With Delayed Audio by Darren Yates
  8. Feature: Computer Bits by Jennifer Bonnitcha
  9. Project: Dual Tracking ± 50V Power Supply by John Clarke & Greg Swain
  10. Serviceman's Log: It's an ill wind... as they say by The TV Serviceman
  11. Back Issues
  12. Feature: Taking the BASF CD Challenge by Leo Simpson
  13. Project: 16-Channel Mixing Desk, Pt.3 by John Clarke & Leo Simpson
  14. Feature: Remote Control by Bob Young
  15. Feature: Amateur Radio by Garry Cratt, VK2YBX
  16. Subscriptions
  17. Market Centre
  18. Advertising Index
  19. Outer Back Cover

This is only a preview of the April 1990 issue of Silicon Chip.

You can view 48 of the 104 pages in the full issue, including the advertisments.

For full access, purchase the issue for $10.00 or subscribe for access to the latest issues.

Articles in this series:
  • Computer Bits (July 1989)
  • Computer Bits (August 1989)
  • Computer Bits (September 1989)
  • Computer Bits (October 1989)
  • Computer Bits (November 1989)
  • Computer Bits (January 1990)
  • Computer Bits (April 1990)
  • Computer Bits (October 1990)
  • Computer Bits (November 1990)
  • Computer Bits (December 1990)
  • Computer Bits (January 1991)
  • Computer Bits (February 1991)
  • Computer Bits (March 1991)
  • Computer Bits (April 1991)
  • Computer Bits (May 1991)
  • Computer Bits (June 1991)
  • Computer Bits (July 1991)
  • Computer Bits (August 1991)
  • Computer Bits (September 1991)
  • Computer Bits (October 1991)
  • Computer Bits (November 1991)
  • Computer Bits (December 1991)
  • Computer Bits (January 1992)
  • Computer Bits (February 1992)
  • Computer Bits (March 1992)
  • Computer Bits (May 1992)
  • Computer Bits (June 1992)
  • Computer Bits (July 1992)
  • Computer Bits (September 1992)
  • Computer Bits (October 1992)
  • Computer Bits (November 1992)
  • Computer Bits (December 1992)
  • Computer Bits (February 1993)
  • Computer Bits (April 1993)
  • Computer Bits (May 1993)
  • Computer Bits (June 1993)
  • Computer Bits (October 1993)
  • Computer Bits (March 1994)
  • Computer Bits (May 1994)
  • Computer Bits (June 1994)
  • Computer Bits (July 1994)
  • Computer Bits (October 1994)
  • Computer Bits (November 1994)
  • Computer Bits (December 1994)
  • Computer Bits (January 1995)
  • Computer Bits (February 1995)
  • Computer Bits (March 1995)
  • Computer Bits (April 1995)
  • CMOS Memory Settings - What To Do When The Battery Goes Flat (May 1995)
  • Computer Bits (July 1995)
  • Computer Bits (September 1995)
  • Computer Bits: Connecting To The Internet With WIndows 95 (October 1995)
  • Computer Bits (December 1995)
  • Computer Bits (January 1996)
  • Computer Bits (February 1996)
  • Computer Bits (March 1996)
  • Computer Bits (May 1996)
  • Computer Bits (June 1996)
  • Computer Bits (July 1996)
  • Computer Bits (August 1996)
  • Computer Bits (January 1997)
  • Computer Bits (April 1997)
  • Windows 95: The Hardware That's Required (May 1997)
  • Turning Up Your Hard Disc Drive (June 1997)
  • Computer Bits (July 1997)
  • Computer Bits: The Ins & Outs Of Sound Cards (August 1997)
  • Computer Bits (September 1997)
  • Computer Bits (October 1997)
  • Computer Bits (November 1997)
  • Computer Bits (April 1998)
  • Computer Bits (June 1998)
  • Computer Bits (July 1998)
  • Computer Bits (November 1998)
  • Computer Bits (December 1998)
  • Control Your World Using Linux (July 2011)
Items relevant to "Dual Tracking ± 50V Power Supply":
  • Silicon Chip article scan, April 1990 - Dual Tracking Power Supply (AUD $10.00)
Articles in this series:
  • 16-Channel Mixing Desk (February 1990)
  • 16-Channel Mixing Desk (March 1990)
  • 16-Channel Mixing Desk, Pt.3 (April 1990)
  • 16-Channel Mixing Desk; Pt.4 (May 1990)
  • Modifications To The 16-Channel Mixer (November 1990)
Articles in this series:
  • Remote Control (October 1989)
  • Remote Control (November 1989)
  • Remote Control (December 1989)
  • Remote Control (January 1990)
  • Remote Control (February 1990)
  • Remote Control (March 1990)
  • Remote Control (April 1990)
  • Remote Control (May 1990)
  • Remote Control (June 1990)
  • Remote Control (August 1990)
  • Remote Control (September 1990)
  • Remote Control (October 1990)
  • Remote Control (November 1990)
  • Remote Control (December 1990)
  • Remote Control (April 1991)
  • Remote Control (July 1991)
  • Remote Control (August 1991)
  • Remote Control (October 1991)
  • Remote Control (April 1992)
  • Remote Control (April 1993)
  • Remote Control (November 1993)
  • Remote Control (December 1993)
  • Remote Control (January 1994)
  • Remote Control (June 1994)
  • Remote Control (January 1995)
  • Remote Control (April 1995)
  • Remote Control (May 1995)
  • Remote Control (July 1995)
  • Remote Control (November 1995)
  • Remote Control (December 1995)
Articles in this series:
  • Amateur Radio (November 1987)
  • Amateur Radio (December 1987)
  • Amateur Radio (February 1988)
  • Amateur Radio (March 1988)
  • Amateur Radio (April 1988)
  • Amateur Radio (May 1988)
  • Amateur Radio (June 1988)
  • Amateur Radio (July 1988)
  • Amateur Radio (August 1988)
  • Amateur Radio (September 1988)
  • Amateur Radio (October 1988)
  • Amateur Radio (November 1988)
  • Amateur Radio (December 1988)
  • Amateur Radio (January 1989)
  • Amateur Radio (April 1989)
  • Amateur Radio (May 1989)
  • Amateur Radio (June 1989)
  • Amateur Radio (July 1989)
  • Amateur Radio (August 1989)
  • Amateur Radio (September 1989)
  • Amateur Radio (October 1989)
  • Amateur Radio (November 1989)
  • Amateur Radio (December 1989)
  • Amateur Radio (February 1990)
  • Amateur Radio (March 1990)
  • Amateur Radio (April 1990)
  • Amateur Radio (May 1990)
  • Amateur Radio (June 1990)
  • Amateur Radio (July 1990)
  • The "Tube" vs. The Microchip (August 1990)
  • Amateur Radio (September 1990)
  • Amateur Radio (October 1990)
  • Amateur Radio (November 1990)
  • Amateur Radio (December 1990)
  • Amateur Radio (January 1991)
  • Amateur Radio (February 1991)
  • Amateur Radio (March 1991)
  • Amateur Radio (April 1991)
  • Amateur Radio (May 1991)
  • Amateur Radio (June 1991)
  • Amateur Radio (July 1991)
  • Amateur Radio (August 1991)
  • Amateur Radio (September 1991)
  • Amateur Radio (October 1991)
  • Amateur Radio (November 1991)
  • Amateur Radio (January 1992)
  • Amateur Radio (February 1992)
  • Amateur Radio (March 1992)
  • Amateur Radio (July 1992)
  • Amateur Radio (August 1992)
  • Amateur Radio (September 1992)
  • Amateur Radio (October 1992)
  • Amateur Radio (November 1992)
  • Amateur Radio (January 1993)
  • Amateur Radio (March 1993)
  • Amateur Radio (May 1993)
  • Amateur Radio (June 1993)
  • Amateur Radio (July 1993)
  • Amateur Radio (August 1993)
  • Amateur Radio (September 1993)
  • Amateur Radio (October 1993)
  • Amateur Radio (December 1993)
  • Amateur Radio (February 1994)
  • Amateur Radio (March 1994)
  • Amateur Radio (May 1994)
  • Amateur Radio (June 1994)
  • Amateur Radio (September 1994)
  • Amateur Radio (December 1994)
  • Amateur Radio (January 1995)
  • CB Radio Can Now Transmit Data (March 2001)
  • What's On Offer In "Walkie Talkies" (March 2001)
  • Stressless Wireless (October 2004)
  • “Degen” Synthesised HF Communications Receiver (January 2007)
  • WiNRADiO: Marrying A Radio Receiver To A PC (January 2007)
  • PICAXE-08M 433MHz Data Transceiver (October 2008)
  • Half-Duplex With HopeRF’s HM-TR UHF Transceivers (April 2009)
  • Dorji 433MHz Wireless Data Modules (January 2012)
CEN'l Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING COUPON Advertising rates for this page: Classified ads - $7 .00 for up to 15 words plus 40 cents for each additional word; Display ads (casual rate) - $20 per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. If you use a PO Box number, you must include your permanent address and phone number for our files. We cannot accept ads submitted without this information. To run your own classified ad, put one word on each of the lines below and send this form with your payment to: Silicon Chip Classifieds, PO Box 139 , Collaroy Beach , NSW 2097. MEMORY CHIPS Prices at Februari, 1 st, 1990 Speed 120ns 100ns BOns Chip type Prices (excluding tax) SIMMS (MACS) (IBM) SIPPS DIP PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS ZIP 2 3 5 4 9 9 8 9 x 256 x 1Mb x 1 Mb x 1Mb HP PS2 9 x 256 9 x 1Mb 7 8 9 10 11 12 13 14 15 ($7.00) 40.00 128.00 122.00 165.00 48.00 132.00 130.00 - 44.00 132.00 52.00 136.00 12.70 13.80 4.10 4.25 2.50 13.40 14.60 4.40 4.60 2.70 18.00 5.00 18.00 - 20.00 411000 (1 Mb) 414256 (1Mb) 41256 41464 (256) 4164 3.50 414256 (1Mb) 41256 411000 (1 Mb) 4400 (4Mb) 4.00 16.00 Sales Tax 20% 6 - 2.30 Overnight delivery 150.00 Credtt cards welcome DISCOUNTS FOR DEALERS Phone for pricing on 70ns. 80ns. PS2 , Compaq, and NTX PELHAM Tel (02) 427 0011 - Fax (02) 428 5460 16 ($7.40) 17 ($7.80) 18 ($8.20) 19 ($8.60) 20 ($9 .00) 21 ($9.40) 22 ($980) 23 ($10.20) 24 ($10.60) 25 ($11.00) FIX-A-KIT Name .. .... .. ........ ..... ..... ..... ............... ....... ... ... ......... ... ... ....... ... ...... ........ ... ...... ...... . Street ............. .. .. .... .... .. .. ... . Postcode Suburb/Town Enclosed is my cheque or money order for$ .... Bankcard O Visa Card D MasterCard . .... or please debit my 0 Card No I Signature ........ .. ..... .. I ................ .. ........ .. ........ Card expiry date ....... / ..... .. / ...... .. ANTIQUE RADIO ANTIQUE RADIO RESTORATIONS. Your one-stop electronic repair shop. Specialising in restoring vintage radios including chassis rewiring, quality new parts, valves, valve sockets, speakers, transformers, cabinet restoration. Quality secondhand radio dials & parts for most brands & models. About 400 radios in stock for restoration & parts. Every restored wireless is covered by a 2-year warranty on parts & service. French polishing of timber cabinets available. Vintage car radios in valve & transistor types available for restoration . Repairs done on tape decks, amplifiers, TVs & videos. Open Sat. 10am-5pm; Sun . 12.30-5pm. 109 Cann St, Bass Hill, NSW 2197 . Phone (02) 645 3173 BH or (02) 726 1613 AH. FOR SALE USED EPROMS, 5 MIXED for $6 .00 plus $2.00 p&p. Used 27MHz remote control crystals $1 .00 each plus $1 .50 p&p any quanity. Many other products available. Send SAE for detailed list. Electronic Toy Services, PO Box 491, Noarlunga Centre, SA, 5168. Phone (08) 382 8919 . PROJECT PCBs. Talk to the outside world . ETl-1643 PC 1/ 0 card , PC 1 6ADC 1 6-channel 8-bit. Both $39.95 each. Rear bracket & DB25 cable $16 . 6502, 6809 , Z-80 mini- $15 PER HOUR LABOUR NO CHARGE FOR KITS THAT CAN'T BE REPAIRED 3 MONTHS WARRANTY ON REPAIRS CONSTRUCTION AVAILABLE HYCAL INSTRUMENTS DESIGN, MANUFACTURE, REPAIR OF ELECTRONIC EQUIPMENT (02) 633 5897 processor with 2 x PIA, RAM , ROM, expansion bus $49.95. Intel 8039/48/49 with wire wrap area B&T $199. Digi-125 125W power amplifier PCB $4.95 . P&P $2.00. PC Computers, 36 Regent St, Kensington , SA 5068. NEW SERVICE - PARTS location and supply. Want just that part of a kit or just a hard to find part? We will find and supply them for you . No search fees. Send SSAE with requirements to Part Search, PO Box 491, Noarlunga Centre, SA 5168 . Phone (08) 382 8919 . SATFAX: NOAA, METEOR & GMS weather satellite picture receiving program for IBM XT/AT. Displays in 64 colours. Needs EGA colour monitor & card and "Weather Fax" PC card. $45 plus $3 postage. RADFAX2: HF WEATHER FAX, Morse & RTTY receiving program for IBM XT/AT. Needs CGA, SSB HF, FSK/tone decoder. Also "RF2HERC" & APRIL 1990 103 r~------------·---------, BINDERS & SUBSCRIPTION COUPON To: Freepost 25, Silicon Chip Publications, PO Box 139 Collaroy Beach, NSW 2097, Australia. NO POST AGE STAMP REQUIRED IN AUSTRALIA. □ Startin, _ _ _ _ _ _ __ □ New subscription □ Please send me _ ___ SILICON CHIP binder(s) at $A11.95 plus $A3 p&p each (NZ p&p $A6). Renewal Name _ _ _ __ _ __ _ _ _ __ _ _ _ _ _ __ _ __ (PLEASE PRINT) Street._ _ _ __ __ _ _ _ _ _ __ _ _ _ _ _ _ _ __ Suburb/town, _ _ _ _ _ _ _ _ _ _ __ Postcode _ _ _ _ __ 1 year ( 12 issues) □ $A42 Australia 2 years (24 issues) □ $A84 NZ & PNG (airmail) □ $A65 □ $A130 Overseas surface mail □ $A62 □ $A130 Overseas airmail □ $A 1 20 □ $A240 Enclosed is my cheque/money order for $ _ __ _ or please debit my 1J Bankcard □ Visa Card □ MasterCard Card No. I~ ____L_.____i_.____L_._,I IL_---'--_,.___._I_] I~ ____L_.____L_.____L_._jl IL_ _ J L __JL__JL_...J Signature _ __ __ _ _ _ _ __ _ Card expiry date_~-- L _______________________ J "RF2EGA" , same as RADFAX2 but suitable for Hercules & EGA cards respectively . $35 plus $3 postage. All programs are on 5.25-inch 360K or 3 .5-inch disc & include full documentation. Only from M. Delahunty, 42 Villiers St, New Farm, Old 4005. Phone (07) 358 2785. TOSHIBA T3100 CO-PROCESSOR kit. This piggy-pack board enables the fitting of an 80287-8 to the early T-3100. Two types available, solder in & plug in. Solder version $250.00. Plug-in version $375.00. Import Technologies (07) 372 5138. LOGIC ANALYSER. Gould Instruments K40 stand alone analyser. Eight nonvolatile memories, 7 -inch CRT, 4 x 2K sample memories, 2 x 16-channel, probes up to 100MHz, asynchronous capture. Weighs 7.7kg. $1345.00. Import Technologies (07) 372 5138 . EPSON PS0 PORTABLE battery rechargeable 80-column printer. Serial interface . Very compact & light. 1.1kg . Uses normal or thermal paper. $175. Import Technologies (07) 372 5138 . 104 SILICON CHIP TOSHIBA LCD SCREEN. Originally to suit T1500 desktop. 240 x 180mm, 640 x 200 pixels. Uses 5V supply & TTL drive signals. Suit experimenter. $150. Import Technologies (07) 372 5138 . PUBLIC DOMAIN & shareware software for IBM & compatibles. Catalog disc $4.00 on 5.25-inch 360K or 3.5-inch 720K disc . Also TVREPAIR.TXT which covers faults in most popular brands. It can save hours of work . Just $29 inc. p/post. Martins Television Service, PO Box 1013, Taree , NSW 2430. BELT KITS FOR VCRs. Please supply brand & model number & $12.00 for each kit required. Prompt dispatch assured. James Cotterill, PO Box 44, Farrer, ACT 2607. BUILD A LOW-COST 280 microcontroller development system. Uses any PC/XT/AT/386 or Z80 system as the host computer. Fast PC machine language cross assembler included . Super fast load to target system via parallel printer port; eg, 8K ROM file in Advertising Index Access Communications ..... .... 3 Allied Capacitors .... .. ... ..... .. .. 81 Altronics ....... ........ .... ..... 42-45 Arista ..... ... .. ... ..... ....... .. ... .. . 67 Board Solutions .... ... ....... 58,59 Dauner Electronics ............ .. 96 David Reid Electronics ... ....... 35 Dick Smith Electronics ..... 1 0-1 5 Electronic Solutions ..... ... 76, 77 Elmeasco ...... ..... .......... ..... IFC Energy Control ....... .. ... ..... ... 98 Force Electronics ..... .... .... ... 39 Geoff Wood Electronics ... ..... 65 Harbuch Electronics ... ...... . 9,63 Hycal Instruments ...... ..... ... 1 03 Jaycar Electronics ......... . 24-27 84-87 Jiloa .... .. ...... ............ ... ... ..... 19 J.V. Tuners ... ..... ......... ........ 63 Oatley Electronics ..... .......... 99 PC Marketplace .. ..... ........ ... IBC Philips ......................... .... OBC Pelham ............. ................ 103 RCS Radio ............... ... .. ...... 82 Resurrection Radio ............ .. 1 9 Rod Irving Electronics ... .. 70, 71 Sheridan Electronics ..... ....... 93 Silicon Chip Binders ... .... ... ... 61 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. • Jemal Products, 5 For£, St, Welshpool, WA 6106 . Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. • Electronic Toy Services, 2/111 Glynville Drive, Hackham West, SA 5163. Phone (08) 382 8919. 3 seconds on standard 4 .77MHz PC . Battery back-up on target system. For more info, send a 41 c stamp to Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043 . WANTED CPM PULSAR LITTLE BIG Board in working condition. Phone Peter (02) 449 1558 (A.H). SERVICE MANUAL for Palec Model valve tester . Phone Garry (045) 78 1359.