Silicon ChipMarket Centre - July 1992 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: When will domestic appliances be quiet?
  4. Vintage Radio: Unusual problems lead to interesting repairs by John Hill
  5. Feature: Understanding The World Of CB Radio by Herb Zallner
  6. Project: Build A Nicad Battery Discharger by Marque Crozman
  7. Project: 8-Station Automatic Sprinkler Timer by Graham Blowes
  8. Serviceman's Log: How do you get to blast a ghetto by The TV Serviceman
  9. Order Form
  10. Project: Portable 12V SLA Battery Charger by Darren Yates
  11. Project: An Off-Hook Timer For Telephones by Darren Yates
  12. Feature: Computer Bits by Paul Lynch
  13. Feature: Amateur Radio by Garry Cratt VK2YBX
  14. Project: Multi-Station Headset Intercom; Pt.2 by Marque Crozman
  15. Feature: Electronics Workbench For Home Or Lab by Leo Simpson
  16. Market Centre
  17. Advertising Index
  18. Outer Back Cover

This is only a preview of the July 1992 issue of Silicon Chip.

You can view 48 of the 96 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.

Items relevant to "Build A Nicad Battery Discharger":
  • Silicon Chip article scan, July 1992 - Nicad Battery Discharger (AUD $10.00)
Items relevant to "Portable 12V SLA Battery Charger":
  • Silicon Chip article scan, July 1992 - Portable 12-Volt SLA Battery Charger (AUD $10.00)
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)
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)
Items relevant to "Multi-Station Headset Intercom; Pt.2":
  • Multi-Station Headset Intercom PCB [01302921] (AUD $7.50)
  • Multi-station Headset Intercom PCB pattern (PDF download) [01302921] (Free)
  • Silicon Chip article scan, July 1992 - Multi-Station Headset Intercom Pt2 (AUD $10.00)
Articles in this series:
  • Multi-Station Headset Intercom; Pt.1 (June 1992)
  • Multi-Station Headset Intercom; Pt.2 (July 1992)
........ T CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. r------- ------------------, : CLASSIFIED ADVERTISING RATES Advertising rates for this page : Classified ads: $10.00 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. To run your classified ad, print it clearly on the form below or on a separate sheet of paper & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Or fax the details to (02) 979 6503. : I I I ANTIQUE RADIO ANTIQUE RADIO restorations. Your one-stop radio repair shop. Specialising in restoring vintage radios including chassis rewiring, re-condensing, quality new parts, valves, valve sockets, speakers, power & audio transformers. Secondhand radio dials & parts for most brands & models. About 400 radios in stock for sale, restoration & parts. Every restored wireless is covered by a 2year warranty on parts & labour. We restore damaged woodwork & cabinets & French polish (approx. 40 coats). Vintage car radios available for sale or restoration. Repairs done on tape decks & amplifiers. Open Sat. 10am-5pm ; Sun. 12.30-5pm . 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 7261613AH. FOR SALE MY AUSTRALIAN DESIGNED low cost super fast Z80 micro-controller development system has gained acceptance already with educational institutions. Pop it on the end of any PC MS-DOS or Z80 machine & away you go. Boards, EPROM & 720Kb disc $76 including postage for a short form kit. Gee, I wish I had this when I was a kid. For more information, send a 45c stamp to Don McKenzie, 29 Ellesmere Crescent, Tullamarine, Vic 3043. Phone (03) 338 6286. Enclosed is my cheq ue/money order for $._____ or please debit my o Bankcard Card No. O Visa Card O Master Card '----'------'L__L__I IL__L--.. L. ___~I IL__L__l____JI IL__L__l____J Signature_ _ _ _ _ _ _ _ _ _ _ _ Card expiry date_ __c/_ __ Name _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Street - - -- - - - -- - - - - - ~ - - - - - - - - Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ _ _ __ XI I I I I I I I I I L--------- ----------------~ 94 SILICON CHIP WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" $35 is a high resolution, shortwave weather fax, Morse & RTTY receiving program. Needs CGA, SSB HF radio & Radfax decoder. Also "RF2HERC", "RF2EGA" & "RF2VGA", same . as RADFAX2 but suitable for Hercules, EGA & VGA cards respectively. $35. *** "SATFAX" $45 is a NOAA, Meteor & GMS weather satellite picture receiving program. Uses EGA & VGA modes, needs EGA or VGA colour monitor & card, plus "WEATHER FAX" PC card . $45. *** All programs are on 5.25inch or 3.5-inch discs (state which) & include documentation . Add $3 post- MEMORY EXPANSION PRICES AT MAY 3RD, 1992 SIMM 1Mbx9 BOns 1MbxB 100ns 1Mbx8 80ns 4Mbx9 80ns 4Mbx8 BOns 256x9 sons (FOR SIP ADD $1) TOSHIBA T1 DOOSE 2Mb T2000SX 4Mb T1600 2Mb T31000SX 2Mb T3200SX 2Mb T3200 3Mb T5200 2Mb T2000SX 8Mb $48 $43 $48 $183 $175 $16 $230 $320 $140 $135 $135 $230 $150 $760 DRAM-DIP 41 1000 80 256 X 4 80 41256 80 1Mbx480Z 1Mbx480S $540 $5.60 $2.00 $25.00 $25.00 DRIVES 3½ PANAS 1.44 $80 S'GATE IDE 64/16 $420 S'GATE IDE 42/28 $325 S'GATE IDE 108/16$475 S'GATE IDE 130/16$530 CO-PROCESSORS 387/33/40 $235/$280 387/20125 $210/$215 SX 20/25 $155/$170 287110/20 $100/$125 Sales Tax 20%. Overnight Delivery Credit Cards Welcome. PELHAM Tel (02) 980 6988 Fax (02) 980 699 UNIDEN SCANNERS DON'T PAY MORE! 50XL RRP $299.95. Our price $211 10 memories, Lo-Hi VHF, UHF 100XL,T RRP $449.95. Our price $409 100 memories, Lo-Hi VHF, Air, UHF 200XL T RRP $549.95. Our Price $477 200 memories , Lo-Hi VHF, Air, UHF, 800 MHz CB, SCANNERS MARINE For more information, write to: TopCom Communications, Reply Paid 336 (no stamp) PO Box 336, Greensborough 3088. Phone (03) 883 9535. Fax (03) 432 0716. TRANSFORMER REWINDS ALL TYPES OF TRANSFORMER REWINDS TRANSFORMER REWINDS Reply Paid No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 761291. Fax: (065) 761003. KIT REPAIRS Kits repaired from all magazines. Switchmode power supplies repaired . Design work from start to finish. Computer software consultancy. Ring any time 9am-9pm Mon-Sun EEM ELECTRONICS 10 Bouverie Place, Epping, Vic 3076 Phone(03)4011393 age. Only from M. Delahunty, 42 Villiers St, New Farm, 4004 Old. Phone (07) 358 2785. VARIABLE TUNING CAPACITORS: brand new military quality metal 4-gang tuning capacitors - $10 ea. * SOLID STATE RELAYS: will switch 240V/10~ from 3-32V DC - $15 ea. * SOLAR PANEL: one watt into 6-8V loads, 150 x 150 x 2.5mm - $10 ea or 10 for $85. * MONOCULAR IR NIGHT VIEWER: complete small scope, plus kit power supply - $269. * MAINS OPERATED LASER: new 4mW tube plus a potted power supply - $249. * LCD DISPLAY MODULE: 16 x 2 with provision for backlighting - $22. * FLUORESCENT BACKLIGHT: for Citizen colour TVs, glows brilliant white whilst drawing 50mA from a 6V battery- $12. * LARGE LCD DISPLAY MODULE: Hitachi LM215XB, 480 x 128 dot display, as used in laptop computers, includes 4 pages of data - $39 ea. * LASER DIODE POINTER: pen sized 5mW pointer in presentation case - $199. * LASER FIX-A-KIT KIT REPAIR & CONSTRUCTION Plans Kits & PCBs 100W Valve Amp PCB ............... $30 Valve Amp PSU PCB .... .............. $25 Universal PSU (±5/±12) Dual Supply .................. ........... .. ... $10 Digi125 1OOW amp/pair ...... ....... $10 ETI 1623 PIA for PCs ................. $40 Max 1/0 Board ........................... $40 Max kit.. ..... .............................. $169 LM380 3.5 amp PCB ................... $7 AEM 35W amp kit ...................... $20 ETI Audio Toolkit PCB ..... ... ........ $10 AGC Amp PCB ................. ............ $7 Z-80 Miniprocessor PCB ........... $50 6502 Miniprocessor PCB ...... ..... $50 6809 Miniprocessor PCB ........... $50 8048/8049 Developers board complete B& T .. ....... ...... ...... $199 IBM PC Prototype PCB ...... ........ $50 EPROM Programmer ............... $299 ESL-1 Electrostatic speaker kit/ pair inc manual .......................... $899 ESL-1 Assembly manual ............ $50 P.C. Computers (08) 332 6513 36 Regent St, Kensington SA. 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION TECHNICAL ASSISTANCE HVCAL ELECTRONICS Design. Manufacture & Repair of Electronic Equipment Forty pages of dreams! z ID ::e (02) 633 5477 DIODE GUNSIGHT: small adjustable 5mW unit with one pistol or rifle mount $299. * VISIBLE LASER DIODE HEAD: 3V battery operation, 5mW/ 670nm - $135. * BINOCULAR IR VIEWER: clip over a standard helmet on special at $550. * 12V OPERATED LASER: one used 3mW Siemens laser head plus a 12V inverter kit - $99. * 12V OPERATED LASER: one new 1mW tube plus an inverter kit - $149. * MAINS OPERATED LASER: new 1OmW tube plus a new potted mains power supply $389 . * 12V LASER BARGAIN: 12V laser inverter kit plus one of our "mystery" tubes, you won't be disappointed $89. * 40kHz ULTRASONIC TRANSDUCERS: $4 for a pair, 40kHz Xtal $3.50. * SECOND GENERATION NIGHT VISION TUBES: very small fibre optically coupled tubes that will perform under starlight illumination, rejects with some blemishes - from $500. * STEPPER MOTORS: 5V, 7.5deg, 6.6ohm, 2-phase - $12. * DUAL TV ANTENNA: Panasonic, extends to over 1metre - $9.50. * CRO TUBES: 1-inch electrostatic deflection type CV1522 on special at $35. * VALVES: 866A $5, 6C6 - $5. * IEC EXTENSION LEAD: 2-metres long - $6. * A 10% discount applies on a 10-off purchase of any one of the above items * All of the items JULY 1992 95 r---------------------- --- , SILICON CHIP BINDERS X Advertising Index Active Media Images ........ ..... .. .. 86 These beautifully-made binders will protect your copies of SILICON CHIP. They feature heavy-board covers and are made from a distinctive 2tone gr~en vinyl that will look great on your bookshelf. Adilam Electronics ..... .. .......... IBC * High quality. * Hold up to 14 issues * 80mm internal width . * SILICON CHIP logo printed in gold- A-One Electronics ................ 74,75 Alpine Technologies ..... .......... ... 90 Altronics ................... ...... ... .. . 60-63 Antique Radio Restorations ... ... 94 Av-Comm ..... .. ...... ................ 67,73 Breakthrough Computers ..... .... . 57 David Reid Electronics ..... ..... ..... . 3 Dick Smith Electronics .... ..... 26-29 EEM Electronics .. ..... ................. 95 coloured lettering on spine & cover. Electronic World ....... .... .. ...... ... .. 89 Yes! Please send me _ ___ SILICON CH IP binder(s) at $A11.95 plus Emona Instruments .. ... .. .... ..... ... 87 $A3 p&p each (NZ $A6 p&p). Geoff Wood Electronics ...... ...... 81 Enclosed is my cheque/money order for $_ _ _ _ or please debit my Harbuch Electronics ............ .. .... 43 o Bankcard Hycal Instruments .. ........ .. .... 71,95 O Visa Card O Master Card Jaycar Electronics ... .......... ... 45-52 Card No. L__L__~I ._I~'------'I I._L__L__c____,I ._I~~ J.V. Tuners .. ... .. .................. ...... . 43 Oatley Electronics ................ 21 ,95 Obiat Pty Ltd ............................ IFC Signature_ _ _ _ _ _ _ _ _ __ Card expiry date_ _-'/_ __ Name _ _ _ _ __ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ __ PC Computers ........... .... ...... ..... 95 PC Marketplace ..... .. ..... .. .... . 88,91 Pelham .. .... ... .. ........ .. ...... ...... ..... 95 Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ __ __ Peter C. Lacey Services ........... 40 Preston Electronics ........ ...... ..... 86 RCS Radio ........................... ..... 96 SILICON CHIP PUBLICATIONS PO Box 139, Collaroy Beach, NSW 2097, Australia. Phone (02) 979 5644 Fax: (02) 979 6503. L _________________________ J Resurrection Radio .... .... ..... ........ 9 Rod Irving Electronics .. .. .. .... 10-15 Rolec Pty Ltd .. ..... ................. 68,69 Silicon Chip Binders ... .......... 84,96 Star Micronics .......... ................... 5 listed are new, unless otherwise stated. * You can obtain an illustrated "flyer" that gives more information on these products: send stamped SAE. Major cards accepted with phone and fax orders. Certified p&p Australia $5, NZ (airmail) $10. Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone: (02) 579 4985. Fax: (02) 570 7910. CUSTOM MADE AUDIO accessories. High quality filters , dynamic noise reduction, compressors and other hard to find devices made to your requirements. Call David on (02) 327 6285 after 7pm. EMERGENCY LIGHTING KIT: includes inverter/charger plus nicad battery pack. Connection modes: normal plus emergency lighting or emergency only on 96 SILICON CHIP mains failure. Will operate 13W fluorescent tube. $12 plus p&p. Phone (052) 78 8298. Stewart Electronics ....... .... ..... .. . 95 Tecnico Electronics ......... .. .. ... OBC Transformer Rewinds ..... ........... 95 TopCom Communications .... 91,95 RC§ RADIO lPTY lLTD ::a·~ RCS Radio Pty Ltd is the only company that manufactures and sells every PC board and front panel published in SILICON CHIP, ETI & EA. RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Jemal Products, 5 Forge St , Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491.