Silicon ChipFebruary 1992 - Silicon Chip Online SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: Service with a smile is truly a pleasure
  4. Feature: The Mobile Telephone Revolution by Garry Cratt & Greg Swain
  5. Vintage Radio: Console receivers from the 1930s by John Hill
  6. Project: Compact Digital Voice Recorder by Leo Simpson
  7. Project: Build A Stereo Power Amplifier by Leo Simpson & Bob Flynn
  8. Project: 12VDC/240VAC 40-Watt Inverter by John Clarke
  9. Feature: Computer Bits by Jennifer Bonnitcha
  10. Serviceman's Log: Some sets go on forever by The TV Serviceman
  11. Feature: Designing A Speed Controller For Electric Models by Bob Young
  12. Feature: Amateur Radio by Garry Cratt, VK2YBX
  13. Project: Adjustable 0-45V 8A Power Supply, Pt.2 by John Clarke
  14. Back Issues
  15. Order Form
  16. Market Centre
  17. Advertising Index
  18. Outer Back Cover

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Items relevant to "Build A Stereo Power Amplifier":
  • Silicon Chip article scan, February 1992 - Plastic Power Twin 50W Amplifier (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:
  • Remote Control (December 1991)
  • Remote Control (January 1992)
  • Designing A Speed Controller For Electric Models (February 1992)
  • Remote Control (March 1992)
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)
Articles in this series:
  • Adjustable 0-45V 8A Power Supply, Pt.1 (January 1992)
  • Adjustable 0-45V 8A Power Supply, Pt.2 (February 1992)
BONUS 112-PAGE ALTRONICS CATALOG AUSTRALIA'S DYNAMIC - ELECTRONICS MAGAZINE~ SERVICING -VINTAGE RADIO - COMPUTERS -AMATEUR RADIO - PROJECTS TO BUILD r-- "m 0 [L ~ ci z z 0 e= <! 0 ::::; (D ::, [L MOBILE TELEPHONES Learn about the technology that's changing the way we talk to each other! f- (J) 0 [L <! ::::; <! er: f- (J) ::, <! >(D 0 w w er: t;; Compact Digital Voice Recorder To Build c3 w er: Power Small Appliances From A 12V Car Battery ncert LIMITED EDITION For a product to win the prestigious CESA award and being voted "Loud- speaker of The Year", it must be of outstanding technological and musical standard. ~This is the case with Jamo's flagship: Concert VII. SOUND &l~IAGE Rev1ew · · test1·f·1es to t h e Concert Aw AR O s after review ~ 19 8 9 Series musicality. The UK based "High Fidelity" magazine have in a recent issue voted the 2-way bookshelf model Concert II the 'Test Winner' in a comparison review with nine other leading loudspeakers. Each of the Concert models has recently been upgraded, and these improvements are now found in the latest range called "Limited Edition". This new range is available in a new black woodgrain finish only, and at prices you would never have CONCERT II believed possible. The speakers r ~ J L~ w IT r1 w A RRA N T Y Now $ are fully imported from Denmark, and covered by a comprehensive five year factory warranty. One of the many features that has made these speakers so highly acclaimed is the ir natural sound - right down to the lowest frequencies. As reviewer Louis Challis put it: "Right from 990 CONCERTV Now $1790 CONCERT VII Now $2690 extensive research into natural sound reproduction. For a limited time only you can enjoy genuine savings on Jamo Concert "Limited Edition": CONCERT II CONCERT V CONCERT VI Normally $1190 Save $200 Normally $2290 Normally $3490 Save $500 Save $800 the start, the most outstanding feature of the Con- Don't miss this opportunity to hear the greatest cert VII's was their bass response which rivalled Concerts of The Year. Call Sole Australian Importer any speaker I have ever brought into my home". Scan Audio now for the name of your nearest dealer. The secret is the two internally mounted subwoofers, which operate through a twin-tuned bass reflex port on the front baffle. A result ofJamo's uarno 52 Crown Str, Richmond 3121. Ph (03) 429 2199 February 1992 FEATURES THIS COMPACT digital voice recorder uses a 60-pin LSI chip, four RAM chips & not much else. It can record several minutes of speech in up to four separate messages. Details page 24. 6 The Mobile Telephone Revolution by Garry Cratt & Greg Swain Changing the way we talk to each other 69 Designing A Speed Controller For Electric Models by Bob Young The overriding consideration is milliohms PROJECTS TO BUILD 24 Compact Digital Voice Recorder by Leo Simpson New design stores up to four separate messages SAY GOODBYE TO tin lid transistors. This new stereo power module uses eight big plastic Darlington transistors & can deliver 55W per channel into 8-ohm loads. Construction starts on page 34. 34 Build A Stereo Power Amplifier by Leo Simpson & Bob Flynn Delivers 55W per channel into 8-ohm loads 42 12VDC/240VAC 40-Watt Inverter by John Clarke Lets you power small appliances from a 12V car battery 76 Adjustable 0-45V 8A Power Supply, Pt.2 by John Clarke Construction & adjustment details SPECIAL COLUMNS 18 Vintage Radio by John Hill Console receivers from the 1930s 50 Computer Bits by Jennifer Bonnitcha More things to do when things go wrong YOU CAN USE THIS 40W inverter as part of a small solar power installation or to operate fax machines or nicad battery chargers from a 12V car battery. See page 42. 56 Serviceman's Log by the TV Serviceman Some sets go on for ever 72 Amateur Radio by Garry Cratt A look at trunked radio communications DEPARTMENTS Publisher's Letter Mailbag Circuit Notebook Bookshelf 52 Product Showcase 62 Computer Update 2 4 13 33 90 Ask Silicon Chip 93 Subscription Page 94 Market Centre 96 Advertising Index 92 Notes & Errata WHAT WOKE THE Serviceman in the wee small hours one morning? Find out by turning to page 56. FEBAUARY1992 1 Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) PUBLISHER'S LETTER Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates Reader Services Ann Jenkinson Sales & Marketing Mgr. Angela Clarke, B.A.(Comm.) Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Jennifer Bonnitcha, B.A. Garry Cratt, VK2YBX Marque Crozman John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. A.C.N . 003 205 490. All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Magazine Printers Pty Ltd, Alexandria, NSW; Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, see the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Editorial & advertising offices: Unit 1a/77-79 Bassett Street, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503. ISSN 1030-2662 2 SILICON CHIP Service with a smile is truly a pleasure Do you have trouble with service people? We all have at some time or other but I'm not going to use this space to have a whinge about service people - quite the opposite. I have just had such a pleasant experience with a service organisation that I think it should be recorded. And I'll name names. The way it came about was that we had a problem with our 24-pin dot matrix printer, an Olympia model NP136-24. This is a real workhorse in our office as it used to print out all the correspondence, advertising proposals, invoices, statements and financial records and so on. It gets a lot of use and it has to be switched between menus to enable it do all these tasks. But one day it decided it could not print anything wider than 80 columns. Clearly, it thought it was an 80-column printer instead of a 136-column model. What to do? This machine is a relatively new model - about 2 years old and it does not have any DIP switches to configure it. So it was not a question oflooking for a switch that needed to be reset. Ultimately, I had to phone the service department at Olympia in Sydney to find out whether (a) we could fix it here, or (b) whether it would need to be brought in for service. When I was put though to the service department, all the technicians were busy and so they took my name and number - "someone will ring you back in about five minutes". "Oh yeah," I thought, "We're in a right mess with this thing and they probably won't ring back. We 'll probably have to borrow a printer to get this urgent job done". (All jobs are urgent, of course). Guess what? About 10 minutes later, a very courteous technician phoned me back. I told him the symptoms and he laughed and said that he knew the problem well. The EPROM was becoming faulty and should be replaced. Oh no! How long will this take and how much will it cost. Well, ifwe brought the EPROM in they would charge $20 and about $35 if we brought in the machine so that they did the whole job. Well, that was quite reasonable but then he went on to say that I could reprogram the machine for the time being using the front panel menu buttons. I did it and we were able to get the job done. Naturally, we'll put in a new EPROM in ·the next few days so that it won't happen again. But wasn't that good? A helpful service organisation which is polite, cheerful and prompt. May they prosper. And may all of you prosper and be happy during 1992. See you next month. Leo Simpson DS-9900 Digital SAMPLER Stereo Mixer VSI Easy-Connect The First Truly Intelligent PHONE-FAX LINE SHARI NG DEVICE NO Confusing Voice Messages. NO Periods of Silence. NO Unusual Dial Tones. NO Delays_ NO Frustrated Callers. The EASY-CONNECT is totally transp arent. Your callers will never k now it's o n t he line ! Save lnatalletlon and rental costs tor a aeperate llne. Switches Incom ing Fax calls automatically on re ceipt o f c elling F ax tones. rn~\~~I~ ~~~1~:i:~0:~TJNt:i~8~lysocKET using aupplled connectors. DOES NOT REQUIRE EXPENSIVE ' TELECOM INSTALLATION. A CD quality digital sampling mixer designed for demanding, continuous use, tailored to the creative ne~ds of dance club OJ and persons alike. The music and creativity never stop. Housed in a professional 19• rack package, This mixer has 3 stereo phono. 4 stereo line and 2 microphone inputs. The preamp and EQ circuits use the same low noise electronics found in professional recording studio equipment. All controls are laid out in a familiar and comfortable way. You have the full mixing control over the eight inputs. Experienced users will understand this mixer at a glance, and beginners will quickly learn the feel of the controls. The unit In a black finish is attractive and the white graphics are highly visible In dim light. SPECIFICATIONS Mlc Input .sen. Phono lnpul sen. Uno Input son. 1mV / 800 ohms 3mY/ 4 7K ohms 150mV / 27K ohm System Max. sampling Ram memory Freq. Rn . 20Hz • 20KHz Sampling ra t e Continuou aly Yariabl• less than 0.09'6 Ian than 0.5% last than 1.2mV lass than 1.5mV lass th an 1.5mV Mode lunctlon Writing luncllon Dlmenatons Waight :1~1::;s;:c(:)u~~g1 i) 5Kg Headphone output VU meter o OdB Mlc low cul EQ conltol Freq . les s than 3.SmV -13dB less than 1.amv 400mV o 8 ohm 0.775V -20dB • 20HZ 60Hz . 15GHz, 400Hz, 1KHZ, 2.4KHZ, 6KHZ, 15KHz +/- 12dB Control range Our ··11or·· new produc t tor '92 4 b\t ACPCMSYSTEM 10 second s 1,024 megabits Phone / Lino Olslortlon Mlc di stortion Mlc S/N ratlo Phono S/N ratio Line/CD S/ N ratio Output Hum / Noise Tatkovor Crosstalk Adds HOLD FACILITY to all phones. Puts a call on hold from any phone. Manual Transfer to Fax before. during or after voice conversation. Can tnterupt a voice conversation, to send or re ceive a Fax, then resume. Works with or without an Answering Machine. Pulse/Ton e d lal compatlabl e . WIii operat e with Fa x . Phon e, Modem and Answering Machine on one line. No restriction to the number o f extensions or other devi c es connected to It. Compact Design , being a little larger and heavier than a packet of cigarettes. Proven Rellablllty backed up with a 2 YEAR Exchange Warranty. Also works with Commander, Keyphon e or PABX (techni c al Installation requ'd) The EASY-CONNECT ta compatible with the changing n e eds . Provides Lightning protection for the Fa x and other device s conn ec ted to It. Made In the U .S.A. Telecom Auatralle Permit Number; AS0/14B/0342. Size; 85mm x 90mm x 33mm. Wgt: 225g. Sing le/ Ropoat/ WrUe 1V Only $399.00 my-power 200 inverter What is my-power 7 My-power is a sensational breakthrough that converts 12 volt power from a battery, to 240 volt mains power. By simply plugging my-power into your cigar ette lighter socket. a host of standard electrical appliances can be used where mains power is unavailable. What will my-power run 7 My-power 200 has a continuous rating of 140 watts when connected to a fully charged battery. For intermittent periods 200 watts can be drawn and for starting motor driven appliances, my-power will supply up to a massive 400 watts for short bursts. As a guide. most appliances with a name plate rating of up to 200 watts should be suitable for operation with my-power. Continuous power: 140 watts, 200 watts peak. Protection: Overload, Undervoltage, Overvoltage, Fused Input & Output. Low battery indicator/audio buzzer. LED indicators monitor IN/OUT volts. Size: 50mm x 135mm x 74mm. -~._-..<I> ~~~~ Computer Diskettes 5 .25" D.S.D.D. 360K $4.20/pkt-10 5 .25" D.S.H.D. 1.2M $7.60/pkt-10 3.5" D.S.D.D. 720K $7.80/pkt-10 3.5" D.S.H.D. 1.44M $16.95/pkt-10 only $0.99/each Great for cleaning keyboards, camera lenses, audio equipment. etc. 9 V battery operated. N o w $9.95 LF-8 Squeeky Clean Mains Filter ·: ;. r---•--------7 ·f~~-:~,~ .~; Only $239.00 Only $ 199.00 Battery Holders MINI VAC This NEW mains filter protects your computer, HiFi, office equipment, TV & video. etc. against Surges, Spikes, RF. Transients. Lightning. The LF-8 contains 2 high performance filter networks protecting the 8 outlets. The outlets are arranged in 2 banks of 4, with t he 1st bank in series with the 2nd. This arrangement allows B bank to give DOUBLE filtration for more sensitive equipment. The filter includes a power analyser circuit that continually monitors the incoming power alerting the user to the ACTIVE, NEUTRAL & EARTH connections. .:~,~ * -·---._~::. , Single "AA" battery holder 2 YEAR Exchange Warranty VCR Head Cleaning System The laslest technology featuring a CHAMOIS RIBBON for maximum protection. Micrometer 0-25mm (0.01mm) A handy tool for any handyperson ,,-,- 3 way "AA" battery holder IBM Joystick QuickShot Warrior 5 suit IBM PC XT / AT only $1.00/each Back -up Battery Verla 3 / VB0R 3.BV NICad only $13.95/each 250V Capacitors 100uf 250V DC RB only $2.95/each 10uf 250V DC RB only $1.95/each AS SEEN ON BEYOND 2000 Only $29.95 David Reid Electronics A.C.N. 001-372-372 Only $25.95 127 York St, SYDNEY 2000 Ph: (02) 267 1385 P.O. Box Q103,SYDNEY 2000 Fax: (02) 261 8905 Only $29.95 Postal Charges $5 - $25 ........ . $4.00 $26 - $ 50 ...... $6.00 $51 - $100 ..... $7.00 $101 - $ 499 .. $9.00 $500 • ............ FREEi MAILBAG· Bulletin board wanted for feedback I get the impression from reading SILICON CHIP that the IBM PC (and clones) seems to have wormed its way into many people's lives and that a great percentage of the magazine's readers own a PC. This is further promoted by Jennifer Bonnitcha's column and recent projects like the Voice Recorder and Talking Voltmeter. Why don't you go a step further and introduce a computerised bulletin board for the magazine's readers. Your readers and contributors could directly upload text, leading to a more efficient office. I think that with a BBS on-line, your computer literate readers would be likely to give you more feedback too. Go on, why not give it a go? Greig Sheridan, Ashfield, NSW. Comment: this has some merit. Do other readers support the idea? Time to update drawing standards I am writing this letter as an ad- . mirer of your magazine and its editorial content which I enjoy each month. I am a subscriber and have been since I discovered your magazine. I have even enjoyed some of the digs made at standards which appear less than useful or not easy to understand. Particularly, I used to support your disdain for the use of circuit symbols to Australian or International Standards. Surely a little zig-zag line, sketched by hand (or just as easily by a plotter) was good enough to represent a resistor? It was disappointing that the current standards didn't represent the practice of drawing in Australia as depicted by the electronics press. However, that attitude received a severe setback when, at a recent meeting of a Standards Advisory Committee, it was pointed out that' Australia spends millions of dollars each year in correcting the bad habits learned early, and teaching correct circuit symbols so that technicians, draughtsmen and servicemen can handle the docu4 SILICON CHIP ment'ation that flows in from overseas. These documents comply with international standards. There is also the odd occasion where documentation from Australia goes overseas, and here again, international standards must be followed. With this realisation and recognising the influence that your magazine has on young readers, I am appealing to you to reconsider your policy on drawing symbols. We hope that you will move progressively to the use of symbols which follow Australian and International Standards. I see no need for a total change, as it helps if people are "ambidextrous" and younger readers will need to be able to read earlier Australian documentation. We would like to encourage you by providing some form of Standards Australia endorsement of the use of standard drafting symbols. Such an approach could provide mutually beneficial results. R. Lions, Group Manager, Information & Communications, Standards Australia, North Sydney. Comment: maybe it is time to review our drawing standards although, as we have indicated in the past, we have reservations about international drawing standards. We also note that most English language electronics magazines use drawing symbols ve.zy similar to ours. What do our readers think? Extensions to Lighting Desk not recommended I wish to comment on the letters from D. P., Wagga Wagga, NSW, and D. P., Rochester, Vic in the December 1991 issue on extending the 4-Channel Lighting Desk. Elektor Electronics published a project which would help them. It is "Stage Lighting 1 & 2" in the October and November 1989 issues. I would like to say that it is able to be done but unless you are fully conversant with electronics and 3-phase power wiring you should not even attempt it. Having 12 years experience in the SILICON CHIP, PO Box 139, Collaroy Beach 2097. entertainment lighting field, I have over the years done comparative costs on making one or buying a secondhand unit. I have always come to the conclusion that it would be better to pick a secondhand unit up at a reasonable cost. P. Kay, Abstract Lighting, Deception Bay, Qld. Radio control receiver wanted Thank you for your wonderful magazine. The radio control articles by Bob Young have rekindled an old urge. I am particularly interested in the circuitry of a receiver featured in the December 1990 issue. The shift register seems a good idea (noise permitting). Is it possible to get a more complete description and perhaps PC board layout as the circuit is old and was most likely printed elsewhere? What is the circuitry for pulsing the transmitter? I once thought I could adapt a television remote control but it was beyond me. I. Wyatt, Willunga, SA. Comment: We hope to have radio control projects sometime this year. Using a VCR as a tape back-up unit A great magazine, keep up the good work. I particularly enjoyed the satellite TV series. Some follow up articles on this subject would now be appreciated - eg, receiver design, cable TV transmission and distribution, etc. Now to the nitty gritty. I would imagine . that most people who own computers would also own a VCR. How about a project to marry the two together with regard to backing up hard discs onto . video cassette? Just think of the potential saving in time, floppys and frustration for us poor hackers. Would you also give some thought to a project for a small exchange or PABX unit for home use? Garry Argus Charters Towers, Qld. Hybrid Panel Meters Combine Analog and Digital Functions with Excellent Readability Portable DC Calibrator for Precision Source and Measurement Functions v' Colour liquid crystal displays - green, yellow, blue and red v' Analog bargraph in 90° quadrant format with 31 segments - length of segments emphasises analog change rate. Analog scale indicates % of full scale . v' Digital read-out uses 3 1/2 digit format v' Cold cathode fluorescent back lighting provides clear bright colours with minimal heat output v' Models for AC and DC voltage or current. Scaling option for direct readout of values v' Analog 0-1 mA or 4-20mA output option v' Over-range, decimal point and unit indication v' 92mm square cut out v' Provides Vdc, mAdc and thermocouple emfs (type K, E, J, T and R) v' Compact NiCad powered with EL back lighting and weighs only 1.2kg v' Auto-stepping output function for repeated adjustments and calibration procedures v' Output division function from 1 to 15 for checking linearity v' 20 output-values storage memory v' Direct thermometer calibration v' Outputs from ±1 00mV to ±36V, 0 to +24mA v' Max resolution of 10µV, 10µA v' High accuracy- ±(0.5% of rdg + 0.06% of range) Model 2433 Tong Tester Measures True HMS v' v' v' v' v' v' Measures voltage to 600Vrms, Current to 200Arms, Power to 200kW Suitable for single phase or balanced 3-phase Jaws accept conductors or bars up to 25mm diameter/wide Analog output READER INFO NO. 21 Autoranging Ideal for noisy waveforms Model 2447 Probe Type Multimeter v' Measures ac and de voltage, ohms and continuity v' 3 1/2 digit 5mm high LCD display v' Data hold function v' Measures to 500V, 2Mn max v' Convenient pocket size v' Continuity buzzer . Pocket Sized Digital Thermometers v' Compact and exceptionally reliable v' 150mm chart width v' One or two pens v' Z-fold or roll chart v' Vertical or flat bed v' AC, DC or Internal battery operation v' 12 calibrated ranges from 10mV to 50V full scale v' 60cm/min to 2cm/hr crystal controlled chart speeds v' 300mm/s max response v' Remote control option v' Semiconductor or thermocouple types v' Choice of probes (standard screw terminal connector) v' ±0.5°C accuracy, 0.1 °C resolution v' Ranges from -50 to 99.9°C (semiconductor) or -50 to +600°C (thermocouple) v' Built-in time display .•. v' Analog battery and hand driven, digrtal battery driven v' AC voltage measurement ranges v' Constant voltage types v' Ranges to 5000Mn v' Automatic hold function v' Seven different basic models , - - - - -- - --,,,// ~. /.,. r • ...-~A•~· , • , /4 '• <ra . /4 V YOKOGAWA 411 Yokogawa Australia Pty Ltd Centrecourt D3 , 25-27 Paul Street North ' North Ryde Fax: (02) 8881844 A.C.N. 003 888 364 v th ~~fo~~u Wales Queensland s.W. Australia Australia ~ Tasmania J 1~~~\~i1rie~s Yokogawa 02 805 0699 Yokogawa 03 8191500 LE Boughen 07 369 1277 Trio Electrix 08 212 6235 Leda Electronics 09 361 7821 Meacon Systems 002) 44 7575 N.EJ (AKL) 64 2732 Tech Fast (02) 988 3865 AT.E. (03) 543 8041 telephone The mobile telephone revolution is well under way in Australia. Here's a rundown on the technology that's changing the way we talk to each other. for Telecom's mobile telephone service), it has attracted over 350,000 subscribers and that figure is growing by about 18,000 per month. The basic concept Motorola's "Business Classic" is one of the smallest & lightest mobile phones on the market. NCE considered the exclusive tool of high-powered executives, cellular telephones are now commonplace. Falling costs coupled with the rapid growth of the cellular network has made mobile telephones popular with anyone who needs instant communications. Mobile telephones are no longer the 0 6 SILICON CHIP preserve of the rich, nor are they any longer a status symbol. Indeed, in terms of per capita demand and usage, Australia has outstripped other countries in a boom which started with the introduction of cellular mobile telephone services in Sydney in February, 1987. In the five years since the launch of MobileNet (the name In simple terms , a cellular telephone is basically a low-power, 2-way radio which transmits and receives FM signals in the UHF (ultra-high frequency) band. These FM signals are picked up by (and broadcast by) nearby base stations which are connected to the normal public telephone network via a computer-controlled switching system. This system allows mobile telephone users to call anyone anywhere in Australia or in the world - as long as the user is within range of one of By GARRY CRATT & GREG SWAIN e revo n the MobileNet base stations. The concept behind MobileNet is quite different to earlier mobile radio communications systems. Those systems employed conventional 2-way radios to establish a link to a centrally-located base station running a powerful transmitter. However, these systems had only limited range, even if a relatively powerful transmitter was used in the car. Once you moved beyond the maximum range or into a no-signal area, the call would be terminated. This technique also limited the number of subscribers (due to the restricted number of frequencies available) and was subject to interference from adjacent areas. The cellular concept The cellular concept overcomes this limitation in an ingenious way: instead of using a single high-power transmitter to cover a wide service area, the area is divided into lots of smaller regions called "cells". Fig. l shows the cellular concept. Each cell is equipped with a lowpower transmitter and receiver, while the transmitter in the mobile phone also operates at much lower power (typically 0.6 to 3 watts). This low power operation limits the range of each cell to only a few kilometres (typically 2-16km) but as the car travels from one cell to the next, the computer network automatically switches communications to the new base station. This process happens so quickly that the user is generally unaware that Base stations like this one in bushland at Terry Hills, NSW, are now dotted throughout Australian cities & along many major highways. FEBRUARY1992 7 to provide billing and to switch mobile users from one cell to the next. Performance limitations BASE STATION Fig.I: each base station in the mobile telephone system is at the centre of a cell which defines its area of coverage & together these cells form an interlocking network. As the vehicle travels from one cell to the next, the system automatically switches communications to the new base station. SIGNAL - BASE STATION ' ---0 = 'II I • !H CELLULAR TELEPHONE Cl Fig.2: signal drop-outs can be caused by large buildings in the signal path (ie, between the caller & the base station) or by geographical features such as hills. anything ha~ happened. In fact, using a mobile telephone is no more complicated than picking up and using a conventional "wired" phone. There are many advantages to the cellular approach when compared to the old system. First, because only low power transmitters are used, the mobile phones can be made much smaller and lighter. Low transmitter powers also mean that interference between adjacent areas is virtually eliminated and means that the same frequencies can be used simultaneously in other non-adjacent cells, thus greatly increasing the system's capacity. Another important benefit of the 8 SILICO N CHIP cellular approach is the ability to reduce the radius of each cell to half and establish new cells to increase system capacity as required. Small cell areas also guarantee a good signal at all times, since the conversation can be handed off to an adjacent cell well before any serious signal degradation occurs. So the MobileNet telephone system relies on a number of different technologies. First, it uses FM radio techniques to transfer signals between the base station and the user. Second, it uses on the conventional telephone system to transmit signals back and forth. And finally, it uses computer switching techniques to direct calls, A number of factors affect the performance of cellular mobile telephones. Unlike cable systems, radio communications are imperfect and international design rules set a socalled 90/90 standard. This means that the signals should achieve 90% coverage of an area for 90% of the time. Because radio signals can be affected in various ways, complete coverage cannot be guaranteed in all areas within the cellular network. That's because UHF signals are easily obstructed or scattered by objects in the signal path. In particular, tall buildings, tunnels , underground carparks and even the terrain can contribute to momentary loss ofreception or signal "drop-outs". Naturally, signal drop-outs are more likely to occur on the edges of the coverage area, although the system is designed to tolerate short drop-outs without disconnecting the call. If prolonged dropouts occur, however, the system may interpret the signal loss to mean that one party has hung up and disconnect the call. Fig.2 shows a typical situation w.p.ere communications can be lost. These sorts of problems are disappearing as cell areas are progressively made smaller, however. MobileNet is now available in all Australian capital cities and over 40 large regional centres, covering around 80% of the population. Thus far, Telecom has invested over $600 million in MobileNet and continues to invest about $50 million annually to upgrade the network. MobileNet features As well as providing reliable mobile telephone communications over a large are, MobileNet also boasts a number of other important features. These are as follows: • Roaming: with the MobileNet system, you're not confined to just using your phone in a particular area. The automatic "roaming" facility allows you to travel to any part of the service area (eg, from Sydney to Melbourne) and still make or receive calls on the same number. • Call Diversion: you can divert calls from your mobile phone to your office, home, pager or any other phone you choose. In addition, you can di- Designed for use in the car, this Audiovox cellular telephone features a large LCD screen, 96 telephone number memories, hands-free operation, an automatic answering facility, a last number re-dial memory & an auxiliary port for fax machines or modems (via an optional interface). It also has comprehensive call restriction & security capabilities, a microphone mute control & numerous other features. vert incoming calls if you are already engaged on a call, or if the phone goes unanswered when it rings. • 2-Way Communication: unlike a 2way radio system, MobileNet allows 2-way conversations in the same manner as a normal telephone (ie, both parties can speak simultaneously). This is made possible by the use of separate transmit and receive frequencies. No special radio procedure is required to use the system. The remaining features are those that you would expect to find on any modern office phone (and on some home telephones as well). These features include: volume control, last number re-dial, on-hook dialling, hands-free operation, memory dialling, and facilities to prevent access to STD and/or ISD services. Some mobile telephones even have a theft alert function. Types of mobile phones Although Telecom is the sole pro- vider of the MobileNet system, there are many different brands of mobile phones to choose from. That said, there are three basic types: car phones, transportable phones and handheld phones. Car phones have a 3-watt power rating and are probably the best choice if more than 50% of the average working day is spent on the road. They take their power directly from the car's electrical system and, because they have the highest power rating, their performance will generally be better than other types, especially when conditions are marginal. Transportable phones are generally rated from 1.6 to 3 watts but lack the convenience of the much more compact handheld phones that are now available. On the other hand, handheld phones are only rated at 0.6 watts and have a more limited "talk-time" between battery charges (typically 80120 minutes vs about 200 minutes for transportables). Their standby time is also more limited (typically 12-18 hours). But whatever the type, all mobile telephones contain a transmitter, a receiver and a control module. The MARK ONE COMMUNICATIONS Specialising in: Mitsubishi , Motorola & NEC mobile phones INSTALLATION & SERVICE 7DAYS Cellular telephones from Motorola Also available from Motorola are the 8800 Ultra Classic portable phone (right) & the Mobile KS2000 car phone (far right). Among other things, the 8800 Ultra Classic features 2.2 hours of talk time, five call timers, six levels of call restrictions & 101 memories. The KS2000 is a fully-featured car phone with an LCD screen & faci lities for hands-free operation, on-hook dialling, electronic locking & microphone muting. Mobile Phone (018) 29 5888 (018) 21 4555 ,-c - - -· • _, 275 Ryedale Rd, Eastwood, NSW 2122. Motorola Micro- T•A•C Cellular Telephone Phone (02) 489 777 Fax (02) 489 7774 FEBRUARY1992 9 Mobile telephones from Telecom Australia Telecom Australia sells a wide range of mobile telephones, including the Walkabout 50 transportable phone pictured at right and the Traveller K car phone at far right. The Walkabout 50 is both a small handheld phone and an "answering machine". In "absence mode", it can actually record the phone numbers of people trying to contact you when you are away from the phone or simply don't wish to be disturbed. Other features include an automatic re-dial facility, call diversion, a call timer & several locking facilities. The unit can store up to 200 phone numbers & has an alphabetic memory that lets you store & view 8-letter names or other information with every phone number. It also has an automatic memory storage feature & lets you scroll through memories in either alphabetical order or according to location number. An optional in-vehicle kit provides hands-free operation, auto-answering & a boost in output power from 0.6W to 3W. The Traveller K car phone has all the features that one would expect in a mobile telephone, including call diversion, hands-free operation, automatic answering & a comprehensive array of memory & security features. A number of optional extras are also available, including a fax/computer interface, a horn alert/music mute relay (beeps the horn if a call comes in while you are away from the vehicle or, alternatively, mutes the car stereo during a phone call), and a facility that stores up to 9 telephone numbers from calling parties for later recall or diversion to a pager. control module is really the brains behind a mobile telephone and includes a microprocessor which oversees all operations. Among other things, it encodes signals from the dialling keypad before they are sent to the transmitter, and decodes any command or status signals received from the base station. These signals are then shown on the alphanumeric display if appropriate. The microprocessor also adjusts the output power of the mobile telephone to optimise the signal that reaches the base station. This does not apply to handheld phones, however, since their output power is fixed at 0.6W. pled to and from the receiver via a coupling box on the other side of the glass. Transportable telephones, on the other hand, are usually equipped with flexible "rubber duck" antennas, although some feature a telescopic whip which is extended while the phone is in use. Because the system operates at UHF (825-890MHz), the antennas are typically only about 10cm in length. Security Antenna requirements A correctly installed antenna is a vital component of a mobile telephone system, especially for fixed in-car models. An antenna mounted in the middle of the roof will provide the best performance. Alternatively, a glass-mounted antenna can be used if you don't fancy drilling a hole in your car's roof, but this will come at the cost of slightly reduced performance. A glass mounted antenna is attached .by adhesive to the rear window and signals are capacitively cou10 SILICON CI-IIP The Delegate 2000 from Mitsubishi Electric can be used in the car or quickly converted for transportable use. It features selectable transmit power, hands-free operation, 99 memories & a host of other facilities. One aspect of obvious concern to mobile phone users is security, particularly when it comes to charging. After all, you don't want to be paying for someone else's call! This problem has been overcome by programming a unique identification number into each mobile phone (usually at the time of purchase) and this ID number is transmitted each time the phone is used. This "initialisation" data is also used by the system to determine whether the mobile is in its home service area or has roamed to a new service area. In addition, you can program a unique PIN number into your phone to prevent unauthorised use. Call privacy, however, cannot be Cellular Phone Batteries Phone Model NOVATEL PTR 800 Premier Code PB 800 Description 7.2V lOO0mAh VOXON 2002 PB 800 7.2V lOO0mAh NEC P-3 PBP3 · 700mAh NEC P -9100 PB9B 6.0V 7.2V Mitsubishi 900 series PB 07S 7.2V 700mAh Telecom Walkabout Mk II PB 07S 7.2V 700mAh Telecom Walkabout Mill PB 110053S 9.6V 1800mAh Dlamondtel 99X PB 99X 6.0V 800mAh Technophone 105 PB 105 7.2V 700mAh Technophone 905 Motorola 6000. 8000. 9000 Motorola Flip (Micro Tac) PB 905 12.0V PB M2 7.2V 1800mAh 1700mAh PB M7FB 6.0V 1200mAh Oki 700/750 PB 750 6.0V 1200mAh Shimatsu PB 842 7.2V 1200mAh Panasonlc/Unlden/ Okl Phillps Fm 9030 PB 1223 12.0V 2300mAh PB 124 12.0V 4500mAh Telecom Traveller PB 124 12.0V 4500mAh ECONOMIC ELECTRONICS, 24 Campbell Street, Bowen Hills, Old 4006. PO Box 481, Fortitude Valley, 4006 Telephone (07) 252 3762. lOO0mAh These Cellular Mobile Phone batteries are direct replacements for original manufacturers products. The batteries are manufactured using high performance cells to provide maximum life and reliability. SOUTHPORT ELECTRONIC SHOP, Shop 1/10 Welch St, Southport, Old 4215. Telephone (075) 32 3632 Fax (075) 51 0543 guaranteed, due in part to the ready availability of low-cost scanning receivers. On the plus side, the restricted range of mobile telephone signals should limit the number of potential eavesdroppers on any call to a relatively small area. In addition, the signal frequency will change if a mobile user moves from one cell to next, thus further frustrating attempts at eavesdropping. What does it cost? The prices for mobile telephones vary considerably but expect to pay $750 to $1500 for an in-car phone and $1200 to $2500 dollars for a portable phone. These are "ballpark" figures only - the price you pay will depend very much on the model and the facilities offered. Once you've purchased the phone, there is a once-only "commissioning fee" of $45 plus a monthly access rental fee of $40. After that, you're charged for calls on a toll basis. For distances up to 745km, the peak daytime rate is 39 cents per minute, reducing to 26 cents per minute for the off peak night-time rate (6-1 0pm MonFri) and 15 cents per minute for the off peak economy rate. According to Telecom Australia, the average monthly bill in Australia is around $136 and charges are generally comparable to or cheaper than in other countries. And unlike some countries, it is the originator of the call who pays the charge. So if someone calls you on your mobile telephone, they pay the toll. The future As the cellular network expands and improves, the demand for mobile telephones will grow tremendously during the next 10 years. This demand will also be fuelled by falling prices and by smaller and more reliable phones. Indeed, Telecom Australia predicts that by the year 2000, 60% of all calls will have a mobile component - that is, either one or both of the calling parties will be using a mobile phone. But for many people, the benefits of a mobile telephone already far outweigh its higher costs when compared to a standard telephone. The mobile telephone has now become an indispensable tool in business, particularly for trades people and sales executives. In the future, prices may fall to the 12 SILI CON CHIP Versatile handheld telephone from Uniden Continuing its successful line of cellular phones, Uniden Australia is about to enter the "micro" handheld market with a unit that's claimed to be the smallest cellular phone in the world; the Uniden CP5500. Due for release in mid-February 1992, this phone weighs only 300 grams (including the battery) and measures just 156 x 52 x 31 mm, making it small enough to fit into your pocket, briefcase or purse. The phone has many features which make calling quick and easy. For starters, you can store your most often used numbers in up to 30 memories for quick recall. You can also store call diversion codes in memory so that you don't have to remember what they are. In addition, there are various timers which record how long the last call took, call progress time, and the total on-air time. Separate volume controls let you adjust the ringing volume, the earpiece volume and the dialling volume, while a missed call indicator lets you know that a call has been diverted to a pager or to your office. Unlike many mobile phones, you don't have to press a specific key to answer a call. Instead, any numeric or function key can be pressed. Last number re-dial is easy-you just press the SEND button again. The CP5500 comes with three locking features. For example, you can lock the phone so that it will only dial numbers stored in the memory or so that it is only able to receive calls. Alternatively, you can disable the phone completely. A battery charge indicator is included so that you can monitor battery condition. Built into the CP5500 is a telescopic antenna which is extended only when placing or receiving a call. In standby mode, the antenna can be left retracted to eliminate the possibility of damage. The CP5500 is supplied with a slide on/off battery, which gives up to 11 hours on standby and 75 minutes of transmit time. Optional accessories include a leather case and a fast extent where just about anyone can afford to own a mobile telephone. They may even become a standard fitting in new cars, in much the same charger that will charge the battery in just one hour. Another option is the "In-Car Kit". This allows the unit to be mounted inside a car as a fully-functional hands-free unit. During in-car operation, you can recharge the internal battery while using the car's own battery to power the phone. In addition to this portable unit, Uniden also has a wide range of other telephones including the fully-featured CP 1500 car phone. For further information on this unit & other Uniden products: contact your local dealer or ring the Uniden office in your state. way as the now mandatory AM/FM radio-cassette player. The future for mobile communications is indeed an exciting one. SC CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. C1 C2 CJ +5V ROW1 10k ROW2 IC1a 4093 ROWJ 14 02 11 1 CLK ROW4 # 21 0112 + 10! IC2 4024 +5V 03 g 6 04 5 05 4 06 +5V 1k 3 s1 l 1 2 CLR .,. .,. .,. 24 17 11 R4 D6 16 12 R3 05 15 13 R2 04 14 14 R1 03 13 5 C3 BAO 7 A1 6 A2 07 5 AJ 4 A4 3 AS 2 A6 1 A7 23 AB D1-D7 7x1N914 ICJ 2716 11 4 22 A9 0110 3 19 A10 DO g 02 IC4 TCM5089 16 C2 DTMF OUTPUT TO AMPLIFIER/LINE C1 18 12 20 -:- -:- 11 Alarm dialler uses an EPROM This circuit dials a stored DTMF tone sequence from EPROM when a control line is taken to OV. IC1a is a Schmitt trigger oscillator, running at around 2Hz. It clocks a 4024 binary counter. The counter's outputs connect to the address leads of the EPROM. A 2716 was used here but the choice of EPROM is by no means critical. Normally the counter is held reset by a logic 1 on its reset pin (pin 2). When the trigger input is sent low, pin 10 of IC1 goes low, pin 3 goes high, and the reset is removed from the counter. It then begins to clock, incrementing the EPROM. When moved from address 000000, the data on bit DO of the EPROM changes to a logic 1 and holds the circuit running. The trigger pulse should be longer than one clock pulse, to ensure that the EPROM has incremented from 000000 and will hold up when the trigger signal is removed. The EPROM is programmed such that to generate a tone, it takes a corresponding row and column lead low. The appropriate 1N914 diodes will conduct and the 5089 will generate the required tone. This is a low level output and will need to be amplified EPROM DATA TO DIAL SILICON CHIP (02 979 5644) 0000000000 11111110 park 11111111 notone 00001 II II II 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 10010 10011 01111011 11111111 11101011 11111111 10110111 11111111 10111101 11111111 10110111 11111111 11011011 11111111 11010111 11111111 11011101 11111111 11011101 11111110 0 notone 2 notone 9 notone 7 notone 9 notone 5 notone 6 notone 4 notone 4 park before it can be used. With pins 2 and 15 of the 5089 left open circuit, it will remain silent if an incorrect number of columns/rows go low (the result of an error when the EPROM was programmed). To increase the number of sequences that can be dialled, simply switch some of the unused address lines of the EPROM from OV to +5V. Further encoding could enable the pre-selecting and triggering to be done simultaneously. Ensure that the tones are separated by a pause (all outputs 1). The speed is by no means critical but excessive speed could cause problems with your decoder/exchange not detecting the pause between repeated digits. The last address should have data 1111111 O to reset the circuit to standby. Greig Sheridan, Ashfield, NSW. ($30) 8-channel ADC for PCs This is a simple 8-bit, 8-channel analog-to-digital converter for PC type computers. It consists of just one 20pin IC (a National Semiconductor ADC0838) and one resistor, and it interfaces to the PC via the printer port. Because the printer port is not equipped with any power pins, +5V will need to be supplied either by a battery or regulated power supply. Data is exchanged serially using the National Semiconductor Microwire serial data standard. Microwire provides synchronous (ie, clocked) serial data transfer over either the data in or data out line and in this case is impleFEBRUARY 1992 13 CIRCUIT NOTEBOOK - CTD mented entirely in software. A terminate and stay resident (TSR) driver is available to allow high level languages to "talk" to the converter. The trigger line is included to allow external triggering of data capture or, with some additional hardware, pacing of the converter. Since most of the work is done in software, this converter is not fast - maximum data acquisition rate on a 386-16SX is approximately 2.5kHz. As well a providing eight singleended analog input channels , the ADC0838's analog input multiplexers may be software configured to provide four fully differential analog input channels or a mix of single-ended and differential inputs. The TSR driver recognises channels 0-7 as singleended and channels 8-15 as differential (8-11 are+/- and 12-15 are-/+; it depends on how you connect them. Refer to schematic for options). After building the hardware, connecting it to the PC and loading the driver, the converter can be tested by connecting a pot (lO0kQ or so) to analog input channel 0 and running one of the example programs. By "twiddling" the pot, you should see the numbers on the screen changing. The trigger input can be tested by connecting a normally open switch between trigger and ground and observing the trigger status as reported by the example program. +SV OUT 4.7k TRIGGER 13 12 20 VREF VCC SE CHO CS CH1 01 3 CH2 CLK 4 CH 3 AofJa38 5 DO CH4 ANALOG IN 18 1 0 1 2 6 5 7 17 6 14 CHS CH6 8 CH7 GND A 11 PRINTER PORT D COM 10 9 GND GND SINGLE ENDED +5V CHO 1+ CH1 2. CH2 3+ DIFFERENTIAL PLUS 1+ DIFFERENTIAL MINUS CHS CH12 4+ CH4 5 GND CHS 6+ TEST CIRCUIT CH6 7+ CH7 8+ 100k "~ CHO CH13 s. CH10 2+ 3 3+ CHS CH3 4+ CHS CH2 3+ CH3 4+ 5 CH14 6 6+ 7+ CH14 CH6 CH11 CH15 8+ CH7 • A software package, on one 360Kb IBM PC format disc, is available from Lamgda Systems, 29 Ashley Ave , Farmborough Heights 2526, for $25.00 including post and packing. This package includes the TSR driver, a SHARP Panasonic AKAi e cARSTEREO e VCRs e STEREO e BUSINESS EQUIPMENT • WHITEGOODS - e PHONES e VIDEO CAMERAS e MICROWAVE OVENS EDSON FIELD PTY LTD (A.C.N. 010 378 588). Trading as: ECONOMIC ELECTRONICS, 24 Campbell Street, Bowen Hills, Old 4006. PO Box 481, Fortitude Valley, 4006 Telephone (07) 252 3762. SOUTHPORT ELECTRONIC SHOP, Shop 1/ 10 Welch St, Southport, Old 4215. Telephone (075) 32 3632 Fax (075) 51 0543 e VAST RANGE OF COMPONENTS e TEST EQUIPMENT e TOOLS e SOLDERING EQUIPMENT • DATA BOOKS e AUDIO/VIDEO ACCESSORIES e CABLE & CONNECTORS SILICO N CHIP 1. 8 + simple data logger (user selectable logging times and a variety of triggers), a timing program and other relevant software. P. 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For this month only Yaesu's top of the line communications receiver comes with a bonus VHF converter. • Modes: AM, LSB, USB, CW, FM • Covers 150 kHz to 30MHz, with selectable tuning rates ~ • Large backlit LCD screen with S/SINPO indicator • Dual 24-hour clocks, inbuilt AC power supply • CAT computer control option • VHF convertor covers 118-174MHz Cat D-2820 SAVE $169 $1295 10 BAND PORTABLE SHORTWAVE RECEIVER The Sangean SG-789 is a neat and compact receiver with the power to pull in radio broadcasts from around the world! • Local AM/FM bands • Receives the 8 most popular international shortwave bands • Bandspread tuning and LED tuning indicator • Superb sound reproduction • Sockets tor headphones and AC adaptor Cat D-2834 16 BAND SHORTWAVE RECEIVER c:::c3 c:::c3 i". "£,;;, ;~1~~~!!=1i:~:l=m~!ll~i!~iy $169 -,~ lr······~J r=om ·.· . · · -= : ODO OD □ DOD c:::'.J= ooocro Pop out stand for desk use □= c:::::::Jc:::::::::> == a::aztlll $269 Listen to the world direct. Covers local AM/FM stations, longwave and 13 international Shortwave bands. • Incredibly compact and portable. • Large LCD screen showing major city times. • With dual alarms, sleep timer and tuning indicator. • Electronic band selection and volume controls. Cat D-2839 MULTIBAND SHORTWAVE RECEIVER Listen in on world news as it happens or your local AM/FM stations. Hear Shortwave, Marine, Amateur and Commercial signals. • Covers 150kHz-30MHz, 87.5-10MHZ • 9 pre-set station memories • 5 tuning functions including direct keypad entry • Backlit LCD frequency screen and 24-hour clock • RF gain control, plus B.F.O. for S.S.B. reception • Battery powered or optional AC adaptor Cat D-2831 An incredibly easy to use 10 BAND hand-held scanner. • With 200 memory channels and memory scan • Manual keypad entry and track tuning • Covers 66-88, 118-174, 406-512, 806-956MHz • Complete with a 600mA/H NiCad battery pack and AC charger • Uniden 2 year warranty. CatD-2810 $469 uniden. Wide Frequency Range! AR1000 HAND-HELD SCANNER An outstanding hand-held scanner with an incredibly wide frequency range (8-600, 805-1300MHz) • Super fast search speed and massive 1000 memories • Easy memory scan arrangement (10 banks of 100) • Manual or auto scan/search • Lock out and selectable channel priority • Includes AC charger, antenna, earplug, car power adaptor and soft case. Cat D-2780 s599 B1277/BL •1 IVIADE IT IVIVSELF!• Exciting new kits that are both practical & easy to build. QQQ INFRA-RED LIGHT BEAM RELAY '.•"::, ' ,$-..•.- ~~~~ -- QQ -~ (Cl' ~~.:•¥ !IS ~~~':,/ ' ' $119 1V COLOUR PATTERN GENERATOR Tune your TV to perform like new again! Generates seven separate patterns for adjusting your picture and tracking down faulty circuitry. It's easy to build and only requires a small amount of wiring . Ideal for video enthusiasts, TV servicemen, hobbyist etc. Comes with all components, hardware, case and pre-punched silk screen front panel. Includes plug-pack. $4995 It's easy to build and great tor monitoring doorways when you're not around. When someone walks through the beam a 1 second alarm is triggered. Ideal as a door bell for shops, etc, or as a warning system around 'off-limit' areas. Connects either to a buzzer or a triggered relay. Comes with all components, hardware, case, front panel label, plug pack and option relay. Cat K-3120 Cat K-7355 NOV/DEC '91 K-J 124 LOW VOLTAGE CUT-OUT :g) 4-CHANNEL GUITAR MIXER MANUAL •12'11Nl 1--- ~IC RESET •12V 00T G °" Q A .high quality audio mixer that's ideal for using with guitars, microphones, keyboards and tape decks, etc. Unlike other mixer kits it has dual low noise op amp ICs for minimising noise and sound distortion . This means you get exceptionally high performance at a low cost With separate input level controls, output control and more. Comes as a short form kit (PCB & components only) so that you can build into an existing unit or designing your own case. $ 3995 Cat K-5400 LOW VOLTAGE CUT-OUT Flat batteries are history with this easy to build kit It monitors your power supply, cutting the power off when it gets low, thus leaving you enough power to re-start the engine. Ideal for boats, campervans or for when you've accidently left the car lights on. With automatic or manual override, and 'OK' LED indicator. Comes with all components, hardware bits, case & front panel label. Cat K-3124 00E~::~~s ~jJ~l~B~L~~~:8=;iteff~~!?6;1~~~i~:~~~~sl~~~~C:~:t~~~ ::li~:}~~~~fF~bt Electronics 684098 COOTAMUNDRA: Cootamundra Music & Ute 42256 1 COFFS HARBOUR: Coffs Harbour Electronics 525684 MAJO R OICK SMITH ELECTRONICS AUTHORISED STOCKISTS: DENILIOUIN : Deni Electronics 813672 DUBBO: Chris·s Hi Fi 828711 F9RSTER: Forster Village Electronics GIJ:ULBOURN: Tunlive 22 1 5 2 tift~~~ ~~r1~~~~~~\~~~A~f~;~i~~~~:L~G~i~t'~~ ~6if ~i~~~T;~:~~v9e;e~T!~~: J ~gfj ~~~~~; 1 1 0 ~~~:rRWiftu~\~W: t:i~~~t f~~~H3~i!~~Bi:~~s~loi ~~~:;~rc~9~~~.rn ~C~2W~y~~!Ba~E~~ •lolloies 813685 NOWRA: Nowra ElectronK:s 210722 PARKES: Slrad Music C1T 623366 PORT MAaJUARIE: Hastings C-OmiXJrer 6 A Sensational Saving! WELLER WTCPS SOLDER STATION A super low price to commemorate our partnership wit h Cooper Tools as a Key Distributor of Weller products. 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Cat T-3000 Service 834574 RlCllMOND: Silicon Crafts 784101 ULLADULLA: Coastal Electronics 553989 WAGGA WAGGA: Phillips Electronics ~::~~~~~~~~i~\~1V~~}~~f~~~lXJ1~~~ ~2i~i:~i~~~~H~i~c,;:z~c~1~i 1i~~~: ~rth East Electrooics 622710 COLAC: Colac Electron,cs 312847 MILDURA: Pullman Auto Pro 232682 SHEPPAATON: Andrew ~~o~rs!1g~~~e~df! i3l9 1 lri~ectrs3~ivt~:o~~:s~~ 1 G!JYfai~~~~~l~~i~L~ ~ :T::A~=~l~~~ BUNOABEAG: ~b Elk,n ~lectronics 52 1785 CALOUNDRA : tle~trmart 918533 DYSART: Dysart Videotrornxs 582107 GLADSTONE : Electromc Enterpnses 726660 INGHAM: Masons Electromcs·763188 lNNISFAll: lnoisfail Hi•R 612014 KINGAOOY: ~ ~:::a~ ~:~IiJ~~~~~::r:Jr~~n~~ ~ff~~~X~f?~~~~ 6 1 \e:tr~~~7:JW1J~~~~~~a:~ Communications 813333 TAS: BURNIE: Electronic City 314760 OEVONPOAT: Al Electronics 248322 LAUNCESTON : Kitrooics 344555 SA: MT GAMBIER: Hutchessorl's Communicatton Ctr 250400 PORT LINCOLN : Basshams 1V & Comp World 822788 WHYALLA: Eyre Electronics 454764 WA: ALBANY : Micro Electronics 41'i!SJTT BUNBURY: Micro Electronics 216222 GERALDTON : !latavia L~h1ill') & Electri.cal 211 218 KALGOORLIE : Today's Electronics 215212 KARRATHA: ~!twa Office Su~ies 854836 ~ANDRAH : Micro Electron,cs 5812206 PORT HEDLAND: Ivan Tomek the Elect 732531 81277/MS AFFORDABLE EXCELLENCE Fluke Series 10 Multimeters Feel the difference with a Fluke. In terms of engineering, reliability and flexibility the FluI~e range of multimeters is without doubt the best around. And right now, a Fluke is more affordable than ever. Cl1eck out the sensational Series 10 multimeters today at Dick Smith Electronics. FLUKE 10 MULTIMETER FLUKE 12 MULTIMETER It's tough, dependable and designed for true one-hand operation. With AC/DC voltage measurements (to 600 volts), continuity beeper, Ohms & diode tester, digital display, auto & manual ranging and overload protection. The Fluke 10, the new generation in speed, versatility and When the going gets tough, you can count on the Fluke 12 for fast answers in complex electronic environments. With it's Min Max record and time stamp you can capture what occurred and when. You can hook it up, walk away and still know what happened . With all the features of the Fluke 10 and more, the Fluke 12 is truly affordable excellence! $ Cat Q-1612 $109 ~:~~~1611 15 FLUKE SERIES 10 HOLSTER Get added protection and convenience with this inexpensive holster and tiltstand. Cat 0-1614 SPECIFICATIONS GENERAL 3 3/4-digits, 4000 counts, updates 4/sec Designed to Protection Class II requirement of UL 1244, ANSI/ISA-S82, CSA C22.2 No 231, and VDE 0411 and IEC 1010 overvoltage category Ill. 2 Years Display: Safety: Warranty: FLUKE SERIES 10 CARRY CASE $2495 FLUKE 9 $2495 Ideal for keeping your multimeter and cables stored away neatly. CatO-1616 FLUKE OHMS & DIODE TEST Ohms-range 400.0ohm 4.000kohm , 40.00kohm 400.0kohm ,4.000Mohm 40.00Mohm Accuracy Fluke 1O Accuracy Fluke 12 1.5% + 2 0.9% + 2 1.5% + 1 0.9% + 1 1.9% + 3 1.5% + 3 DIODE TEST: Displays voltage drops to 2.4V CONTINUITY: Beeper comes on at <25ohms and turns off at >250ohms. The meter detects opens or shorts of 250us or longer. CAPACITANCE (Model 12) VOLTAGE dcV-Range 4000mV, 4.000V 40.00V, 400.0V, 600V acV-Range 4000mV, 4.000V, 40.000\i 400.0V, 600V Accuracy Fluke 10 1.5% + 2 1.5% + 1 Accuracy Fluke 10 2.9% + 3 Accuracy Fluke 12 0.9% + 2 0.9% + 1 Accuracy Fluke 12 1.9% + 3 Accuracy Capacitance - Range 1.9% + 2 10% + 90 typical 1.000uF, 10.00uF, 100.0uF 1000uF, 10,000uF RECORDING (Model 12) MIN MAX Recording with Relative Time Stamp: Elapsed time from Oto 100 hours (99:59). Resolution to 1 minute. DS XPRESS PHONE & MAILORDER SERVICE Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries - 888 2105 FAX: (02) 805 1986 or write to DS XPRESS, PO BOX 321 N/RYDE NSW 2113 A ll Major Credit Cards Accepted. O/Nite Courier Available. 24 HOUR DESPATCH OF ALL ORDERS · PHONES ECURITY AUDIO COMPUTERS STORE LOCATIONS : NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 671 7722 • Brookvale 905 0441 • Bondi 387 1444 • Campbelltown 27 2199 • Chatswood Chase 4111955 • Chullora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 6633 • Hurstville 580 8622 • Kotara 56 2092 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 61 1896 • North Ryde 878 3855 • Orange 618 4P0 • Parramatta 689 2188 • Penrith 32 3400 • Railway Square211 3777 • Sydney City 267 9111 • Tamworth 661711 • Wollongong 28 3800ACT• Belconnen (06) 253 1785 • Fyshwick 80 4944 VIC • Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St 326 6088 & 246 Bourke St 639 0396 • Richmond 4281614 • Ringwood 879 5338 • Springvale 547 0522 QLD • Brisbane City 229 9377 •Buranda 391 6233 • Cairns 311 515 • Chermside 359 6255 • Redbank 288 5599 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 •SA• Adelaide City 223 4122 • Beverley 347 1900 • Elizabeth 255 6099 • Enfield 260 6088 • St. Marys 277 8977 WA • Cannington 451 8666 • Fremantle 335 9733 • Perth City 481 3261 • Midland 250 1460 • Northbridge 328 6944 TAS • Hobart 31 0800 NT• Stuart Park 811977 STORE ACROSS AUSTRALIA AND NEW ZEALAND 11•1•i ,I ri til iIi AX3 1i! 5i li ,., ,! :fJ •~C•Hi :t 1 = DICK SM ITH (WHO LESA L E) PTY LTD A.C.N. 000 908 716 B1277/M3 VINTAGE RADIO By JOHN HILL Console receivers from the 1930s Console receivers from the 1930s have a particular charm of their own and many are excellent performers. This month, we take a look at some of those old-timers. Many months ago, I wrote a story about radio receivers from the 1920s era. It was mainly about the difficulties of locating early receivers and spare parts. Although 1920s receivers and their accompanying loudspeakers are much sought after items, these particular radios do not give me a great deal of satisfaction for a number of reasons. First and foremost is their cost. These truly antique radio receivers carry ridiculous prices considering how little one gets for the money. This 1936 AWA Radiola is a 5-valve, dual-wave receiver. It is a good performer for its age and still retains its original loudspeaker. 18 SILICON CHIP Second is the almost non-availability of spare parts, either new or used. And finally, wh0n they are made operative, their sound reproduction and general performance is poor to say the least. However, I must admit that a few early radios with their odd looking loudspeakers give a good balance to any vintage radio collection. But I don't get wildly enthusiastic about them! Console receivers My personal preference leans more to the console style receivers of the 1930s era. This particular decade encompassed all manner of radios, including regenerative detectors, TRFs, and superhets. Receivers from the 1930s range from simple 3-valve and 4-valve types to highly complex affairs boasting a dozen or more valves. Virtually all manner of radios were available in the 1930s - from the most humble to some of the grandest ever made. The 1930s dawned in the midst of a world-wide economic recession. Yet despite this, many radio manufacturers remained in business and radio development accelerated at a quickening pace. Due to the depressed economic situation, there were a wide number of options available to buyers. Although the superhet was well established at the time, TRF and simple regenerative receivers were also made in considerable numbers for these sets were The chassis in this 1939 AWA Radiola is interchangeable with those used in some mantle sets. It is the first receiver that the author restored. the "el cheapo" receivers of the depression years. They were often made to look pretty good but a quick peep in the back soon indicated which section of the market they were intended for. No-frills receivers Many austere, no-frills console radios, including superhets, were also built in the early 1930s. These can be readily identified by their minimal valve .complement and light weight due to the thinness of the plywood used in the cabinets. Other cost cutting measures included no lids on IF cans and no tone control or automatic gain control. These sets were so impoverished that some carried a special notice explaining that the receiver was a cheap, budget-priced model that should not A typical dial escutcheon with a blank name space. Many "no name" sets were produced in the 1930s and some retailers even had their own names engraved into the blank space. be confused with more up-market models (see photo). Despite their initial cheapness, many of these low-priced consoles are still around today and can bring a surprisingly good price at auction. These simple receivers are usually easy to restore and they work reasonably well considering the circumstances in which they were produced. The console radio was indeed the most desirable form of receiver in the 1930s. Radio historian, John Stokes, claims that during the 1930s 60% of radios produced in Australia were consoles and that some manufacturers made only console models. There were many large houses at the time with enormous lounge and dining rooms and a console radio looked very elegant in such a setting. Although very desirable, the console style radio was also considerably more expensive than its mantle model counterpart but there were ways of reducing this price difference. The kit console In keeping with the low-cost models mentioned earlier, the "kit console" was another alternative. The word "kit" is not used in its true context for these kits were bought in only three pieces: a factory built chassis, a loudspeaker and a fully finished timber cabinet. Assembly of the kit involved little more than mounting the chassis and loudspeaker in the cabinet. Drilling the holes ih the front panel for the control shafts and cutting an opening for the dial escutcheon were the most difficult parts of the whole operation. If you look closely at some of these "do it yourself" radios, you will find that the control knobs are sometimes positioned off-centre and that the escutcheon is often poorly aligned with the dial that fits behind it. Most of these kit consoles are unbranded and usually have a blank space on the metal dial escutcheon where a name could be engraved if so desired. Smaller retailers who frequently assembled these sets often had their own trade names engraved in this space, so as to make the receiver appear to be of their own manufacture. Actually, every unbranded console that I have seen has had an ''Eclipse Radio" chassis in it. I have been told by a couple of old guys who were around at the time that anything that came out of the Eclipse factory was likely to be a bit cheap and nasty. Yet many of these old receivers are still working today - approximately 60 years after they were made - so they couldn't have been all that bad! The better known brand names were also available as console models and names such as Stromberg Carlson, AWA Radiola, Airzone, His Master's Voice and many others were there for the buying. Perhaps these more upmarket receivers came into their own towards the latter part of the 1930s Some very elegant console models appeared towards the end of the 1930s as typified by this 1937 5-valve Airzone. Timber cabinets require a lot of restoration work but the end result is very pleasing. A 4-valve Howard receiver from 1932. This particular receiver is of tpe regenerative detector type and has an 8-inch electrodynamic speaker. when the hard times of the early depression years had mostly passed. Console advantages I like console style receivers for two reasons: they look good and they sound good. The large timber cabinet F EBR UA RY1992 19 This handsome set is a dual-wave Radiola from 1937. The cabinet restoration was difficult because someone had . previously "restored" the cabinet by applying many coats of thick lumpy lacquer. is not only attractive but gives excellent baffling for the speaker. A well restored console radio has a very distinctive sound indeed. Push-pull outputs Old consoles offer other advantages as well. Some have push-pull output stages, whereby the loudspeaker is driven by two valves instead of the usual one. Such receivers are capable of high power outputs that are remarkably free of distortion. I recently acquired a 1937-model 8valve Stromberg-Carlson that has a lot to offer. It has several shortwave bands, magic eye tuning, a stage of radio frequency (RF) amplification, a push-pull output stage and a 10-inch loudspeaker built into a vented enclosure. The set has always been kept ·indoors and the cabinet is in very good condition. Hopefully, the receiver will restore OK but at this stage I have done nothing with it. Receivers like this StrombergCarlson are well worth the effort of restoring because they work so well when the job is finished . Although a 20 SILICON CHIP Affectionately known as "Old Henry", this monster was made in the early 1930s. It is typical of many unbranded receivers of that era and carries an Eclipse Radio chassis, a 7-valve superhet unit with two 59s in the output stage. 5-valve set may perform quite adequately, an 8-valver free-wheels, so to speak, with plenty in reserve. Some time ago, this column carried a photograph of an old Precedent console cabinet with turned legs. Unfortunately, that's all it was - an empty cabinet. Well, a suitable chassis and speaker have since been found and, eventually, a fairly early 1930s superhet will emerge from what could well be described as an uninteresting assortment of junk. It should end up as a very attractive old console radio. Incidentally, the metal escutcheon on the Precedent bears the motto "Realism Realized". It doesn't sound very convincing today does it? Originality Although the· missing parts problem has been solved with the Precedent, a similar situation has arisen with another console cabinet; in this instance, a Univox. Once again, the empty cabinet is a stately affair on turned legs so the search is on again for suitable innards. It will matter little whether they be original or bits and pieces that can be adapted to suit. That last statement may,upset a few readers because there is a difference of opinion among vintage radio restorers regarding the subject of originality. Naturally, I have my own views. I believe that, generally speaking, originality is not very important, especially with a set that is to be used as distinct from one that is for display. If the overall effect looks OK, well and good - what goes out of sight under the chassis doesn't really matter. If an old valve radio is to be installed in the lounge room and is intended for regular use, then an alloriginal set may not be the best way to go. I have a mid-1930s console in my lounge room (a no-brand model) and if I had retained the original loudspeaker, I would not bother to listen to it. The old 12-inch Eclipse electrodynamic loudspeaker not only had a warped cone but had also developed a loose or misaligned voice coil, resulting in a buzz somewhere in the normal speech range. Some voices RESURRECTION RADIO .Receiver is . . .• , . .,., • ''>· . . .• .. .. . . ·.·" uteu-1 by Radto . . . ra;q.o t1·~ty. J:,td: .to meet . p opular demand . a . fo¾'.~pri<:ed qonsoJe Superhet. · · '. ,•:i}irJti~'c~ye~eq by ·!~Y. a ..fa~ory guarantee, and ~09~ • :tp<:1~er1als a11d , workmanship have been , U §~a . 1P .1ff/ CQ.tisttu,i:tion. It .should be dearly C,u ndtrstood, ,.·. however; that it.: is not possible to ·embody in . a Receiver seiling at this price tl1e refoiements of design, materials · ·and workma11sl1ip are incorporated in tbe ·well known range of Receivers manufactured ~J,'~e same ComprmL 0 ··, ,,.,;-4 -"t~- } This notice is typical of those attached to many mid-1930s "el cheapo" models. It left no doubt as to what the buyer was purchasing. came through perfectly, while others buzzed and rattled on every second or third word. It depended on the pitch of the voice. Buzzes and rattles are very common with old electrodynamic loudspeakers and are quite irritating if you want to listen to that particular radio on a regular basis. jt is for this very reason that my lounge room console has a permanent magnet speaker in it of about 1950 vintage. It may not be original but it is far more listenable than the old Eclipse speaker. The 2.5kQ field coil of the original speaker was replaced by two 20 watt resistors in series. These resistors have been installed in a corner underneath the chassis where their dissipated heat will not affect other components. alter the set's originality. Som e of the receivers in my collection are very original, others are not. In conclusion, console receivers from the 1930s are very collectable and are worthwhile items to restore. They range from budget-priced m odels to the ultimate in domestic valve radio receiver design and can be a pleasure to own an d use. SC Vintage Wireless Specialists Repairs - Restoration - Sales Our skilled technicians offer QUALITY repairs and restoration . We also have a large stock of bakelite and timber radios fu lly restored and for SALE. Parts are available fo r the enthusiast, including over 900 valve types, high voltage capacitors, transformers, dial glasses, knobs, grille cloth etc. Circuit diagrams for most Australian makes and models. Send SAE for ou r catalog. WANTED : Valves, Radios, etc. Purchased for CASH Call in to our showroom at: 51 Chapel Street (PO Box 1116), Windsor, Vic 3181. Telephone: (03) 529 5639 Silicon Chip Binders Valve transplant This particular receiver had also undergone other modifications long before I became the proud owner. At some time in the past, it had be given a power transformer transplant and I suspect that, at the same time, it had been converted from 2.5V valves to 6.3V valves. Now I'm not that concerned about originality that I feel compelled to convert the set back to 2.5V operation. That, I believe, would be taking this originality aspect of restoration to extremes. However, if I was restoring something that was rare and valuable, then I would not be so hasty to These beautifully-made binders will protect your copies of SILICON CHIP. They are made from a distinctive 2-tone green vinyl & will look great on your bookshelf. Price :-$A11 .95 plus $3 p&p each (NZ $6 p&p) . Send your order to : Silicon Chip Publications PO Box 139 Collaroy Beach 2097 The author's mid-1930s lounge room console is a 6-valve receiver with a non-original 12-inch permag speaker. It gives a very good performance. Or fax (02) 979 6503; or ring (02) 979 5644 & quote your credit card number. FEB RUA RY1992 21 RITRON POWER RITRON QUALITY ( 286 .. 1§ <?> ( 286-21 80286·12 CPU ' - - - - - - " " 1 MEG RAM EXPANDABLE TO 4 MEG 16Mhz LANDMARK SPEED TEST 1.2M JAPANESE BRAND F.D.O 42M HARO DISK DRIVE 28ms ACCESS 101 EXTENDED "CLICK" KEYBOARD JAPANESE KEYBOARD SWITCHES MINI CASE & 200W POWER SUPPLY SUPA VGA COLOUR MONITOR (1024 x 768 res) SERIAL, PARALLEL., GAME PORT 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY 256K VGA CARD. IBM• COMPATIBLE SPREADSHEET, WOROPROCESSOR & DATABASE SOFTWARE INCLUDED. $ ASSEMBLED & TAX INC. 1 , 19 9 TESTED IN AUSTRALIA $1,050 TAX EX 80386SX·20 CPU 1 MEG RAM EXP TO 4 MEG 27Mhz LANDMARK SPEED TEST 1.2M JAPANESE F.F.O. 512K VGA CARD 43M HARD DISK DRIVE, 101 EXTENDED "CLICK" KEYBOARD MINI CASE & 200W POWER SUPPLY SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) SERIAL PARALLEL GAMES PORTS 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY IBM• COMPATIBLESPREAOSHEET, WORDPROCESSOR & DATABASESOFTWARE INCLUDED. $1 49 5 ' $1,290 TAX INC. ~86-75 80286· 16 CPU 1 MEG RAM EXPANDABLE TO 4 MEG 21Mhz LANDMARK SPEED TEST 1.2M JAPANESE BRAND F.D.D 42M HARD DISK DRIVE 28ms ACCESS 101 EXTENDED "CLICK" KEYBOARD JAPANESE KEYBOARD SWITCHES MINI CASE & 200W POWER SUPPLY SUPA VGA COLOUR MONITOR (1024 x 768 Rea) 2 SERIAL, PARALLEL., GAME PORTS 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY 256K VGA CARD. IBM• COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. ASSEMBLED & TESTED INAUSTRAUA $1 ' 249 $1,090 •SHAREWARESOFTWARE TAX EX. c 386 .. $1 ' 795 TAX INC. $1745 D 80386-40 CPU 64K CACHE ON BOARD MEMORY 1 MEG RAM EXP TO 16 MEG 65 Mhz LANDMARK SPEED TEST 126 MEG HARD DISK 12ms ACCESS TIME 1.2M JAPANESE BRAND F.O.D 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL., GAMES PORTS 512K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) MINI CASE & 200W POWER SUPPLY 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED, •SHAREWARE SOFTWARE ASSEMBLED & TESTED {N AUSTRALIA. WITH 200 MEG DRIVE $2,195 ~tt $2,595 TAX INC. $2,295 TAX EX. c486-1s1) TAX WITH 200 MEG DRIVE INC. $2,995 TAXINC. $2,495 $2,450TAXEX. $2,095 TAXEX. ss. ) RITRON EXECUTIVE ASSEMBLED & TESTED IN AUSTRALIA. ' PLEASE NOTE SYSTEMS DO NOT COME WITH DOS. RITRONEXECUTIVE 80486SX·20 CPU 64K CACHE ON BOARD MEMORY 80486·33 CPU 1 MEG RAM EXP TO 32 MEG 128K ON BOARD CACHE. 1 MEG OF RAM 75Mhz LANDMARK SPEED TEST 157Mhz LANDMARK SPEED TEST 43 MEG HARD DISK 43 MEG HARD DISK 1.2M JAPANESE BRANO F.0.0 1.2M JAPANESE BRANO F.0.0 101 EXTENDED "CLICK" KEYBOARD 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL, GAMES PORTS, 512K ; VGA CARD , SERIAL, PARALLEL, GAMES PORTS SUPA VGA COLOUR MONITOR (1024 x 768 Resolu1ion) . 512K VGA CARD. IBM• COMPATIBLE MINI CASE & 200W POWER SUPPLY VGA COLOUR MONITOR (1024 x 768 Resolution) 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY MINI CASE & 200W POWER SUPPLY SPEADSHEET, WORDPROCESSOR & DATABASE 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY SOFTWARE INCLUDED. •SHAREWARE SOFTWARE SPREADSHEET, WORDPROCESSOR & OATABASE SOFlWARE. $ 2 095 ff / . OS 4.01 AN EXTRA•••• ••••••••. >DOS 5.01 AN EXTRA••• ••• ••••••• \ DR DOS 6 . TAX INC. 80386·33 CPU 64K CACHE ON BOARD MEMORY 1 MEG RAM EXP TO 16 MEG 57Mhz LANDMARK SPEED TEST 43 MEG HARD DISK 1.2M JAPANESE BRAND F.0.0 101 EXTENDED "CLICK" KEYBOARD SERIAL PARALLEL GAMES PORTS SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) MINI CASE & 200W POWER SUPPLY 512K VGA CARD (256 COLOURS) IBM• COMPATIBLE 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. ASSEMBLED & TESTED IN AUSTRALIA. / 512K VGA CARD .... ....... •.......••• $50 / lM VGA CARD ......................... $150 { TO CHANGE A \ 40M HARD DRIVE TO A fr 85M HD add ...................... $195 > 126M HD add ......................... $395 200m HD add ......................... $750 \ EXTRA RAM / 1 MEG add ........................... $75 >::: 2 MEG add •••••••• ••••• •••••••••••••• $150 TAXEX RITRON EXECUTIVE c ) c·3ss-s1 ) (386SX-27) 3865X-21 .... $1,395 C ADD PRICE TO BASE SYSTEM COST. RITRON EXECUTIVE RITRON • SHAREWARE SOFTWARE ASSEMBLED & TESTED /N·AUSTRALJA. OPTIONAL EXTRAS RITRON RITRON WITH 200 MEG DRIVE TAXINC. TAXEX. ROD IRVING ELECTRONICS Est. 1977. MAIL ORDER HOTLINE: 008 33 57 57. (ORDERS ONLY) ENQUIRES: (03) 543 7877 HEAD OFFICE: 56 RENVER RD, CLAYTON. PH: (03) 543 2166. FAX (03) 543 2648 CITY 48 A'BECKETT ST. MELBOURNE. PH. 663 6351 / 6391640. FAX: 6391641. OAKLEIGH: 240C HUNTINGDALE RO, OAKLEIGH. PH: (03) 562 8939 NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX: 489 8131. SYONEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX: (02) 519 3868 MELBOURNE DEALER: BLUESTAR COMPUTERS: 271 MAROONOAH HWY, RINGWOOD, 3134. PHONE: (03) 870 1800 FAX: (03) 879 3n7 $3,095 $2,595 TAXINC TAX EX 80486-33 CPU 128K ON BOARD CACHE. 4 MEG OF RAM 157Mhz LANDMARK SPEED TEST 200 MEG HARD DISK 12ms ACCESS TIME 1.2M JAPANESE BRAND F.D.D 3.5" 1.44M JAPANESE BRAND F.D.O 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL., GAMES PORTS 1 MEG VGA CARO. IBM• COMPATIBLE VGA COLOUR MONITOR (1024 x 768 Resolution) TOWER CASE & 220W POWER SUPPLY 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY SPEADSHEET, WORDPRCESSOR & DATABASE SOFTWARE. ASSEMBLED & TESTED IN AUSTRALIA. IDEAL CAD MACHINE! TAX INC. $ ·■ -=-CT.)I ~ •i> ■ $3 295 - FRBGHTCHARGEBASEDON 35KG COMPUTER SYSTEM Melb-Metro.$12.00 Adelaide ..... $17.00 Bribane ...... $17.00 Canberra .... $18.00 Darwin ........ $40.00 Perth. .......... $31.00 Tasmania .... $53.00 9 3 '7 5 Vic country.... $19.00 NSW country.$39.00 S.A country... $39.00 OLD country.$55.00 W.A country.. $74.00 lnsursnce:$1 / $100 Value. ~ · .,1 , TAX EX. All sales tax exempt orders to : RITRONICS WHOLESALE 56 Ronvtr Rd, Clayton, Victoria. Ph: {03) 543 2166 Fax: {03) 543 2648 MAIL ORDER & CORRESPONDENCE P.O BOX 620, CLAYTON, VICTORIA. 3168. Error• & omml ■ aon ■ excepted. Prien & ■peclftcaUon ■ eubject lo change. 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PH: 562 8939 NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX: 489 8131. SYDNEY:74 PARRAMATTA RD, STAN MORE. PH: (02) 519 3134. FAX: (02) 519 3868 Postage rates $1 • $9.99-.... $3.00 ThHo pootago $10. $24.99 .. $3.50 rote• o.-. bulc $25. $49.99.. $4.50 pootago only up to 0 $50 • $99.99.. $6.00 $100 -$199 ... $7.00 lton-. wiN o. $200. $500... FREE cho,god ot dlfloront :~it, : ;:a:.ia•~ TO LL FREE MAIL ORDER HOTLINE: 008 33 5757 - - -J.!:::=~===:::::;:;:;;;;;;;;;::;;;;:;;;J_J BLUESTAR COMPUTERS: 271 MAROONDAH HWY. RINGWOOD. PH: (0:_: 3)_:8.:,: 70:_;1:: 8:: 00:...__J,:$::500::...:.P_:LU::5:_:·::_ ·F:,::RE::E: _ '"_'",,, • -.r . ., ~ . : ~ :..:: r.;", . ' . .., Build this compact VOICE DIGI This compact digital voice recorder board uses a new 60-pin surface mount LSI chip, a bank of four RAM chips and not much else. It can record up to 512 seconds of speech ir,. up to four separate messages. By LEO SIMPSON We last featured a digital voice recorder board in the December 1989 issue of SILICON CHIP and it proved to be very popular (and still is). The basic circuit of that design was a little more complex than the present design because the main voice chip did not have op amps on board. That design also featured trigger inputs and logic so that it could be part of a security system or car monitoring system. This new design reduces the circuit to its basics and provides just the recording and playback controls. Apart from the 60-pin LSI chip which is the heart of the unit, there is an LM386 audio power amplifier, four RAM chips, a 3-terminal 5V regulator, some diodes and a handful of passive components. All the circuit, including the battery and function selector switch, can be fitted onto a PC board measuring just 120 x 80mm. That is about one quarter the size of our previous design. And since there is a lot less on it, the new board will be even easier to assemble. Let's make one point clear right at the outset. This device is a not a voice synthesizer which is normally controlled by a computer or EPROM. Synthesizers are often corny or virtually unrecognisable. By contrast , the project to be described here is a complete digital audio storage system based on a new LSI (large scale integration) chip made by Samsung Electronics, of Korea. It can be used to record and play back any audio signal but it is mainly intended for voice messages. You can record voice messages in exactly the same way as you would with a telephone answering machine. When played back, the recording will not sound like a synthesizer; it will sound like you. We won't attempt to list all the uses to which this project might be put. In December 1989 when we published the previous voice recorder board, the ultimate number of applications was far beyond our range of suggestions. We expect that this project will be even more popular, because it's a lot smaller. Method of recording The Samsung voice recording chip used here, the KS5915, uses an Adaptive Delta Modulation (ADM) method (or algorithm). This is similar to the Delta Sigma Modulation method used PARTS LIST 1 PC board, 120 x 80mm, complete with surface mount KS5915 voice recorder IC 4 MCM511000 1-megabit dynamic RAM ICs (U2,U3,U4,U5) 1 LM386 power amplifier IC (U6) 1 7805 5V 3-terminal regulator (REG1) 5 1N4001 power diodes (D1-D5) 1 red light emitting diode (LED1) 1 electret microphone 24 STLTCON CHIP 1 640kHz ceramic resonator 1 8-way DIP switch (SW1) 1 4-way DIP switch (SW2) 1 pushbutton on/off switch (RECPL) 3 momentary contact pushbutton switches 1 2.1 mm DC input socket (SK1) 1 3.5mm socket (SK2) 1 2.5mm socket (SK3) 1 9V battery 1 9V battery snap connector 1 57mm loudspeaker an Capacitors 2 100µF 16VW electrolytic 2 1OµF 16VW electrolytic 4 1µF 16VW electrolytic 10 0.:1 µF monolithic 1 .01 µF monolithic 2 27pF ceram ic Resistors (0.25W, 5%) 1 5.6kQ 1 1kO 2 1.2kO 1 3300 2 4. ?kn 8-way resistor networks RECORDER in the PC Voice Recorder article described in the August 1991 issue of SILICON CHIP. Briefly, the method of recording is as follows: a sound signal from the on-board electret microphone is amplified by the on-chip op amp and then processed by the ADM block which is essentially a comparator turned on and off by the sampling rate oscillator. The output of the ADM is a 1-bit data stream. This stream is stored in a block of RAM (random access memory). When the signal is played back, it is clocked out of the RAM and fed to a 10-bit digital to analog converter (DAC). This DAC output is then fed to a low pass filter to remove hash and then fed to an amplifier and loudspeaker. The RAM used for this project is in four 1-megabit (1,048,576) chips, the maximum possible for the KS5915 voice recorder chip. Sound quality vs duration In any digital audio. storage system there is a trade-off between recording quality and recording length. If you FEBRUARY1992 25 t,,:I 'O ~ n :z: n 0 r::: Cl) c:, .,. ..... I j1 ":" ii .,. 1+ C4.,j,j R1 5.6k " Vee 1 C3 7 .,. 0.1t Cl C21 1 +■.- C7 100 '-' C6 27pf:r SC2 R 13 14 15s 11 la jg 11 Q,.c:,-c:,..-t/)NC") a:cciio.>a..a.. BUSY CASE CASE CASE CASE RA W DOU Mm OM1 ACO 1 0 CREF VREF A MP21 A A A A ~O =i= A U1 KSS91S => ~1 1 . I/ SK2 rSPEAKER CS 27pf:r 'AO IAl IA2 IA3 39 138 (37 136 (35 (34 (33 (32 131 rr rI t;~ei§!~~~~~~C~c .,...,_v.i~:e PAUSE ~ Vee ) RECPL Vee j2 j3 J41 -------------------t-----------t-----le-- DIGITAL VOICE RECORDER TBl RPANEL RESET SWITCH (OPTIONAL) FP~~u ELECTRET MIC TB2 VENTS ":" 8~~1t F 0 Vee 17 C:,: -1 I .,. RN1 8-PIN DIN a 1.,. c11• 0.1 l Vee DIN 1 2 3 ":" GN D C161 01! I 01! c11l ":' ... RAS w 01-04 4x1N4001 YM ~ 05 1N4001 01+ cm! 7 3 iDI~ a A3 I .,. 8 BATT TB2W Vee 1r-l - •• ho •• 113 =al16 A4 A7 CAS2 - V I SK1 216 BATTERY ~ I SNAP 01! c20l us 1M Vee j Vee .,. U2 1M I ~r.-x' c1a! 0.1J A3 A1 AO WE RAS DIN A9 a CAS1 C13 + C12 100 0.1 ! 16VWI IN '"~- .,. I GN!.,_J 18 U4 1M Vee Vee ":" GNO 18 U3 1M Vee • C15 0.1! RAS DIN w C18 + 101 +5V A1 AO RAS WE ◄ Fig.1 (left): a Samsung KS5915 voice recorder IC & four 1-megabit RAM chips form the basis of the circuit. DIP switches SWl/7 & SWl/8 set the sampling rate & thus determine the recording time & the speech quality. want longer recording times, you have to sacrifice sound quality. If you want better sound quality, you have to accept shorter recording times. In a typical digital recording system, the sound quality is primarily determined by the sampling rate and, as a consequence, by the anti-aliasing input filter. The normal practice is to set the anti-aliasing filter so that its cut-off frequency is half the sampling rate. For example, if the sampling rate is 10k/s, the input filter should roll off frequencies above 5kHz. In this circuit though, the input filter is fixed while the sampling rate can be one of four values ranging from 8k/s to 32k/s. Therefore, the built-in bandpass input and output filters are set to roll off frequencies above 2.5kHz. (By contrast, our previous digital voice board had external input and output filters and it was possible to select the filter components to increase or reduce the ban<;l.width). Table 1 shows the various combinations of sampling rate and recording time available when the circuit is fitted with 1-megabit RAMs. The sampling rate is selected by setting switches 1 and 2 of the 8-way DIP switch (SWl) on the PC board. For the maximum recording time, both switches would be set to OFF. For the minimum recording time, both switches would be set to ON. Board features As already noted, this voice board is quite compact. This is partly because the circuit has been kept to the bare essentials but also because it uses a 60-pin surface mount LSI chip. This is a great deal smaller than a conventional dual in-line chip with the same number of pins could be, if in fact there was such a thing (which there isn't). In fact, this project is a first for SILICON CHIP in that the PC board will be supplied with the surface mount chip already soldered to the copper Fig.2: here's how to install the parts on the PC board. The board comes with the surface-mount chip already soldered in. Note that the 640kHz ceramic resonator is mounted on the copper pattern side of the board. pattern. All you have to do is to mount the conventional components. So if you were a little concerned about having to solder a large surface mount chip, do not worry. It will already be done for you. The chip is mounted on the copper pattern side of the board. All the rest of the components are mounted on the topside of the board. Other features to note are the small sockets for connection of an external power supply, loudspeaker and external microphone. There is a 4-way bank of pushbuttons, one a push-on/pushoff type which is the recording on/off switch. The other three are momentary contact types for Start, Stop and Pause. Circuit details Now let's have a look at the circuit of Fig. l. On the lefthand side of the circuit is an electret microphone which is fed with DC via the 5.6k0 resistor Rl. The electret signal passes via the socket (SK3) for the external microphone. In practice, you would Table 1: Bit Rate Selection SW1/7 SW1/8 Bit Rate Time Off Off 8K bps 512 sec. Off On 22K bps 186 sec. On Off 16K bps 256 sec. Off On 32K bps 128 sec elect to build the circuit for use with either the electret or with an external microphone only. If the external microphone is to be used, the 5.6kQ resistor should be omitted (otherwise a DC current of about one milliamp will pass through the microphone) . The signal from either of the microphones is fed via a lµF capacitor (C3) to pin 49 of Ul. It is fed through two internal op amps , then into the digital processor. Pins 1 & 60 are for connection of the timebase oscillator which can use either a crystal or a ceramic resonator. In this case, it is a ceramic oscillator running at 640kHz. Pins 18-30 connect to the four RAM chips, all of which are connected in parallel except for the CAS lines, one of which goes to each RAM chip. Pins 25-30 are the A4-A9 address lines while the other seven pins are labelled as follows: WE ................................. write enable DrN .............................. ..... ...... data in CASl .......... column address strobe 1 CASZ .......... column address strobe 2 CAS3 .......... column address strobe 3 CAS4 .......... column address strobe 4 RAS .................. .. . row address strobe Pin 17 lights a LED to show that recording is in progress. When in playback mode, the filtered output signal is fed from pin 56 to the volume control 5k0 trimpot (VRl). From there, the signal goes via a lµF capacitor to op amp U6, an LM386 which drives an 80 loudFEBRU ARY 1992 27 used for recharging the onboard battery if it is a rechargeable type. If not, this RAM selection - normally on SW1/1 resistor should be omitted. Remember that if you RAM selection - normally off SW1/2 wish to maintain a recordSW1/3 6-phrase selection - normally on ing in memory, then power must always be present. This Bit rate selection (see Table 1) SW1/7 can be supplied either by Bit rate selection (see Table 1) SW1/8 the battery or the external supply. On for voice trigger mode SW2/1 There are two DIP SW2/2 On for beep mode switches on the board and these select all the operatOn for variable phrase mode SW2/3 ing functions of the voice (normally off) recorder chip. We have alSW2/4 Off for mute (pseudo ALC) ready mentioned how the sampling rate and recording time can be selected. The speaker via a lO0µF capacitor. other switch functions are shown in Power for the circuit comes from a Table 2. Each DIP switch is associated 9V battery which can be mounted on with a resistor network shown on the the PC board. It feeds a 5V 3-terminal circuit as RN-1 and RN-2. These are regulator via diode D5. The 5V output both 4.7kQ networks (ie, eight 4.7kQ from the regulator is bypassed with a resistors with a common return, pin lOµF capacitor and with seven 0. lµF 1). monolithic capacitors dotted around Assembling the PC board the PC board. As an alternative, the board can be Putting this board together is little powered from an AC or DC plugpack different from putting any other PC of up 12 volts. This is fed via bridge board together except that the main rectifier diodes D1-D4 to the input of chip is already soldered into place. the 3-terminal regulator. There should also be much less chance Note that there is a lkQ resistor in of solder bridges between pads or parallel with diode D5. This can be tracks since the board has a green Table 2: DIP Switches Where to buy the kit A complete kit for this project is available for $135. This kit comes with all parts, including a screen printed and solder masked PC board with the voice chip already soldered in place. An optional case with screen printed front and back panels is also available for an additional $19.99. An approved 12VAC plugpack can be supplied fot a further $17.95. Add $10 for postage and packing where applicable. The kit is available from the following suppliers: • PC Marketplace Pty Ltd, PO Box 1100, Lane Cove, NSW 2066. Phone (02) 418 6711. Fax (02) 418 6713. • Geoff Wood Electronics Pty Ltd, 229 Burns Bay Road, Lane Cove West 2066. Phone (02) 428 4111. Fax (02) 428 5198. • Bitware Pty Ltd, 14/260 Wickham Road, Moorabbin, Vic 3189. Phone (03) 532 2274. Fax (03) 532 2279. • Colourview Electronics, 5 Commerce Street, Salisbury, Qld 4107. Phone (07) 275 3188. Fax (07) 275 3238. • C. L. Burton Associates Pty Ltd, 20a Maple Avenue, Forestville, SA5035. Phone (08) 293 8955. Fax (08) 293 8903. Note 1: data sheets on the KS5915 voice recorder chip and MCM511000 RAMs will be included with the kit, as will a listing of all DIP switch settings. Note 2: the copyright for the PC board associated with this project is owned by Comma Corporation. 28 SILICON CHIP solder mask over the pattern side. The component layout is shown in Fig.2 and as you will see when you assemble the board, it is identical to that screen-printed on top of the board. One additional component is soldered onto the copper pattern side and that is the blue 640kHz ceramic resonator. It goes right next to the main chip and should be glued to the PC board as well because its leads tend to be on the fragile side. Use super glue for this job. Install all the tinned copper wire links first, followed by the resistors, diodes and monolithic and ceramic capacitors. This done, install the electrolytic capacitors, making sure that each is polarised correctly, then install the switches, multi-turn trimpot, the LED and the three sockets. Finally, install the ICs and the electret microphone. Check your work carefully, then set the DIP switches to the settings you want. If you haven't worked those out yet, use the following settings: DIP switch SWl - Sl On, S2-S8 Off; DIP switch SW2 - Sl & S2 On, S3 & S4 Off. Now connect a 9Vbattery and measure the voltage at the output of the regulator (LK13). It should be close to +5V. The same voltage should be present at pin 9 of the RAM chips and at pin 6 of the LM386. Now depress the Ree/Play button and press the Start button momentarily. This starts the recording cycle. The LED should flash while this is occurring. If you need to pause during a recording, press the Pause button once, then again to resume recording. At the end of your recording, press the Stop button. The speaker will then beep. Alternatively, if you run out ofrecording time, the speaker will also beep. To play back a recording, unlatch the Ree/Play button (ie, it should be in the out position) and then press Start briefly. The recording should then play back. You can control the volume with trimpot VR1. The speaker will again beep at the end of the recording: Ifno recording is present, as occurs at first switch-on, pressing the Start button will cause the speaker to beep. The beep can be disabled if you set switch SW2/2 to off. Now you can play around with the other recording modes by changing the switch settings - see Table 2. SC ELECTRONICS JAYCA R Et ECTRONICS JAYCAH !::L!::C I HUNIC:::i JAYCAH t-Lt:l.. I h'.UN JL:::, JAY LAH ELECTRONICS JAYCAR - ELECTRONICS JAYCAR . ELECTRONICS JAYCAR ELECTRONICS ,JAVCAR . 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ELECTRO' E,ECTRO' ELECTRO~ ELECTRor E-EC-RQr E_::crnor E,ECTROt ELECTROr ELECTROr EcECTRO' ELECTRO~ ELECTRO' ELECTRO' ELECTRO' ELECTROr ELECTROr ELECTROr ELECTRor ELECTROr ELtCTROr ELECTRQr ELECTRQr ELECTRQr ELECTRO' ELECTRO~ ELECTRQr ELECTRQr ELECTRQr ELECTROr ELECTRQr ELECTROr ELECTRDr ELECTROr ELECTRDr. -i '"' _,,,.·.· ELECTRONICS JAYCAR ELECTROMCS JAYCAR ELEC ~RONICS JAYCAR ELECTRONICS JAYCAR cLECTRONfCS JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTf10NICS ELECTRONICS ELECTRONICS ~E..CJ RflN!C~ IAYCAR i=-1 1=r.rnor..1cs 14vc !\R F 1FCT90NI C S JAYCAR JAYCAR JAYCAl1 JAYCAR JAYCAR 1osc oa ELECTRONICS ELE'CTRONICS l::LECTRONICS l::LECTRONICS l::LECTRONICS JAYCAR JAYCAR JAYCAR JAY CAR JAYCAR "'"'""'""""'"'""'==== ELECTRON ICS ELECTRONICS EISCTRONICS cLtCl RONI CS EL:CTRO:\iCS El f:-TT RO"'-Hrs 14yc C\B El c. c, 1~or--·1cs oAYCAn JIIYCAR JAYCAR ,AYCAR oAYCAf1 E LlCTROI\ICS ELECTRO,~ICS cLECT90:\iCS ELECT901'slCS I lECTRONICS :-.vCAH t i 1=cT:3ory1cs JAYCAR JAYCAf, J,\YCAn JAYCAf1 JAYCAR Elf C I H()f\;ICS EL[CHION ICS ELfClHONICS ELECTHO\ICS cLcCI ROt\lCS Je\YCAB Fi JAYCAR JAYCAR JAYCAR ,IAYCAH .IAYCA.1 ELECTRONICS ELECTRONICS ,:i i CTRONICS EL"C'f f10NICS lL:cCTHONICS JAYCA f, JAYCIIR .JAYCAR JAYCI\R JA\'CAH ON/CS E,EC I H()f\;1CS I I ECTROt-.,cs ELEc-r,O'JIC.'' ! LLC f no-.,e,s [ LEc,l fiO'JICS ,J, JI JI ~, ,ii :, rCTRONJC:S..JAYf'Jili LI i.:.c..IB{lli_J_C.s....J.AfCAB...i:..Lt.CTRONICS ._,, ,R ELECTRONICS JAYCAR ,R E:LE:CTRONICS JAYCAR ,R l=LtCTRONICS JAYCAR ,R ELECTRONICS JAYCAR ,R ELECTRONICS .IAYCAR ,R ELlcCTRONICS JAYCAR ,R ELECTRONICS JAYCAR •~ mg .R ELEC .R H FC R ELEC ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTHONICS JAYCAR FLECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAH ELECTRONlCS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAY AR ~~pEo sw1TcH Box 1 ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTHONICS JAYCAR ELECTRONICS -lAYCAR ELECTRONICS JAYCAR ELFCTRONICS JAYCAR ELECTRONICS JAYCAH ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR E E TRONIC AYCAR ELECTRONICS JAYCAR NEw TV has not got enough inputs, :R E:.LEC lhen this R ELtc switch R ELEC will solve R ELEC · your problems. Most TVs have only one set of Inputs. 11 becomes difficult ~~~g when you purchase a second VCR or a TV game or a laser disc, etc. How do R ELEC you connect 2 or more components Into one socket? This swllch will solve R ELEC lhat problem. 11 has 3 Inputs and one output to lhe TV. All connections are via R ELEC RCA plugs and each Input has 3, one for video and two for audio (Land R). R FLFC once wired, all componenls can be left wired in permanently. The swilch ~t~g requires no power lead for connection from the video switch box and TV is =tt~g = = ~ Im· ~:~:~1~::c$4;];s~L)x46(D)x28(H)mm. R ELcC R ELEC R EL 1-C If your amplifier has not ~mg =~~~g R El FC R ELFC R ELEC R 1-LE:c ~~~g R ELEc· R ELEC R ELE'C R ELEC = : ~t~g· R ELFC R ri FC R CLFC :R ELtC ~t~6 -------- AUDIO SWITCH BOX V Pa e NEW ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAH JAYC~R ELECTRq1cs ELECTRq1cs ELECTRq1cs ELECTR01cs ELECTRq1cs ELECTRq1cs ELECTRO r.,ii.1ta•· · s·;.;;d-Leve-,· Met-er-6 5 6 :11iI l o/ This quality sound level meter is made by TES and has many practical applications for l professional an home use. These applications include measuring noise levels In l factories, schools, auditoriums and home HiFi applications as well as noise pollulion, ~ l soundmakers including car alarm sirens, home burglar alarm bells, molar vehicle engine !; sign noise levels etc. The precisely calibrated meter features a large LCD display and function and unit indicator for instant measurements anywhere. l FEATURES: • Maximum level hold • Over and under range indicator ; • Pocket size and lightweight• AC and DC signal oulput for dala l analysis and recording • Internal oscillation system for calibration _., \ ,, <~& ,,.... r _ • • ..,.... , ~ ~ regulations as well as acoustic analysis• Fast and s l o w * i l dynamic response sellings lo check peak and average ! noise levels • Includes qualily case vr ) See 1992 catalogue for full specificalions L~~~~~~~~;~yJay~:.~t=~~-!S2~~~.~~- - ) ! ._9,, l • A and Cweightings for checking in compliance wilh safety i. _. ( . ...... ,, .. - - -~ / - l . ~·---"~ --,, J 'METEX' END OF MODEL R~OUT SALE Model 3650 ·got enough inputs, • then this switch will solve your problems. There are many components available now for Hi Fi systems including tuner, casselle deck or 2, VCR, CD player Stereo TV, DAT, laser disk etc.. Most amplifiers don't have enough lnpuls. This audio swilch box has 3 sets of RCA sockets on the rear for any lhree of the above, and one set for lhe outpul to the amp. This output lead is supplied with the switch (2 RCA to 2RCA plugs). There is more input on the switch and ils for awalkman. So, now you can play your walkman through your Hi Fi stereo with a minimum of fuss. The connection lead for this is also supplied (3.Sm plug to 3.Sm plug - stereo). The selector switch has push bullons and once the unit is wired up, all components can be lefl connected. Requires no power. Size 138(L) x 29(H) x 39 (D)mm. CatAC-1660 ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR El FCTHONICS JAYCAR FLECTRONICS JAYCAR ELECTHONICS JAYCAR ELECTRONICS JAYCAR FLECTRONICS JAYCAR ELECTRONICS JAYCAR fLECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR $49.95 3.5 Digit display frequency_.capacitance transistor test, 20 amp current, carry case. Cat OM-1555 Normally $129.50 Now $109.50 ,Lr,,u. 15% $93.08 Model 4650 4.5 Digit, frequency, transistor test, capacitance, data hold, 20 amp current, carry case. Cat OM-1560 Normally $189.00 Now $169.00 LeA4 15% - , ·. • · · • $143.65 R E:LEC R El FC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R 1::LFC = ~~~g CELLULAR PHONE BATTERIES & BATTERY ELIMINATORS R l::LEC R ELcC H Hf-C R ELECR ELcc· R ELEC R 1::LbC R EIFC R FI FC R FLEC 9 FLFC R FLEC R ELEC '1 ELEC '11-LEC '11:: LEC: '1 ELEC , , 1-11cc , 'I ELECl 'I 1::1 EC 'I ELEC 'IHcC '1 l::LE:C , ELf-C 'I ELFC Battery Eliminators Whenyouarelnyourcar,useyourcars power and save your telephones batteries: Simply slide the battery pack out of the phone and replace ii with the Eliminator. ii has a curly cord attached wilh a cigarette lighter plug. Batteries Why not keep a 2nd battery charged up for your cellular phone. You just don'I know when you may need ii. MOTOROLA 9800/9500 XL NEC P300 SERIES Battery Eliminator caI MP-3114 $59.95 Battery Pack Cal SB-2314 $89.95 Battery Eliminator . Cat MP-3116 $59.95 Battery Pack (6v ?oomA) ~ Cat~B-2316$79.95 ~ $109.50 _,,1e44, 15% $93.08 CatOM-1520 : ~~~g, NOVATEL ,PT_ R-800 SERIES HLECl : ~~~g ' ELEC '1:-LECl ~ ~~~gl MOTOROLA MICRO TAC PT SOO FLIP Battery Eliminator 1u:c ELECl Cat MP-3110 $59.95 1 ELi-c 1 ELECT ~~~g 1 ELECl FLECT (6V 200mA) 1 1 FLECl CatSB-2310 1 1 i • Capacitance • Transistor test • Logic • One hand opcralion • 3'" Digil Brand new model for 1992. Save $20 over old model which it replaces. This DMM is housed in a brighl yellow drop-proof case. II has a frequency counter capability to 200KHz in 3 ranges, as well as a capacitance tester In 5 ranges, logic circuit and continuily beeper and over range indicator, low battery indicator, auto power off, 31•digilal LCD display, 12 months warranty. Also includes the unique one hand operation feature whereby probes can slide mount into either side of case, so only one had is needed to hold both the meter and probe tip in contact wilh the test point. Slide mount will store text leads and probe. Size (87(L) x 88(W) x 37(H)mm .. Call into any Jaycar store for full specificalions. B tt a ery Pack Battery Eliminator Cat MP-3112 $59. 95 B tt p k · a ery ac cat SB-2312 .--.._......, $99. 95 ---~- * NIEW IKll1f - 4 CHANNEL GUITAR MIXER! PREAMP KIT . ;'-,~;,\..)\, Ref Silicon Chip Jan 1992 ll This kit replaces our very popular Ell 467 mixer preAmp released way back in 1980. Thisprojecttakesadvantageofthenewlow noise, low cost op amps available. This kit features separate bass, midrange and lreble conlrols, very low noise and distortion, separate input level controls plus an output level control. Ideal for use wilh most musical instruments from keyboards to guitars lo tape decks. In facl, you can leed it with just aboul any audio signal. ll's not just limited lo guitar oulputs. Kit includes PC Board, potentiometers, input socket and all specified components. The kit does not include optional ground phone nor the 15V supply board (Cat KC-5038 $12.95) ~ i1E:LFCT_ ~~~g; $79.95 CalKC-5107 $49.95 _,,1e44, / 5% $42.46 .,____ _ _ _ _ _ _ _ _ _~~-~~-----------=============================''=====-' 1 ELECTRUNICS JAYCAH 1 ELECTRONICS JAYCAR 1 ELECTRONICS JAYCAR : EL~~~~;:NI;:~ ~~~S:AR l::LcCTRONICS JAYCAR f-LECTRONICS JAYCAR [LECTRONICS JAYCAR ELECTRONICS JAYCAR E'LFCTRONICS ELECTRONICS ELE'CTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS JAYCAR EL,CTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J.~:CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ~L~~TRONICS JAYCAR ICS J ELECTRONICS JAYCAR ELECTRONICS ·JAYCAR ELECTRONICS JAYCAR ELECTRfcs J ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTR\cs J ELECTRONICS JAYCAR ELECTRONICSJJAYCAR ELECTRONICS JAYCAR ELECTR\cs J ELECTRONICS JAYCA~ ~L~~~~ICS JAYCAR ELECTRONICS JAYCAR ELECTR\cs J 11cs IICS IICS IICS IICS IICS I JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS El FCTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS FLECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR lLEC TRONIC.:S ELFCTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYC.:AH JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR cL~C.: I HUNIC.:S FL FCTRONICS ELECTRONICS ELECTRONICS E:U,CTRON/CS ELE:CTRONICS JAYCAH JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR l=LcC I HUNIC.:0 ELECTRONICS ELECTRONICS ELECTRONICS ELE:CTRONICS ELECTRONICS JAYL;AH JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR cLcL; I HUNIL;b ELECTRONICS ELECTRONICS ELECTRONICS cLECTRONICS ELECTRONICS JAY\.,Ati c JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR E E E E E f"'ii;iiiiiiiiiiiiiiiiiiiiiiiiiiiii;iiiiiiiiiiiiiiiiijiiiiiiiiiiiiii~iiiiiiiiiiiiiiiiiiiiiiiiiii•iiiiiiiiiiiiiiiiiiiiiilAYCARE users c:uide to Cellular Telephones • Asia/ Pacific $9.95 .L&SS 15% $8.46 l All $3.95 each Sa,ge oo.e,r, !lOV AC i Amp Plug !Pack i This plugpack l is used lo a l large extenl In ; modems l answering l machines and ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRON/CS JAYCAR JAYCAR JAYCAR JAYCAR J_A_Y_CAR ELECTRONICS_JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR RF DESIGN l lhis one will replace a fN AC plugpack. Supplied i., In l mosl cases AYCAR AYCAR A'rCAR AYCAR ,.J AYCAr1 AYCAH with hundreds of helpful diagrams and quolalions, lhis book covers everylhing from AYCAR antennas lo lransislors, including how lo: • Repair variable AYCAH AYCAI-< capacilors • Align RF circuils • Design and wind induclor AYCAR coils • Cope wilh eleclromagnelic inlerterence • Design YCAR and conslrucl simple wire anlennas wilh 10 basic programs ~\'CAR • Design and build RF amplifier and preseleclor drcuils WCAR • Build a digilal RF amplifier and preseleclor circuils ......... YCAR ,CAR and much more. You'll also learn lhe basics of receiver YCAR operation, lhe proper use and repair of componenls in RF YCAR circuils and lhe principles of radio signal propagation from YCAR low frequencies to microwave. 403 pages soflcbver. \YCAR YCAR Cal BT-1340 \YCAR - ~ YCAR FLFCTRONICS JAYCAR E:LcClROMCS JAYCAR bLECTRON ICS JAYCAR ELEC1f10NICSJAYCAR ELECTRONICS JAYCAR ELI-CTRONICS JAYCAR ELECTRONICS JI\YCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELt.CTRONICS JAYCAR LLLCHiONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR f-LFCTRONICS JAYCAR FLfCIRONICSJAYCAR f Lf-CTRONICS JAYCAR ELECTRONICS JAYCAR L LI CTRONICS JAYCAf, LLfCI RON/CS JAYCAR 19 $39.95 ELECTRONICS ELECTRONICS ELECTRON ICS ELECTRONICS El ECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR r l phones '. ,!. ·,:. 1E F f' E E E F E E: E E E: F fc F E I F t. /F L l l E F F c /E f f I t f 1\YCAR F ! SECRETS OF !.----------------------------------------------------------.. lo . !CS JAYCAR ELECTRO'IICS JAYCAR lcs JAYCAR EL,ECTRONICS JAYCAR ICS JAYCAR ELECTRO'JICS JAYCAR \CS JAYCAR ELECTRONICS JAYCAR ~ S JAYCAR ELECTRONICS JAYCAR f\1 (~AH I ~-'. :i~~~~~~~~~~ :~~~~~~C:~~m ~~~~ L~~t-~~-~ -~::""'' . . ~ . :.95 . . ··-""'~ , . . . 60% f E F t. j j ~ some i cordless By Joseph J Carr l wilh 1.5 melres of cable and terminales to a In clear, non lechnical language lhe l 2.1 mm DC plug. ~ aulhor explains what RF Is, how ii ' $ ~ Famous University Palen brand type HK 35 edge-type panel melers. All are 0-200mA FSD, impedance 6600. Require panel cut out 35W x 14mm H. Units can be back-lit. 4 Scales available: A- 'VU' -20dB lo +3dB black and red on silver background 11 Cal OP-5070 ■► I •j • B - 'VU' -20dB lo +3dB sliver and red on black background . • 1 Cal QP-5071 C- 'S' (Communicalive signal slrenglh meler) 3-9 in black scale.and slol lo 40+ on red againsl silver background. CatOP5072 D- 'Low/Normal' - low scale (In red) occupies approx 60% of scale. Normal scale lhe righl hand 40% Cal QP 5073 All melers are olherwise idenlical. They can be pulled apart wilhoul damage and any scale you like easily inserled. Grab a few while lhey lasl! Oualily! A,CAR AYCAR AYCAR , A'ICAR AYCAR 1 AYCIIR $10.95 $7.50 scoop purchase of university paten panel meters E E E E E E E E E E E E E E E E E E E c E E EE E E E E E: F E E E F E: E: F F This product is designed lo clean compuler screens. lls anli-slalic and is supplied in a bollle wilh a pump action spray. Simply spray on and lhen wipe off. 250ml bollle. CatNA-1030 This product is specifically designed to clean computer By N Boucher keyboard, This book addresses lhe fealures, myths and the facts cases, cabinets, that are an Important part of cellular radio. With this information you should be well equipped lo choose lhe best mobile phone for your · etc. Supplied in a pump purposes. Knowing how ,cellular radio works, you will be able lo get the most out of your investmenl. Chapter headings include: • Choosing ,a phone• Cellular action plastic syslems • The nelwork • Anlennas • BaUeries • Faults • Functions and features bottle. Spray • Coverage • Fax and other devices • Privacy• Roaming • Digilal cellular. II on and wipe lhen covers each counlry separalely including Australia, NZ, Hong Kong and olher off. Asian countries. An excellenl book. See review In EA Sept 91. Cat NA-1032 Cal BC-1140 AYCAR AYCAR AYCAR AYCAR AYCAR IAYCAR AYCAR AYCAR JAYCAR AYCAR 9/WCAR AYCAR AYCAR AYCAR JA YCAR AYCAR IAYCAR AYCAR AYCAR AYCAR IAYCAR AYCAR AYCAR AYCAR fAYCAR IAYCAR IAYCAR fAYCAR AYCAR AYCAR AYCAR IAYCAR IAYCAR IAYCAR IAYCAR IAYCAR AYCAR AYCAR IAYCAH IA'rCAR IA YCAR IAYCA f, IAYCAR AYCAR AYCAR IAYCAR IAYCAR AYCAR AYCAR AYCAR AYCAR IAYCAR AYCAR AYCAH AYCAR IIYCAR AYCAH AYCAR AYCAR AYCAR 'AYCAR IIYCAR AYCAH AYCAR AYCAR AYCAR AYCAR AYCAH 'AYCAR AYCAf1 AYCAR AYCAR AYCAH A,CAH 1,YCAR E: l E /cl IEl fl H El E:1 FI Fi FI E-1 El 1-1 El [/ E-1 El El El El EL EL EL EL EL BOOKSHELF Microwave techniques for amateurs Microwave Handbook, Vol. 1. Components and Operating Techniques. Edited by M. W. Dixon, G3PFR. Published 1989 by the Radio Society of Great Britain. Soft covers, 182 x 242mm, 225 pages. ISBN O 900612 89 4. S70.00. The Microwave Handbook could be described as the amateur's reference guide to microwave transmission. It effectively supplants the esteemed VHF/UHF Manual, the last of edition of which was produced by the Radio Society of Great Britain in 1983. Everything from antenna design and construction to waveguides, system analysis and components are covered. The beginning of the book covers operating techniques used in microwave communication. Topics include antenna systems, comparisons with VHF/UHF transmissions, portable operation, choices of site, forecasting conditions, mapping and path plotting. System analysis and propagation is discussed in chapter 3. Although mathematical calculations are included, the concepts are explained in a largely non-mathematical manner. Diagrams and grap)ls are used extensively to explain the text. There is a large section on antennas. Yagis, phased arrays, horns, para- bolic reflectors and omni-slot antennas are all discussed in terms of application, gain and design. Practkal advice on mast design and material selection is included. A heavy emphasis is placed on construction and examples are given throughout. Components, waveguides and transmission lines are given close attention. Chapter 5 deals with transmission lines and passive components whereas chapter 6 covers active components. Examples of both commercial and home-brew equipment are given, along with tips on putting your own system together. For anyone interested in microwave techniques, this must be one of the most comprehensive books on the subject. We can thoroughly recommend it, even at the relatively high price of $70.00. Our sample copy came from Stewart Electronic Components Pty Ltd, 44 Stafford Street, Huntingdale, Vic 3166. Phone (03) 543 3733. ing in isolation from SMPS design. And it does full justice to the subject, starting with the fundamentals of SMPS design. The list of chapter headings is as follows: (1) Basics of Power Supply Design; (2) Filtering: An Intuitive View; (3) The Graphical Attenuation Methodology; (4) Filter Load Impedance: Mains; (5) Filter Termination Impedance: Power Supply; (6) Filter's Effect on Stability; (7) Controlling Filter Q; (8) Common Mode Filter Design; (9) Differential Mode Filter Design & Integration; (10) Radiation Coupling to On-Board Power Line Filters. While this book is well written and generally easy to read, there was one really frustrating point about it - a consistent reference to a standard loading network called an LISN. This is interposed between the output of a switchmode power supply and the load and is used to ensure that consistent test results are obtained. But nowhere in the text does it actually say what the letters LISN stand for. Overall though, our reaction to this book is that it covers the subject very well and would be a worthwhile purchase for anyone involved in SMPS design or servicing. Now if only we could find out what LISN stands for. Our review copy came from Thomas Nelson Australia, 102 Dodds Street, South Melbourne, Vic 3205. Phone (03) 685 4199. SC Filter design for switchmode supplies Power Line Filter Design for Switched-Mode Power Supplies, by Mark Nave. Published 1991 by Van Nostrand Reinhold, New York. Hard covers, 155 x 235mm, 210 pages. ISBN 0 422 00453 2. $109.95. Most books on switchmode power supplies (SMPS), and there are not that many about, try to cover the whole subject but this one is different. It covers just the design of the output filter. This strikes me as just a little odd as you would think that a power designer would design a unit as a whole and not just add the filter after the rest of the design had been finished. In fact, the text itself makes the point that "the power line filter is part of the power supply itself!". Having made the point emphatically, the book then goes on to develop the whole subject of power supply filter- FEBRUARY1992 33 New stereo module delivers up to 160 watts into 4-ohm loads By LEO SIMPSON & BOB FLYNN The last time we published a power module using bipolar transistors was back in December 198 7. That single channel design used 2N2955/2N3055 TO-3 metal-pack transistors to deliver either 50 watts into an or 100 watts into 4Q, depending on whether two or four output transistors were used. Later, in February 1988, we upgraded the module by substituting the more rugged (and more expensive) MJ15003/4 TO-3 power transistors. Both designs have been very popular and are still available but recently we have seen the need for a more compact, multi-purpose amplifier module which would drive 4Q or 8Q loads without having to change the design. In fact, the real stimulus for the design was that we wanted to produce a new integrated stereo amplifier which would fit into a midisized chassis; ie, about 340mm wide. We had a target of 50 watts per 34 SILICON CHIP Say goodbye to tin lid transistors and hello to f antas tic plastic. This new stereo power module uses four big plastic Darlington transistors in each channel, making a rugged and compact design incorporating full protection. channel for the new design and initially we intended to base it on one of the Japanese-made stereo modules. These are used in very large numbers in today's lower cost stereo amplifiers and particularly in the all-in-one rack systems. In fact, we went ahead with a design based on such a module , capable of delivering 50 watts per channel. But after building several prototypes we had to give the game away. There were just too many compromises in the design. Those modules looked great ,on paper but, in practice, they have drawbacks which cannot be cured, since the core circuit is contained in moulded black plastic. So it was back to the drawing board. OK then, having spent a great deal of development time which had so far come to nought, what was to be the next approach? We did not want to use TO-3 power transistors (hence our into 4Q loads, has low distortion and very low residual noise. The total power output will depend to a great extent on the regulation of the power supply. We will have more to say about this later. Protection reference to tin lid transistors at the start of this article). Sure, TO-3 power transistors give plenty of power for their size (particularly the MJ15003/ 4s) but after 30 years or more, they are a bit old hat and are becoming more expensive as time goes by. By contrast, plastic encapsulated power transistors are becoming more rugged and cheaper. And they are much easier to design into PC boards and have single screw mounting. So the transistors we have selected for the new design are the TIP142 (NPN) and TIP147 (PNP) plastic Darlingtons. Made by Philips, Motorola and a number of other companies, they are housed in the so-called plastic TO-3 encapsulation (ie, TO3P) although Philips list it as the SOT93 pack and Motorola as the TO-218. Either way, these new Darlingtons (first listed by Philips in July 1988) are quite rugged, with the following ratings: power dissipation 125 watts (TMB = 25°C); collector-emitter voltage 100 volts (V CEO - open base); collector current 10 amps DC, 15 amps peak; DC current gain (hFEl >1000<at> 5 amps; and a maximum junction temperature of 150°C. In fact, they compare very favourably with the old favourite 2N3055s which have a power dissipation of 115 watts, 15A maximum collector current and VCER of 70 volts. They also compare quite well in the critical area of "second breakdown". Performance The performance of this new stereo power module is very respectable and certainly better than the vast majority of the low to midrange amplifiers. In particular, it delivers lots of power This aspect is most important in any medium to high power amplifier design and we have followed the same approach as we have used in our designs of December 1987 and February 1988 - fuses in the positive and negative supply rails and a Polyswitch PTC (positive temperature coefficient) thermistor in series with the output. While some readers may regard PTC thermistors as a needless option they will bless them if ever they are called into operation. They are much cheaper than having to replace the drivers in your loudspeakers and they are excellent insurance against loudspeaker fires which can happen in some cases of amplifier failure. The trouble with today's power amplifiers is that they use big power supplies which can deliver a great deal of current. If just one of the transistors in the amplifier fails, the result can be that the circuit applies the full positive or negative supply rail to the loudspeaker. Typically, an 8Q loudspeaker will have a voice coil resistance of about 5.5Q. When that cops the full positive supply of this amplifier, it will have to dissipate around 150 watts or more. Now maybe the fuses will blow and save it but the most likely result is that the voice coil will be burnt out. That's not all. In some cases, the red hot voice coil sets the loudspeaker on fire which then generates huge quantities of acrid smoke from the acetate filling material in the cabinet. There have been documented cases of this happening - and big insurance payouts for smoke and fire damage to homes. So the PTC thermistor in this amplifier is highly desirable. Note that you cannot rely on the fuses to give protection to the loudspeaker. They are selected to protect the amplifier and its supply more than for output protection. And in the case of the fault condition outlined in the preceding paragraphs, they may not What Is A Darlington Transistor? The TIP142/147 plastic power transistors specified in this new amplifier design are referred to as Darlingtons, after S. Darlington, who first proposed the Darlington transistor pair in the early 1960s. Effectively, they are a compound transistor pair, with the emitter of the first transistor connected to the base of the second. Hence, the current gain of the pair is approximately equal to the product of the two transistor gains. The internal circuit configuration of the TIP142 is shown in Fig.1. It includes a reverse diode from collector to emitter of the second transistor. This diode is very handy for reverse voltage protection in amplifier and switching circuits. These days, these integrated transistors are shown on circuit diagrams by the conventional transistor symbol, with nothing to distinguish them from ordinary discrete transistors. NPN TIP140 TIP141 TIP142 COLLECTOR r--_ - -_ -- - 7I _......., 1 I I BASE I I I I I L ___ - - - - __ _j EMITTER Fig.1: the equivalent circuit of the TIP142 NPN Darlington which has inbuilt base-emitter shunt resistors and a reverse protection diode. The collector is connected to the metal tab of the plastic package. However, while Darlington transistors have the advantage of high current gain and space saving on printed circuit boards, they are at a disadvantage in switching circuits where their saturation voltage (V CEsat) is usually not as low as can be achieved with discrete transistor switching circuits. FEBRUARY1992 35 +38.5V 01 f1 0.22! 5A 02 0.22! 010 03 l BC556 C .,. .033 _j L1 6.8uH D.4m 3W 0.1 1 B o--1 INPUT OUTPUT 22k i 2.2pF 0.15! ,. o.4m 3W 1k 1.,. 2xTIP147 + 47 16VW+ 8 68pf 011 4.7k 1 2.2V 4.7k C 05 04 8 2xBF469 37.2V E F2 SA 0.22J 2.2V 1000 i 1.6V -38.SV 0.221 A PLASTIC SIDE YELLOW 8 + 240VAC +38.SV 4700 N + sovw YELLOW ELJc VIEWED FROM BELOW ~ ECB BF-,BD139 ~ BCE TIP- GND . 4700 + sovw -38.SV TWIN SOW POWER AMPLIFIER Fig.2: the voltages shown on the circuit diagram are nominal values & are what can be expected if you have a 240V mains supply. If your mains supply is higher, you can expect most of the voltages to be higher in proportion. Note that the DC voltage on the output should be within ±30mV. blow soon enough, if at all. Note that this loudspeaker (and fire) hazard is common to all modern amplifier designs , commercial and do-ityourself, not just the design under discussion here. PTC protection thermistors were first used in loudspeakers from the UK about seven or eight years ago. To our knowledge, we were the first to incorporate them in the output of an amplifier design although they are also used in the high voltage rails of amplifiers such as the NAD which have very high music power output. Normally, PTC thermistors have a 36 SILICON CHIP very low resistance, a mere 0. H1 or less in the case of the ones specified for this amplifier. They stay that way while ever the current through them is below their cutoff rating (around 5 amps in this case). If the current rises above this value, the PTC thermistor's resistance suddenly rises to a high value, around several hundred ohms, effectively disconnecting the amplifier from the load and thus protecting it and the loudspeaker. Thus, the PTC thermistor is very effective in protecting the loudspeaker against overdrive from the amplifier or worse, a catastrophic failure in the amplifier. When the fault condition is removed, the PTC thermistor's resistance gradually returns to normal although this may take several minutes or more to fully recover. The PTC thermistor will also protect the amplifier against short circuit loads1although in this respect the supply fuses give backup protection. The circuit Now let's have a look at the circuit of Fig.2. This is very similar to the design featured in December 1987 except that we have substituted the TIP142/147 Darlingtons for the 2N2955/2N3055 output transistors and their MJE340/350 driver transistors. The input signal is coupled via a lµF metallised polyester capacitor and 1.8kQ resistor to the base of Ql which together with Q2 makes up a differential pair. Q3 is a "constant current tail" which sets the current though Ql and Q2 and thus renders the amplifier largely insensitive to variations in its supply rails (known as power supply rejection). Diodes D1 and D2 provide a voltage reference of about 1.2V for Q3 so that it applies a constant voltage to its 680Q emitter resistor. This sets the current through Q3 to close to lmA. This means that Ql and Q2 each operate with a collector current of about 0.5 milliamps. Signals from the collectors of Ql and Q2 drive another differential pair, Q4 and Q5, which have a "current mirror" as their load. The main advantage of the current mirror, D3 and Q6, is that it makes the second differential pair highly linear and therefore low in distortion. The output of Q5 drives the classAB output stage consisting of Darlingtons Q8-Q11. By class-AB we mean an amplifier which is essentially classB (ie, each half of the output stage conducts for only half the signal) but which has a small current bias to minimise cross-over distortion. PARTS LIST 1 PC board, code SC01102921, 80 x 233mm 1 60 x 60 x 290mm 3mm-thick angle aluminium 19 PC stakes 8 SOT-93 (T0-218) transistor mounting kits 2 SOT-32 (T0-126) transistor mounting kits 8 20mm fuse clips 4 5A M205 20mm fuses 2 Philips 4322-021-30330 or Neosid 60-601-72 coil formers 2 RDE245A polyswitches 2.5 metres 0.8mm enamelled copper wire 1 power transformer 2 x 25V, 160VA (from Harbuch, Altronics or Torrtech) 2 500Q horizontal mount trimpots 2 560Q 5W resistoris (for setting quiescent current) Semiconductors 4 TIP142 NPN Darlington transistors (08 ,010) 4 TIP147 PNP Darlington transistors (09,011) 4 BF469 NPN transistors (04,05) 2 BF470 PNP transistors (06) 2 BO139 NPN transistors (07) 6 BC556 PNP transistors (01,02,03) 6 1N4148 signal diodes (01 ,02,03) 1 P04 6A bridge rectifier Capacitors 2 4700µF 50VW electrolytics 2 47µF 16VW electrolytics 2 1µ,F 63VW 5mm pitch metallised polyester 8 0.22µF 63VW 5mm pitch metallised polyester 2 0.15µF 10% 100VDC 10mm pitch metallised polycarbonate (Philips 2222 344 21154) 2 0.1µF 63VW 5mm pitch metallised polyester 2 .033µF 100VW 5mm pitch metallised polyester 2 820pF 50V ceramic 2 68pF 100V ceramic 2 2.2pF 50V ceramic Resistors (0.25W, 5%) 6 22kQ 4 680Q 215kQ 0.5W 4180Q 44.7kQ 101000 24.7k01W 2 6.8Q 1W 2 1.8k0 8 0.47Q 3W 10% 21kQ Vbe multiplier The current bias in the output stage is controlled by transistor Q7 and trimpot VR1 . Q7 is a Vbe multiplier, so called because the voltage between its base and emitter is multiplied by the ratio of the resistors between base and collector and base and emitter, respectively. VR1 adjusts this voltage to give a voltage between the collector and emitter of Q7 of about 2 volts. In practice, it is adjusted to give an output stage current of 40 milliamps. Q7 is a BD139, a transistor normally used in amplifier driver stages and video circuits. It has a dissipation rating of 8 watts and so is only doing light duty. However, it is specified here because it gives better Vbe tracking with the output stage transistors and therefore better stability for the quiescent current. The Darlington transistors Q8 and Q10 and Q9 and Ql 1 are connected as parallel pairs to share the output current. Each Darlington has a 0.47Q emitter resistor which helps ensure equal current sharing. As well, the emitter resistors improve the output stage bandwidth and the stability of the quiescent current. The value is a compromise though; bigger emitter resistors would give better stability and current sharing but would reduce the maximum output power capability. The 100Q base resistors for the Darlingtons serve a number of functions. First, they reduce any tendency for the output stage to oscillate; always a possibility with emitter follower stages. Second, they limit the base current in the event of a short circuit in the output and thereby reduce the possibility of damage to the Darlingtons. Negative feedback is applied from the output stage back to the base ofQ2 via a 22kQ resistor. This resistor, and the lkQ resistor also connected to the base of Q2, sets the voltage gain to 23. The low frequency rolloff of the voltage gain is set by the 47µF capacitor in series with the lkQ resistor. This sets the -3dB point at about 3Hz. However, the lµF input capacitor is the main factor in the low frequency response of the amplifier and sets a -3dB point at 7Hz. The overall effect of the two time constants is a -3dB point at 10Hz. The 820pF capacitor and the 1.8kQ input resistor feeding Ql form a low pass filter which rolls off frequencies above l00kHz. This filter is a little more savage than we have used in previous designs but we have done this to give a greater margin of safety in the output in case the preamplifier stages have any tendency to high frequency instability. The 68pF capacitor between base and collector of Q5 and the 2.2pF capacitor between base and collector ofQ2 are used to roll off the open loop gain to ensure stability with feedback applied. We have also used our standard RLC network in the output stage. A configuration originally proposed by Australian engineer Neville Thiele, it uses a 6.8µH air-cored choke, a 6.8Q resistor and a 0.15µF capacitor. FEBRUARY1992 37 The beauty of this network is that it effectively isolates the amplifier output stage from any nasty impedance dips which may occur at high frequencies and which could cause the amplifier to be unstable. It also has another favourable effect because it kills any RF signal pickup by long speaker leads. Power supply The power supply for the amplifier is shown in Fig.2. This uses a 160VA transformer with a centre-tapped 50V winding feeding a 6-amp bridge rectifier and two 4700µF 50VW electrolytic capacitors. PC board design The PC board for this stereo amplifier has been designed so that it can be built as two separate modules. The stereo pair can be built with an onboard power supply which will also feed a preamp stage. Alternatively, if you want to use a bigger bank of filter capacitors, a higher rated bridge rectifier and the capacitors would be mounted off the board. Do not substitute a transformer with a higher secondary voltage. If you do so, you run the risk of blowing the Darlington transistors, particularly if you are driving 4Q loudspeakers. The specified heatsink is a 3mm-thick aluminium angle extrusion, 60 x 60 x 290mm long. This heatsink is adequate where the amplifier is intended for normal program material. If you envisage using it with a bigger capacitor bank and more onerous signal conditions such as a guitar amplifier, then a bigger heatsink or thermal cutouts would be desirable. For the remainder of this article though, we will assume that the reader is building a stereo module on the specified heatsink. Note that the parts list specifies all the components for a stereo amplifier and makes reference to transistors such as Ql, Q2 etc. Transistors Q1-Q11 are shown on the circuit diagram (Fig. 2) and these are duplicated in the second channel. The same goes for the diodes. Assembling the board Fig.3: the parts layout for a complete stereo amplifier power module with on-board power supply. The 6.8µH output inductors (Ll) are each wound on a Philips 4322021-30330 or Neosid 60-601-72 coil former using 24.5 turns of 0.8mm enamelled copper wire. Fig.2 shows the pinout details for the transistors. 38 SILICON CHIP We suggest that you mount the PC pins, resistors , diodes and wire links first , followed by the capacitors. There are only two electrolytics on the board, apart from those in the power supply. Make sure they are mounted with correct polarity. Most of the remaining capacitors are moulded metallised polyester capacitors which have a standard lead spacing (pitch) of 5mm. We recommend against greencaps as they won't fit. The fuses specified are M205 20mm-long types as widely used in commercial amplifiers. The main reason we have specified them is that they take up less board space than the larger 32mm 3AG fuses and cost no more. All the TO-5 transistors (Q1-Q3 , etc) are mounted with the flat side facing towards the front; ie, away from the heatsink. Similarly, the TO-126 transistors (Q4-Q6, etc) mount with the metal side facing to the front. The exception is Q7 which naturally mounts with its metal face to the heatsink (with a mica washer, of course). The 0.47Q 3-watt resistors are made by Philips and again have been specified to save board space, being a lot more compact than the common 5W cement "bathtub" types. Mount them so that they clear the board by about 3-4mm. The 6.8µH output inductors are each wound on a Philips 4322-02130330 or Neosid 60-601-72 coil former using 24.5 turns of 0.8mm enamelled copper wire. Clean and tin the ends of the inductors before installing them on the board. Output transistors There are several ways of mounting the output transistors but the way we did it is as follows. First, all the Darlingtons and the two BD139s were mounted on the aluminium heatsink. In each case, they were mounted using the specified mounting kit consisting of a mica ~asher and plastic insulating bush for the screw. Heatsink compound is applied sparingly to both sides of the mica washer before it is set between the transistor and heatsink. The details are shown in the diagram of Fig.4. With all the transistors mounted on the heatsink, set your multimeter to a low ohms range and check that the transistor collectors are isolated (ie, infinite resistance) from the heatsink. That done, set the heatsink upside down on your workbench and fit the PC board over the transistor leads. You may need to adjust some of the transistors so that their leads line up with the board holes. Tack soider a couple of Darlington transistor leads at each end so that the top board surface is about 8mm from the bottom edge of the heatsink. You will also need to slightly crank the leads of the BD139s (Q7) to line them up with their respective PC board holes. When you are satisfied with the lining up of the board, soldE;Jr Performance of Prototype Output power .. .. .......... .. ..................... 55W into 8 ohms, 80 watts into 4 ohms (one channel driven) Frequency response ......................... 15Hz - 35kHz ±1 dB Input sensitivity .................................. 900mV (for clip point into 8 ohms) Harmonic distortion ........................... typically less .05% from 20Hz to 20kHz) Signal to noise ratio ........................... 105d8 unweighted; 11 ?dB Aweighted Separation between channels ........... 84d8 or greater (1 00Hz - 10kHz) Protection .......................................... 5A fuses plus RDE245A Polyswitch Damping factor .................................. <50 (for 8 ohm loads) Stability ............................ ................. unconditional all the transistor leads to the board pattern. Power up Before applying power, check all your work very carefully against the wiring diagram of Fig.3. This done, remove the four SA fuses and solder a CAPACITOR CODES Value IEC Code EIA Code 1µF 105 0.15µF 0.1µF 1u0 220n 150n 100n 820pF 68pF 2.2pF 820p 68p 2p2 0.22µF 224 154 104 821 68 2.2 560Q 5 watt resistor across each of the on-board fuseholders. These are current limiting resistors which reduce the likelihood of any damage to the output transistors in case you have done something silly like swapped a TIP142 for TIP147. But of course you have already checked to see that nothing like that has happened, haven't you? Now connect the positive and negative supply leads to one channel of the amplifier. Set trimpot VRl fully anticlockwise - this gives the minimum setting for quiescent current through the output transistors. Set your multimeter to the 200VDC range (or no lower than S0VDC if an analog meter). Do not connect a loudspeaker or output load at this stage. Now apply power and measure the positive and negative supply rails. RESISTOR COLOUR CODES D D D D D D D D D D D No. Value 4-Band Code (5%) 5-Band Code (1%) 6 2 4 2 2 2 4 4 10 2 22kQ 15kQ 4.?kQ 4.?kQ 1.8kQ 1kQ 680Q 180Q 100Q 6.8Q red red orange gold brown green orange gold yellow violet red gold yellow violet red gold brown grey red gold brown black red gold blue grey brown gold brown grey brown gold brown black brown gold blue grey gold gold red red black red brown brown green black red brown yellow viole! black brown brown yellow violet black brown brown brown grey black brown brown brown black black brown brown blue grey black black brown brown grey black black brown brown black black black brown blue grey black silver brown FEBRUARY1992 39 The stereo power amplifier module will form part of a complete stereo amplifier to be described in a future issue of SILICON CHIP. This photo shows the unit in company with its companion tone control board at bottom left & the input preamplifier board at right. temporarily short out the PTC thermistors. Troubleshooting They should be within a few volts of ±38.5 volts. Now measure the other voltages on the circuit. They should all be within ±10% of the nominal values, depending also on whether your 240VAC mains supply is high or low (it is above 240VAC more often then not). The voltage at the output should be within ±30mV of 0V. Now switch your multimeter back to the 200VDC range and connect it acl'oss one of the 5600 5W resistors. Adjust trimpot VR1 for a reading of 22.4 volts. This gives a total quiescent current of 40 milliamps. After 5 minutes or so, check the quiescent current again and readjust VR1 if necessary to get the correct voltage across the 5600 resistor. (If you are doing power tests on the amplifier and the heatsink becomes very hot, you can expect the quiescent current to at least double. When it cools down though, the quiescent current should drop back to around 40mA). Measure the voltage across each 0.470 3W emitter resistor. They should all be about 9- lOmV, which means that each Darlington transistor is getting its rightful share of the quiescent current. Now switch off and connect the positive and negative supply rails to the other channel. Measure the voltages as before and adjust VRi in 40 SILICON CHIP that channel for the correct quiescent current. If all is well, switch off, remove the 5600 5W resistors and fit the 5A fuses. The amplifier module is now ready for work. Nate that if you intend running continuous power tests on the module, the PTC thermistor will operate before you can get full power into a 40 load. They will let full power be delivered on music signals but not for continuous sinewave signals. To do such full power tests, you will have to INSULATING MICA WASHER -~~JI 'SCREW r mnmfs --.._ HEATSINK 1 T0220 DEVICE Fig.4: transistors Q7-Qll are each isolated from the L-shaped heatsink using a mica washer & insulating bush. Smear the transistor tabs & mica washers with heatsink compound before bolting the assemblies together & use your DMM to check each transistor as it is mounted to ensure correct isolation. What happens if one of the amplifiers is not working? If the other channel is working correctly then you have an ideal cross-check. Check the voltages in the good channel and then in the bad channel and you can usually get a fair idea of what the problem is. It is unlikely that you will get the same fault in both channels, unless you have made the same assembly mistake in both! And now we'll give you a few clues which may help you solve any problems. First of all, let's assume that most of the amplifier voltages are correct but you have zero quiescent current. Look for a short across VR1 or Q7. If you have lots of current through the 5600 resistors and cannot control it with VR1, look for an open circuit in the 6800 base resistor to Q7 or a defect in that transistor. What if the output of the amplifier is fully latched up at either +38V or -38V? The most likely cause of this is a defect in the first or second differential pair of transistors, or something silly like the wrong transistor, say a BF469 where a BF470 should be. Solder bridges between tracks can also cause this fault. The above are the more common problems with build-it-yourself amplifiers. Most times though, you can expect the modules to work perfectly at switch on. SC Easy to build Digital Voice Recorder A Voice recorder you can build in a afternoon This digital voice project has hundreds of uses and will only take you a couple of hours to build. You can also install up to 4MB of RAM for longer recording times. Power is supplied from a low voltage plug pak (optional) and you can also purchase a case with front and rear panels to complete your digital recorder. Low power consumption The CMOS LSI chip used for this project uses a minimum of power. Recording and reproduction of the signals is processed through the CMOS chip using an (ADM) Adaptive Delta Modulation algorithm. This provides a clean clear recording. You are also able to select four different rates of recording and playback depending on the quality and length of the recording your application requires. An electret microphone is used, and the CMOS chip has a built-in microphone amplifier as well as a mutingcircuit.A57mm speaker is provided to ensure quality reproduction. A5mm LED is included to show the unit is recording. Prefitted CMOS Surface mount Chip The CMOS chip used in this kit is a surface mounted device, and so we have had these premounted to the board so you will not have to be an expert to mount this corn ponent. When you receive your kit you will find a complete set of instructions, so you will not have any trouble during the assembly stages. Each kit has also been weighed to ensure all components are included. The kit comes complete with a full set of instructions and lMBofRAM. Features: * Voice recording and reproducing LSI using an ADM algorithm.* Can be used with either 256K or 1MB DRAM in combinations of 1 to 4 pieces. * Capable ofrecording and reproducing up to a maximum of 16 phrases. * 4 different bit rates can be selected. (BK, 16K, 22K, 32K bps). * Pausing function. * Beep sound output. * Mute Circuit. * Built-in DRAM refresh circuit. * Built-in band pass filter. * Built-in microphone amplifier. * Built-in 10 bit DAC. * Built-in DAC output buffer. * Uses a 640K resonator. * +5V single power. * Clocked CMOS for low power consumption. * Variable debouncing time for start, stop and pause by the CPU terminal. Only available from the following locations: r Pfii[ (jfeeson s "' PC MARKETPLACE Pty Ltd PHONE (02) 418 6711 FAX (02) 418 6713 Mail Order Address: P.O. Box 1100 Lane Cove NSW2066 FREIGHT CHARGES Include $10 with order for all normal ~ma. 14 day money back guarantee. Unleaa Insurance is declined It will be charged at 1% of total purchase. This is for your protection. -- [Z] Q Bitwore Ptv Ltd Bitware Pty Ltd 14/260 Wickham Rd, Moorabbin, VIC, 3189 PHONE (03) 532 2274 FAX (03) 532 2279 A.C.N. 005 366307 <at>:>tourview Electronics Complete Kit Colourview Electronics $135.00 5 Commerce St, Salisbury, Options: QLD,4107 Phone (07) 275 3188 UB 1OCase with front & rear panels. Front Panel is punched and screened, rear panel is punched. $19.99 Fax (07) 275 3238 Approved Plug Pak $17.95 C.L.BURTON ASSOCIATES PrY.LTD. 20A Maple Avenue, Forestville, 5035, S.A. Phone (08) 293 8955 Fax (08)293 8903 GeoffWood Electronics P/L 229 Burns Bay Rd, (Comer Beatrice St.), Lane Cove West, NSW Phone (02) 428 4111 Fax(02) 428 5198 Power mains appliances from a 12V car battery with this ... 40-WATT INVERTER This compact 40W inverter can drive low power appliances such as shavers from a 12V battery. It is ideal for use when camping in areas where a 240V AC supply is unavailable, or as part of a small solar power installation. · By JOHN CLARKE An inverter which operates from a car battery can be a very useful item to have for powering mains equipment. While some equipment can be powered either from the mains or from a DC supply, there are some appliances which do not have this option and must be operated from 240V AC. This 40-Watt Inverter is suitable for use with appliances which draw 40W or less (eg, fax machines, electric toothbrushes, battery chargers for mobile telephones and incandescent lamps). It is not suitable for fluorescent lights, however, since the start- ing current and peak voltage required are too great for the inverter to supply. The inverter circuitry is housed in a plastic case measuring 155 x 158 x 54mm. This has a panel-mount mains socket attached to the front panel, along with a power switch. The power leads which go to the battery emerge from the rear of the case, just below the fuseholder. To operate the inverter, you simply connect the power leads to the 12V battery, plug in the mains appliance and switch on. The appliance should then operate in its usual manner. The 40-Watt Inverter is housed in a small plastic case & can be used to power all sorts of small appliances (eg, battery chargers & fax machines). The rating can be easily increased to 60W by substituting a larger transformer (see text). 42 SILICON CHIP As can be seen from Table 1, the inverter has quite good voltage regulation and is reasonably efficient at full power. The poor efficiency at lower powers is mainly due to the use of a low-cost transformer to step up the voltage to mains output. Lack of feedback voltage regulation is another contributing factor. This poor efficiency at low output powers is tolerable since the extra circuitry and cost is not warranted in a low-power design such as this. The circuit As the accompanying photographs show, relatively little circuitry is used in the inverter. Apart from the power transformer, it uses two inexpensive !Cs, two Mosfet transistors and a few other sundry bits and pieces. Fig.1 shows the circuit details. At the core of the circuit are Mosfets Ql and Q2 which are used to drive transformer Tl. This transformer is a standard mains transformer with two separate low voltage windings which are connected together as a centretapped primary winding. By alternately switching the 12V supply across each half of the primary winding using Ql and Q2, the transformer produces an approximate 240V AC output across its secondary. Ql and QZ are switched on and off out of phase so that when Ql is on, Q2 is off and vice versa. These Mosfet transistors are Motorola MTP3055E devices which are specifically designed to switch inductive loads (such as a transformer) without the need for external transient protection. Instead, these devices each have an internal avalanche diode for transient protection and for commutating reverse voltages. We can not recommend any alternative devices to the MTP3055E, so do not substitute for this component. F1 POWER +12V~o-------tt-------------------, 100n Vee 100 + 16VW:r OUTPUT SOCKET 02 MTP3055E 1k T1 r,!'~--r---,M2165_ T __,__ 150k 240V IC1 7555 47k D.1I Vee 47k T 10k Vee 100n B 15k ELJC VIEWED FROM BELOW ~ GDS 1.6k 8.2k 47k OEAO TIME COMPARATORS T 40W INVERTER 10k The remaining components in the circuit are there to provide the out-ofphase drive signals for Ql and Q2. ICl is a CMOS 555 timer which is set up as an oscillator operating at 50Hz. This is wired in a somewhat unconventional manner, however. Normally, the astable configuration uses a timing capacitor (on pins 6 & 2) which is charged via a resistor connected to the positive supply rail and then discharged into pin 7. In this circuit though, the timing capacitor (O. lµF) is alternately charged and dis- charged by the pin 3 output via a 150kQ resistor. The circuit works like this: at switch-on, pin 3 of ICl goes high and charges the O. lµF timing capacitor via the 150kQ resistor. When the capacitor voltage reaches 2/3Vcc (ie, 2/3 the supply rail voltage), pin 3 switches low and the capacitor discharges via the 150kQ resistor until it reaches 1/3Vcc. At this point, pin 3 switches high again and so the cycle is repeated indefinitely while ever power is applied. Table 1: Performance Input Voltage Input Current Load Output Voltage Efficiency 13.8V 1A ON 279VAC O"lo 13.8V 2.2A 15W 265VAC 49% 13.8V 4A 40W 248VAC 72% 12.0V · 3.8A 40W 230VAC 88% Fig.1: 555 timer IC1 & transistor Q3 provide antiphase clock signals to comparators IC2a & IC2b. These comparators then drive Mosfet transistors Ql & Q2 which in turn switch the primary of the step-up transformer (Tl). IC2c & IC2d are the dead-time comparators. Note that the 50Hz output from ICl is a genuine square wave with very close to 50% duty cycle since pin 3 swings fully to the supply rails due to the CMOS output. The waveforms of Fig.2 show the square wave output at pin 3 of ICl and the capacitor voltage at pins 2 and 6. The square wave output from pin 3 of ICl is fed to the inverting input of IC2a (pin 10) via a voltage divider consisting of two 47kQ resistors (one in series and the other to the positive supply rail). The resulting waveform at pin 10 is a square wave which swings between the +12V supply rail (Vee) and ½Vee. IC2a is a comparator and its output at pin 13 goes high each time the inverting input (pin 10) goes lower than the non-inverting input (pin 11). If the non-inverting input is at ¾Vee, then IC2a's output will be low when pin 10 is at Vee and high when it is at ½Va: The open collector output at pin 13 FEBR UA RY1992 43 Vee Variations On A Theme PIN3 IC1 ov As this project was being developed, one of our readers enquired about its suitability to drive a telescope. To do this, its output frequency needs to be varied between about 40Hz and 60Hz. ~ 20ms V e e ~ 2/3Vce PINS2,6 1/3Vee IC1 OVt--------------Vee 3/4Vec PIN1 IC2e ov 3/4Vee In the meantime, Altronics has indicated that they will have a kit available for this project shortly after this issue goes on sale. Priced at around $90, it will use an improved and larger version of the transformer specified above and will deliver more power - around 60 watts at 230VAC. See the Altronics catalog in this issue for further details. ~ ~ '"! PIN2 IC2d This can be achieved by substituting a series 120kQ resistor and 5QkQ potentiometer, as shown in Fig.6. However, this will not be the most efficient way of powering a small telescope motor. We hope to present a low power version of the circuit in a coming month. erated to drive QZ. First, the square wave signal at pin 3 of IC1 is inverted Vee using transistor Q3. This inPIN14 verted signal is extracted from IC2b the junction of the two 4 7kQ resistors in Q3's collector cirOV cuit and, as before, swings Vee between Vee and ½Vee. The inverted signal is then fed to PIN13 IC2a the inverting input (pin 8) of ICZb and the output of this ov comparator then drives the Fig.2: this diagram shows the waveforms gate of QZ. generated by the major circuit sections. Note Note that the non-invertparticularly the waveforms generated by the ing inputs (pins 11 & 9) of deadtime comparators (IC2c & IC2d) & how ICZa and ICZb and joined tothey effectively narrow the positive-going pulses from IC2a & IC2b. gether and are nominally at ¾Vee (we'll look more closely at this shortly). However, because the has a lkQ pull-up resistor and drives signal on pin 8 of ICZb is inverted the gate of Ql via a 100Q resistor. compared to the signal on pin 10 of Each time ICZa's output is pulled high, Ql turns on and switches one half of ICZa, the outputs from these two comparators (and thus the drive signals to the transformer primary to ground. Ql & Q2) are 180° out of phase. Tlrnt lakes care of the drive cirThus, Ql & QZ are alternately cuitry to Ql. We now return to IC1 to switched on and off to drive their see how the out-of-phase signal is genov RESISTOR COLOUR CODES D D D D CJ D D D D 44 No. Value 5-Band Code {1%) 1 6 150kQ 47kQ 15~Q 10kQ 8.2kQ 1.6kQ 1kQ 100Q brown green black orange brown yellow purple black red brown brown green black red brown brown black black red brown grey red black brown brown brown blue black brown brown brown black black brown brown brown black black black brown 1 2 2 5 SILICON CHIP respective halves of the transformer primary winding. At least, that's the basic scheme. In practice it's not quite as easy as that. If we simply use out-of-phase waveforms to drive the transistors as described above, both transistors will be on for a short time at the transition points. That's because these devices take some time to change state, which means that the next transistor in the sequence will turn on before the other has had a chance to turn off. This will cause heavy transient currents to flow in the output stage and cause overheating of the Mosfet devices. Dead time comparators To avoid this problem, we have added a "dead-time" circuit to ensure that both transistors are off at the transition point. Essentially, we turn the active transistor off early in the cycle and the other transistor on late. This job is performed by comparators ICZc and ICZd. Let's see how this circuit works. A voltage divider consisting of a series resistor string between the Vcc supply rail and ground is used to provide the reference voltages for ICZc and ICZd. From the Vee rail, we have a l0kQ resistor, then four resistors (100f.!, 1.6kQ, 8.ZkQ & 100Q) which total 10kQ, and finally another 10kQ resistor to ground. Note the 2/3Vcc and 1/3Vcc voltage points shown on the circuit. These correspond to the switching voltages used for oscillator IC1. The 2/3Vcc point is tied to pin 5 of IC1 which is also nominally at 2/3Vcc. Fig.3 (right): here's how to install the parts on the PC board & complete the wiring. Use mains-rated cable for the connections between the transformer & the mains socket & note that Ql & Q2 must be electrically isolated from the rear panel using TO-220 mounting kits. We have connected these two 2/3Vcc points together to remove any slight variation that may exist between these two voltages. The non-inverting input ofICZc (pin 7) connects to the voltage divider at the junction of the 1000 and 1.6kQ resistors. This pqint is at 0.663Vcc, which is just slightly less than 2/3Vcc (0.666Vcc). Similarly, the inverting input of IC2d (pin 4) is connected to the junction of the lO0Q and 8.ZkQ resistors in the bottom half of the divider. This points is at 0.336Vcc, which is slightly higher than 1/3Vcc (0.333Vcc). To complete the dead-time circuit, the inverting input ofICZc (pin 6) and the non-inverting input of ICZd (pin 5) are connected to the timing capacitor on pins 2 & 6 of ICl. As shown in Fig.2, the signal voltage across the timing capacitor takes the form of a triangular waveform which swings between 2/3Vcc and 1/3Vcc. Fig.2 shows the resulting output signals generated by comparators IC2c & IC2d. Note that the output of IC2c (pin 1) swings low just before the voltage across the timing capacitor reaches 2/3Vcc and then swings to ¾Vee again shortly after this point. Similarly, pin 2 of ICZd swings low just before the capacitor discharges.to 1/3Vcc and swings to ¾Vee again a short time later. The open collector outputs of IC2c & ICZd are tied together and connected to a voltage divider consisting of 15kQ and 47kQ resistors (to produce the ¾Vee voltage). Thus, the combined outputs of IC2c & IC2d produce brief low-going pulses every lOms which straddle the transition points of the switching waveform produced by ICl. (Note: the outputs from IC2c & ICZd are shown separately on Fig.2 for clarity). This pulse waveform is applied to the non-inverting inputs of IC2a & IC2b (pins 11 & 9). Each time the outputs of IC2c & IC2d swing low, the outputs of IC2a & IC2b are also forced ► ~ \/5,)J ,\ ( + METAL REAR PANEL FUSE HOLDER INSULATING BUSH MICA WASHER SUPPLY LEADS 'XcoRD GRIP GROMMET I) O 0 01 02 GDS GDS 240V <at> OUTPUT SOCKET 0 FRONT PANEL low and both Ql & QZ are off. For the rest of the time, the outputs of IC2c & ICZd are at ¾Vee and so IC2a & IC2b gate through the respective waveforms WARNING This project produces an output voltage at mains potential. For this reason, exercise care when working on the unit and make sure that any equipment to be used with it is in a safe condition . on their inverting inputs to drive the switching transistors. The resulting outputs from IC2a & ICZb are shown at the bottom ofFig.2. Because, the switching pulses that are applied to the transistors are slightly narrowed, the transistor that's on has time to turn off before the other turns on and so the possibility of contention is eliminated. Power for the circuit is derived from a +12V car battery. This supply connects directly to the centre tap of transformer Tl via a 5A fuse and power switch S1. The remainder of the cirFEBR UA RY 1992 45 Fig.4: here is the full-size etching pattern for the PC board. cuit is powered via a 100Q decoupling resistor and voltage clamping diode ZDl. This zener diode is used to quench any high voltage spikes which could otherwise damage the 7555. Finally, the decoupled supply rail to the ICs is filtered using 100µF and 10µF electrolytic capacitors. Construction Most of the parts for the SILICON CHIP 40-Watt Inverter are mounted on This oscilloscope photograph shows the output waveform produced by the dead-time comparators (IC2c & IC2d) at top and the sawtooth voltage developed across the 0.lµF timing capacitor (bottom). a PC board coded SC11203921 and measuring 125 x 46mm. Fig.3 shows the parts location on the PC board. Begin the construction by installing PC stakes at all external wiring points, then install the resistors. Check each resistor value on your multimeter before installing it on the board, just to be sure that you have the correct value. Now install the two ICs , Q3 and ZD1 as shown on Fig.3 . Make sure that these parts are all correctly oriented (see Fig.1 for Q3 's pin connections). Finally, install the capacitors on the board. The two 0. lµF capacitors can go in either way around but take care with the polarity of the two electrolytics. The completed board assembly can now be mounted on the lid of the case at the rear and secured with four selftapping screws (the board mounting holes align with the integral plastic standoffs on the lid). Use an oversize INSULATING . MICA WASHER -~~jl drill bit to shorten the unused standoffs so that the board sits neatly in position. Once the board is in position, install the metal rear panel and mark out the mounting holes for the two Mosfets. These devices should be mounted directly behind their respective PC stakes (see photo). Drill these mounting holes to 3mm, then mark out and drill mounting holes for the fuseholder and cordgrip grommet. The Dynamark label can now be affixed to the plastic front panel and the cutout made for the power switch. This done, remove the front section of the power socket and use the back section to mark out its mounting and lead access holes. These holes can now drilled to size and the socket secured to the panel. Nylon screws The transformer is mounted towards the front of the lid in an area which is free of ribs, and is secured using two 4BA x 12mm nylon screws and nuts. Do not use metal screws to secure the power transformer, as they could represent a safety hazard if the transformer breaks down to frame. Similarly, for safety reasons, do not use a metal front panel or an aluminium front panel label. Instead, be sure to use a plastic panel and a plastic adhesive label (or a plastic panel with screened lettering) as specified in the parts list. The remaining hardware items can 120k SCREW r lllillD{s 50k IC1 --...._ CASE .L T0220 DEVICE This is the 240VAC output waveform that's delivered when driving a 40W load (obtained used a 20:1 probe). 46 SILICON CHIP Fig.5: mounting details for Mosfet transistors Ql & Q2. Smear all mating surfaces with heatsink compound before bolting the assemblies together, then use you DMM to check that the metal tabs are indeed isolated from the rear panel. Fig.6: this simple modification to the clock circuit based on 555 timer IC1 will let you vary the output frequency from about 4060Hz, so that the unit can be used to drive a small telescope motor. The 50kQ pot should be mounted on the rear panel. PARTS LIST 1 plastic instrument case, 155 x 158 x 64mm, with metal rear panel 1 plastic Dynamark front panel label, 140 x 56mm (note: do note use an aluminium front panel label) 1 PC board, code SC11203921, 125 x 46mm 1 M2165 60VA transformer 1 panel mount mains socket 1 panel mount 3AG fuse holder 1 5A 3AG fuse 1 cord grip grommet 1 panel mount 15A rocker switch 2 TO-220 mounting kits 11 PC stakes 2 4BA x 12mm nylon screws, nuts & washers 1 1-metre length black heavyduty hookup wire 1 1-metre length red heavy-duty hookup wire 2 large alligator clips (or cigarette lighter socket; see text) The PC board is secured to the lid of the case using self-tapping screws , while the transformer is secured using nylon screws & nuts. Use cable ties to bundle the various leads together, to keep the wiring neat & tidy. now be installed on the front and rear panels and the wiring completed. Note that the front panel must be installed upside down on the lid, as shown in the photographs; ie, with the power switch to the left. Follow the wiring diagram (Fig.3) carefully and use 240VAC 10A cable for all wiring to reduce voltage losses. Similarly, use heavy-duty colour coded cable (red for positive, black for negative) for the external battery leads. These leads should be fitted with large alligator clips to make battery connections quick and easy. Alternatively, you can terminate the battery leads in a cigarette lighter socket but make sure you get the polarity right. No earth connection Note that the Earth pin of the mains output socket is not connected to any part of the circuit. It does not have to be and nor should it be in a fully floating supply such as this. The same rule applies to portable 240VAC generators. The two Mosfets must be isolated from the metal rear panel using stand- ard TO-220 insulating kits (ie, mica washers and plastic bushes). Fig.5 shows the mounting details for these two devices. Smear all mating surfaces with heatsink compound before bolting the assemblies together. Finally, check your work carefully before installing the fuse and completing the case assembly. Testing To test the unit, connect it to a 12V car battery (or to some other 12VDC supply capable of 5 amps or more) and plug a 40W lamp into the mains socket. Check that the lamp lights as soon as power is applied and that it delivers about the same light output as it does when plugged into a standard mains outlet. If the inverter does not function, switch it off immediately and check carefully for wiring errors and for bad or missed solder joints. If these checks don't reveal anything, disconnect the transformer from the + 12V rail, then re-apply power and check the voltage on the supply pins oflC1 & ICZ . These pins should be at about 12V, depending on the output from the battery. Semiconductors 1 7555 CMOS timer (IC1) 1 LM339 quad comparator (IC2) 2 MTP3055E 12A, 60V power FETs (01 ,02) 1 BC548 NPN transistor (03) 1 16V 1W zener diode (zo·1) Capacitors 1 100µF 16VW RB electrolytic 1 10µF 16VW RB electrolytic 2 0.1 µF metallised polyester Resistors (0.25W, 1%) 1 150kQ 1 8.2kQ 6 47kQ 1 1.6kQ 1 15kQ 2 1kQ 2 10kQ 5 100Q Miscellaneous Machine screws and nuts, selftapping screws, mains-rated cable, tinned copper wire. Finalfy, if you have access to an oscilloscope, you can check the circuit waveforms against those shown in Fig.2 and the accompanying photographs. Note, however, that the waveform at the outputs of ICZc & ICZd will be a combination of the separate waveforms shown in Fig.2, as indicated previously. SC FEBRUARY1992 47 ~LTRONICS ELECTRONICS 1992 COMPONENTS YOURS FREE with this month's Silicon Chip and Electronics Australia Magazines QR CATALOGUE Send $1.00 to cover P&P to: AL TRON I CS MAIL ORDER, PO BOX 8350, Perth Stirling Street, Perth WA 6849 Our 1992 Catalogue has even more fantastic new products and greater value than last year's. We still offer the technical help that only a staff of electronic enthusiasts like yourself is able to give. Of course, in addition to this we have our FAMOUS OVERNIGHT DELIVERY Australia wide and Bankcard phone order service to 4pm (E.S.T.) Monday to Friday. All on our quality products at DIRECT IMPORT PRICES that enables YOU TO SAVE UP TO 50% off competitors' prices. Jack O'Donnell Managing Director Redford Poly Emulsion Coated Cone S~eakers 250mm PECC Woofer 10·· . 8 Ohm. 130 watts max. 1.17kg magnet C 3026 Normally $ ~ 5 $85.oo 2 up $75.oo Massive 380mm PECC Woofer This month Redford Woven Carbon Fibre LoudsP. ker 100mm Full 165mm Woofer 200mm Woo er Range 8". 8 Ohm . 100 watts max. For those 6 'h"". 8 Ohm. 70 watts max. Superb 4". 16 Ohm. 25 watts max. Ideal replacement speaker or for the car. Wire two in parallel to get 8 ohms! Massive 226g magnet. c 0643 Normally $_,38'.95 bass response for Hi-Fi's or even the ca r! 567g magnet. C 3034 Normally $29 .95 5 up $24.95 Tweeter Bargain Less Than ½ Price! This month $B2':s5 $65.oo 2up $55.oo Thi• month C 3036 Normally $ ~ 5 $85.oo 2up $75.oo Thi• month 15". 8 Ohm . High power rating of 200 watts max. makes this loudspeaker excellent for guitars, bass bins etc. 1.8kg magnet . Superior bass reproduction. C3032 Normally $~00 Cross Overs $175.oo $155.oo Thi• month 2 up Attention Audiophiles/ Optimise Your Sound Syatem With Thi• Oxygen-Free Speaker Cable Dome Tweeter with Ferro Fluid 60 Watt Max. Power. Silky smooth frequency response 1.5kHz to 20kHz. Wide angle dispersion . Massive power handling capacity. Diam. 94mm. Twm Jumbo Cable Twin Mega ~ Jumbo Cable •. , High spectrum. Purity. Incredible low price! who really want to wake up the neighbours. 848g magnet. C 3012 $'9'.'95 $12 .00 10 up $10.oo Thl1 Month $8.95 C 4003 3 Way 80 Watts $19 .50 C 4002 2 Way 60 Watts I 204 x 16 AWG. 504 x 12 AWG. W 0138 Normally ~ 5 W 0138 Normally U8'.oo · Thll Month $20.oo f:~ Roll Thi• Month . $45.oo f:~ Roll , .' i . Trace Oscillos This model is a dual trace 20MHz Oscilloscope using a high brightness CRT. The vertical amplif iers have high sensitivity of SmV/ div and a frequency characteristic response with smooth roll off exceeding 20MHz. The TV sync. signal operator circuit is provided to ensure stable observation of video signals. Triggering is obtained by sampling the AC power waveform, external waveform or internally generated trigger. Highly recommended for Service Workbench, Design Laboratory, Manufacturers, Universities and the dedicated enthusiast. 0 0156 This Month Only Id Max $599 a·o Micron Soldering Station ____ T 2440 Normally $J,B1J.95 This Month 1 GHz Frequency Counter $140.oo The MICRON T 2440 soldering station offers the ultimate in controlled temperature hand soldering. Temperature range is switch selected. So there is no MK II Replacement Tips need to change soldering iron tip. ts.50 All ea T 2~7 0.8mm T 2428 1.6mm T 2429 3.2mm • Zero Voltage Switching • Grounded Tip • Low Voltage Element • Chrome Plated Iron Clad Tip A fantaatlc addition to your work bench. Feature,: • Display 8 digits, 7mm red LED display with decimal point, gate, overflow, KHz, MHz and us indication • Check: Counts 12.6V centre-tapped. 150mA. Save on Dis-continued Tansformers MA2851 Normally Thla Month Only 10 Up $5.oo $4.oo FSD MU52E type. Overall a 0531 1A dimensions BOW a 0535 a 0538 30V x 66mmH. 50mm hole. internal 10MHz time base oscillator. A must for all SP.rious hobbvists and technicians. $110 WERE sov NOW $15.oo $15.oo $15.oo FAMOUS AL TRON/CS QUALITY KITS Studio 200 Stereo Control Unit Two Channel Pro Power Amp 90 Watts Per Channel Out performs Commercial Unlla Coating $600 or More The Studio 200 Stereo Control unit makes a great companion to the K 5770 stereo power amplifier (and other power amps). It features a slim 1u rack mount profile, stereo/ mono switch and bass, treble and volume controls. Inputs include phone, tuner, V.C.R. and tape loop. Virtually all components mount on PCB's, making assembly and construction a breeze. Altronics kit includes fully professionally punched and printed panels. K 5015 $229.oo BUY BOTH KITS FOR $750 & SAVE! Playmaster "Pro Series One" High Power Amplifier Thla atereo amp la Ideal for background/foreground appllcatlona. Fantastic for reItaurantI, ahopa, dlIco'I, aerobic,, PA aound IyItema and home. • 90 watts RMS per channel minimum into 8 Ohms from 20 to 20,000Hz with less than 0.05% THD • 2 large power meter indicators • EIA panel with handle device • XLR socket for speaker te rminal • Output relay to eliminate turn-on and off transients • Dirr.ensions: (W x H x D) 482 x 92 x 295mm • Weight: 10.Skgs • Ideally suited to A 2210 sterno tuner. A 2040 $ji25'.oo Thla Month $599.oo AM/FM PLL Tuner Build this professional high powered stereo amp. Features 140 watts RMS per channel into 8 Ohms, with harmonic distortion less than 0.007%. This design has been carefully developed to produce a high definition audio output with reliabi lity ease of construction and low cost. Kit comes complete with all components, ' toroidal transformers and case. The diecast front panel doubles as the heatsink. The chassis is supplied in kit form and assembles in minutes. Features: • Individual toroidal transformers for each channel for low residual hum and total channel separation • Individual power supply components for each channel • Diecast front panel doubles as the main heatsink • Diecast front panel doubles as the main heatsink • Straight forward construction • Mosfet technology for ultra-high performance • Overload indicator illuminates when distortion is above 0.05% This fantastic tuner la the Ideal add-on lo any aound 1yItem. Can be uaed aa background ~~;:;~•~~-~_re1taurant1, shops elc or any PA application. Alao a great upgrade for the • Digita_l LED frequency readout display • FET FM front end for high image rejection • Phase-linear ceramic filters are incorporated In both AM and FM IF section• Phase-lock loop (PLL) IC for FM multiplex stage • Dimensions: (W x H x D) 435 x 60 x 232mm • Weight: 3kgs. A 2210 $~.00 Thla Month $199 .00 COMPUTER BITS BY JENNIFER BONNITCHA More things to do when things go wrong This month we have more troubleshooting tips particularly ways of repairing damaged files. Should you encounter problems with unexpected program termination, one of the first things you should do is check for file damage. When you need to find out if there is any file damage, the DOS command CHKDSK (CHecK DiSK) is a good starting point. Its job is to check the formatted size and available space on a disc, indicate the amount of disc space consumed by system files, data files and bad sectors, and finally show the standard memory size and amount of memory available. As a safety measure, it's a good idea to run CHKDSK occasionally on all your regularly used hard and floppy discs to prevent minor problems from turning into major ones. This is an external DOS command, so you need to make sure a copy of the file is available either in the current directory or its location CHKDSK has two switches you can use in conjunction with the command: /f (FIX) instructs CHKDSK to attempt to correct any errors detected. CHKDSK always asks if it should attempt to correct errors it detects, however it will actually do nothing unless this switch is specified /v (VERBOSE) this switch directs CHKDSK to display filename and path specifications for each file on the disc. Using the DOS pipe (I) and FIND commands, you can find a file on a hard disc: CHKDSK C:/V I FIND FILENAME You should initially run CHKDSK without the /f switch to determine what type of error may have taken "Should you receive an Abort, Retry, Fail, Ignore command while running CHKDSK, avoid the Ignore option. If you do choose Ignore, the corrective action taken by CHKDSK could cause further problems." must be included in the Path command. CHKDSK analyses the entire disc and in doing so, compares each subdirectory entry size against the File Allocation Table (FAT), checks the integrity of each allocation chain in the FAT and can optionally repair some forms of file damage. 50 SILICON CHIP place. You should also note that CHKDSK is not designed for use with the DOS commands JOIN, SUBST or ASSIGN since it only reports on real rather than logical drives. For this reason, CHKDSK should not be run on a network disc drive either. The command CHKDSK [drive] will typically return something like that shown in Fig.1. The disc is examined and if all is OK, no errors are reported. The status report displays information about the disc and the computer's memory. The first four lines report on the total amount of disc space, the number of files on the disc and the remaining available space. You may see a bad sector report as well. The remaining two lines report . on the amount of conventional memory used and the amount still available. You can re-direct the output from CHKDSK to either a file or printer if you wish using the command: CHKDSK [drive]> [FILENAME] or CHKDSK [drive] > PRN In addition, if you include a filename in the command, CHKDSK will display the number of non-contiguous areas (or sectors) on the disc that contain the name files. Although fragmented files (ie, those with non-con- · tiguous blocks) are acceptable to DOS, they can slow down your computer's performance quite considerably. If you use the DOS wildcard . * , CHKDSK reports on each fragmented file in the current directory. Should you receive an Abort, Retry, Fail, Ignore command while running CHKDSK, avoid the Ignore option. If you do choose Ignore, the corrective action taken by CHKDSK could be incorrect and only cause further problems. Try the Retry option several times if needed and then for preference use the Fail or Abort option. Ignore•is the absolute last resort. · Problems you may have CHKDSK can get confused over two problems and thus will abort the procedure itself: Cannot CHDIR to <file specifier> CHDIR .. failed trying alternate method Failures are usually caused by car- When the file is closed, DOS writes ing the chase eventually become the new information to the FAT and if memory-resident interrupted, the FAT chain is incomplete, the file's directory entry is inin the DOS disc Volume LABELNAME created Dec 12, 1991 3:15p consistent and the data may or may buffers, so the drive 71442432 bytes total disk space light will go out not actually exist on the disc. A physi110592 bytes in 3 hidden files cally or logically damaged directory until you restart the 225280 bytes in 34 directories computer. Listen may also create this problem. 57335808 bytes in 960 user files also for a rhythmic Provided you used the If switch 13770752 bytes available on disk pattern to the disc when running CHKDSK, you can reply "Y" to the convert message. DOS will movement. 655360 bytes total memory then create a separate file for each Detecting the 320704 bytes free lost chain. These files are named problem file is FILExxxx.CHK (where xxxx represents easier if you redirect the CHKDSK a sequential number starting with rupt interrupt tables or insufficient output to a printer (CHKDSK > PRN). 0000). Should you decide to answer RAM. In the first instance, the file tree You will most likely receive another "N", DOS converts to zero the entries cannot be processed beyond the point error message, then CHKDSK will fail in the FAT that correspond to the lost specified. When directories are cre- again. Once this happens, halt the chains and marks those areas as availated, DOS automatically inserts two program, restart DOS then use the Iv able for new files. entries. The first entry in each switch so CHKDSK can display the If you have not used the If switch, subdirectory is the "." entry (dot) name of each file it checks. The last CHKDSK reports the amount of disc which represents the directory itself. file shown is usually the suspect file. space that could be freed, regardless The second entry is the given name When (if) you find the problem file(s), of your answer to the conversion ques" .. " (double dot) which represents the you can either delete the file and hope tion. Answering "Y" will cause parent of the current directory. If ei- all the associated chains are also deCHKDSK to report the number of files ther of these entries is corrupted, leted. You could use a program like that would be created. CHKDSK displays the first message. Norton's FASTSAVE or Mace Utilities You could, depending on the value CHKDSK will ask if you want to SAVE-RESTORE to repair the FAT or of the lost chains, answer "Y" to the convert the directory to a file. Answering yes creates a standard file containing the contents of the subdirectory (ie, the file names). The ac"A cluster is lost if the FAT entry for the cluster is tual contents of the files become lost a non zero number but the cluster does not clusters when the subdirectory is conbelong to any file. A contiguous set of lost verted. However, you get the chance to do something about the lost clusclusters is a lost chain." ters at the conclusion of the CHKDSK command, provided you used the If switch. finally, format the disc to re-generate conversion question then examine the You could get this message during the FAT (but, of course, destroy all file's contents. CHKDSK if you have a temporary hardexisting information). Cross linking ware glitch in the disc controller or Little orphan Annies interface. FILENAME is cross-linked: If CHKDSK locks up, it has entered a xxx lost clusters found in yyy chains On cluster xx loop in which one link in the file''s Convert lost chains to files (YIN)? Two files are cross-linked when the chain in the FAT points back to an A cluster is a unit of space on a FAT indicates that a cluster belongs to earlier link. During processing, should disc. A cluster is "lost" if the FAT both files. The message is displayed a wayward entry point to a previous entry for the cluster is a non zero once for each file that is cross-linked. FAT entry for the file, CHKDSK enters number but the cluster does not be- CHKDSK doesn't take any action and an endless loop moving backward and long to any file. A contiguous set of the files can often be salvaged by copyforward to trace the chain. The trace lost clusters is a lost chain. ing them to another physical disc or continues forever and can be broken The most probable cause of this partition. You should then delete the using the <CTRL BREAK> or <CTRL ALT problem is that a program or DOS Gross-linked files and examine the DEL> key sequence (or, if you have stopped before DOS finished closing copies. !f the files are intact, run one on your computer, press the Rethe file. This error occurs only when CHKDSK again for the suspect disc set). extending a previous file or when cre- and if all is OK, copy the files back to You can be reasonably certain you ating new files. CHKDSK has found the original disc. Remember that once are in a loop when CHKDSK displays some clusters without an owner. When you delete the files, they are almost no message, there is no disc activity a file is created or extended, DOS impossible to recover. for approximately 30 seconds, or the marks the clusters it will write to as We'll have more adventures next drive keeps working beyond an acin-use, thus creating the link in the month on checking and repairing disc ceptable limit. The FAT sections causfile's FAT chain. damage. SC FIGURE 1 FEBRUARY1992 51 IPRODUCTSHOWC~SE I Ultra-slim cooling fan is very quiet Semiconductor lasers from Siemens Siemens has just released two semiconductor lasers for applications in laser soldering, isolated energy transmission and the repair of detached retinas in eye surgery. The small high power lasers, packaged in a TO-220 case, are available with a plain window or with a spherical lens and welded connector socket. The lasers are suited to situations where high power is a more important requirement than narrow wavelength range . In these applications, semiconductor lasers can forego a built-in Peltier element in favour of external cooling but at the expense of frequency stability. This allows the construction of high power lasers in much smaller cases. The lasers, types SFH487401 and SFH487406, have an emission wavelength of 809±5 nanometres and a continuous power of 1 watt. Versions in the 780-860 nanometre range can also be supplied. For more information, contact Edgar Sandy, Electronic Components , Siemens Ltd, 544 Church Street, Richmond, Vic 3121. Phone (03) 420 7314. Micronel has released a new 12V cooling fan that is only 14mm thick, 62mm in diameter and has an acoustic emission level as low as 20dB(A). The new fan comes in two models, F62 LM and F62 MM, with a flow rate of 340 litres/minute and 420 litres/ minute respectively. Micronel also has an extensive range of miniature fans from as small as 24mm in diameter. For further information, contact RAE Electronics, PO Box 76, Thirroul, NSW 2515. Phone (02) 232 6933. 5WDC/DC converters Low cost crimp press from Scope This unit is designed o replaGe hand-held ci;imping tools when output volume sizes increase. The Panavise 1/4-tonne pi;ess (model 560) will cr,imp anything fr.am coax to solid wire rterminals and optical fibi;e to telephone cable. At under $400, it is a cheap way to shorten production times and reduce hand and wrisli strain problems. For further informarion, confact Scope Laboratories, 3 Walton St, 52 SILICON CHIP Airport West, Vic 3042. Phone (03) 338 1566. Alpha Kilo Services has extended its range of Newport Components DCto-DC converters from 2W to 5W. The NMX series of converters are EMI compatible and utilise the industrystandard 2-inch square package. They cater for input voltages of 5, Bose Acoustimass 5 Series II speaker system Bose has released the Acoustimass 5 Series II speaker system which provides improved performance compared to its predecessor. The system consists of two arrays of stereo imaging cubes and an Acoustimass bass module, placed out of sight on the floor. A full review of this system and the Bose Lifestyle Music System appeared in the November 1990 issue of SILICON CMIP. The Acoustimass 5 Series II speaker system is compatible with amplifiers rated from 10-200 watts ELECTRONIC WORLD DISPOSALS Common transistor pack over 60 for just Varistors 230V surge protection only 60c each BA317 (similar 9148) per channel. For more information, contact Mychelle Vanderburg at Bose Australia, 11 Muriel Avenu<at>, Rydalmere, 2116. Phone (02) 684 1022. $2.80/100 Bulk capacitor packs Wima's, polycarb, disc etc $9.30 Variable gang capacitors open gang receiver type $6.95 12" sq blank PCB $4.00 DB25 right angle female $2.50 Assorted Hivolt capacitors 80c Silver mica capacitors 30c Electro's 100µF 160V $1.30 Electro's 10µF 40V 12 and 24V and have regulated output voltages of 5, 12 and 15V. Both single and dual output configurations are available. The devices offer regulation better than 0.5% and isolation of 500V, with typical efficiencies of 70%. For more information, contact Peter Dau, Alpha Kilo Services, 1/144 Burns Bay Road, Lane Cove, NSW 2066. Phone (02) 428 2906. RS232 breakout box from Rod Irving tester, monitor and patching box. It doesn't require any external supply, has multi-colour indicating LEDs and comes with jumper leads. The unit also has 24 switches to allow you to break out circuits or reconfigure and patch up to 24 lines. The break out box retails for $99 and is available from Rod Irving Electronics in Sydney and Melbourne. Phone/FAX line sharer $2.20/100 RF inductors assorted values from 60c to $1 .30 Relays 12V 5A PCB mount $2.00 Filters 21 MHz 10-pole 15kHz 1.5kQ $16.00/100 BUZ90 power FETs $4.75 1 amp Triacs only 45c each Used AA nicads ?00mAh 60c each Rotary switches David Reid Electronics has a new phone/fax line sharer which makes a separate fax line unnecessary. When you are in the office, calls are taken in the normal way. When answering the phone, a pleasant beep is heard if the call is a fax transmission. You hangup and the call is redirected to the fax. When you are out of the office, incoming calls will be redirected to the fax after eight rings. An option allows $20.00 High intensity LED's Oak type $5.50 Wafer type $2.55 5mm former & cores If you're in the business of checking out computer communications cables, then you'll find this a welcome addition to your box of tricks. It's an RS232 DB25 in-line circuit $6.95 now 50c Coaxial relays $36.00 Bulk ICs at low prices 8049 X 9 LM324 x 25 CD4049 x 25 TL082 x 50 $18.00 $10.55 $12.00 $35.00 Numerous components all reduced to selL Come and browse and sweep up the bargins. Electronic World Disposals 27 The Mall (Cnr Eastfield & Bayswater Rds) South Croydon, Vie 3136 Telephone: (03) 723 2699 FEBRUARY1992 53 the number of rings to be changed from 1 to 10 rings or the option can be turned off completely. If an answering machine is connected to the line, autodialled fax transmissions will be detected within 3 seconds of the machine answering and will then be redirected to the fax. Voice callers will be totally unaware of the switch and can leave messages as normal. The Easy-Connect phone/fax switch also has a hold facility. Any phone connected to the same line as the switch will be able to park a call and allow it to be picked up by the same or another phone. Ea$y-Connect is compatible with Commander, Keyphone or PABX systems , as well as single line installations. For more information, contact David Reid Electronics, 127 York St, Sydney, NSW 2000. Phone (02) 267 1385. and vertical fields as standard. For more information, contact Anitech, 52/2 Railway Parade, Lidcombe, NSW 2141. Phone (02) 749 1244. Phone/answering machine with remote 2-channel scopes for the serviceman Anitech now has a range of 2-channel oscilloscopes from Meguro Electronics, specifically suited for service work. Compact and lightweight, the MO-1240 Series contains a battery and charging unit for situations where a mains supply is unavailable. The whole unit weighs only 5.5kg and recharging takes just two hours. There are three models in the range , with bandwidths of 20MHz (MO124 lA), 40MHz (MO-1242A) and 60MHz (MO-1243A). All have a sensitivity of lmV to 5V/division and voltages, time differences and frequencies can be displayed on the screen in digital form. An additional feature is the provision of video sync on both horizontal PREST N ELECTRONICS 217 High Street, Preston, Melbourne Victoria 3072 (Cnr of Bell & High Street) Mic UHF/Remote Control Car Alarm $99.00 Altron ics/Labtech CRO. 20MHz Dual Trace $699.00 Economy 15W Soldering Iron - 240V Fine Point $19.95 SS-750 Smoke Detectors. Meets Australian Standards $24.95 CMOS/TTL Logic Probes $29.95 0 -1056 Economy 17-Range Digital Multimeter $39.95 'ff Mail Order Hot-Line B/Ca rd-Mast/Card-Visa-Cheque Phone (03) 484 0191 54 SILICON CHIP The Audioline 915 combined phone and answering machine comes with a remote control for operating the answering machine. It also incorporates pulse dialling which can be switched in. The unit can also be remotely switched on by calling up the answering machine number from another phone. This is ideal for businesses Compact powered subwoofer Yamaha has incorporated their Active Servo Technology into a new compact powered subwoofer. The Active Servo Technology is a motional feedback system that monitors cone excursions and output power. The information gathered is fed back to the amplifier, thus ensuring excellent bass reproduction from the compact cabinet. The YST-SW50 measures 210 x 475 x 334mm, can be oriented either horizontally or vertically, and is magnetically shielded to permit placement near a video monitor. It uses an 18cm driver and the built-in amplifier can deliver 50 watts at frequencies down to 25Hz. The top end is cm;itrolled by an 18dB/octave filter variable from 50 to 200Hz. The system incorporates a 180mm multi-range driver and a 600mm air woofer. Since the subwoofer is self-contained and selfpowered, it poses no extra load to your audio system. It retails for $499 and is available from all Yamaha agents. For more information, contact Yamaha Music Australia, 17-33 Market Stteet, South Melbourne, Vic 3205. Phone (03) 699 2388. n II QUALITY NO BRAND DISKETTES Double contact coax switch The Revex S20N is a double contact coax switch for switching high frequency signals on a 50Q line. It is intended for use in switching a transmitter between antennas or for switching an antenna between transmitters. Rated for use up to 1.5GHz, it has negligible insertion loss, high isolation between terminals (>70dB at 200MHz) and can handle up to lkW PEP. The coax contact mechanism is self-cleaning and the central line is made from the same phosphor bronze used in"the springs, which gives high contact reliability. The unit is housed in a sturdy alloy case and stands on three rubber feet. Self-tapping screws are also 5.25" DSDD 5.25" DSHD 3.5" DSDD 3.5" DSHD ****** * ** *** * ** JAPANESE BRAND 'S-;N'/w'/i/1.,,. FLOPPY DRIVES -:c- SUPER -~ 3.5" 1.44M $99.00 ~ 5.25" 1.2M $125.00 ~,tt~"' SPECI~~ ----------- supplied for surface mounting. Connections are via standard SO239 sockets. It is available from Dick Smith Electronics stores for $99.00 (Cat. D-5202). and homes alike. You'll no longer miss that message because you forgot to turn it on. The unit also allows incoming messages up to 3 minutes long to be recorded and can record personal messages fo r other users of the system. The 915 retails for $249 and is available from any Jaycar Electronics store. Butane gas-powered soldering tool This butane gas-powered soldering tool is designed for craftsmen and professionals, and is suitable for those hard-to-get-at jobs where a normal soldering iron won't go. It comes with a set of accessories for using it as a soldering iron, blow torch, hot air blower and a hot knife. $4.70 $8.95 $8.50 $16.95 It ignites easily with the built-in flint ignitor and can be controlled for an equivalent 10-60 watts rating. You can get yours for just $79 .95 (fuel not included) from Rod Irving stores in both Sydney and Melbourne. .,.m:...;. ,~i;;.:.~: RCS Radio Pty Ltd is the only company whi ch manufactures and sells every PCB f., front pan el published in SILICO N CHIP, ETI and EA. 651 Forest Road, Bexley, NSW 2207 . Phone (0 2) 58 7 34 9 1. s, E "'ILLS Every year, thousands of people die from ■ smoke inhalation caused during minor • • home fires. Most of these deaths and , considerable property loss could have •• been avo ided with UNIVERSAL'S SMOKE SIGNAL early warning smoke ', • ' detector. The SS-750 features: ■ Ionization sensor to warn of smoke and fire even before flames are visible ■ Extra loud warning horn to penetrate closed doors ■ 9 volt battery (supplied) operation to protect even during power failures ■ Installs in minutes · ■ Built-in test button ■ Audible beep signal to indicate battery replacement required * * * * * * * * * * * * * * *~ ~ PRIME SPEC SEP,,IS .,.<~ ~ DYNAMIC RAMS 4164-10 ........... $3.25 41464-08 ......... $2.75 41256-08 ......... $2.75 414256-08 ...... . $7.95 411000-08 ..... $7.95 256KSIM,SIP. $23.50 IM,SIM,SIP .... $79.00 4M SIM,SIP. $335.00 REGULATORS 7805T .............. $0.50 7812T .............. $0.50 7815T ....... ....... $0.50 7905T .............. $0.60 7912T .............. $0.60 7915T .............. $0.60 317T ................ $1.50 337T ............... . $2.10 723 .................. $0.80 DIODES IN4148 ............ $0.04 IN914 ............ .. $0.05 IN4004 ........ .... $0.08 IN4007 ......... $0.10 IN5404 ............ $0.20 IN5408 ........ .... $0.25 BRIDGES W04 ................ $0.50 BR64 ............... $1.50 BR104 .. $2.50 BR254 ......... .... $3.50 BR354 .. ....... ... . $3.95 LEDS 5mm RED ........ $0.15 5m m Green .... . $0.25 5mm Yellow .... $0.25 TRANSISTORS BC547/8/9 ........ $0.1 5 BC557/8/9 ...... .. $0.15 BD139 .............. $0.45 B0140 .............. $0.45 TIP31C ............. $0.80 TIP32C ..... $0. 80 MJ15003 ... ...... $6.50 MJ15004 .... ..... $6.50 MJ2955 ......... .. $2.50 2N3055 ............ $1.50 LINEAR & SPECIAL FUNCTI ON 1488 ............ .. $0.50 1489 ......... . $0.50 8250 .......... ...... $7.50 82C450 .......... $17.50 16C450 .......... $18.00 16C550 .......... $29.50 XR2206 ............ $8.50 ICL7106 ......... $14.00 324 .................. $0.75 339 ............ ...... $0.50 358 ................ $0.90 555 ................ $0.45 741 ...... $0.55 t-HLE PRICE LI UPOt-. EQU ,. 1--N\'-..f/'-w 1/I , I.J :,,:·' 5% OFF "7--Z., < ALL OR DERS ':/ 'z/: YOU MENTION~ VJ1 THISA~ ~ ~,.,,~" ELECTRONICS & COMPUTER SUPPLIERS 289 LATROBE ST MELBOURNE, VICTORIA 3000 PHONE: (03) 602 3499 FAX: (03) 670 6006 MAIL ORDER HOTLINE: (008) 33 5901 ALL MAJOR CREDIT CARDS WELCOME POSTAGE RATES $1.00-$9.99 ........ . $3.00 $10.00-$24.99 ..... $3.50 $25.00-$49.99 ..... $4.50 $50.00-$99.99 .. ,. $5.50 $100.00-$199.00 $6.00 $200.00+ ..... FREE FEB RUARY 1992 55 SERVICEMAN'S LOG Some sets go on forever There is always a small percentage of older sets being presented for service and they usually call for a special approach. Are they worth fixing? Are any hard-to-get components involved? How valuable is the set to the customer? In practice, each case has to be treated on its merits. This story concerns one of those old timers - a Rank Arena model C2053. This was one of several Rank models which appeared shortly after the introduction of colour TV in Australia. These included the C-2601, 02, 03, 04, 05 and 06 (all 63cm models), and a similar range of 51cm models starting at the C-2201. The set in question comes from a third range with the 20 prefix - 48cm (20in) - but the suffix 53 suggests that it is a later model than those listed above. However, there is some doubt about this and I am not sure exactly where it fits into the manufacturing sequence. Significantly, it has a VHF only front end. However, the point about mentioning these ranges is that all the sets from them are very similar. Many of the boards are used in all models, the main differences generally being confined to just one or two boards. Typically, this includes the output deflection board which is changed to suit different size picture tubes. Something old In this case, the set was almost the same as the 2601/2201 series, the most obvious difference being the "Deflection Out" board which is designated PWC-497 (PWC-315 in the 2201). The customer brought it in together with a Sharp video recorder which, in addition to its normal role, was being used with the Rank as a UHF downconverter. Both units needed attention but the video recorder was a fairly routine problem. The Rank TV set was not quite so straightforward. These early Rank sets must have set some kind of record for longevity; some owners have likened them to the old DC3 aircraft - they just seem to go on forever. One 2601 that I know of started life just after colour was introduced (in 1975), probably chalks up three hours or more a SON\~ OWN~'R'S 'r\A.\J6: day, and is still going L-\ Ke:.N E.t> 1l-lE.SE::'. S:.A"R\..-'( strong with plenty of RANK St;."'t'"S , D OL-D brightness and con-OC. 3 A\~Ct<.AF~, .. trast in the tube. 56 SILICON CHIP And that raises the question as to how long is it economical to keep any particular set going. Much depends on the condition of the tube. If it is in good nick, and the fault is unlikely to involve other specialised components, then repairs may well be justified. It is really up to the owner. On the other hand, the need for a new tube is another matter. Normally a reconditioned tube would be available and, for what it is, the price is very reasonable. But by the time fitting and other costs are added, the proposition begins to look a bit dubious. To justify it, one must assume that the set is going to run for several more years without developing any serious faults. Again it is up to the owner but, when I point out these factors, most decide to cut their losses and put the money towards a new set; one which will normally offer more features than the old one. And so the old set finishes up on the tip. But not before yours truly has picked it over. The various boards, in particular, are well worth salvaging, especially in view of their universal nature, as mentioned above. Something wrong And that brings us back to the set in question. A quick check suggested that it was well worth saving. It was working (almost) and the picture tube appeared to have plenty of life left in it. The main problem was that it had no vertical or horizontal sync. 1\viddling the vertical hold control brought this back into sync and with a good.normal locking range. No problem there. But the horizontal system was a different matter. I could lock it but it was extremely critical. Something was obviously very wrong. Nevertheless, I felt that the set was well worth saving and advised the customer accordingly. I was banking on the fact that the fault would almost certainly be in the "DefBoard", PWC- PWC - 367 DEF BOARD RS6C 6. 2 K I 1 RS':> 5 ~ - ~== ~.5'l. 1 ..''c,' fi~J.~ SL:' :;, _: R.:."~ 1$C~!lJ..~.L 0501 s~if~1M ~-~l; J;;: ◄ 7 l ; ii~R t~3~ ~~s~ ,.,.. -,. ~~i~ r ~~J ... 1n~:~ "-,~,:',::::~,·";::_l~.-c,-_s,,_: _-,;;-_-~.-':S !____ , f/;_'..:,_. ,. ~,, _,_. - - - - - - c""'-o~ 5=,- ' ... I ~•;~·/':/ _j "' SJ ; ':'CF - ,-. . f :>??. ,I I l 3.. 7 l- ~·! 1 ~:-:·f' i ~}--:c ., • ;i:' i l ; ~ -- f'-+ - I r!!io ,J, --'-'-0 ~~;;::'-_-·. ·-~;-_ ,:~_-~\-._ ______,I n. I 'f',_,,, ,I Il ' I ~-LJ 9:~-- - - - t.___. ,,. :- : ,, Fig.1: part of the horizontal deflection circuitry in the Rank Arena C-2053. The horizontal output transformer, T552, is at extreme right, the connection between PWC-497 and PWC-367 at centre, and diodes D501 & D502 at left. 367, which carries the vertical and horizontal oscillators, plus the sync circuitry. And, with the stock of spare boards I mentioned earlier, it should be a snack. In fact , this is a technique I have been using extensively on old sets like these. A board replacement is usually all that is needed, the old board can be tossed,, and there is no time wasted searching for elusive faults. Nothing to it! So it was out with the box of discarded boards which quickly yielded a PWC-367. I then tackled the fiddly job of unplugging the umpteen connectors on the suspect board, fitting the replacement board, and replacing the connectors. The only snag was that it didn't achieve anything; the fault was just as evident as before which was a bit of a blow. I had been so confident that the fault would be on this board that I hadn't considered any other possibilities. But now I had to. The next likely suspect was the Video IF board, PWC-312 , and the possibility that it was not delivering proper sync pulses. The video signal comes out of PWC-312 on connection B1, enters PWC-367 on B1, and goes to the sync separator (TR401). I took a look at this waveform on the CRO and, as far as I could judge, all was normal. But I was at something of a disadvantage here because the circuit diagram carried no waveforms - a common shortcoming of the Rank manuals. The closest data I had was from the 2201 manual; one of the few that did carry waveforms. In this case, the relevant waveform, from TP17, looked similar to the one I was viewing. However, the manual's reproduction wasn't particularly good and I couldn't be certain that there were no subtle differences. I decided that the easiest way to be sure was to make another board switch - except that when I delved into the box for a replacement PWC-312, there was none. So that brought the whole exercise to a halt for the moment. In any case, pressure of other work dictated that I put the set aside for the TETIA TV TIP Sony KV2764EC Symptom: the set had been cutting out but finally died altogether. The fault was on the 20V rail and turned out to be a shorted sound output chip IC252. Within a few days, the set was cutting out again and the serviceman attended to it in the owner's home. Cure: it turned out that the owner had connected two large external speakers to the set. The sound output chip wasn't intended to drive this sort of load and is fitted with a very small heatsink. Removing the speakers solved the problem, although a larger heatsink might have been an alternative. TETIA TV Tip is supplied by the Tasmanian branch of the Electronic Technician's Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston Bay, 7015. time being, which would also give me time to think. It was a couple of days later before I thought much about it again and then only because I was looking for something else in the storeroom. Among other things, this storeroom also houses scrapped sets and components and I realised that there was a complete Rank chassis waiting to be stripped. So there was the PWC-312 video IF board I needed. I fished it out, dusted it off and fitted it into the set. And that was the second setback; the fault w as still there, exactly as before. That meant that the time for short-cuts was over; I now had to get the brain _into gear and do some real troubleshooting. Something on my mind However, right now, there were more important jobs to be attended to and so, once again, the set was put to one side. But it was never too far out of mind; I once knew these sets inside out and it was shock to realise that time had erased this familiarity. If the fault wasn't on either of those two boards, where was it? I was obviously missing something but I couldn't figure out what. The set was apparently more on my mind than I realised. In the wee small hours one morning several days later, I awoke with a start and could visualise the circuit quite clearly. More than that, I knew where to look for the fault (the brain sure works in a mysterious way). Cursing myself for being all kinds of a stupid clot, I realised that the third board in this group, the "Def Out" board (PWC-497), had to be the culprit. Why? Because the discriminator section of the flywheel sync cirFEBRUARY 1992 57 SERVICEMAN'S LOG - CTD cuit- diodes D501 and D502 on PWC367 - needs a reference pulse from the horizontal output transformer before it can function. I could hardly wait to get to the bench that morning, fish out the circuit, crank the set up and delve into it w ith the CRO. But there was the major snag I mentioned earlier; the manual has no waveforms and very few voltages. The best I could do was fall back on the 2201 manual but this was of limited value in this case because the Deflection Out board for the set in question uses a different circuit arrangement. However, the 2201 manual was of some help. It shows the pulse line coming off pin 3 of the horizontal output transformer and designates this as waveform TP32. This shows sharp spikes, at horizontal frequency, with a value of 250Vpp. The 2053 shows the pulse line coming off pin 9 and the CRO indicated a virtually identical waveform. But 58 SILICON CHIP whereas the 2201 pulse line uses a passive arrangement, the 2053 adds a transistor (TR505) as an AFC amplifier. In both circuits, the pulse line leaves the Def Out Board and enters the Def Board via the H4 pins. The 2201 manual gives no waveforms along this line - which features various wave shaping comp£?nents - but it does show the waveform (TP26) at the junction of the discriminator diodes as a sawtooth pattern with a value of 4 Vpp. From this , I felt that it was safe to assume that a similar waveform would be required at this point in the 2053 . Well that was something, even ifI had no indication of what to expect at various points along the line. In fact, a check at H4 on the Def Out Board was most revealing. The best description of the waveform is that it was similar to that from a half-wave rectifier, consisting of a series of roughly sinusoidal pulses separated by spaces of approximately equal length, and with an amplitude of about 2Vpp. Well, even if I didn't know exactly what the waveform should be, I was fairly certain that it shouldn't look like that. And because there was no problem with PWC-367, the fault had to be on PWC-497. Something suspect My first suspects were two electrolytic capacitors in the pulse line: a lµF type, C558, ahead of the AFC amplifier transistor (TR505); and a 10µF type, C556, following it. Low value electrolytics are notorious for drying out and these were quite old. The lOµF capacitor was marginally easier to get at, so I lifted this first. It checked OK. Not surprisingly, lifting this capacitor completely killed what little horizontal sync there had been. I could float the picture but that was all. But the real surprise was that this also killed the vertical sync. I have no explanation for this. I have poured over the circuit trying to find a link - even an accidental one but without success. No doubt, given the time and the right facilities, the reason could be found but there is a practical limit to the time one can spend on such problems. Perhaps a reader has the answer, in which case I'd be happy to hear it. Getting back to the main problem, I next tried the lµF capacitor, feeling certain that it would be the culprit. Again I drew a blank. I also drew a blank with all the resistors in the chain, which left only one thing - the transistor. It tested perfectly but I've been caught that way before. The only real test is to replace it. I didn't have a 2SA539 on hand, so I substituted a BC556. And that was it - the system locked rock solid with a good wide locking range. Problem solved. And when I checked the waveform at H4, there was a sawtooth similar to the one shown at the discriminator diodes in the 2201. Its amplitude might have been a fraction less but, if anything, it was a better sawtooth than the one shown. But what was wrong with the transistor? It tested as having normal gain and there was no indication of leakage. I can only speculate that, for some reason, it had lost its high-frequency response . As a result, it could no longer handle the higher frequencies which make up a sawtooth waveform and reduced it to something like a sine wave. So that was the end of the exercise and the set went back to a very satisfied customer. However, one of the points arising out of the exercise is the difficulty of working without waveform and voltage information in service manuals . And I'm not just harping on about the Rank manuals; they are history. What I'm really concerned about is a similar trend in the latest manuals; a complete lack of waveform data and only limited voltage data. Samsung is one of the most serious offenders at present. So serious is this that I am looking for some convenient way of building up my own waveform references as sets pass through the workshop. Photography is one approach but it has serious practical limitations. For starters, this would require a suitable photographic jig attached to the CRO, to reduce the process to simply pressing the button. And there is a real need to record the test point details on the film, along with the waveform. Any other arrangement is prone to mistakes . A more recent approach is a system which can couple the CRO to a computer and, ultimately, reproduce the waveform via the computer's printer. I'm looking into this one. But it would be a lot easier if the makers did their job properly. FRACARRO SAVES... ... more than $10. from every UHF television antenna you buy. Fracarro's 4PUN for better performance from weak UHF signals. Peter C. Lacey Services Pty. Ltd. P.O. Box 678 (74Fulton Rd.) Mount Eliza 3930 Tel:03 787 2077 Fax:(03) 787 3460 ACN006893438 Something new For a change of theme, we now go from one of the oldest sets around to one of the latest. This is a 37cm colour TV set which I recently acquired for use as a workshop monitor. Apart from a minor technical problem, there are a number of interesting points about this set. It carries the Hitachi brand - or Hitachi Fujian Model HFC- AUSTRALIAN MADE TV TEST EQUIPMENT Happy New Year Specials. 10% discount on all test equipment. 15% discount on two or more items SHORTED TURNS TESTER Bu ilt-i n meter to check EHT transformers including sp lit diode type, yokes and drive transformers . $78.00 + $4.00 p&p 1425B to be precise - but it is not marketed by Hitachi. It is made in China and marketed in Australia through the China Trade and Exhibition Centre, 26-34 Dunning Avenue, Roseberry, NSW 2018. I have dealt with Chinese sets before in these notes and, not to put too ANTRI TOROIDAL TRANSFORMERS HIGH-VOLTAGE PROBE Built-i n meter reads positive or negative vo ltages from 0-50kV. For checking EHT and other HT vo ltages. $98.00 + $5.00 p&p DEGAUSSING WAND Strong magnetic fie ld. Double insulated for your safety with momentary switch operation . 240V AC 2.2 amps. As important as a soldering iron! $75.00 + $10.00 p&p REMOTE CONTROL TESTER Designed to test infrared or ultrason ic contro l un its. Supplied with extension infrared detector lead . Output is via a LED and piezo speaker. $84.00 + $4.00 p&p :s.. _, "S;'-- -.J\+~// t-~ ~~ -- TUNER REPAIRS -~ ~~~ From $19 exchange plus post & pack Cheque, Money Order, Visa, Bankcard or Mastercard .,;v! !,U~ERS} ~~~e~Jl~:i~.~~1d2, Phone (02) 774 1154 Fax (02) 774 1154 • • • • Now made in Australia Standard range 1SVA to 2kVA Large ex-stock quantities available Competitive pricing available for OE Ms & resellers • Simply the best transformers all round HARBUCH ELECTRONICS PTY LTD 90 George St, Hornsby, NSW 2077. Phone (02) 476 5854 Fax (02) 476 3231 FEBRUARY1992 59 spare parts backup? This a grey area at the moment. The set is sold with a 12-month replacement warranty; that is, if the set fails within 12 months, it is replaced with a new set. After that, it appears that you are on your own. This may not be too bad provided there is a guaranteed supply of major spares but I have not been able to get a clear ruling on this to date. Frankly, I consider that this point could make or break the commercial operation in Australia. SERVICEMAN'S LOG - CTD fine a point on it, I was not particularly impressed by the workmanship involved. So to be fair, I must say that this effort appears to be a better proposition. Time alone will tell, of course, but my first impression is of a very wellmade unit offering a large number of features at a very competitive price (around $350). Recently, I was interested in acquiring another VCR monitor for the workshop and so, when my dealer colleague put some on display, I had a closer look. In fact, he was happy to lend me one to evaluate, as much for his benefit as mine. I was particularly interested in the remote control features and on-screen displays, which are quite extensive. This can be very valuable in practice, as when soak-testing VCRs for intermittent faults. It also allows the monitor to be located in the best viewing position, regardless of accessibility. The remote facilities include: on/ off control; off-timer, selectable for 30, 60, 90, or 120 minutes; program Something wrong mode providing brightness, colour and volume control (with on-screen value bars); on-screen clock; and step-bystep channel selection or specific channel selection via a set of 12 pushbuttons. In the end, the features were impressive enough for me to clinch a deal with my colleague. But what about the warranty and Getting back to my own set, I soon discovered a problem with the onscreen clock, which seemed to work OK initially but, after about a day, appeared to be running fast. Sure enough, a more careful check revealed that it gained nearly five minutes over 24 hours. That puts it on a par with the old alarm clock that used to tick away on our kitchen mantlepiece when I was a kid but I expected something better from a crystal. The crystal in question (Z101) is the same crystal that serves the microprocessor and is connected between pins 28 & 29 of this IC. It is marked as Introducing the Protel advantage. Protet®for Windows':' Prate!for Windows is an entirely new Printed Circuit Board design system created for Windows 3 . Prate! for Windows brings the professionalism of Protel's proven PCB design software to the highly productive Windows 3 environment. New Prate! users will start designing sooner and experienced users will work more efficiently than ever. In 386 advanced mode, Windows 3 provides vi11ual memory capability, which allows advanced PCB users to design without restrictions on the total number of components, nets, tracks, etc. Prate! for Windows supports the multiple document interface (MDI) standard. Any number offiles can be loaded Special-------~ Copper Trace Layers □ Midl - □ Mid8 - □ Mid9 □ Mid 3 !ll □ MidlO l!ffll □ Mid 11 iZITop □ Mld4 - □ Mid12 □ Mid 5 OMid6 □ Mid 7 liifil □ Mid 13 □ Drill Guide □ Drill Draw - fiiil - 181 Keep Outs Ill IZl Multi Layer !iifil - M - - Rats Nest Selections CJ Background ech 1 D Mech 4 IPoslScript Printer on LPT1: D Bottom D Batch Mode I [Silks Bottom - . IZl Tc 0 IZl Grid 211tiJ Seperate Page For Each Print 0 Composite Print ® Panels (Multiple Layers Per File} Border Between Prints ~ at the same time, using standard Windows routines, to move iriformation between different files or different applications. The Prate! for Windows family consists of Advanced PCB - - ~--~ IZ] Transparent Ill D Mech 3 lll.ll D Dithered Colors ech 2 - IZ] Bottom - rsMT Paste Mask LD Top D hanical Layers ! Solder Mask I D Top □ DRC Errorsfiiil IZ] Grid 1- CJ fll CJ - □ Mid14 (Ill Visible- advanced level PCB layout - $1990. Options: Advanced Place $995 , Advanced Route $995 . Professional Schematic' - schematic capture -$129,.5. Option: Digital Simulator• $795. ■ Protel Technology Pty Ltd PO Box 204, Hobart Tasmania 7001 Phone (002) 730100 Fax (002) 730944 Tollfree 008 030 949 T?! chnology ~Available April 1992. Prate/ is a registered trademark. Admnced PCB and Professional Schematic are registered trademarks of Protei Technology Pty Ltd. V1indows is a registered trademark of Microsoft Corporation Inc. 60 SILICON CHIP 4MHz, although I considered the possibility that this may be only a nominal value. Initially, I had some ideas about trying to find out exactly what had gone wrong but the more I delved into the problem, the more complex it became. For one thing, what was the precise intended frequency of the crystal? Was it exactly 4MHz or merely something very close to it? On the basis of a simple sequential 2:1 division chain, a 4MHz crystal is not practical. But 4.194304 will divide exactly to lHz, or 3.932160 will divide exactly to 60Hz, either of which can form the basis for a clock display. But the simple 2:1 sequence is not the only option. Modern chips can provide virtually any order of division and it is quite conceivable that the makers used a more complex network in order to accommodate a standard 4MHz crystal. These are used extensively in computers and are quite cheap. The situation was further complicated by the virtual impossibility of making an accurate crystal frequency measurement directly across it. Any connection here would load the crystal and make the reading meaningless. Significantly, several computer buff acquaintances have told me that they have similar problems with the realtime clocks in their personal computers. In all cases, their clocks run fast. One enthusiast, who uses the clock mainly to maintain the calendar, realised recently that, since he had last set it, it had gained 17 minutes! I finished up using the more or less brute force approach of loading the crystal circuit with additional capacitance until an acceptable result was achieved. The circuit shows two 33pF capacitors, C152 and C153, connected from each side of the crystal to chassis. I decided to add some capacitance in parallel with each and started with two 13pF units, tacked on under the board. This came out better than I had hoped. Not only did the crystal accept the idea - they can sometimes drop out or behave erratically with excessive loading - but the error was significantly reduced. The clock went from gaining five minutes in 24 hours to losing about 25 seconds over the same period. Electronics Workbench® 66660660 Build and simulate both analog and digital circuits, complete with simulated instruments on your computer! FEATURES • Quick and simple circuit entry • Digital and Analog Modules included, complete with all components • Simulated instruments: dual trace scope, spectrum analyser, function generator, multimeter, digital word generator and logic analyser • Complete control over all component values and parameters • Print: circuit schematics, parts list, instrument readings, macros • Logic conversion -truth table to Boolean formula to logic gates • Customisable hypertext help system THREE VERSIONS • Professional Version: EGA/VGA colour display; unlimited components • Personal Plus Version: Monochrome display; unlimited components • Personal Version: Monochrome display; limited to 20 ----------------I YES ■ Something logical OK, so I had overshot slightly and needed to decrease the additional capacitance. A small trimmer seemed to be a logical alternative at this stage. I didn't have anything suitable in stock but, while looking for something else later on, I found an old VCR board with a miniature trimmer across a crystal. It was close to ideal. It measured from 7-20pF and needed only minor doctoring of the leads to make it suitable. I removed the 13pF fixed unit from C152 and fitted an 11 pF capacitor in its place. I then fitted the trimmer across C153. Over the next few days, I juggled the trimmer on a trialand-error basis and eventually reduced the error to a couple of seconds a day. And that's probably as good as I will do, because there does seem to be some drift which is probably due to small variations in the trimmer's value. A better quality unit ::nay help but would be hard to justify. Well, that's it for this month. If I learn anything more about this set, I will pass it on. SC ~ want ELECTRONICS WORKBENCH m my computer $429 $299 $149 Professional Version Personal Plus Version Personal Version Plus $7 Delivery Enclosed is my cheque/money order for $._ _ _ _ _ or Please debit my Ca rd No.I J J O J J O Bankcard J J J J J J Mastercard J J J J J I Signature _ _ _ _ _ _ _ _ Expiry Date _ _/_ _ Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/Town _ _ _ _ _ _ _ _ Postcode _ __ Send to: Emona Instruments, PO Box 15, Camperdown, NSW 2050. ~-----------------· Tel: (02) 519 3933 Fax: (02) 550 1378 FEBRUARY1992 61 area and are gently moved in and out, using a clean part for every session. This avoids further contamination. Cleaning cycles are repeated until there is no further improvement in the signal. The heads are thus kept in peak condition. Also included on the disc is a diagnostic program to troubleshoot intermittent drives. All software is menu driven and has extensive help facilities. For more information, contact Fred Rode, Westinghouse Brake and Signal Company, Stephenson Street, Spotswood, Vic 3015. Phone(03)3911300. Microsoft Word for Windows 2.0 Microsoft has just released Microsoft Word for Windows version 2.0. New features include the customisable Toolbar (which uses buttons to automate common tasks such as formatting), Drag and Drop (for simple text editing), Envelope Generator, Print Merge Helper and Help for WordPerfect users. Other features are a customisable Grammar Checker, Graphical File Finder (for previewing the contents of documents before opening them), improved tables (created using the Toolbar), WordArt (for adding creative looks to documents), Columns, Drawing tool and Charting (like Microsoft Excel 3.0, users can create 30 charts). New computers from : Dick Smith Electronics ~. t~~f/§~{f{;}}~~f~f:;'" ~ ,1_-,_:! ,,;, \,~,.. •. ..........,:-..,- >,)t,~ ,~ , .r~... ,-..... ·. "'¥"I" .t.•;;;t,.,."t~ A."<'1 \()c'l ...<~.W. ,, ..= . . .~- ~ -=,~, ~:,-. ~ 1","'~; ......,,./\':l,..1~ V:,, : io.,. ; .,-, ...-.,,.,6,,• , . . , , , . ..,,,-,:.~ «;~;...-·~<J,,....;·><•\>",» .... , ..•..:·~-"~<·.-,t, ....... ......,. ..,,,,. ..-~ ~-~.. ,.s~ v <>,., .,,..~,.'r'. • · ··s~-... .,1 ~j .."it/'~- <Yiv ............ , .... , •--~...,..~ •.-;,;,,, ,-,,...-c-. 1 The product supports OLE (Object Linking and Embedding) which enables a user to embed information from any Windows application which supports OLE and also contains a graphical Equation Editor. For more information, contact Jennifer Zanich, Microsoft Park, 65 Epping Road, North Ryde, NSW 2113. Phone (02) 1370 2200. Intelligent head cleaner for floppy discs Floppy disc heads are highly polished and in theory should not become contaminated. In reality however, the discs you put into your drive can be dusty. Most computers also suck dirt in through their cooling fans and if not filtered, can soil the heads of floppy drives. To compound matters, a small speck of dirt can scratch the polished surface, causing the head to collect oxide from the disc. This build-up can lead to permanent damage of the floppy disc. Headmax is claimed to be the first intelligent floppy disc head cleaning and diagnostic tool to effectively address the problem without abrading 62 SILICON CHTP the heads. The outside of the disc contains the software program, the middle, an accurate calibration pattern and the inside, a specially formulated cleaning medium that will not damage heads. During a cleaning request, the head signal is monitored using the special calibration track. The heads are then automatically placed over the cleaning Dick Smith Electronics has two new IBM compatibles with the Digitor brand name, a 286/16 AT and a 386/ 20 SX. Both machines come with 1Mb of RAM, expandible to 4Mb for the 286 and 8Mb for the 386SX. The motherboards feature 5 x 16 bit and 3 x 8 bit expansion slots and have the ability to support a second floppy drive and a hard drive. The Digitor 286 is $1595 and the 386SX is $1895. Both prices include a colour VGA monitor. For more information , contact any Dick Smith Electronics store. Desktop publishing with.By Design WordPerfect users can now perform desktop publishing functions from within WordPerfect. "By Design" operates within and expands WordPerfect and WordPerfect for Windows. It includes 11 design tools; over 50 page designs; on-screen previews of all tools, designs and WP- New anti-virus disc combats stealth compatible graphics; a library of clip art and graphic elements; four graphic fonts; a customise program that adds personal details and logos to designs; repeat and undo functions; and online help. A hot key within WordPerfect accesses By Design menus which pop up on the WordPerfect screen. You can use design tools to highlight, enhance and personalise text with a variety of special graphic fonts. By Design for Windows incorporates all the features of the DOS version as well as some additional features. These include a new windows interface that contains the Browse preview as part of every dialog box. Two new design tools are also included - a Text Highlight tool that provides a simple method of highlighting any block of text and a Page BackDrops tool that inserts full page graphics as text backdrops. By Design supports any printer and requires a hard drive. It sells for $199 and works in conjunction with WordPerfect 5.0 and 5.1 . By Design for Windows requires WordPerfect for Windows. For more information, contact Julieanne Green, Logo Distribution Services, Unit 1, 91 -93 Old Pittwater Road, Brookvale, NSW 2100. Phone (02) 905 1844. Document holder for cramped conditions DSC Innovations has produced a document holder for use where clipon or free-standing holders will not fit. The ''foot" is designed to fit on keyboard trays or tucked under the keyboard. It also has a cutout which enables it to slip under the corners of The latest in a string of new "stei3.lth" viruses has prompted the release of a new version (V84) of McAfee Associates well known anti-virus software Scan, Clean and VShield. It combats the new FAT or DIR-2 virus. Discovered in Hungary in September last year, the FAT virus uses a completely new method of replication, which does not corrupt data, but alters the directory pointers. This means that once valid directory entries now point to the FAT virus. Once resident in memory, the FAT virus will infect any non-write protected disc accessed by the system. The result of the operation of this virus becomes evident when the system is booted from an uninfected disc. Copying infected files will result in the virus program being the only item copied. Checking of discs with CHKDSK will also result in a large number of errors being found. Attempting to fix these errors using CHKDSK/F will result in extensive loss of data. Version 84 now detects this dangerous new virus and can also remove it using Clean. Also released is WScan for Windows, which allows the virus detection package to operate under Windows 3.0. For more information, contact Richard Preston, Doctor Disk, Suite 201, 64 Kippax Street, Surry Hills, NSW 2010. Phone (02) 281 2099: P~!~~d Computer Watchdog & 48-line 1/0 Card : $318.00 • Provides 48 TTL inputs or outputs. • On-board watchdog (PC fails, dog will hardware reset the bus) • Useful for unattended computers so that if they stop you can have the watchdog independently reset your PC. • Fully addressable & programmable by the user (even in Basic). • eg, Turn ON/OFF devices in your home, office, workshop, industry. • Address & examples of software or hardware supplied. 24-lnput Opto-lsolator Board: $229.00 nearly all keyboard designs, including older IBM terminals, without affecting access to the keys. The elevated desktop stand is made from 3mm acrylic and comes with a clear document clip and white cursor slide. Retail price is $30 (ex tax). For more information, contact Stan McTighe, DSC Management, 46 Cappella Circuit, Glen Waverley, Victoria 3150. Phone (03) 562 5549. • 24 opto-coupled inputs. • Either transistor pull-down or current loop input. • Pin compatible with 1/0 Watchdog Card (optional leads available) • High voltage isolation. • Provides immunity from EMI, RFI & earth loops. • 16-output & 8-input board also available. AC/DC Interface Card .................... $185.00 Relay Board With 8 Relays ............ $259.00 Temperature Board (4 Inputs) ...... $189.00 PO Box 628 Willoughby, NSW 2068. Phone (02) 809 1083 Fax (02) 808 1432 FEBRUARY1992 63 386SX notebook computer has 63Mb hard drive Notebook computers are so numerous at the moment that it's difficult to distinguish any one from the pack but the Auva 945 from Rod Irving Electronics stands out. It boasts the 386SX 20MHz Intel chipset which makes it one of the most powerful notebooks~around, as well as Pheonix BIOS on ROM. It also comes with 4Mb of RAM fitted as standard and a 3.5-inch 1.44Mb floppy drive. One of its most outstanding features however is its 63Mb hard disc, one of the highest storage capacities available on a notebook computer. The unit comes with a 640 x 480 pixel VGA-compatible paper white LCD back-lit screen, as well as an external VGA port to connect to any VGA monitor. The keyboard is an 83-key type but has all of the standard AT keys except for the numetic keyboard section. Behind the screen, a back cover opens to reveal the external VGA port, an external floppy drive/ parallel printer port and two RS232C communications ports; The computer comes with its own 11 V nicad battery back which lasts for about 2 hours, and a power supply/ battery charger is also supplied. The comprehensive user guide explains the operation of the computer, as well as providing all pinouts for the various ports on board. The price? - just $3495 ($2950 tax exempt) from Rod Irving Electronics stores in either Melbourne or Sydney. Call (02) 519 3134 or (03) 543 2166. Universal typeface conversion software Forest, NSW 2068. Phone (02) 452 0440. Software applications are bundled up with a variety of scalable soft fonts which are often inaccessible to other applications. As a result, a user with several packages may wind up with many fonts but may have only a fraction available at any one time. This problem is solved by AIIType, which provides a quick and simple means to translate a font from one format to another. Alltype's translations maintains font quality and clarity at smaller point · sizes. By means of a 'Variation' feature, a user can create bold, oblique, condensed, expanded and two dozen other standard variations of an original font. A customize function allows alteration of the typeface's weight, pitch and italic angle, leading to a limitless variety of new fonts from the original. AIIType for DOS and newly released AIIType for Windows retail for $115 and are available through most PC outlets. For more information, contact Bernie O'Brian, Computer Products Division, Mitsui Computer Ltd, Unit 1/14 Aquatic Drive, Frenchs Software package for legal offices 64 SILICON CH I P Legal Management Consultancy Services has just released the Lawyers Workstation, a complete legal desktop package designed to provide support for all the major functions of a lawyer's practice. The package includes a suite of templates for functions like litigation support, conveyancing, legal document drafting and financial calculations, along with a range of working examples. Standard features include word processing, spreadsheet, personal information manager, desktop utilities, drawing facilities, automatic document generation software, communications with access to LawNet, word and file search, GU I's and document exchange. A range of hardware and networking options expand the system to encompass automated litigation support services, precedent service and precedent and data conversion. The legal desktop is designed to run on an IBM PS/2 running DOS and Windows 3.0. For more information, contact Steve McNamara, Legal Management Consultancy Services, 128 Fullerton Road, Norwood, SA 5067. Phone (08) 370 9132. PC-based digital circuit simulator Pulsar is a PC-based digital logic circuit simulator which has fully programmable signal sources, a printable logic analyser display that can catch glitches down to 1 picosecond , and adjustable component models. The tutorial section in the manual makes Pulsar ideal for education and training. For more information, contact BTC, PO Box 432, Garbutt, Old 4814. Phone (077) 25 3189. SC t:Lt:'lv I nul\llV0 .Ji"\ 1 vnri '- l.! u fLECTf1ONICS JAY CAR ELECTRONIC!:i JAYC,\R EU:::GIHOl\ilCS JAYCAH E .... EClHON:Cs J,.:. i'CAA !:::LECTR(')/\ r~· lol , r,'.l;R , •~F~I\.JU ... n, ,._,,", ....... ._ ELECTRO'JICS EL!::CTRQNICS ELECTRONICS ELFC'T HOr-.JICS FI r-r1nnN1r.c:; =_c(;TR ,_EC!H :: ~.C"'.'R1 :._fCTFil ,_::C-R< =_EClR' =_E:C-F .EC-R :._t::CP; :'Cl• ,_EClil '-ECTR ,_ECTR _ECTR J1\YC1\R JA\ CAR JAYC,\n JA\ C,\R ..,,\'1 C,\H - I FC n,ONICS .,,\YCAR FcFCTRONICS JAYC,\R ':Lf'CTRm11cs J1\YCAi-1 l :-C: H01\!C~ JA'iCAH t:lJ:C I HONICS JAYCr\R =LECfHONJC~ ,J/\'{CAH \ :·c 1 ROt~1r,0 .JA'iC/\ll f; FC rHOf\iiCS .JAYC,\n 'L:":(: rnO'J1CS JAYC/,H L!cC HO'!ICS _!-C -:,u•\1C::-. l ~ r,~ Hu~... :c<, l f ( rr~():',:C') l ! 1. ·r~;. )rifC ~ J:1YC1\H !::Lr Cl HO"JIC, .JiJ. "r"Cl\il i- --~ .,.; : ;iO\·f~. JA \,Afl t'. ;-cl {() ', ' ) ,-. ,( Mi f '. f Ii-!( · . 1 ',\,( r,11 ~1 ft tilr ·... .-lh )~.:{ H~ •~1( ~ JAYCAR No1 FOR KITS =-Ec-r-; =-ECTH - - _, 1 ELECTF FLECTf ELECTF ELECTF cl~C-R =LECTF cLE'CTF cLECTF cLECTF :'LECII cLECTf:'LECTF cLECTF =c FC-F cLECTF ELECTF ELECTF E:...::CTF "L:cCff ELECTF ,cLECTf' EacCTF E_ECTF c-ECII· :=- .... ECT;:--; "LECTF E-ECTI' 0 _ECTR c_ECTR , ...... ,....,...., ..,, JAYCAR !:LE CT/1O\J,CS JAYCA/1 fLLCI huf!i(;S JAYCAR cl':C' HO'JICS ,AYCAH FL.FCl R,Jt\lCS J_AYCAH ::::...E :;-R0\; CS JA'YCJ\R rLr:c1qo,.cs J4.YC~\H i-'.. t ''T""HC'\JICS JAYCAH t::LFCT=-11:'.!CS ;;;Y('.Af' =1 ; ➔ H(".",Jl(';S. ;\YCN{ F. [CTd• )'. .!C!:l Ref: EA September 1991 Increase your talk JX)wer. Connects in-line with existing mlc and acts as a preamp, compressor and speech filler. NORMALLY $29.95 LESS 15% $25.46 SAVE $4.49 Cal. KA-1737 ·no~.' Ref: EA August 1991 Jaycar kil includes PCB, ; I specified components, Scolchcal panel and meter scale. cat KA-1736 ·1,,11 ;1;' NORMALLY $79.95 , 11-!lJ\)I( ~- . , I '10'. C' :rncv-..:1r::· LESS 15% $67 .96 SAVE $11.99 UNIVERSAL STEREO PREAMP KIT : I f\l,1\/;1_'', l H•,r\if ' :; ! LESS 15% $28.01 SAVE $4.94 '.ll ,Pt)' .it'' 11-, '/{1 )'\ ( 'f•:,_) ' , ( -11 0-~.,(.' 'f,: ,•;11, ~ NORMALLY $159.50 rr, '.1r DIGITAL TACHO KIT __::J '~~,,- ,_ECTR ;:,, ',!:_ , ·q ·.1· i f t ) 1, ~ 0 • I )'\ t, J . IH ',,,;{ I H:J',,,C'1 .J rpm. Cal. KC-5098 NORMALLY $34.95 LESS 15% $29.71 SAVE $5.24 PARRAMATTA AND BANKSTOWN OPEN ON SUNDAYS 10 • 4pm c. cCTR I di \di, 1 i \, 1~~1· Ref: SC August 1991 This LED digital tachometer features a 4 digit readout thal indicates from O• 99 , , 1,·: LESS 15% $135.58 SAVE $23.92 ,_ECTR ,_ECIR ,_~c-11, '_Ec-111 <=:J<=:J<=:J<=:J !Hi J'JI' IHl\r-.JIC rqor~ 1r,. • fn t·iiC ' ·1.-: r.(', :_t:c·Hr =-=c~·8r 0 _:cC"RI ,.cc-11 ,_=c-R =-ECTR c_EC"R =-=CTR =-ECTR ,_EC-R =_cC,R =_Ecrn __ ECTR ,_ECTR c_::CTR :._EC-R =_ECTR ,_ECTR ,_EE;TR ccECfR, :. ... ECTRr '-ECTR• ,_ECTR, :: ... !=.CTR1 =_ECTR, ,_ECTR• -:_ECTR c_ECTR ,_ECTR c_ECTR ~- CCTR !~::CTR ccEC1R E-ECTR< 15~ OFF EVERYTHING cat. KC-5094 • ,_Ecrn ,_Ecrn ,_Ec,R i~im :; 0 .. ., .. ,. . O/,<+l'.:'_),.~1t·:•-- ♦»:f; <j,<$+ff••<>O<,.,. ~ ~ LESS 150/o $245.15 NORMALLY $69.95 r ....--...._"' ~~T • ~ SAVE A MASSIVE ./ -:1 ~ \J!' (. 1GHz DIGITAL FREQUENCY METER KIT TI~· ~. ( 'HU'. C J• !Hi '11( 1:v:r .-c . 115-:1'"1217 I I t:::,.::::J 1...1 "" LESS 15% $254.15 SAVE $44.85 'fit "-jll, J: ' f -il LESS 15% $67 .96 SAVE $11.99 JAYC:AH ,;/1YCAH .,AVCAn .JAYCAn JAYCAf1 JA (CAR ~,., ------- t:~t:L. I HU'\.IL:::; JAVL,At"I f-, re fHQ\;IC:-:; H FCT HO\ICS Ld C I ;1O,1cs ELfCTRO\,CS ElfC ... nO"\!CS JA"1'C,\H Jr\YC,\h J,\YC,\I, JA',(.'ilfi ... ,\·r·c,;h .: 'fSr)',l'' 1; "iR,/.iV~ 1i , I; . ~l( 'I '\i: ~ $269 ,\ l ! ,Mi t:Ltl, I KU!'\il,~ J}-1.Y\.,Ht"I l:L~·C ! HQ,1(,:') ,;,i'\ l (',\Ii f l ~(; I HO~.:c.s ,;X'! C,\H fl ! C I HO\IC~i J,·,-cAH ~-l:. Cl HO\ICS _J/,YC,\H I L: C I IJOtJIC''.' A"<CAH U.t ,·rno •; CS ,JAY CAii ElcC'I R(J'"C S ;,y C,\H f It ! fl()\;ICS JA\'C,\R :.LC.C I HUNll,'> ,J;, c,\H ~ .... t l . hL~\.. CS JAYCAH :::.LtL, I M\,.JI\JII_ "I ~ -.1 I\ Tr{1-l',I(,,, 1· IH''·',1:... J." -~i~ ·1sr ·,1. LESS 150/o $228.65 SAVE $40.~ '-.LECTRONICS E-_,_~c 1nONICS h f-C ➔ RONI CS c-LC' 11CNICS clcCI HONICS ~ _!:.C.,..RONICS r t/ li\•.i•.:( NORMALLY $299 JAYC.O.H JAYC,\H JAYCAH .JA'CAR JA'• CeH J;..VCJ\F1 i F-, ,r,;1: Rei: EA November 1987 rnv,"'.:" :mt::;,;~ ~;: EcECTR~~~~ ~~~~~~~~~ ~~~~~~~~~ ~;;;;;;;;;;;;;;;;;;;;;;::::;:;;:~========~=======:..I bU:.CTAONICS t:LECTRONICS EU:.CTHONIC0 ELECrnONIC.S ELECTRQ,;iCS f:Lr"CTRO/\.ICS !, ldL-'·W:' lhU\1C~ lh ()' , ( Cal. KC-5013 JAYCAR JAYCM-l JAYCAR JAYCAH JAYCAR .J,\','CAq T:,:O';,(,. THO'✓ I,..' $94.85 Ref EA September 1985 Cal. KA-1610 NORMALLY ELECTRONICS E:U:C I H0/\1CS !:::LF CTP01'.ICS ELECT~OMCS , LcCTl•o,;,cs EL::.C'"GC)~.ICS J, J, i;(')~.,c:) ;, - ;,iU~·JI:~;• T1 f •-.1 ,.., 12-230 VOLT INVERTER KIT JAY CAR JAYC,\R JAYCAR JAY CAR JAYCAR JAYCr\R J, ~ ~ IH()\.;iC ~ !/ IH\/-.iC!.. ,; Tf \1 )' ,iC~ i lriO' ,,C~ J/ fi\l)'ilC. j. DTMF DECODER KIT ELECTRONICS EU-:CTRONICS El ECl HONICS E:LECTRONICS Elc·CTROf\lCS ELECTRQ!\ICS 1. THI Jf.1 L~ {''!;.:;'::-':'~·~t:->,14'<::..... '"';'" ..... Rei SC May 1991 Control home appliances viayour telephone Cal.KC-5095 NORMALLY $79.95 JAYCAR JAYCAR JAYCAR .JAYCAR JAYCAR JAYCAR c,> "f,Qf\F ;..> IM:.~~;!' 1~ar.·c -.,~ .. NORMALLY $349 SPECIAL PRICE $299 LESS 15% $59.46 SAVE $10.49 =-ECTHONICS :'....ECTRO!\ICS :: .... EC TRON CS ,_ECTRON'CS :_ECTRONiCS ~-ECTAON CS TRO:-,. ·i.,01\ \ • Ref: SC September 1989 QUAD 'DI' BOX KIT ="ECTR . h~;~ ;It, ... J. 'iU_J"· , '..,. ~ ,Jt Stereo unit with 20 sliders for each channel. Cat. KC-5055 Ref: EA June 1991 This simple kit will replace four separate direct injection (DI) boxes, but at a fraction of their Iola! costs. ,-_ECTR ;;,c¾<?, < ~~~1WlC5tJl!tl;;!W$<)¾f.. > f ( ~ STEREO 1/2 OCTAVE EQUALISER KIT LESS 15% $33.96 SAVE $5.99 · =LE Cl R ,_EClH ,LECTR =~g;~ " "0 - NORMALLY c"ECTR, i ~ • $39.95 cat KA-1734 I 1/ . -F;(i'd" 'T.;<"'~ ,1:~, , STEREO AUDIO EXPANDER KIT Ref: Sc May 1991 This project will add sparkle to your music cassettes, video or FM receiver by increasing the dynamic range of the signal. ::.:,_fCTA -. _ECTR ,_ECTR ,_ECTR ccECTi< :: .... ECTR HI )~,ii, 'Hl r,,;it__, $39.95 !fa Cal. KA-1735 j 1 HlY,1_ CRO ADAPTOR KIT FOR MONITORS Ref: EA June 1991 .·c, ·ri-.:,)~..(' * NORMALLY 1· : I H(J~; C' I 'I ;.ii)\,.('<. I Ref: EA January 1992 Experience cinema sound in your own lounge room. The Dolby "Surround Sound" process Increases the sensation of "being there" by producing an effects channel lo creale surround sounds which aconventional stereo system can't produce. Hook th is simple kit in conjunction with your Hi Fi VCR or stereo TV and lake full adv,mlage of movies recorded wilh Dolby encooing. Short torm kit• includes PCB, and all on board components. Cal. KA-1741 $32.95 ;.,;,:1 •,/' • ··1 rn DOLBY SURROUND SOUND DECODER KIT Ref: SC June 1990 A high quality, low noise universal preamp kit ideal for magnetic cartridges, tape player or microphones ~"!IC lfh.J\. THI~ IHO:. TH t;i, LOW COST 18 VOLT 1 AMP BENCHTOP POWER SUPPLY KIT SPEECH PROCESSOR KIT FOR TRANSCEIVERS cat. KC-5077 rH0~•.1< • T~, "HONIC , Ji l t" L I HO\:lr"S .1/ I~(. ~IH l'.lc: · ,' u:c·rHO"JICS ; 11 CH< l' ;I(: , LI .C I HC\JI( ; ,1; LE.CTHtY·JIC'"> J; CAR CAR CAR CAR CAR ELECTRONICS ELECTRONICS fLECTRON ICS FLFCTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR J-AYCAR -l,!.YCAR ELECTRONICS FLFCTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELFCTRONICS ELECTRONICS tLEcCTRONICS ELECTRONICS ELECTRONICS CAH t:LbCf R()Nlr.S .flt'Yl.AR FI Fr.TA(')J'\11r c:: 1eivro ~ CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAl-1 CAI, CAI, CAR CAR C,\R CAH CAR CAR CAR CAR CAR CAR C,\R ELECTR FLFCTR ELECTR cLtCTR f LECTR ELECTR ELECTR ELECTR ELECTR ELECTR ELl=CTR EU,CTR cLtCTR ELECTR ELECTR ELECTR f-Lf-Cl R Hf-CTR ::.Lf-CTR cLECTR ,LECTR lLECTR f-Lf-ClR cLECTR cLECTR •ccCTR ELECTR ELECTR EL!cClR ELECTR ELE-CTH ':L[CTR ELECTR CAR t:u::c ... H CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR CAR cLFCTR 0 LECTR ~L:=CTR cL~cT1-1 FLECTR cLECTR ELECTR ELECTR EL!cCTf1 l=LFCTR ELECTR ELf-ClR ELECTR ELECTR ELEClR ELECTR [LECTR ccECl R r LE.Cl 1-1 FLFCTR FLlcClR FLECTR ELECTR ELFCTR FLf-CTR ELECTR ELtCTR• fLFCTR ELECTRELECTR ELECTR FLECTR ELECTR E~cClR EL!cCTR ELECTR cLEC I R cLbCTR cLECTR cLECTR FU-CIR CLFCTR ELF-CTR :TECTR cLECTR• :'LfCTR, =LECrR cU,CTR •Lf crn, ·LECTR, c;.,ii 'CAR CAR CAR CAR CAR CAR CAR CAR CAR 'CAR CAR CAR CAR CAR CAR CAR C,\R CAR CAR CAR CAR CM, CAr' CAR CAR CAR CAR CAR CAR CAR CliR CAR i::1 JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRON ICS JAYCAR JAYCAR JAYCAR JAYCAH JAYCAR FLECTRONICS ELECTRONICS ELECTRONICS cLECTRONICS Fl FCTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAY CAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS i:::rn~nr-.111.<::. IAYf"'AA FI F(':TAnN1r.,q .IAYr':AR FI Fr.TRON!{':~ .IAV(;AR FI i=-r.TRONIC':~ .I AYf':AR FI FCTR ON IC S JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRON ICS JAYCAR ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAP ELECTRvS ELECTRvS ~LECTRvS ELECTR(;S ELECTRvS JAYCAR ELECTR(;S ;s JAYCAR No1 FOR KITS KARAOKE BOX KIT LOW VOLTAGE CUT OUT KIT FOR CARS AND BOATS With this kit you can remove the lead vocal from almost any recording and replace ii with your own voice via a standard microphone (not supplied), Microphone lo suit Cal. AM-409C NORMALLY $19,95 LESS 15% $16,96 caLKA-1738 Ref: EA January 1992 Build this simple kit and avoid getting caught out with a flat car or boat battery NORMALLY $27.95 LESS 15% $23. 76 SAVE $4.19 Cal. KA-1739 NORMALLY $22.95 TV COLOUR PATTERN GENERATOR KIT LESS 15% $19.51 SAVE $3.44 Ref: SC November/December 1991 Ca!. KC-5103 MAGGYLAMP NORMALLY $110 THAT'S A REAL BARGAIN Every serious technician should have one!! The Maggy Lamp Is a widely adjusted magnifier with a12,7cm diameler bi-convex lens, 4,00 dioptres focal length of 25,4cm, II is essentially a microscope with lighting, The Maggy Lamp has flexible arms for easy positioning, handsome, sturdy construction assues a lifetime of service, Cal. SL-2700 HAS YOUR CLOCK AT HOME JUST DIED? NORMALLY $299 LESS 15% $93.50 SAVE $16.50 Well, don'l lhrow ii away fi x ii with aJaycar Clock Movement and bring ii back lo life, • Supplied with three sets of hands • Uses 1 x AA ballery (nol supplied) Cat XC-0100 LESS 15% $254.15 SAVE ~w /l ~ }:®J . $44.85 ~ NORMALLY $12.95 LESS 15% $11.00 15% OFF EVERYTHING ~u=-c I Ri STEREO AUDIO MIXER BRAND NEW MODELS FOR 1992 ' ® □ ~[;)C\Du® ® <at>QDu[;)C\Du® Brand new model This mixing console is packed with features, It combines the qualities of a broadcasting or mixing console with the fealures needed by a disc jockey, sound amaleur or home mixer, Wi ll accept inputs from microphones, turntables, tuners, tape decks, CD, video etc, FEATURES• lwo microphone inputs • 4 stereo inpuls • level control for each stereo Input • VU meters, headphone socket • 240 volt operaled SPECIFICATIONS Inputs Sensilivily Impedance Mic 1 & 2 1mV 600n Phono 1 & 2 3mV 50kn Line 1 & 2 150mV 100kn Oulpuls • Amplilier outpul - max 3Sv rms (1 kHz) • Recording output - max 3,5V rms (1 kHz) • Headphone oulpul200mW Frequency Response • Mic - 20Hz - 20kHz :12dB • Phono - 20Hz - 20kHz (RIM) ±1dB • Line - 20Hz - 25kHz :12d8 Signal to Noise • Mic - 60dB • Phono - 60dB • Line - 70dB THD • Mic - less lhan 0,1 % • Phono - less than 0, 1% • Line - less than 0,05% Dimensions • 382(L) x 200(W) x 75(H)mm Cat AM-4202 $169 Less 15% NOW $143.65 CAR cLEC-R< CAR cL!'CTR< C/\R ~ LfCTRl CAR ~LE:.CTR1 CAH ell crn, CAR ccf'CTR1 CAH c'Lf-C1R1 CAR cLl=CTR< CAR ·LFCTR< CAR cLECTR< CAR fLFCTR( CAR fLEClRi' CAR cLECTR< CAH E-LEC I RI FEATURES • lwo microphone inputs • six stereo inpuls • level control for each stereo input - swilchable • LED bargraph VU meters • rack mount • talkover • fader • bass and treble conlrol CAH tLlcCIRI (Equaliser)• master output volume control • headphone monitor volume control • cue monitor• sound effects- bombing, laser, ambulance, shooting, siren, machine gun, telephone, storm• 240V CAR ti.SCTR! operated, CAR ELECTRI CAR ELECTR< SPECIFICATIONS. same as AM-4202,. Dimensions 482(L) X 200(W) X 75(H)mm, Standard 19' rack mounling, CAR FLECTR, Cal. AM-4208 CAR ELECTR, CAR t,LcCTR CARFLfCrR _ _ '" ,_ _________ ___ _ CAR fLECTf10:,,JICS ,JA YCAR 1 11 ClRONICS ,JAYCAR I LETTRONICS ,JAYCAR ELECTRONICS JAYCAR ELtCrRONICS JAYCAR FLFCTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR CAR ELECTRONICS JAYCAl1 ELE'CTRONICS JA'/CAF1 LLF-CTRONICS JAYCAR ELECTRONICS JAYCAR fLECrROt-.lCS JAYCAR FLFCTRONICS ,JAYCAR ELECTRONICS 1JAYCAH ELECTRONICS JAYCAR CAR ELECTRONICS JAYCAR FLECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR FLFClf10N ICS JAYCAR ELcCTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR CAR ELFCTRONICS JAYCAR FlECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR FLECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSjJAYCAR ELECTRONI CS JAYCAR STEREO AUDIO MIXER WITH EQUALISER, AUTO TALKOVER AND SOUND EFFECTS ® OfmCPQD'D'<at> ~ <at>QD'D'CPQD'D'<at> 19" RACK MOUNT• Ideal for professional DJ's etc $249 Less 15% Now $211 .65 CAP'ICCTDOt11r· ,.rr•T1-.r.o.ur,~~-~-=,._r-~-••-'~~ • ...........,.."'"r•,r .... _ _ --- ··- •- - - -- :TR ELECTR ELECTR ELECTR ELECTR I - )..,Q ,Jf't,) VAH CL.I::\., ::,;s j:;S j:;S j:;S j:;S JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR 8S 8S GS 8S ....... i tii...Ji"iil..,U .JM T \.,/'"\h t:L.t:i.., I hVi',111..,,'.) Ji-\ Y \.,AH C.Lt:I.., I J-\\...11',lll...,..:J .JI"'\ 1 Vl"'IM C..L.C:.V I nv1~ 1v u ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS cLFCTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS clECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELLCTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS lLtCTRONICS JAYCAR JAYCAR JAYCAR ,JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICci Vr'\ I Vl"'I! l LLLV JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR 1 1 iv,~ovv ELECTRONICS FLFCTRONICS ELECTRONICS ELECTRONICS ELECTRONICS tLECTRON ICci v,,, ...,,,. , JAYCAR JAYCAR JAYCAR JAYCA-R JAYCAR JAYCAR ._ ._._...,,, ,..., , .,...,..., ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ,,. , , -.,, " . ._~~ ..... , .. _., .. _ .., JAYCAR ELECTRON!CS JA.YCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS -· .. __ . JAYCAR JAYCAR .JAYCAR JAYCAR JAYCAR ,JAYCAR GRINDER/MINI DRILL ENGRAVER DIGITAL HYGRO-THERMOMETER One of the most powertul small tools we have seen! This unil fits neatly into the palmof your hand (11 0mm long), ye! It's powertul 12V DC motor enables you to drill PCB's up to 2mm dia. II can also be used as an engraver as well as a miniature grinder. The unil is supplied wilh 2 grinding wheels, one engraving burr, a10mm HS steel PCB drill and 2 brass collet ch1J1;ks. A 9 -18V DC, 1-2A power source is required. Cat. TD-2485 This is a high quality digilal (LCD) readout temperature and humidity thermometer. It can be wall mounted. Unit requires 1 x AAA battery but another can be installed for longer use. Measuring range: Humidity 20% to 95% • Temperature -50°C to 70°C tor full specifications see !he Jaycar catalogue. cat. OM-7230 FANTASTIC VALUE AT $24.95 THROW AWAY MINI ENGRAVER This very powertul but low cost dedicated engraver has a1.8mm dia ball head burr interterence filled onto a molar drive shaft. We have engraved literally dozens of metal objects with this tool and the burr seems as sharp as ever! Obviously a quality HS steel bit. Once the burr wears out, however, ii may be difficult to replace the bit, so we are calling ii a'throw away' engraver. We must emphasise that the filled burr may be able to be removed and replaced but we can't guarantee ii. Who cares anyway at this price. This engraver will probably last anormal user a lifelimet Requires 12V DC at 1-2A. Cat. TD-2480 MINI VACUUM ATTACHMENT KIT There are so many different mini vacuum cleaners on the market, most of them are expensive and don't really · work all that effectively. This unique product simply plugs into the end of your existing household vacuum cleaner hose and way you go. Supplied with: • an adaptor to suit all vacuum hoses • 1 x 80cm clear flexible tubing • 1 x straight and curved extension pipe • 1 x oval brush • 1 x round brush • 1 x crevice tool Great for cleaning computers, typewriters, office machines. stereo and video equipment etc. ; Cat. XV-5060 NORMALLY $14.95 ONLY $16.95 ULTRASONIC CLEANER This product wi ll clean an amazing range of products including jewellery, glasses, dentures, watches, relays, swilches, etc. Cat. YH-5400 NORMALLY $199 LESS 15% $169.15 SAVE $29.85 COME INTO OUR RHODES SHOWROOM TO LOOK AT OUR DISCOUNTED PRODUCTS, SAMPLES, END OF MODEL RUNOUTS AND FAULTY GOODS AT SILLY PRICES, COME IN AND GRAB A BARGAIN AND SAVE YOURSELF A BUNDLE - OVAL BRUSH ROUND BRUSH LESS 15% $12.71 DON 'T MISS THIS SUPER SPECIAL!! 6.5MHz OSCILLOSCOPE useful bandwidth up to 10MHz 8.8MHz (·&dB), 10.6MHz (·10dB) All In stock now. On demonstration In all stores SA50 NORMALLY $69.50 LESS 15% $59.08 SAVE $10.42 SA70 · 2way kit. 30 watt rms Spks/cabs normally $369 Cat. CS-2450/52 2 way kit. 50 watt rms Spks/cabs normally $449 Cat. CS-2471/72 15% OFF $313.65 15% OFF $381.65 SA100 SA130 2 way kit. 70 watt rms Spks/cabs normally $699 Cat. CS-2460/62 3 way kit. 90 watt rms Spks/cabs normally $999 Cat. CS-2465/67 15% OFF $594.15 15% off $849.15 Features: sensitivity10mV/div • attenuator 111, 1/10.1/100 • sweep frequency 1OHz -1 OOkHz 4 ranges • crt 130mm round screen • 1 year warranty Fo.r full specifications see Jaycar 1991/92 catalogue cat. ac-1910 ELECTRONICS JAYCAR ELECTRONICS JAYCAR lLECTRONICS JAYCAR HECTRONICS ,JAYCAR ELECTRONICS JAYCAR ELFCTRON ICS JAYCAR :S JAYCAR :s JAYCAR :s JAYCAR :s JAYCAR either desk or :s JAYCAR :S .JAYCAR :S ,IAYCAR :s JAYCAR :S JAYCAR :s JAYCAR :s JAYCAR :s JAYCAR :S JAYCAR :S JAYCAR :s JAYCAR :s JAYCAR :s JAYCAR :s JAYCAR :s JAYCAR :s JAYCAR :S JAYCAR :S JAYCAR :S JAYCAR :s JAYCAR :S JAYCAR :s ,JAYCAH :s JAYCAR :S JAYCAR :s JAYCAR :S JAYCAR :s JAYCAR :S.JAYCAR :S JAYCAR :s JAYCAR :S ,IAYCAR :S JAYCAR :S JAYCAR S JAYCAR S ,IAYCAH S .JAYCAR S JAYCAR S .JAYCAR :-; JAYCAH S JAYCAH S JAYCAR S JAYCAR S JAYCAR S JAYCAR S .JAYCAR ::; .IAYCAR S .JAYCAR S ,IAYCAR S IAYCAR S JAYCAR S .JAYCAR S JAYCAR S J AYCAR S .IAYCAH S JAYCAR S JAYCAR S JAYCAR S .IAYCAR S JAYCAR ci .IAYC·AH S .IAYCAR S JAYCAR S JAYCAR S ,JAYCAr1 S .JAYCAH S ,JA'r'CAR NORMALLY $399 ~) ,J/\·rCAR CRO PROBE to suit, 1x, 10x. Includes BNC socket to two banana plugs adaptor cat. ac-1912 NORMALLY $45 ~; JAYCAR S JAYCAH S IAYCAR S ,JAYCAR S l/\YCAR S IAYCAR , IAYCAR , JAYC~R . JA',CAR , .JAYC.L\R 3 JAYCAH ; .IA',CAH 3 JA·, CAR i .IAYCAR ,./ LESS 15% $38.25 SAVE $6.75 FAN BARGAIN A DIGITAL CAPACITANCE METER FOR UNDER $85 Oualily Sulfon brand 80mm (31/2') 115VAC tan. Connect two of these in series for 240V AC operation. Voltage 115V AC 50/60Hz, current 0.13A, size 80 x 80 x 38mm. Impedance protected. Cat. YX-2520 NORMALLY $10 (under half price) Ideal for checking tolerances, measuring unmarked and unreadable values, measuring· cable, etc. Will measure from 200pF - 20mF. 31/2 digil LCD display over 9 ranges. Includes zero adjustment knob. Suppliedwilh battery, leads and instructions. Cat. OM-1572 LESS 15010 -~ i'C $8.50 , •• ,,,... • ~ ,...., ,....,,...Tnl""\ ~ 11,,...r- i '"''"'"n et cr-Ton,...u r ~ IL!.VrL!.R i:=1 l=f'TRr'll\llr~ t:Lt:L, 1HUNlt.;::i EL lCTRONICS ELECTRONICS ELECTRONICS JAY CAR JAYCAH JAYCAR JAYCAR J,\Vf"",\D c1 LrTDf""IP..11r-c i"vr-11u f-LL(, 1 RON ICS ELECTRON ICS ELECTRONICS ELECTRONICS LI cr-T9QNICS JAYCAH JAY CAR JAYCAR JA\'CAR JAY CAR LLLC I RONICci [LFCTRONICS ELECTRONICS ELECTRONICS FLECIBOOJ.CS U fl EL El EL l L E, FI F! c. El FI U tl U FI El F' f' h i. El 1· FI FI F. H f I :·I El FI F• f I El l I E1 F fI f r JAYCAH JAYCAR JAYCAR JAYCAR JAYCAR tLtC I KUN IC0 ELECTRON ICS FLECTRO",ICS ELECTRO"ICS FLFCTRONICS ~ fl fI b f I F l 1 l f E r r( f I L fi j~~g:~ ~: ; ; .JAYCAH ; ,IAYCAR , IAYCAR ; ,IAYCAR ( FI f- 1 E1 FI 3:~g:~ ~: , JAYCAR F-1 ; ; LESS 15% SAVE $84.96 $1.50 SAVE $14.99 ~ - - - - - . ; __ _ _..,._...,_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ JI-IYL,I-IH JAYCAR JAYCAR JAYCAR U EL JAYCAR El JAYCAR FI .> JAYC,\11 EI ,JA,CARfl NORMALLY $99.95 J AYt.;AH JAYCAR ' - - - - - - - - - - - - - - - - - - ~ JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR FLFCTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS H EL EL S IAYCAH h LESS 15% $339.15 SAVE $59.85 For freight costs on SA?0/100/130 please contact Mail Order Dept before ordering. EL EL EL EL EL EL El EL EL El EL FL El El EL EL El EL EL EL E'l EL EL EL tl EL EL cl EL El El JAYCAH JAYCAr1 JAYCAR JAYCAR JAYCAh ;j:~g::~: ; ~:~g:: ~: JAYCAR El , JAYCARFI JAYCAR fl tLtCI HONICS JAYCAR El ELECTRONICS JAYCAR El ELFCTl,ONICS JAYCAR FI ELECrRONICSJAYCAR fl ~l f-:CTR_QNICS JAY CAR El ;;;;;;;:__■-1 - , ICS"' ICS J ICS J ICS. ICS" ICS. ICS > ICS, ICS J ICS; )'ilCSJ JNICS J )~ICS l\lCS J J~ICS J )NICS J REMOTE CONTROL BY BOB YOUNG Designing a speed controller This month, we will discuss some of the factors influencing the design of a simple low-cost speed controller which will be presented in this magazine. The overriding consideration is that of "milliohms" - the fewer, the better. To begin, a brief description of how our speed controller functions is in order. Speaking in very broad terms, a speed controller is an electronically controlled variable resistor inserted in series with the motor (Fig.1). The control elements are usually FETs (field effect transistors) or bipolar transistors. The control voltage is derived from the receiver battery which brings us to the first problem. FETs in particular require drive voltages of around 12V to reduce their ON resistance to the lowest possible value. As the re- ing from the receiver battery to provide the drive voltage. The choice between bipolar or FET transistors is an easy one. There are problems associated with paralleling bipolar transistors and since we are after a very high current with a very low ON resistance, parallel semiconductors are more or less forced upon us and the clear choice is FETs. There is only one practical way to use the FETs in a continuously variable speed control and that is to rapidly pulse them on and off. A linear control system (ie, virtually a variable "It must be stressed that in this project we are moving into the world of high current devices and therefore we are primarily concerned with making improvements which will be measured in milliohms." ceiver battery is usually only 4.8V, some voltage doubling or tripling is therefore required in the drive circuitry. We could use the motor drive battery which is often 7. 2V or as much as 30V in some cases. But in some applications, the motor battery is only 4.8V, particularly in the case of very small motors. To allow maximum versatility of the final unit, I have therefore decided to use a voltage doubler work- resistor) could not work because at the half throttle setting, the amount of power dissipated in the FETs would be the same as in the motor. Clearly, this is very wasteful of the batteries but also means a very large amount of heat that the controller must dissipate. So modern speed controllers are all switching designs. This switching frequency usually ranges from 50Hz to 2.5kHz and I have decided upon 2kHz as an achiev- able figure. The problem here is that each gate has an input capacitance of about 1500pF and this will begin to round off the gating pulse. The 2kHz signal to the gates of the FETs is pulse width modulated (PWM) and the output power of the speed controller is proportional to the width of the switching pulse. Thus, a 50% duty cycle delivers half throttle. At full throttle, the pulse signal becomes a constant DC level. High currents The foregoing factors are the major design considerations. However, from the very outset it must be stressed that in this project we are moving into the world of high current devices and therefore we are primarily concerned with making improvements which will be measured in milliohms. The idea of dealing in milliohms is a little strange to most people, particularly to electronics buffs who are more used to dealing in ohms, kilohms and megohms. Most of us are very familiar with the milliwatt (mW), milliamp (mA) and millivolt (mV), but how many of you have ever encountered the symbol for milliohm (mQ)? Yet lmQ is a very significant amount of resistance in circuits drawing 1000 amps or more. A resistance of lmQ at 1000A will result in a voltage drop of 1V and a power dissipation of 1000 watts. By the time we have finished the next two articles, you will all be very aware of the effect of just a few milliohms on even reasonably low current circuits. To fully illustrate the point, let us look at a real life situation. Perhaps one of the best examples of high current devices we all encounter in an everyday situation is the automotive starter motor. A typical starter motor draws about FEBRUARY1992 69 400 amps when cranking the engine. I have not seen the instantaneous startup current quoted for a starter but it must be in the order of 1000 amps or more. (Editor's note: typical "locked rotor" currents are around 1200 amps or more). If we take 1000 amps as an average figure, then parasitic resistances in series with the armature of just 12 milliohms would result in most of the energy available from the car battery being dissipated as heat before it ever reached the starter motor. Such a situation does arise from time to time as the starter components age. Batteries sulphate up and the internal resistance begins to rise. The solenoid contacts burn and the corrosion that forms on the battery terminals gradually builds up until one cold morning the system finally falls over. Out comes the spanner and emery paper for the battery terminals and warm water for the battery. There is little we can do for the solenoid contacts, as they will have to wait until we can get to a garage. In the meantime, if we can at least shed a few milliohms then we can get the car started and be on our way. You can now afford a sate IIite TV system For many years you have probably looked at satellite TV systems and thought "one day". You can now purchase the following K-band system for only: $995.00 Here's what you get: * A 1.8-metre prime focus dish antenna, complete with all the mounting hardware. * *magnetic One Ku-band feedhorn and a signal polariser. * 30 metres of low-loss coaxial cable with a single pair control line. * A 99-channel infrared control satellite receiver with adjustable IF One super low-noise LNB (1.4d8 or better). and audio bandwidth, polarity and dual digital readout. Extraneous resistances Your receiver is pre-programmed to the popular AUSSAT transponders via the internal EEPROM memory. This unit is also suitable for C-band applications. Call, fax or write to: AV-COMM PTY LTD PO BOX 386, NORTHBRIDGE NSW 2063. Phone (02) 949 7417 Fax (02) 949 7095 All items are available separately. Ask about our C-band LNBs, NTSCto-PAL converters, video time date generators, FM 2 and EPAL. I I I I I I I I I I ----------YES GARRY, please send me more information on K-band satellite systems. Name ............ .... .................... .. ........ Address ........................................... ........................... P/code ................ Phone .............................................. ACN 002 174 478 01/92 I I I I I I I I I I ·----------- ■1 70 SILICON CHIP Fig.2 shows the basic problem in simple terms. A motor fitted with an llQ armature is supplied from a 12V battery. The motor installation has a number of miscellaneous parasitic resistances in series with this armature. These are typically made up of the switch, connectors, wire, battery internal impedance, and brush and commutator resistances. These we will lump together and define as RLP (lumped parasitic). RLP does not include the armature winding resistance as this is defined as the load resistance and is a separate item. RLP is the actual parasitic resistance introduced by the practical requirements for using the device in the real world. They derive from the insertion of wire looms, contacts for ease of charging and servicing, fuse holders, switches for turning the system on and off and ageing of the brushes and commutators. Now the problem is that all of these lumped parasitic resistances can add up to a considerable resistance if care is not exercised in the design and maintenance of the motor installation, and this problem compounds with the amount of motor current required. + T I I ...,_ PULSE GENERATOR Fig.1: the basic scheme for an electronic motor speed controller. The pulse generator controls the on-time of the FET which in turn acts as a variable resistor & thus controls the speed of the motor. l +T 1 ...,_' 12V Fig.2: a parasitic resistance of just Hl in series with a motor with an 11n armature will rob the motor of 1W of power. This problem gets worse as currents get higher. Thus, ifwe give this lumped parasitic resistance a value of lQ, the total cir" cuit resistance becomes 12Q. This will result in an instantaneous start-up current of one amp. With a start-up current of lA, one full volt is dropped across the parasitic resistances, thereby robbing the motor of one watt of badly needed power. This is serious enough but consider the situation where we require much greater motor performance such as in our car starter motor. Consider what happens if we replace the 1 lQ armature with a 12mQ winding. With no parasitic resistance in series, this" armature will require 1000 amps instantaneously at start up. With just 12 milliohms of parasitic resistance in series with the armature, we halve the instantaneous current.to 500 amps and worse, half of the initial power is wasted. This means that the available power at the instant of startup is down to a quarter. Thus, it is TABLE 1 Model WHD Max. Voltage Min. Voltage Max. Current Cont. Current KoCx-111 412544 8.4V 6V 2100A 510A 0.05V 0.004 ohms Novak 410-M1c 3619 40 12V 4.8V N/A 250A 0.06V 0.005 ohms Novak 410-MXc 45 19 43 12V 4.8V N/A 500A 0.04V 0.003 ohms Tekin 411 P 41 19 36 13.75V 5V 1050A NIA 0.06V 0.005 ohms Tekin 420F . 38 19 51 20V 4V N/A 400A 0.04V 0.003 ohms easy to see that in order to deliver the maximum power required for starting the car engine, we must hold the parasitic resistances down to less than lmil Now lmQ is not a lot of resistance. Car designers do not specify 10mm thick cables for the starter leads for nothing. Even car designers get it wrong occasionally, though. The starter solenoid is a high current switch which has two windings: the "pull-in'' winding and the "hold-in" winding. At switch on, both coils are activated but once the solenoid is fully engaged, the "pull-in" coil is released, leaving only the "hold-in" coil energized. The total current consumption of the full solenoid is typically 35A, with 20A a typical figure for the "hold-in" coil only. . The problem is that the designers originally passed this current (35A) through the keyswitch on the steering column with the result that the keyswitch usually melted at some stage in its career. Modern practice is to mount a solenoid boost relay very close to the solenoid and run only the coil current of this relay through the keyswitch. The solenoid coil current is run through the relay contacts with very short leads. "ON" resistance Similar problems arise in the design of speed controllers for model aircraft, with one additional problem. As already noted, we are deliberately introducing an electronically variable resistor in series with the motor. In the ideal world, this would not be too bad, for there would be no voltage drop across the control semiconduc- tor in the full "ON" condition. Unfortunately, in the real world, there is a voltage drop and it can be quite considerable and extremely detrimental to the performance of the electric motor we are controlling. The typical "ON" resistance for even an exotic FET such as the IRFZ44 is given at .028Q or 28mQ Now we can see immediately that here is a potential source of power loss of very significant proportions. Remember, too, that these figures were derived under laboratory conditions. We are faced with the task of converting this device into a practical working model so great care must be exercised if undue losses are to be avoided in our finished design. Commercial benchmarks At this point it would be interesting to establish what modern commercial speed controllers are achieving in the way of performance to establish the benchmark for our own efforts. Table 1, based on data from the November 1991 issue of the American magazine "Radio Control Racer", shows comparative figures for several modern speed controllers. The figures quoted are, at first glance, quite stunning, with instantaneous currents of up to 2100 amps and sustained currents of 250-510 amps being quoted. The resistance of the systems was measured at the 5cm point, being in the range 3-5mil The voltage drop at this point was typically 0.04-0.06V. But hang on, 2100 amps at 4mQ gives a voltage drop of8.4Vacross the 5cm of wire alone. Where do we find enough electrical headroom for a mo- Voltage at 5cm Resistance at 5cm tor armature in series with the 4mQ of parasitic resistance? And what is the 0.05V drop at the 5cm point all about? Here we encounter a real problem in that figures quoted at random without their companion figures are completely useless. Thus, we need to know what was the test voltage for the 2100 amp result. In all probability it was a short circuit test at 8.4V but we can only guess, for nowhere in the text accompanying that table does the magazine give any hints. Likewise, the 0.05V drop at the 5cm point; at what current? Here at least we have a clue. The resistance at this point is given as 0.004Q (4mQ). Thus Ohm's Law gives us a figure of 12.5A, a reasonable enough figure. These are still very good figures and one wonders just how accurate they are? To prove the point I obtained access to a brand new car fitted with a Novak 410-MXc, a 6-cell pack and a Kyosho Super Stock 20 motor. At 7.51V, the motor drew 3.65A driving the back wheels with no load. A voltage drop of0.02V was measured across the negative battery terminal and the FET side of the motor terminals. Loaded to BA, the voltage drop was 0.04V which gives a calculated 0.06V at 12A. At 8A, the tyres nearly took the skin off my assistant's hands, so we did·not try for 12 amps. You will notice that I was too smart to try to hold the tyres. I did the hard stuff on the transmitter throttle. Let me tell you right here and now that these units may be expensive but they are good and comparable performance represents a difficult goal to achieve. But we think that our proposed design will stack up pretty well. SC FEBRUARY1992 71 AMATEUR RADIO BY GARRY CRATT, VK2YBX Trunked radio communications While trunked radio techniques are not yet used by the amateur radio fraternity, they are widely used by commercial organisations. In the years to come, trunked radio services may displace some the amateur bands as pressure on radio space increases. Throughout the world, the radio spectrum available for mobile radio services is becoming more congested. The major capital cities of Australia are no exception, where demand is growing at an alarming rate. Latest DOTAC licensing figures show that there are now more than 400,000 commercial operators in Australia, sharing VHF and UHF commercial frequency allocations, and these are increasing at a rate of 25% per year. low coverage of such cells, when compared with VHF and UHF systems. In addition, not all users require access to the PSTN telephone system , and some wish to deliberately avoid such access. Also, there are significant charges incurred every time a cellular call is made and this cost is intolerable to many commercial users such as taxis, couriers, etc. Fortunately, there is an alternative communications system which has "Standard mobile radio operates on a single channel and thus calls can only be made when the channel is free. Trunked radio uses a number of discrete frequencies within a small band and allows a call to be made whenever any channel is free" As the demand for spectrum increases, there is no doubt that the relatively uncongested and highly prized VHF and UHF amateur allocations will become valuable targets for commercial users. Some of the increased demand has been met by the Telecom Cellular system (see 1ast month's issue) but there are significant drawbacks in using this system for some commercial users. High hardware costs exist to service cells at 800MHz, due to the relatively 72 SILICON CHIP been in use in some of the more densely populated European countries for some time. Called "trunked radio", it goes a long way towards solving the problems of increasing spectrum congestion. There are several conflicting standards that are presently being evaluated for use in Australia. The most well known is "MPT1327", the standard adopted by the British government, which has been in use since 1988. Other standards claim to have various advantages over MPT132 7 but for the purpose of this article, those differences are immaterial. Multiple frequencies In essence, the basic difference between trunked mobile radio and standard mobile radio is this: standard mobile radio operates on a single channel and thus calls can only be made when the channel is free. Trunked radio uses a number of discrete frequencies within a small band, and allows a call to be made whenever any channel is free. Obviously not all users will wish to call at the same time and even if several do, there are multiple frequencies available. So more users can share the band of frequencies and achieve the same grade of service as a single channel would allow. One disadvantage of a trunked system it that one channel must be used to transmit call data to all mobiles in the system. Whilst this means that one channel in the system cannot be used for 2-way communications by a mobile, this disadvantage is overcome once three or more channels are trunked. In the UK, wide-area networks have been set up and now cover much of mainland Britain, allowing up to 10,000 subscribers. These networks allow secure voice and data communications with other mobiles and allow mobiles to connect to private telephone, PABX systems as well as the PSTN where requested. PSTN features include conference calls, transfers, automatic call holding until a channel becomes available, a call-back facility for unattended mobiles, roaming and priority calling. In addition, the system features include: a capacity of one million addresses per system code, automatic SPARE RECEIVER OUTPUTS RECEIVE ~ - - - - < DISTRIBUTION MODEM DIPLEXER How it works SYSTEM CONTROL UNIT TSC BASE RF 1 TSC ·BASE RF 2 TSC BASE RF3 TSC BASE RF 4 TSC BASE R~S CENTRAL COMPUTEII COMBINER& EXCHANGE LINES PABX SWITCH SPARE TRANSMITTER INPUTS COMBINER~ COMBINERS Fig.1: block diagram of a trunked radio system. The Trunk System Controller (TSC) connects callers, validates mobiles, records billing details where required, and manages the band of radio frequencies at its disposal. user location and registration, auto release of traffic channels at call termination, periodic checking of serial numbers for subscriber security, etc. The system is completely transparent to the end user. One of the main differences between a cellular telephone and trunked mobile radio is that TMR is usually a simplex system, meaning that the mobile cannot receive and transmit at the same time, as is the case with the cellular system. This has the advantage that it simplifies transceiver design and also means that two transceivers in close proximity can share the same pair of channels. Block diagram Fig.1 shows a block diagram of a trunked radio system. At the heart of any trunked radio system is the TSC (Trunking System Controller). This is the computer which connects callers, validates mobiles, records billing details where required, and manages the band of radio frequencies at its disposal. All data signalling which takes place on an MPT1327 system uses FFSK (fast frequency shift keying). Data is sent at 1200bps. Each bit is represented by either one cycle of 1200Hz tone, or one and a half cycles of 1800Hz, where 1200Hz = 1 and 1800Hz = 0. This data is always phase continuous and bit transitions always fer to another traffic channel. CLEAR - used by the base to clear a mobile call. occur at the zero crossing points. This reduces the required bandwidth compared to FSK. Data transmitted on the control channel consists of two types of data word sent alternately. These are the CCSC (control channel system codeword) and data codewords. The CCSC identifies the trunked radio system (useful where there are more than one in operation) and it identifies which type of mobile can access the system. In addition, it acts as a synchronisation pattern for radio modems. Data codewords are used to control and direct mobiles active on the system. Some common data codewords are: ALOHA (ALH) - this message is sent by the base station to indicate that it is free to accept messages at that time. Aloha messages can be used to address specific groups of mobiles. AHOY (AHY) - this word is used to call a mobile to see if it is available. REQUESTS (RQS) - this word is used by mobiles to request a call. These messages can also be used to call for data, to signify an emergency, to call status and to divert calls. ACKNOWLEDGE (ACK) - used to confirm a request or an ahoy. These messages can also indicate that the service request is accepted, denied or queued. GO TO TRAFFIC CHANNEL (GTC) - this message is used to send a mobile from control to a traffic channel, or to trans- In a trunked radio system, the available spectrum is shared by a number of mobiles. If there is no available channel, the call is placed on hold for a few seconds until a channel becomes free. In simple terms, the system operates like this: Each mobile transmits a control signal on a dedicated channel to the system computer. When the user wishes to make a call, the mobile transmits the request in the form of a data signal to the system computer. The computer locates the called party by means of the control channel and checks its ability to receive the call. When both called and calling parties are ready to communicate, the computer allocates the first available traffic channel. When the call is terminated by either party, the mobile sends a signal to the system computer, releasing the channel. When not in use, each transceiver is tuned to the control channel and the transceiver microprocessor can communicate with the system computer. Finally, when roaming across geographic boundaries, the mobile calls the system computer to register its presence at a new location, so that the system computer knows where to locate the user for the next incoming call. As can be seen from the above explanation, Trunked Radio Systems offer improved spectrum usage whilst maintaining a high standard of service. Presently, in Australia, there are several private and public trunked systems in operation, with others planned to come on line during the next few years. No doubt there will be further developments in this field, which will affect the spectrum allocation and operating efficiency of all mobile radio users, including amateur radio operators. Acknowledgments (1) "Trunking Test Solutions"; "What's New in Communications" Feb/March 1991. (2) "MPT1327 Trunked PMR"; What's New in Communications" Feb/March 1991. (3) "Discussion Paper on MPT1327"; Japanese public domain 1991. SC FEBRUARY1992 73 SOUND COMMANDER The affordable P.C Sound The Sound Commander is a plug on sound board for y ou r *IBM PC, AT, 386 , 486 computer. 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Cl 6025 .. .... .. ..... .. ..... ... ..$11.95 120 x 5 114" LOCKABLE C16028. .. . .... ......... $19.95 ~P.RINTER STANDS , ~ 31/2"x 40 DISK CAPACITY ' ONLV... $6.95 I PRINTER SWITCHES . ) RS232-2 WAY .. . .. .... $39 RS232-4 WAY.... ......... $69 RS232·X OVER ................... $69 RS232·2 WAY AUTO ........... $89 CENTRONICS 2 WAY ... $49 CENTRONICS X OVER. ...... $69 CENTRONICS '2:way auto ..... $79 CENTRONICS 4 WAY............. $69 RS232 BREAK OUT BOX A simple way of morntonng RS232 interlace lead activity lnterl~re powered. pocket size for circuit testing. monitoring and patching 10 signal powered LEo ·s and 2 spares 24 switches enables you to break out c1rcuIts or ;reconfigure and patch any or all the 24 active posItIons DELUX PRINTER STAND C21058 .......... ........... ...$89.DO SPECIFICATIONS: Connectors: 0B25 plug on 80mm ribbon cable and 0825 socket Indicators: Tricolour LEo ·s for TO :1 C21056 .. 132Column.... $34.95 Jumper Wires: 20 tinned end pieces Power: lnterlar:e power Enclosure: Black high impact plastic Uimensions: 85 x 95 x 30mm X 15 700 NEW BUDGET MOUSE f) Moo \ l Sf The famous time l or less chips) • Chip drawer has conductive foam pad • Mains powered • High UV intensity at chip surface e n s u res EPAOMs are thoroughly erased PC MONITOR EXTENTION CABLE 9 WIRE STRAIGHT THROUGH Without timer DB9 M/M 1.8 M. ••• $14.95 X14950 .............. .......$99 DB9 M/M 3.0 M .... $19.95 DB9 M/M 5.0 M .... $29.95 with Timer........$169 $99.95 DB9 M/F 1.8 M ..... $14.95 ---;-. B- U_ D_ G_ E _ T- - - - - - - ' i l o B 9 M/F 3.o M ..... $19.95 . . 0B9 M/F 5.0 M ..... $29.95 · RS232 EXTENION CABLE 25 , i:, WIRE STRAIGHT THROUGH IBM i" 1, , _ "'!!"''T DB25 M/M 1.8 M .... $14.95 · -, , DB25 M/M 3.0 M .... $19. 95 0B25 M/M 5.0 M .... $24.95 DB25 M/M 10 M .... . $39.95 DB25 M/F 1.8 M ..... $14.95 Compatible with IBM, PC, . DB25 M/F 3.0 M. .... $19.95 XT, AT Elegant appearance DB25 M/F 5.0 M.- .. $24.95 & durable mechanism DB25 F/F 10 M ...... $39.95 0B25 F/F 1.8 M ...... $14.95 Auto. return cantering DB25 F/F 3.0 M .... .. $1.9.95 An incredib le .............. $24.95 . 0B25 F/F 5.0 oi ...... $24.95 RD. RTS. CTS. DSR CD TC . RC . DTR. (E)lC WIRE PRINTER STAND C21054 .. 80 column ....... $29.95 UV EPROM ERASER It will erase up to 9 x 24 pin devices in comp1ete safety, i n about 40 minutes (less Microsoft OUICK MOUSE compatible streamline design Mouse&,, an amazing lmage72 software $29.95. only $39.95 Oy TICK -- : MICROSOFT MOUSE The top of the range! Supports hunderds of C21087 .. ~ ... t14.95 RITRON EXECUTIIVE CASE X11089. Includes power supply..... $119 ··~ ,• 2 FREE TELEPAI NT DISKS! X19951. ... ..... . ..... $119 applications. MINI VACUUM CLEANER SPECIFICATIONS: $69.95 ~:~.~~ :ORTI .. $199.95 ~ Add1t1onally. CPF s filtering capability helps eliminate troublesome and annoying 1nterlerence. general hash cre.ated by small motors fluorescent lamps . and !he like that threaten the performance and shorten equipment life of unprotected electronic components CatX10088 SUPER BUS MOUSE 2 DESIGNED TO FIT THE PAl'.M ·~. / ·.. OF YOUR HANOI~ / GREAT FOR . / TOP OF THE RANGE_ E lectrica l rating: 220-260 volts {AC) 50Hz 10 Amp Spike/RF! Protection : 4 .500 amps for 20mi second pulses Maximum c lamping voltage: 275V d1tterent1a! mode ~ house & mouse MINI TOWER ., • SCREW CLAMP CAN BE MOVER 90" CASE ' UNIQUE CONSTRUCTION. LOCKS IN PLACE WITH MONITOR ON TRAY. · 200x415 , C21082 ........................... $199 x 330mm with 200w power supply x11100 ............. ...... ..... .. $199 10+ o· QUICK MOUSE · 1 {) FREE MICROSOFT PAINTBRUSH SOFTWARE BRINGS YOUR COMPUTER TO LIFE. X19958 .. .. . ...... $179 IBM* CARDS XT HO CONTROLLER ....... $129 AT HO CONTROLLER ....... $149 RS232/SERIAL CLOCK..... $49 MONO COLOUR CARD ...... $76 MULTI 110 CARD ................. $99 PRINTER CARD .................. $29 EGA CARD .......................... $179 DIAGNOSTIC CARD........... $795 TTL PRINTER ...................... $89 6M AT EX/EXP..................... $325 FAX CARD........................... $595 4 PORT SERIAL CARD ...... $199 2 WAY FDD CONT (360) ..... $39 RS/232 SERIAL CARD ........ $39 GAMES CARD..................... $29 AT SIP/G 2 SIP/G ................ $49 4 WAY FDD CONTROLLER (360-1.44M) ......................... $129 2 WAY FDD CONTROLLER (360-1.44M) ......................... $89 CLOCK CARD .................... $~9 SMART DRIVE ADAPTOR IDE/FDC............................... $49 SMART DRIVE ADAPTOR IDE 110 FDC ......................... $89 512K/576K RAM CARD ....... $99 VGA CARD 16 BIT 250K .... $89 VGA CARD 16 BIT 512K.... $129 VGA CARD 16 BIT (1 MEG).$199 IBM PRINTER CABLE, 25 WIRE STRAIGHT DB25/CN36 M/M 1.8 M. .. $14.95 DB25/CN38 M/M 3.0 M. .. $19.95 DB25/CN36 M/M 5.0 M ... $24.95 DB25/CN36 M/M 10 M .... $39.95 IBM PRINTER CABLE, 2s WIRE RIIGHT ANGLE DB25/CN36 M/M 1.8 M..:$19.95 DB25/CN36 M/M 3.0 M ... $2 4.95 DB25/CN36 M/M 5.0 M ... $29.95 DB25/CN36 M/M 10 M. .. $44.95 RS232 EXTENION CABLE 25 WIRE STRAIGHT THROUGH DB25 M/M 1.8 M .... $14.95 DB25 M/M 3.0 M .... $19.95 DB25 M/M 5.0 M .... $24.95 DB25 M/M 10 M ..... $39.95 DB25 M/F 1.8 M ..... $14.95 DB25 M/F 3.0 M ..... $19.95 DB25 M/F 5.0 M ..... $24.95 DB25 F/F 10 M ...... $39.95 Adjustable 0-45V 8A power supply, Pt.2 This month, we feature the construction and setting-up procedure for the adjustable 0-45V 8A power supply. Virtually all of the components are mounted on one large PC board, leaving only a small amount of hand wiring to be done. By JOHN CLARKE The new power supply is housed in a large instrument case measuring 355 x 250 x 122mm. Available in black, beige and blue (the colour we chose), the case is made exclusively for Altronics and gives a very good appearance to the unit. For this project, the case requires the addition of alu76 SILICON CHIP minium front and rear panels plus a steel baseplate (also available from Altronics). Most of the circuit components are mounted on a PC board measuring 189 x 167mm (coded SC04201921). The remaining components either mount onto the steel baseplate or on the front and rear panels. You can begin assembly of the power supply by checking the copper pattern on the PC board. It should be free from any shorted, missing or open circuit tracks. Check the copper pattern against the published pattern to be sure that the PC board has no faults. Shorted pads and tracks should be cleared with a sharp knife, while breaks in the copper pattern can be repair,ed by soldering a short length of tinned copper wire across the gap. Once the PC board has been checked, you can start mounting the parts onto it. Fig.4 shows the parts layout details. Install the PC stakes first and then the wire links and resistors. The resistors are all 1 % types with the exception of the ½W, 1W and Fig.4: here's how to install the parts on the PC board. Make sure that all polarised parts are correctly oriented & refer to the text for details on mounting the optical fibre link. The text also gives the winding details for L1 & L2. , ~ sV ~-1~R ~ MINAL + I .........-s3 A• • Ke ~="' 0~ • =~ • • 02 '-' _ 5W types. It's easy to mistake the value of the 1 % types when reading the 5band codes, so we recommend that you check each resistor with your multimeter before installing it on the board. The 5W resistors should be mounted about 2mm above the surface of the PC board to allow air to circulate free~ , Several different diode types are used in the power supply. These are the 1N4004 rectifier diodes (Dl, D3D6}, which are· usually black with a silver stripe; the 1N4148 or 1N914 switching diodes (D7, D8-D11) which are smaller than the 1N4004 diodes and have a transparent body and white or black stripe; and the zener diodes. ZD1 will be marked 1N4744, ZD2 will be marked 1N4733 and ZD3 marked 1N4761. ZD4 is a 3-pin device marked 336Z-2.5. When installing the diodes, make sure that each one has the correct orientation. Wrongly installed diodes qm be hard to spot if you have to track them down later. Note that di- _ _ _ __ ode D2, the MUR1515, is not installed at this stage. Optical fibre link The light link components are inserted next. Install LED 1 (the SFH750V) and insert the short length of optical fibre cable into the collet (with the collet loose) and push it in as far as it will go. This done, insert the other end into the SFH5 51 V receiver (!Cl) and check how much length of cable needs to be cut so that IC1 can be installed with just enough CAPACITOR CODES Value 0.1µF 820pF IEC Code 100n 820p EIA Code 104 821 TRIM POT CODES . Value EIA Code 50kQ 503 soon 501 '-' ~;; EAR~ _ _ _ _ _ _ _ CHASSIS _ _____, cable length between the two units. The ends of the optical fibre can be cut to length using a sharp knife but make sure that each end is square and neat. There is no need to polish the ends to prevent end reflections since the optical fibre length is short and light losses are small. !Cl (the receiver) can now be installed with the optical fibre in position. Once LED 1 and !Cl are both soldered in place, their collets are tightened to secure the optical fibre between them. The remaining ICs can now be installed but again pay careful attention to their orientation and type number. When soldering these in place, check that yo~ don't get any solder bridges between the IC pins. Now install the 12V regulator and the transistors . (see Fig.2 in last month's issue for the pinout details) . Don't install Ql (the power Mosfet) at th)s stage. That step comes later, when the PC board is mounted in the case. The capacitors can now be installed on the board. Make sure that the elecFEBRUARY 1992 77 This close-up view shows how the two inductors are wound & secured to the board. Ll is wound using 10 turns of1.2mm enamelled copper wire on the larger of the two cores, while L2 is wound using six turns of1.2mm enamelled copper wire. Make sure that the turns are evenly spaced on each toroid. trolytic types are inserted the right way around. Wiring the toroids Ll is wound on the larger ironpowdered toroidal core. First, wind on 10 turns of 1.2mm enamelled copper wire, evenly spaced around the core. This done, strip the enamel insulation back on each end and tin the bared copper ends. The toroid is then mounted vertically on the PC board and secured by a loop of tinned copper wire. To do this, solder one end of this wire loop to the PC board, then solder the other end while pulling it tight with a pair of pliers. Finally, solder the toroid windings to their respective PC stakes. L2 is wound with six turns ofl.2mm enamelled copper wire evenly spaced around the core. It is mounted on the board and secured in a similar manner to Ll. Mounting the hardware With the PC board complete, work can now begin on the case. We will assume that most readers who elect to build this power supply will purchase a complete kit of parts with the necessary metalwork ready to assemble. At the time of writing, Altronics has indicated that they will have kits available shortly after publication of this article. The price will be $375 .00. The method of assembly is to first 78 SILICON CHIP mount all the hardware (ie, the two transformers, bridge rectifier and terminal blocks) on the baseplate, which is then installed into the case. The front and rear panel hardware is then mounted and the wiring installed. Fig.6 shows the assembly details. The main toroidal transformer is mounted using a single bolt, one large · clamping plate, rubber washers at top and bottom, and a nut and lockwasher. Its 240VAC primary input wires (check the colour code supplied) are connected to an insulated terminal block, while its secondary wires are con- .........____ M!CA. BiJSH WAS\HEII SC11EW NUT \ -~~~ J PCB .le \ FINNED ilEATSIIK Fig.5: transistor Ql & diode 02 must both be isolated from the rear panel using a mica washer & insulating bush. Smear all mating surfaces with heatsink compound before bolting the assemblies together, then use your DMM to check that each · device is correctly isolated. . nected to the AC terminals on the bridge rectifier (BRIDGE 1). Apply a smear ofheatsink compound between the face of the bridge rectifier and the baseplate to provide good thermal contact. The small power transformer is mounted near the bridge rectifier and its 240VAC primary wires terminated to the same insulated terminal block as before. The two secondary wires are terminated to an adjacent 2-way insulated terminal block. The solder lugs for the various earth connections to the baseplate and front and rear panels should each be secured using a machine screw, nut and star washer to ensure reliable contacts. The PC board is mounted on 6mm spacers and secured using machine screws and nuts. Note that a solder lug is installed under one of the board mounting screws - see Fig.6. This provides an earth path for the output filter network. Rear panel assembly The single sided heatsink (ie, fins on one side only) is bolted to the rear panel using a single screw and nut. Apply a smear ofheatsink compound to the back of the heatsink and rear panel before they are fastened together. You can now mount diode D2 and Mosfet Ql in position. The metal tabs of these two device must both be insulated from the rear panel using a mica washer and insulating bush. Fig.5 shows the mounting details. Apply a smear ofheatsink compound between the mating surfaces of both devices before bolting them to the rear panel. Now switch your multimeter to the OHMS range and check that the metal tabs of both D2 and Ql are indeed isolated from the rear panel. If not, remove them and clear the fault. The rear panel assembly can now be completed by installing the fuseholder and the mains cord. Make sure that the mains cord is securely clamped with a cordgrip grommet. Front panel assembly Assuming that you have purchased the kit from Altronics, the front panel will be supplied with all cutouts and holes drilled and screen printed. However, before installing the meters, you will have to fit the new meter scales included in the kit. ~FUSE (~,~HOLDER REAR ALUMINIUM PANEL ----~===============~~ ' ,'-..._ _ _ _ _ _ _ _ - - - - - - - - - - - - - 12.6V _ ..... ~--------------------- PCB ROWN 2• 8• 10• EARTHT' CHASSIS 10 EARTH 13• 5• 14• 9• •3 •4 •12 e11 •1 •6 1• <at> METAL BASE PLATE ~ S1 POWER FRONT ALUMINIUM PANEL Fig.6: exercise care with the mains wiring & be sure to use heavy duty cable where specified in the text. FEBRUARY1992 79 This close-up view shows how Qt & D2 are bolted to the rear panel & their leads soldered to adjacent pins on the PC board. Note that their metal tabs must be isolated from the metal rear panel as shown in Fig.5. The finned heatsink is bolted to the back of the rear panel, directly behind these devices. To change a meter scale, first remove the clear plastic escutcheon by undoing the screws on either side of the meter. The original scale is then removed by undoing the small screws on either side of the meter movement and by then sliding the scale away from the meter without damaging the pointer. Finally, the new scale is installed and the meter re-assembled RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 80 No. Value 5-Band Code (1%) 1 1 9 3 1 2 2 4 2 1 6 470kQ 270kQ 100kQ 47kQ 27kQ yellow violet black orange brown red violet black orange brown brown black black orange brown yellow violet black red brown red violet black red brown red red black red brown brown grey black red brown brown black black red brown blue grey black brown brown yellow violet black brown brown red red black brown brown brown green black brown brown brown brown black brown brown brown black black brown brown grey red black black brown yellow violet black black brown orange white brown gold (4-band code) red violet brown gold (4-band code) red red black black brown brown black black black brown yellow violet black gold brown 1 1 6 1 3 1 1 1 2 1 SILICON CHIP 22kQ 18kQ 10kQ 6.8kQ 4.7kQ 2.2kQ 1.5kQ 1.1kQ 1kQ 820Q 470Q 390Q 270Q 220Q 100Q 47Q using the reverse procedure. Before mounting the meters, install an earth solder lug adjacent to the voltmeter as shown on Fig.6. This is secured using a screw, nut and star washer. This done , install the meters and secure them using the nuts supplied. The two pot shafts can now be cut to a length suitable for the knobs, after which the pots can be mounted on the front panel. Orient the pots exactly as shown on Fig.6 and install the knobs. Finally, complete the front panel assembly by installing the switches, LEDs (use bezels) and the output terminals. We used green for the earth terminal, black for the negative terminal and red for the positive terminal. Wiring Once all the hardware has been mounted, the power supply can be wired up. Follow the wiring diagram (Fig.6) carefully to avoid mistakes and be sure to use 250VAC insulated cable for all mains wiring (ie, to the fuseholder, earth lugs, 3-way terminal block and switch S1). Before soldering the Active (brown) leads to the fuseholder, slide a length of heatshrink tubing over both wires so that the fuseholder can be completely sheathed. Similarly, when wiring the mains switch, slide the wires • RAM Card SELLOUT NEW PRODUCT 2MB XT Card Complete with 2MB fitted This card does it all $299.00 SAVE $75.00 IDE2 x Hard Disk controller with 2 x Floppy Disk Controller and 2 Serial Ports, 1 Parallel and 1 Games port. Introductory SPECIAL for this month only 2MB AT Card Complete with 2~ fitted $299.00 SAVE $75.00 $49.00 32MB AT Card complete with 4MB fitted $599.00 SAVE $146.00 ·Normalpricewillbe$75.00 We also stock a range of motherboards, external disk drives, hard disk drives, add-on interface cards, as well as a huge range of cables, adaptors, switch boxes and chips. Call today for competitive pricing. DEALER INQUIRIES WELCOME BUILD YOUR OWN FAX/MODEM ONLY $299.00 Time saving The Comma Fax/Modem will also receive faxes in background while you continue to work. When faxing out the Fax/Modem will redial an engaged number so you can be sure your faxes are sent. The software also automatically keeps a complete log of both incoming and outgoing faxes. Also supported are cover pages, broadcast faxes, and scheduling. The software keeps a database type register of regularly used fax numbers for easy retrieval This is a fully featured kit The Comma Fax/Modem is a commercially designed kit you can build. It will turn your PC (or Macintosh) into both a fax machine which can transmit faxes up to 9600 baud, as well as a Modem which supports both 1200 and 2400 baud. You get all the necessary components as well as a professional case, and power supply. You also receive FREE Fax/Modem software. All this for less than $300. The Comma Fax/Modem uses the latest technology in digital signal processing to ensure lasting troublefree operation. Send faxes from home The Comma Fax/Modem is a fully featured fax machine similar to units costing over $1000, which will transmit faxes at up to 9600bp. Your faxes can now be sent directly from your PC without having to print them first. Programs supported such as Ventura Publisher, Wordperfect, Windows, TIFF and Dr Halo to name but a few. You can view incoming faxes on-screen or print them using a standard dot matrix printer. Incoming files can also be exported in either TIFF or PCX format for use in most popular graphic packages. Only print the faxes you want to keep - just think of the savings on expensive fax paper. As well it's also a modem The Comma Fax/Modem is a fully AT command series V compatible modem. Features include V22/V22bis standards (V21/23 is an option) both 1200 and 2400 baud rates are supported as well as auto answer, dialing and disconnect. You will find it compatible with all popular communication services including most bulletin boards. Now Available MNP and V42bis option. V21/23 option. $99.00 $39.00 FREE Software With each kit you will receive the QL2 Fax/Modem software featuring both pull-down menus and mouse support. Value packed kit Each kit has been specially prepared to ensure you are able to build the Comma Fax/Modem with a minimum of specialised skills. We have also weighed each kit to ensure every componentfa included. There is also a step-by-step guide to testing your Fax/Modem throughout the building process. Note: This device does not have an Austel permit in force. Connection to Telecom lines is an offence . TRY PC MARKETPLACE SUPERFAST MAILORDER - PHONE OR FA X TODAY! pfii[ (jfeesons PC MARKETPLACE Pty Ltd FREIGHT CHARGES Include $1 o with order for all normal items. Heavy items e.g . monitors add $15. 14 day money back guarantee. PHONE (02) 418 6711 WU - I SERVICE JS THE DIFFERENCE e FAX (02) 4186713 Mail Order Address: Order by phone (use credit card), by fax or by mail. Unless insurance is declined it will be charged at P.O. Box 1100 Lane Cove 1% of total purchase. This is for your protection. NSW2066 PRICES CURRENT FOR MONTH OF PUBLICATION OR WHILE STOCKS LAST e SERVICE IS THE DIFFERENCE e SERVICE JS THE DIFFERENCE e I SERVICE IS THE DIFFERENCE The terminals of the fuseholder & the mains switch are sleeved in heatshrink tubing to prevent accidental contact with the mains. Note that the power transformers, terminal blocks & PC board are all mounted on a steel baseplate which is securely earthed. The front & rear panels are also earthed - see Fig.6. through some heatshrink tubing before soldering them to the switch terminals. After soldering, push the heatshrink tubing over the switch body and shrink it into position. When wiring the unit, use heavyduty hookup wire between the PC board and the (-) output terminal, and between the board, switch S3 and the (+) output terminal. Similarly, use heavy duty wiring between the bridge rectifier and the PC board. The remaining wiring can be run using medium-duty hookup wire. Use various colours so that it is easy to check your wiring after it has been completed and the wires are all bundled together. We installed insulating sleeving over the LED leads to prevent shorts to the case. Diode DZ and Mosfet Ql can now be soldered to their respective PC stakes on the PC board. The leads are 82 SILICON CHIP simply bent towards the PC stakes and soldered. Testing & setting up Before switching on the power supply, check your construction and wiring carefully. Make sure that the transformer and rectifier leads run to their correct destinations and check that all capacitors are correctly oriented. In particular, check the 4700µF and lO00µF electrolytic capacitors since they may overheat and leak if incorrectly connected. When you are sure that everything is correct, you can perform the following voltage checks: • set your multimeter to the 20V DC range and connect it across zener diode ZD1. This done, apply power and check that the voltage across ZD1 is 15V ±1.5V. • check that there is 15V between pins 7 & 14 of ICZ and that the voltage across ZDZ is 4. 7V ±0.5V. • check that pin 3 of IC3, pin 3 of IC4 and pin 4 of IC5 are all at +12V with respect to the tab of the 7812 (GND) . • check that there is 2.5V across trimpot VR4. If these checks are all OK, connect your multimeter between the (+) and (-) output terminals and check that the output voltage can be adjusted from 0-45V (make sure that the Load switch is on and that S4 is set so that the voltage can be adjusted). If any of these tests give an incorrect reading, switch off the power immediately and attempt to·find out why before switching the power on again. In particular, check for wiring errors, incorrectly oriented components, and for missing solder joints and shorted and open circuit tracks on the PC board. If these checks don't reveal the fault, refer to the troubleshooting procedure below. Assuming everything is OK so far, you can calibrate the voltmeter by wax, FOR CHIPS... WOXI FOR CHIPS... WOXl FOR CHIPS... WCXJD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD Why pay up to $150 for a label? Take a close look at these APPA 90 SERIES Look lamlllar? That's NEW mulUmeters. because they're sold under different Loot at lh• feature,brand names. And that means you • Lll'p8 high fOntrasl d/1p/,y · pay a lot more than you need T,,. 96 and 118 hw• analog ,,,,. 100 could to. graph• too We'lle seen the top of the line • Colour co•d Input llrmlnat, SERIES model selling at around $150 more and tuncllan lwitch tar •asy than our price. So you're paying that much extra Just for the brand label! It's also an Indication of how good Appa meters are th"3.t other people want to put their names on them! _ _ _ _ _ _ _ _ __ . • Automatic paw11r-ott • M111t lEC 348 Clan II and UL 1244 standards tar sallty • Full 12monlh wa"1nty • Extra tough tar Industrial uars • High energy tun and PTC P.roteclipn against overloading • 0-rfng na/ed can, switch aiid /at:lts agalMt dirt and molstu,. • Pro/lCtive /lo/st,r and lilt stand with /,ad storage • Test prob111 hive Oliger 1/1/eld, Ind s/etWed p_lugs • Thit:11 wallsd ABS can and shot:11 mounted LCD withstands 2m drop on ID concrete floor • Unique rota,y switch with ber,ylium copper fOntacll and Model93 • 1999 count • Large 20mm high contrast LCD readout • 8 Functions - Vdc, Vac, Ade, Aac, gh~M~~e, Frequency, • O.~, de accuracy • 4000count • Digital update twice/second, analog 20 times/sec • 8 Funclions - Vdc, Vac, Ade, Aac, Ohms, Diode, Continuity, Frequency, Capacitance • Data hold & Relative functions • 0.5% de accuracy $298.80 Also available Madi/ ll3T with transistor tester In place of 2A range · $142.80 $119.00 u lax $249.00 81 lal Vdc 400my, 4V, 40Vi 400V, 1OOOV Vac 4V1 40v, 400V, 50V Ade 4-'IOOmA, 1OA Aac 4-400mA, 10A Ohms 4000, 4kn, 40kn, 400kn, 4MO, 40MO Frequency 100Hz, 1kHz, 10kHz, 100kHz, 1MHz Capacitance 4nF, 40nF, 400nF, 4µf, . 4(,¥. Mods/ 105 his slml/ar sp,cs but with Improved /ICCuracy of 0.1% typ an Vdc and 0.5% al 50Hz $358.80 $291.00 II tax Model96 Mod,198 • • • 3 1/2 digit plus 41 segment • 3 112 dl~t plus 41 segment analog bar graph Autoranglng or manual selection analog ar graph 6 lunctlons • Vdc, Vac, Ade, Aac, • Autoranglng or manual selection Ohms, Diode · • 8 Functions • Vdc, Vac, Ade, Aoc, • Water resistant Ohms, Diode, Frequency, • Data hold • • Memory offset • Memory offset Ran~•r Rang111 Vvdc 200moomvv, 221/V, 2200VV, 2200Voov' 7150000VV Vdc 200mV, 2V, 20V, 200V, 1ooov A~ 200uA.' 2mA, 20mA, 200TIA, Vac 200mV, 21/, 20V, 200Y,,_]3.0V 2A, 20A · Ade 200&t, 2mA, 20mA, l\/UITIA, ~~ 2mA. 20mA, 200mA, Aa~1·JJ. 2mA, 20mA, 200mA, Ohms 2000, 21<n, 201<n, 200kO. 2A. 20A. 2Mn, 20MO Ohms 2000, 2kn, 20kn, 200kO, 2 $166.80 MO. 20Mn $139.00 11 tax Frequency 2kHz, 20kHz, 200kHz Capacitance 2, 20, 200nF, 2, 20-lf Appa 90 Carrying Case $14.10 $179.ot2e:J~ $12.20111 ta, Model 76 Componsnt Tester Ap no u I6 II PI • no r _ Does what your multimeter doesn't! 111 20 • Capacitance 200pF to 20µ1' ~ai~~,ce APPA 35 CLAMP METER • • • • • 4(1(10 count display Autoranging Measures fa 350A 11,: Conductors ,o 25mm dlamstsr Measureivoltage ID 750Vac, Ohms ta 4/JIIO and continuity with 11eep,r • Large 12.5mm LCD dlrplllf • Dara Hald button • Built-In 111/lcllp $142.80 $119.00 81 lal Rang,s Vdc200mV, 2V, 20V, 200V, 1000V Vac 200mV, 21/, 20V, 200V,.]~OV Ade 200uA. 2mA, 20mA, 2l.WlA, 2A, 20A. Aac 200uA. 2mA, 20mA, 200mA, 2A, 20A Ohms 2000, 2kn, 20kn, 200kO, 2MO, 20MO Frequency 2kHz, 20kHz, 200kHz Ca~~tance 2nF, 20nF, 200nF, 2µf, MlJJ1 J1Jeg't'Ss Rang_ss nning · • Pro/M 11Drag1 cl/pi bu/11 In tar 11a,y two hlnMd n.asuremsntr • T/111 96 lr wallr resistance tar /nduslr/1/un •• Shod/proof fora drop al 1.5ml Bui/I-In II/I stand - -.. . .Rack . .---~-~ - - - -• §o Cases &........ Frames • • • • • Aluminium construl'tlon with removable top and bottom st1191 covers Conforms to lntemallona/ Standards Natural or B/acfc anodised finish Ven/1/ated lids Assemble yourself In minutes Panel ease Ca No PrlCI Black He~ht Hole SpaCI Height Deplll Wldlll Natural 430 H0401 44 RUi 34 38 254 H04 11 159.95 88 2RU 57 82 254 430 H0402 H041 2 711.95 13 (3R 1J. 89 38 254 430 H0403 H04 13 89 .95 Blank Panels to Sult He~ht Natural 44 RU .H0421 12.50 88 2Rul H0422 f1a.5o 13 (3RU) H0423 $21.90 Blacll Anodised H0426 13.60 H0427 fU.5o H0428 $29 .95 Economy Rack Cabinet =- Value at $119.95 Rack Frames • • • • • • Ideal For Professional Users or Home Stereos etc Six sizes -4 6, 12, tB, 30 and 3BRU Snaps togeiher In minutes- no skiff required Push flt and then aign with rubber hammer Aval/able with or without side panels Each pack contains 12 custom extruded natural .KJOdlsed aluminium secnons, BABS comer connectors, 6 cllp-ln captive nuts and 6 mounting screws • Side iKJdTop panels In powdercoat blue 12RU 630mm H0368 18RU 900mm H0370 30RU 38RU 1430mm 1790mm H0375 H0380 $169.00 $189.00 $229.00 $269.00 $39.00 12 pact $110.00 $159.00 $195.00 100 pacll H0386 19.95 H0391 19 .95 H0396 45.50 .50 H0385 H0390 H0395 · _ ~ Mull/meter • 3 1/2 digit dlsp/q • Autoranging_ • 7 /uncttans Vdc, Vac, Ade, Aac, Ohms, Continuity • Single handed ap,ratlon • Bul1t-/n 111/t clip • Large 12.5mm LCD dlsplllf • Dara Hald button • Bui/I-In pro/M hold•r $94.80 $79.00 II lax Just what the Servlcsman nBBds! ~:;:o~h1~~dt1~~n • Diode displays VI al 1mA • LEO displays VI at 2Ma and 1OmA _ _ • Battery tests Wand 1.5V cells -CL..0--.L • SCR Pass/Fall test ~ GENUINE PREMIUM GRADE DISKS · 51/4 2S/2D $16.95 per 10 5 1/4 2S/HD $24.95 per 10 3 1/2 2S/2D $24.95 per 10 3 1/2 2S/HD $49.95 per 10 .95 2.95 .95 H0377 H0382 e $1 42.80 $11 9.00 u tax APPA 88 Low Cost Basic H0372 • PHS seriss to UL/DIN standards • 40kV/mm brsakdown • 600V rating • 9(1'C shrink temperature • Supplisd in metrs lengths ~~M $16.00~1X l~: alt $142.80 $119.00 11 lal ~ ideal for Amplifiers, Power Supplies, Char{l8rs etc Built-In I/ea/sink Side Panels · Up to 120W Audio Output Stages accomodated ~ Easy Installation of cooling fans ~ lntemal dimensions 125x370x25<mm ~ , External dimensions 130x440x252mm Choics o/ Grey or B/acfc Powdercoat Front Panel H0369 Miss E.A. December? Then send for 8 page FREE Semiconductor Listing Geoff Wood Electronics Pty Ltd ~ ~ ~ High Energy 3RU Rack Case Size 4RU 6RU Height 280mm 370mm Frame H0362 H0365 Price $139.00 $149.00 Panel H0363 H0367 Price $49.oo $55.00 AcceaorlH Rack Screws Natural Rack Screws Black Rack Captive Nuts N Ion Washers f'> ~ Black Powdercoat H0434112 .50 H0435 19 .50 H0436 24.50 • Solid steel co~strucllon • Black anodised front panel • t32mm (3RU) standard size • Ventilated top and side panels Only$6U5 • • • • • • • ~ 2 "6 Size Thickness Shrinks ID 1.Smm0.4mm 0.8mm 2.5 0.4 1.5 3.5 0.4 2 5 0.4 2.9 7 0.5 4.2 10 0.5 6 13 0.6 8.5 16 0.6 11 20 0.6 13 25 0.6 15 • 125x200mm slid-out tray with ,nti-st,tic p1d • UV indi"tor • 15, 000mi"uw, tt/sq cm intensity • 7700 hour lamp /ill • S1/ety interlock switch (inc In N s W) 229 Burns Bay Road, (Corner Beatrice Street),-Lane Cove West N S W Mail Orders to - PO Box 671, Lane Cove N SW 2066 Telephone: (02) 428 411 1 Fax : (02) 428 5198 8.30am to 5.00pm Monday to Friday. 8.00am to 12 noon Saturday Mail Orders add $5.00 min to cover postal charges Next day delivery in Sydney add $5 .00 All prices INCLUDE sales tax unless stated otherwise Tax Exemption Certificates accepted if the line value exceeds $10.00 BANKCARD, MASTERCARD, VISA, CHEQUES or CASH ch eerfull y accepted. $133.80 ex lax $155.20 inc lax ~ (") ;!; "lj ~ l. CLASS-2.5 MU-65 ~ l. CLASS -2.5 MU-65 First, a word of warning if you are troubleshooting with an oscilloscope. The various sections of this power supply circuit operate at different potentials so, to obtain meaningful results, make sure that the oscilloscope probe earth is connected to the relevant section of the circuit. If using two probes, avoid using more than one earth point to prevent shorting out different DC potential sections of the circuit. If the output voltage is always above 40V and cannot be controlled with the voltage adjust control, check the voltage at the gate of Ql with respect to its source pin. Ifit is at 15V or close to it, check the voltage on pin 1 ofIC2. If this voltage is different, then suspect IC2. If pin 1 of IC2 is at 15V, check the base of QZ. If this is at about 0.6V, then the transistor is not functioning. If the output voltage is always OV, check the voltage at the gate of Q1 with respect to its source pin. If this is close to OV then check pin 1 of IC2. If this has a different voltage, then suspect IC2. If pin 1 ofIC2 is at OV, check the base ofQZ. If this is at OV, then the transistor is short circuit from collector to emitter. Control circuit checks Fig.7: here are actual-size artworks for the two meter scales. adjusting VR5 until the reading on the voltmeter matches that on your digital multimeter. Note that the voltmeter is not as accurate (typically only ±2.5% of full scale deflection) as a digital multimeter. This means that it will not track your digital multimeter exactly over the full output voltage range. The 13.8V fixed supply can now be calibrated. To do this, set S4 to the 13.8V position and adjust VR6 so that the output voltage is 13.8V. The ammeter is calibrated by setting your multimeter to the 5A range and connecting it in series with a 0.22Q 5W resistor across the output (ie, between the + and - terminals). Adjust the output voltage until the multimeter indicates a current of 4A, then adjust VR2 to get a reading of 4A on the ammeter. If the current over84 SILICON CI-IJP load LED lights during this procedure and you cannot obtain the 4A setting, just wind up the current adjustment knob. Now, with the resistor and multimeter still in circuit, press the current set switch and wind back the current adjust control until the current overload LED just lights. If you now wind the control back further, the current should reduce. That completes the construction and setting up procedure of the power supply. Troubleshooting Apart from the simple voltage checks that were made in the testing and setting up section, there are some further checks that can be made to test various sections of the circuit if you cannot get it working. You may also need to test the control section of the circuit. Note that the common ground supply for this section is at a different potential to the circuit for IC1 and IC2. For this reason, connect the negative lead of your multimeter to the tab of the 12V regulator (GND) when testing the control circuitry. IC3a is the triangular waveform generator and this should produce a waveform which swings between 4V and 8V peak to peak. The DC voltage at pin 14 of IC3a should be at about 6V while an AC measurement should give a reading of about 1V RMS, depending on the frequency response of your multimeter. If the voltages measured here are significantly different from those stated above, suspect the IC3a oscillator stage. Under normal operation, with no load on the power supply, the DC voltage at pin 1 of IC3 (as measured by your multimeter) will be close to ground, since the pulses to LED 1 are relatively short. If this voltage is at 12V, suspect comparator stage IC3b or the error input voltages. Fig.8: use this full-size PC artwork to make your own board & to check the finished board for etching defects. The error input voltage at pin 7 of IC3b should be close to 4V. If it is much higher or much lower than this, then suspect the current, voltage and overcurrent error outputs. These error output voltages are easy to check. First, measure the voltage on pin 7 of IC5 with no load on the supply. It should be about 3.4V. Pin 8 ofIC5 should be above 10V, while pin 13 of IC3 should be above 11 V. Pin 5 of IC5 should be adjustable from 02.5V using VR4 when S4 is switched to the voltage adjust position. These checks should enable you to at least locate the faulty circuit section. After that, it's a matter of checking the relevant circuitry carefully until you locate the fault but remember that most problems with projects are due to incorrect wiring or faulty soldering (solder bridges between IC pins, missed or bad solder joints, etc). It is very unusual for new !Cs to be faulty unless they are incorrectly oriented on the PC board, so don't be in too much of a hurry to replace ICs if you strike problems. The same goes for the other parts - only rarely will new parts be faulty. SC FEBRUARY1992 85 DIGITAL MULTI METER HC -4510 DISPLAY:41 /2 DIGIT BASIC ACCURACY: 0.5% DC V DC VOLTAGE: 0·1000V DC CURRENT: 0·10A AC VOLTAGE: 0•750V AC CURRENT: 0·10A RESISTANCE: 0·20M OHMS CONTINUITY TEST, DIODE TEST DATA HOLD ~<;;,~~ 20 MHz DUAL TRACE OSCILLOSCOPE DC VOLTAGE: 0·1000V DC CURRENT: 0-10A AC VOLTAGE: 0·750V RESISTANCE: 0·20M OHMS CONTINUITY TEST, DIODE TEST, DATA HOLD, TR HFE GAIN, AUTO RANGE DMM WITH BAR GRAPH CTR DISPLAY:, 150 mm rectangular VERTIACAL DEFLECTION: • Deflection Factor: 5mV to 20V I Div on 12 r~nges in 1-2-5 step with fine control • Bandwidth DC: DC to 20 MHz (·3dB) AC: 10Hz to 20 MHz (-3dB) • Operating modes CH-A, CH-B, DUAL aad ADD (ALTICHOP L202 only) • Chop Frequency: 200 KHz Approx . • Channel separation: Better than 60dB at 1KHz TIME BASE • Type: Automatic & normal triggered in automatic mode, sweep is obtained without input signal , Sweep Time: 0.2m Sec to 0.5 Seel Div on ranges in 1-2-5 step with fine control and X-Y. CAO Probe to suit , Magnifier: X5 at all times. $39.50 each • Cat. 012201. TRIGGERING • Sensitivity lnt: 1 Div or more Ext: 1Vp•p or more. • Source: INT, CH-B, LINE or EXT • Triggering Level: Positive and Negetive, continuously variable level: Pull for Auto. • Sync: AC, HF Rej, TV (each+ or-) at TV Sync. TV-H (line) and (frame) sync are switched automatically by SWEEP TIMEIDiv switch. HORIZONTAL DEFLECTION • Deflection factor: 5mV to 20VI Div on 12 ranges in 1-2-5 step with fine control • Frequency response: DC to MHz (-3dB) • Max Input Voltage: 300V DC+ AC Peak of 600V p-p • X-Y operation: X-Y mode is selected by SWEEP TIME/ Div switch. • Intensity Modulation Z Axis: TTL Level (3Vp-p- 50V) + bright, - dark OTHER SPECS: • Weight: 7Kg Approx , Dimensions: 162 (H) x 294(W) x 352(D)mm. Q13040 ..................... RRP $99.95 O12105 .......................... RRP $750 NOW $129.95 Q13030 ........... RRP $149.95 DISPLAY: 3 17'2 DIGIT BASIC ACCURACY: 0.5% DC DC VOLTAGE: 0·1000V DC CUR RENT: 0·1 0A AC VOLTAGE: 0•750V AC CURRENT: 0·10A RESISTANCE: 0·20M OHMS CONTINUITY TEST, DIODE TEST Sf\.~~ ~\O Q13010 .................... RRP $119.95 NOW$99.95 DIGITAL MULTI METER HC-889 DISPLAY: 3 1/2 DIGIT NOW $89.95 ------------------------t DIGITAL MULTI METER HC-3500T NOW $695 DISPLAY:3/12 DIGIT BASIC ACCURACY: 0.5% DC DC DC AC AC VOLTAGE: 0·1000V CURRENT: 0·20A VOLTAGE0•750V CURRENT 0·20A RESISTANCE: 0·20M OHMS TEMPERATURE:•20C ·1200C CONTINUITY TEST, DIODE TEST TEMPERATURE CAPACITANCE FREQUENCY, hfe TEST, DATA HOLD. Q13000 ................... RRP $169.95 NOW $149.95 ANALOGUE/DIGITAL MULTIMETER HC-5050DB 3 1/2 DIGIT BASIC ACCURACY: 0.5% DC ~£, $~ AC CURRENT: 0·1 OA RESISTANCE: 0-20M OHMS DC AC RMS:-45d8 -+50d8 "TEMPERATURE: ·20C-1200C AC FREQ SPREAD : 50Hz-2KHz CONTINUITY TEST, DIODE TEST FEATURES: , Compactness, lightweight, ruggedness and simple design. · , The diecast frame provides compactness lightweight and ruggedness. • Easy Operation Light torque lever switches and push button switches are used. High Brightness CTR, high acceleration voltage and high beam efficiency of the 150mm rectangular CTR ensures a bright high speedsweep observation • Mu lti mode display system CH1, CH2, CH3, Add any combination or all the channels may be viewed simultaniously. Maximum 8 trace displaying is possible with the ALT sweep function. • High sensitivity and wide frequency bandwidth . The maximum vertical sensitivity is 1mVIDIV (when x 5 MAG)at 20 MHz or greater 3dB and mVIDIV at 100 MHz or greater -3dB. High input impendance The input impendance of CH1, CH2, CH3, is 1Mnt2%, 25pF t3pF . It."" -:r;,i,, $ 1_4_9_.9_5_ _ _ _ _ _-t a_1...a_o...2_0_ ..._.._............._......._.. R __ R_P_s_1_6_9_.9_5_N_o_w__ - LOG IC PROBE (LP-2800) USEFUL FOR TTL AND CMOS. HIGH & LOW INDICATORS PULSE MEMORY. FOR THE HOBBIEST OR SERIOUS TECHNIICIAN FOR TRACING THOSE HARD TO FIND FAULTS ON LOGIC BOARDS. Q11272 ............................ RRP$29.95 This instrument meets the customers needs in quality of performance, efficiency, function, design, and cost! Being rugged, highly reliable and a multi-purpose 3 channel, 8 trace oscilloscope with a 6 inch domed mesh type 14kV post deflection acceleration cathode-ray tube and with a fine red internal graticule. DC VOLTAGE: 0-1000V DC CURRENT: 0-10A AC VOLTAGE: 0·750V 100 MHz 3 CHANNEL 8 TRACE MODEL 5510 NOW $19.95 • Q12109 ......... RRP $2995.00 NOW $1,995 SCHOOLS & COLLEGES TAKE NOTE! ONLY $1,695 tax exempt. LEDS ~F= r ~F= BNC MALE PLUG 1-9 10-99 100+ ""'" ~,,.~ BNC.PANEL SOCKET 1-9 10+ 100+ P10516 $2.50 $2.25 $1.50 BNC CRIMP PLUG 1-9 10-99 100+ P10530 $3.95 $3.75 $3.00 ,~n,fi~,-:-. ~) BNC SOLDERLESS TWIST ON PLUG ·,:- Designed to transmit at 1-9 10-99 100+ ') 40kHz (L 19990) & recieve Z10140(R) $0.15 $0.12 $0.10 at 40kHz (L19991) withup Z10141(G).. $0.20 $0.18 $0.15 ·'· to 20V 1/P on the Z10143(Y).. $0.20 $0.18 $0.15 i transmitter. These units Z10145(0).. S0.20 $0.18 $0.15 ) can't be heard so are QUALITY 5mm LEDS :·: ideal for TV remote ' Z10150(R). $0.15 $0.12 $0.10 ::c controls, water level Z10151 (G). $0.25 $0.20 $0.18 / dectectors, burglar Z10152(Y) .. $0.25 $0.20 S0.18 alarms, motion dectectors & information carriers as they can be either pulsed or used in a continuous wave mode. FLASHING LEDS Transmitter 1·9 10+ RED 5mm 1·9 10+ L19990.......$2.95 $1.95 210159 $1.10 $1.00 Receiver L19991 .•.....$2.95 QUALITY 3mm LEDS < 7 I PICK UP YOUR NEW 1992 MAIL ORDER 1 CATALOGUE AT ANY OF OUR ROD IRVIIIG I I ELECTRONICS STORES or PHONE 008 33 5757 : FOR YOUR FREE COPY or WRITE TO PO BOX 620, I I CLAYTON. MEI!!- . VICTORIA. 3168 I L---------------------------J ---- 2 WAY................ $59.95 4 WAY..•......•...... $69.95 MONITOR & KEYBOARD SWITCH BOXES only $69.50 _.,.. -== RECTANGULAR LEDS Save a fortune on expensive throw away batteries with these quality Nicsds and Rechargersl Size AA 450mAH 1·8 10+ $2.95 $2. 75 SlzeC 12AH $9.95 $9.50 100+ $2.50 $8.95 SlzeO 12AH 1-9 10-99 100+ P10962 $3.50 $2.95 $2.50 ==-:::ru CANNON TYPE 3 PIN LINE FEMALE 1·8 1().88 100+ P10964 $3.95 $3.50 $2.90 & LOW PROFILE IC SOCKETS Save a small fortune on these "Direct Import" low profile IC sockets! PCB mounting solder tall. All tin plated phosphor bronze or borrylllum and dual wipe lor rellablllty. 1-9 10+ 100+ CANNON TYPE 3 PIN CHASSIS FEMALE 1-8 D TYPE IDC PLUGS 1·8 10+ • DESP Spin plug Pl2166 $1 .50 $1.20 $1.00 • 0A15P 1 Spin plug P12168 $1.50 $1.20 $1.00 10-89 100+ P10966 $4.95 $4.50 $3.50 P10550 8 pin 15C 12C 10C P1056014pin 20c 18C 15C P10565 16pin 20c 18C 16C P1056718pin 30e 25c 22, P 10568 20pin 35c 30c 25e P10569 22Pln 35C 30C 26C P10570 24pin 35C 30C 26C P10572 28pin 45C 35C 30C P10575 40pin 45e 40C 35C 1-9 10-99 COMPUTER CABLES • Six conductor •Melded computer lnterfac:e cab)e, W12670 • CIC6 6 con. 1•8M 10M+ 100M+ $1.30M $1.10M $1.00M W12672 • CIC9 9 con. 1-9 M 10M+ 100M+ $1.60M $1.SOM $1.20M W12674 • CIC12 12 con. 1·9M 1CIM+ 100M+ $2.50M $2.20M $1.90M W12676 • CIC16 16 con. 1-9M 1CIM+ 100M+ $3.50M $3.20M $2.SOM W12678 • CIC25 25 con. 1-SM 1 0M+ 1 DOM+ $3.90M $3.40M $3.00M • DESS 9 pin eocket P12167 $1.50 $1.20 $1.00 .• OA 1SS 15 pin eocket WIRE WRAP IC SOCKETS Thoso quality 3 lovol wire wrap sockets are tin plated phosphor bronze . P10579 Spin $1.50 $1.40 P10580 14pin $1 .85 $1 .70 P1058516pin $1 .95 $1.80 P10587 18pin $1.95 $1.80 P10590 20pin $2.95 $2.75 P10592 22pin $2.95 $2.70 P10594 24pin $3.95 $3.50 P10596 28pin $3.95 $3.50 P10598 40pin $4.95 $4.50 ~O+ $9.50 $8.00 $10.00 $9.50 $8.50 $8.00 · $9.50 $8.90 P12169 $1.50 $1 .20 $1.00 • 0825$ 15 pin eocket P12171 $4.50 $3.95 $3.SO 1•9 100+ P10960 $4.50 $3.50 $2.50 We have a great range of panel meters at great pricesl 010500 MU45 D· 1mA $9. 95 010502 MIJ45 50/SOuA $9.95 010504 MU45 0·100UA $9.95 010533 MU52E O·SUA $12.95 010538 MU65 0·50uA $12.95 010540 MU65 0•1mA $12.95 010550 MU650-100uA$12.95 010560 Muss0-2ov s 1as MOSFET SPECIALS DTYPE IDCSOCKETS 1-8 JDC CENTRONICS 36 WAY PLUG & SOCKET CANNON TYPE 3 PIN LINE MALE $9.95 0825 CONNECTOR SPECIALS 1-8 10+ P10880 DE9P $1.00 $0.80 P10885 DE9S $1.00 $0.70 P10891 DA15S $1.00 $0.70 P10892 DA15C $1 .00 $0.90 P10895 DA15S $1.00 $0.80 P10902 DB25C $1.00 $0.80 P10904 DB25P $1.00 $0.80 P10905 DB25S $1 .00 $0.80 10+ • Plug P12200 $3.95 $3.00 • Socket P12201 $3.95 $3.00 100+ $2.95 Oeecriptfon 1-9 10+ 7805UC 7812UC 7815UC 7905UC 7912UC 7915UC 78L05 78L12 LM324 555 741 $0.50 $0.50 $0.50 $0 SO $CJ.GO $0.60 $0.40 $0.40 $1.00 $0.40 $0.50 $0.45 $0.45 $0.45 $0.55 $0.55 $0.55 $0.30 $0.30 $0.90 $0.38 $0.45 1-9 2155 240V 6-15V 1A M12155 .........$8.95 $7.95 2156 240V 6-1 SV A2 M12156 ........ $13.95 $12.95 2851 240V 12•6V CT 250mA M12851 ... .....$4.95 .. $4.50 c[f 12V DC FANS 80 x 80 x 25.4mm 12V oc. 1.7 Watt 0.14 Amp 112469.••••..••••••••• $18.95 10+ fan1, only $17 .95 FANS Quality fans for use In power amps, computer hotspot cooling etc. Anywhere you naod plonty of air. 240V 4 5/8" T12461..$16.95 115V 4 518" T12463 .. $16.95 240V 3112" T12465 .. $16.95 115V 3 112" T12467 ..$16.95 10+ fana {mixed) Only $14.85. TOGGLE SWITCHES $9.50 HEATSINK COMPOUND Heatsink compound is applied to the base and mounting studs of transistors & diodes. It maintains a positive heatsink seal that : improvea heat transfer from the device to the .. , heatsink, thus -: increasing overall efficiency. H11800 .. 109 ... $2.00 H11810.150g. $29.95 WIRELESS MICROPHONE Silicon Chip BACK COPIES July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid; Booster For TV & FM Signals; The Discolight Light Show, Pt.1; Tone Burst Source For Amplifier Headroom Testing; What Is Negative Feedback, Pt.3 ; Amplifier Headroom - Is It A Con? August 1988: Building A Plasma Display; Universal Power Supply Board; Remote Ch ime/Doorbel l; High Performance AC Millivoltmeter, Pt.1; Discolight Light Show, Pt.2; Getting The Most Out Of Nicad Batteries; Data On Insulated Tab Triacs. September 1988: Hands-Free Speakerphone ; Electronic Fish Bite Detector; High Performance AC Mi llivoltmeter, Pt.2; Build The Vader Voice; Motorola MC34018 Speakerphone IC Data; What Is Negative Feedback, Pt.4. October 1988: Stereo FM Transmitter (Uses Rohm BA1404) ; High Performance FM Antenna ; Matchbox Crystal Set; Electronic House Number; Converting A CB Rad io To The 28MHz Band ; Oueensland 's Powerful Electric Locomotives. November 1988: 120W PA Amplifier Module (Uses Mosfets); Poor Man's Plasma Display ; Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten The Fan In Your Computer; Screws & Screwdrivers, What You Need To Know ; Diesel Electric Locomotives. December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1; Diesel Sound Generator; Car Antenna/Demister Adaptor ; SSS Adaptor For Shortwave Receivers ; Why Diesel Electrics Killed Off Steam; Index to Volume 1. January 1989: Line Filter For Computers; Ultrasonic Proximity Detector For Cars; Simple Computer Sound Repeater; 120W PA Amplifier (With Balanced Inputs) Pt.1 ; How To Service Car Cassette Players; Massive Diesel Electrics In The USA; Marantz LD50 Loudspeakers. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System ; LED Flasher For Model Railways (uses LM3909); Build A Simple VHF FM Monitor (uses MC3362), Pt.1 ; Lightning & Electronic Appliances; Using Comparators to Detect & Measure. March 1989: LED Message Board, Pt.1; 32-Band Graphic Equaliser, Pt.1 ; Stereo Compressor For CD Players; Map Reader For Trip Calculations; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Electronics For Everyone Resistors. April 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know About Capacitors ; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2; LED Message Board, Pt.2. May 1989: Electronic Pools/Lotto Selector; Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference ; LED Message Board, Pt.3; Electronics For Everyone - All About Electrolytic Capacitors. June 1989: Touch-Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3. July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor); Extension For The Touch-Lamp Use this handy form to order your back copies --------------------- - ------------ Please send me a back issue for: 0 October 1988 0 November 1988 0 March 1989 0 April 1989 U August 1989 D September 1989 O January 1990 0 February 1990 O June 1990 0 July 1990 0 November 1990 0 December 1990 0 April 1991 0 May 1991 O September 1991 0 October 1991 0 July 1988 O December 1988 0 May 1989 D October 1989 0 March 1990 O August 1990 O January 1991 O June 1991 0 November 1991 O 0 0 0 0 O 0 0 O August 1988 January 1989 June 1989 November 1989 April 1990 September 1990 February 1991 July 1991 December 1991 Enclosed is my cheque/money order for $_ _ _ __ or please debit my: O Bankcard l - - -7 0 September 1988 February 1989 0 July 1989 D December 1989 0 May 1990 O October 1990 O March 1991 0 August 1991 O January 1992 o o Visa Card 0 Master Card Card No. ~~' '~ ~ ~II I I'--'-------"--'------' Signature _ _ _ __ _ __ __ __ _ Card expiry date_ _ /_ _ Name _ _ _ _ _ __ __ _ __ _ _ _ _ _ _ _ _ _ _ __ _ _ Street _ _ _ _ __ __ _ _ _ __ _ _ _ _ _ _ _ _ __ _ _ Suburb/town _ _ _ __ _ _ __ _ __ __ Postcode _ _ _ _ __ ------ 88 $5.00 each (includes p&p). Overseas orders add $1 each for postage. _NZ orders are sent air mail. Detach and mail to: SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROV BEACH NSW 2097 Or call (02) 979 5644 & quote your credit card details. Fax (02) 979 6503 x I I --------------------------- --- --~-- SILICON CHIP ice Tips For Your Microwave Oven; Active CW Fi lter For Weak Signal Reception. May 1990: Build A 4-Digit Capacitance Meter; High Energy Ignition For Cars With Reluctor Distributors; The Mozzie CW Transceiver; Waveform Generation, Using A PC, Pt.3; 16-Channel Mixing Desk, Pt.4; What To Do When Your Computer Goes Bung , Pt.1. June 1990: Multi-Sector Home Burglar Alarm; Low-Noise Universal Stereo Preamplifier; Load Protection Switch For Power Suppli es; A Speed Alarm For Your Car; Design Factors For Model Aircraft; Fitting A Fax Card To A Computer; What To Do When Your Computer Goes Bung, Pt.2. Dimmer; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm; NSW 86 Class Electric Locomotives. August 1989: Build A Baby Tower AT Computer; Studio Series 20-Band Stereo Equaliser, Pt.1; Garbage Reminder - A 7-Day Programmable Timer; Introduction To Stepper Motors; GaAsFet Preamplifier For The 2-Metre Band; Modern 3Phase Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; AlarmTriggered Telephone Dialler; High Or Low Fluid Level Detector; Simple DTMF Encoder; Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669) . October 1989: Introducing Remote Control; FM Radio Intercom For Motorbikes (Uses BA1404 & TDA 7000) Pt. 1; GaAsFet Preamplifier For Amateur TV; 1Mb Printer Buffer; 2-Chip Portable AM Stereo Radio , Pt.2; Installing A Hard Disc In The PC; A Look At Australian Monorails. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY and Morse) ; Super-Sensi tive FM Wireless Microphone; FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio , Pt.3; Floppy Disc Drive Formats & Options; The Pilbara Iron Ore Rai lways. December 1989: Digital Voice Board (Records Up To Four Separate Messages); UHF Remote Switch; Balanced Input & Output Stages; Data For The LM831 Low Vo ltage Amplifier IC; Install A Clock Card In Your PC; Index to Volume 2. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Speeding Up Your PC; Phone Patch For Radio Amateurs; Active Antenna Kit; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. February 1990: 16-Channel Mixing Desk; High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2; PC Program Calculates Great Circle Bearings. March 1990: 6/12V Charger For Sealed LeadAcid Batteries; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC . April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3; Simple Serv- July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die; Low-Cost D\Jal Power Supply; Inside A Coal Burning Power Station; What To Do When Your Computer Goes Bung, Pt.3; Weather Fax Frequencies. August 1990: High Stability UHF Remote Transmitter; Universa l Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2; The Tube Vs. The Microchip (Two Shortwave Receivers Compared); What To Do When Your Computer Goes Bung , Pt.4. September 1990: Music On Hold For Your Telephone; Remote Control Extender For VCRs; Power Supply For Burglar Alarms; Low-Cost 3Digit Counter Module; Simple Shortwave Converter For The 2-Metre Band. October 1990: Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; The Bose Lifestyle Music System; Using The NE602 In Home-Brew Converter Circuits. November 1990: Low-Cost Model Train Controller; Battery Powered Laser Pointer; A Really Snazzy Egg Timer; 1.5V To 9V DC Converter; How To Connect Two TV Sets To One VCR; Introduction To Digital Electronics; Simple 6Metre Amateur Transmitter. December 1990: DC-DC Converter For Car Amplifiers ; The Big Escape - A Game Of Skill; Wiper Pu lser For Rear Windows; Versatile 4-Digit Combination Lock; SW Power Amplifier For The 6Metre Amateur Transmitter; The Great Green CD Pen Controversy; Index To Volume 3. January 1991: Fast Charger For Nicad Batteries, Pt.1 ; The Fruit Machine; Two-Tone Alarm Module; Laser Power Supply; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers When Servicing Microwave Ovens; Electric Ve hicles - The State Of The Art. February 1991: Synthesised Stereo AM Tuner, Pt.1; Three Inverters For Fluorescent Lights; LowCost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages; Tasmania's Hydroelectric Power System. March 1991 : Remote Controller For Garage Doors, Pt.1 ; Transistor Beta Tester Mk.2; Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose 1/0 Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateurs & TV; A Look At The Config.Sys & Ansi. Sys Files. April 1991: Steam Sound Simulator For Model Railroads; Remote Controller For Garage Doors, Pt.2; Simple 12/24V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2; Playing With The Ansi.Sys File; FSK Indicator For HF Transmissions. May 1991: Build A DTMF Decoder; 13.SV 25A Power Supply For Transceivers ; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1; Motors For Electric Vehicles; Setting Screen Colours & Customising The Display On Your PC . June 1991: A Corner Reflector Antenna For UHF TV; 4-Channel Lighting Desk, Pt.1; 13.SV 25A Power Supply For Transceivers ; Active Filter For CW Reception; Electric Vehicle Transmission Options; Tuning In To Satellite TV, Pt.1. July 1991: Battery Discharge Pacer For Electric Vehicles ; CD Error Analyser, Pt.1; Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tun ing In To Satellite TV, Pt.2; PEP Monitor For Transceivers August 1991: Build A Digital Tachometer; Masthead Amplifier For TV & FM; PC Voice Recorder; Error Analyser For CD Players, Pt.2; Tuning In To Satellite TV, Pt.3 ($1000 Satellite Ground Station Reviewed); Installing Windows On Your PC ; StepBy-Step Approach To Vintage Radio Repairs. September 1991: Studio 3-55L 3-Way Loudspeaker System; Digital Altimeter For Gliders & Ultralights, Pt.1; Build A Fax/Modem For Your Computer; Ultrasonic Switch For Mains Appliances; The Basics Of AID & DIA Conversion; Windows 3 Swapfiles, Program Groups & Icons; How Glass-Mount Antennas Work . October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator Mk.II; Magnetic Field Strength Meter; Digital Altimeter For Gliders & Ultralights, Pt.2; Getting To Know The Windows PIF Editor. November 1991: Colour TV Pattern Generator, Pt.1 ; Battery Charger For Solar Panels; Flashing Alarm Light For Cars; Digital Altimeter For Gliders & Ultral ights, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2; Error Analyser For CD Players Pt.3; Modifying The Windows INI Files. December 1991: TV Transmitter For VCRs With UHF Modulators ; Build An lnfrared Light Beam Relay ; Compact Solid-State Laser Pointer; Build A Colour TV Pattern Generator, Pt.2; The Miracle Piano Teaching System ; Windows 3 & The Dreaded Unrecoverable Application Error. January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V 8A Power Supply; Baby Room Monitor/FM Transm itter; Automatic Contro ll er For Car Headlights; Experiments For Your Games Card; The Global Positioning System (Satellite Navigation). PLEASE NOTE: All issues from November 1987 to June 1988 are now sold out. All subsequent issues are presently in stock. For readers wanting articles from issues out of print, we can supply photostat copies (or tearsheets) at $5.00 per article, including postage. When supplying photostat articles or back copies, we automatically supply any relevant Notes & Errata at no extra charge . FEBR UARY 1992 89 ASK SILICON CHIP Got a technical problem? Can't understand a piece of jargon or some technical principle? Drop us a line and we'll answer your question. Write to:Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Skipping the light fantastic on CDs I have a relatively large collection of compact discs and have recently found that some of them have begun to malfunction on my CD player. The nature of the fault is that the CD will play normally for most of the disc and will then suddenly jump back to a point some 20 or 30 seconds before. This can happen several times on the disc and generally happens towards the end; ie, when the outer section of the disc is being played (because CDs play from the centre outwards). Some of my acquaintances have had a similar problem with some of their discs. I have played some ofmy troublesome discs on their players and the results have not been fully conclusive; sometimes they performed better and sometimes worse. I was wondering if you have heard of this fault and what might be the cause of it and if there is a cure. I am pretty sure that all of these discs did not play up to begin with, so I wonder An answer to the charred resistor value I am writing in reply to the letter from S. S., Zillmere, Tasmania, in the December 1991 issue entitled "The Wonderful World of General Electric". The resistor found charred is on the horizontal PC board but has nothing at all to do with horizontal deflection. Its sole purpose in life is to do exactly what it had done; ie, burn to unrecognisable condition. After many of these sets had come under my soldering iron for that problem, I had been putting lOOQ resistors in too. Finally, I received one with a vertical fault and wasted no time looking for R731. It turned out to be 56Q (not bad guess work I suppose). 90 SILICON CHIP if the discs might be deteriorating in some way. (P. N., Cremorne, NSW). • We have not heard of this problem but from your description we think that it might be a fault with the tracking mechanism in your CD player. Perhaps the mechanism is binding in some way, either in the gears or on the two rods which carry the laser pickup. This type of fault cquld be intermittent and may be more likely on some discs which have a greater degree of eccentricity or warpage. Also it might depend on how well the disc is centred on the spindle - there is always a certain amount of slop on the spindle and you have no control over this factor. In the absence of any other information (perhaps other readers have some clues?), we suggest that you check for the presence of dust and dirt in the tracking mechanism and perhaps give it a clean. We are assuming, of course, that the discs in question are in pristine condition, with no scratches, fingerprints or damage to the label. Just recently I received one for this problem and the owner also had the service manual with it. After repairing this set, I decided to glance through the manual and to my surprise this resistor forms part of an over-voltage protection circuit. As I said before, it is designed to go open circuit if the protection circuit detects over voltage. But in all of the sets I have repaired, the voltage was correct. It seems to me that this is a classic case of the protection circuit giving more trouble than what it is supposed to protect. In the letter, it stated that the rail was 20 volts but it is actually 120 volts or was this a printing mistake? If the set gives more trouble with this resistor, I suggest replacing some components in this protec- Nicad cells should be fully discharged I have began using nicad rechargeable batteries in my Walkman cassette player/recorder (2xAA) and this has led to me becoming interested in them. I have read the article "Getting the Most Out of Nicads" in the August 1988 issue of SILICON CHIP and found it most interesting. However, this has led to a number of questions. I have an Arlec Multipurpose Charger which charges AA batteries at 50mA. However, I use Arlec superperformance 600mAh batteries on which is stated "l.25V 600mAh, normal charge 15 hours at 50mA". This is the same charge time that is recommended for their 500mAh batteries. This is a little confusing as from your article I understood that rechargeable batteries need to be charged to 140% of their capacity. That would indicate that 500mAh batteries should be charged for 14 hours <at> 50mA and 600mAh batteries should be charged for 17.8hours<at> 50mA. Is this correct? tion circuit. They are TR56, TR57, TR58, C720 and C722. I hope this information is helpful. (C. L., Ingham, Qld.) And the same answer again In reply to S.S. ofZillmere, Qld, (Ask SILICON CHIP, page 90, December 1991), the value ofR731 is 56Q ±5% 0.5W fusible. The resistor is intended to burn up whenever the protection net~ work based on TR56, TR57 and TR58 senses a potential hazard. Unfortunately, the network senses more hazards than ever really exist and experience has shown that the transistors can be removed without introducing untoward rtsk. (J. L., Hobart, Tasmania). month a typical cell will still have It has been stated that rechargeable 73% of its full capacity and after 100 batteries maintain their voltage until days will have 36% of its capacity. they go flat suddenly (when their outFor your application then, you can put drops to 1V) but it has been further stated that they may not neces- recharge your cells and after two sarily be completely discharged and weeks they will still have 87% of in order to maintain them in top con- their capacity remaining. If your application depended on having the batdition they should be completely discharged to 1V before recharging! Jaycar teries charged to maximum capacity, have a kit which will do this. Do you such as in competition air racing, model boats or model cars, then you consider this a necessary item? would be wise to have the cells It would be an interesting project to construct. I keep a spare set of charged the night before, as recomcharged batteries in storage so that mended in Bob Young's article in the when the set in use go flat, I can September 1990 issue of SILICON CHIP. We will see what information is immediately replace them with the charged cells. From your article available regarding the capacity of dry cells and perhaps publish an article though, it is stated that charged baton the subject. teries whilst not in use (stored) lose 1 % of their efficiency each day. Does this mean that they will go flat in 100 Using a clock radio to days? I usually go through one set every turn on a light Like L.T., of Lake Cargelligo, (Ask fortnight as I record as well as play Silicon Chip, October 1991), I wanted cassettes. I have read on one manufacturer's literature that a spare set of my clock radio to trigger another debatteries should be kept on charge at vice (in my case, a tape recorder to all times. But unless you had a charger record shortwave broadcasts at three that would automatically switch to a in the morning). I have found the foltrickle charge, they would be damlowing, low-budget method to be exaged if left for any lengthy period on tremely reliable and it doesn't involve full charge. Jaycar have a charger kit messing about with the internal wir(Cat KA-1718) which automatically ing of the radio, either! switches to a trickle charge once fully When my clock radio turns on, it charged. Would this type of charger lights up a LED to indicate it is funcbe preferred to say the one I have and tioning; my solution was to use this how long can batteries safely be left LED to trigger the external device. I constructed a cheap, simple Dick on a trickle charge? One further question: on ordinary • Smith Funway light activated switch batteries, the current capacity is not kit. My (admittedly ancient) tape stated. I would like to know what the player has one of those 2. 5mm remote capabilities of the different types are; control plugs for its external microeg, Eveready General Purpose, Heavy phone. By replacing this remote on/ Duty, Extra Heavy Duty, Energiser off switch of the microphone with the relay in the light activated switch, (alkaline). W. C , Adamstown Heights, whenever the LED turned on, the tape NSW). • In brief, you should take the recom- recorder would activate. What does this have to do with mendations of the manufacturers when charging your batteries. It is L.T.'s problem? By placing a power also preferable to discharge the bat- relay across the normally open termiteries and the Jaycar kit you mention nals of the light activated switch, the will do that job, although the pre240VAC supply to the lamp can easferred "end point" voltage is 1.1 V and ily be controlled by the clock radio, without messing about with the ranot 1V. The statement about charged batdio's internal wiring. Of course, this only works if the teries losing 1 % of their capacity each day is a general rule meaning that clock radio has a LED or some other light source which only comes on they lose 1 % of their remaining charge each day. Some cells will be better when the radio is playing. If the clock than this while others will be worse, radio does not have its own light depending on cell age and condition source, a Funway sound activated switch, with the sensitivity turned and temperature. Taking the 1 % loss figure as a guide though , after one right down (so your snoring, sleep- GAS LASER INTRODUCTORY KIT If you could never afford the fascination of owning a gas laser, have a close look at the "trio", in this "SPECIAL LASER INTRODUCTORY OFFER". The tubes are used but have plenty of life left in them. They are GUARANTEED! You get one small tube with an output of around 1mW, one high quality low divergence SIEMENS laser head with an output at about 3mW, and one of our reliable and efficient 12V UNIVERSAL LASER POWER SUPPLY KITS. A tube and the supply will easily slide into inexpensive 50mm SWV pipe, 8 1 ~~~fef~.r ~~ie~f1 ~ ~~I: ~h~~~ r~~~~~~:~:~~;t!~ ~!~ 1¥ NIGHT, THE BEAM FROM THE SIEMENS WAS VISIBLE UP TO 4km AWAY! The kit comes with full instructions and it even includes a prewound transformer. The unlimited applications include laser pointers, surveying, optical experiments, medical field , holography, and fascinating laser displays. We are still offering this "TRIO " ~-?t~b~1~i~1tl s14 9 c';~R PICTURE) IR BINOCULAR VIEWER High quality military binocular IR viewer. Self powered, and originally intended to be mounted on a helmet. Focus is adjustable from 1 metre to infinity. Requires some IR illumination. Powered by one single 1.5V battery. Original -fibreglass carry case provided. Two very small monocular viewers, could easily be made from ~~~i: !~~~!/ii11:. If~~e~·~JSntity at ONLY 5 649 IA filters: 75mm dia. plastic $16, 130mm dia. pyrex $69 GREEN LASER TUBES We have a limited supply of some 0.6mW laser tubes with an output at 543nM: Green beam! Because of the relative response of the human eye these appear as bright as a ~~~Jtl~~~i~::~t r~iii~::r\:i~~c:t: at s399 BIGGER LASER TUBES For the more se r'i ous applications we have some brand new, large 4mW and 10mW tubes . Both the tubes are of exceptional quality and would normally cost about three times this price. Call for a special deal for a tube and supply co~~~ag~nLY 10mW ONLY $155 s3s6 These precision glass prism assemblies are in excellent condition and were originally used lo form a periscope in a tank navigation system. Their original price would have been over $1000! The two glass prisms can be removed from their holding assemblies. Make a high quality periscope or use in optical systems. A must for ~~~~eq~!~~;s~;~~~: s19 FOR THE TWO PRISMS Melbourne Distributor: Electronics World (03) 723 3860 or (03) 723 3094 OATLEY ELECTRONICS PO BOX 89, OATLEY , NSW 2223 Telephone: (02) 579 4985 . Fax: (02) 570 7910 Certified p&p : $6 in Aust. NZ (Airmail): $10 . FEBRUARY 1992 91 Problem with remote control extenders I built the "Remote Control Extender for VCRs" as described in the September 1990 of SILICON CHIP. It wmked successfully so I built a second one and installed wiring in my house for three points to plug the extenders into. I also installed and wired a distribution system for video signals and hifi. I could now place the video and amplifier together and control both from one of a number of remote viewing rooms. A~er a lot of work setting the systems up, experimenting with video mixers, amplifiers and splitters and installing wiring, the system worked well. Noting the need to ensure that the circuits did not become sensitised, I kept the extender at least 400mm away from the TV and with a piece of furniture between it and the TV. Despite these precautions, the extender started to become sensitised in a matter of weeks and was almost unusable after a number of talking or passing trucks don't activate it) and the condenser mike placed right over the radio speaker works just as effectively. I hope that this information helps. (S. L., Hall, ACT). • Your suggestion for controlling a 240VAC lamp is technically correct but potentially hazardous since it is doubtful that the DSE light controller was designed to switch 240VAC appliances. At the very least, you would n.e ed a 240VAC rated relay and the board would need the required isolation between the low voltage and high voltage sections of the circuit. We still think it would be cheaper and safer to ditch the old clock radio an d buy one of the newer ones with an inbuilt light. Queries on satellite TV reception I am very interested in the recent series of articles by Garry Cratt dealing w ith satellite TV as applicable to Au stralian viewers. I have a number of qu estions on the subject. (1) Could you include some discus92 SILICON CHIP months. I noticed that the red LED often seemed to be responding to fluorescent lights. This was difficult to counteract as most of the lights in our house are energy efficient units. I would like to know if other people have experienced this problem. Having spent so much time and money building this total system which relies on the extender, I would like to make it work. However, it is not practical to build new units every couple of months. Do you have any suggestions to assist me? (D. W., Essendon, Vic). • We do not know why your extenders initially worked satisfactorily and then become sensitised to external lights. Are you sure that this is the case? Do the extenders work satisfactorily in total darkness? If so, maybe you will need to shield them from excessive ambient light. Check also that you are using the correct infrared photodiode; ie, either a BP104 or BPW50 which has an integral infrared filter. sion as to the legalities of receiving the various signals that are broadcast in our direction? I believe that there are restrictions placed on radio signals that are not specifically intended for everyone to receive. (2) Wind loading on these antennas is important, not only to avoid losing your own investment but also to avoid damage to a neighbour's property should they come adrift in high winds. Are there particular precautions to be noted here? (3) What permission is required, and who from, to install or construct an Earth station in a private backyard? (4) Do you know of any magazines currently available in Australia dedicated to satellite TV interests. I have purchased a few copies of "The Home Satellite Television Magazine" and "TV Satellite Videoworld" in 1986, but they don't seem to be available any more. (5) Do you know of any groups active in Australia with a special interest in satellite TV. (E. D., Mt Gravatt, Qld). • It is absolutely legal to receive any signals that are being transmitted via satellite television. There are restrictions relating to privacy and copyright which are enforced to protect users of any satellite or radio communications system. Much the same regulations apply to scanning receivers. It is perfectly legal to use a scanner receiver, however, it may not be legal to divulge information that has been received, or to make any commercial use of such information. With regard to AUSSAT, it should be remembered that all Australian taxpayers have funded the organisation and satellites serving Australia, so reception of such signals is similar to listening to the Royal Flying Doctors Service, Sydney Radio , or other HF radio services. We believe the situation regarding proprietary transmissions, scrambling, and copyright of program material was quite clearly spelt out in our August issue. With regard to wind loading, satellite dish antennas such as those shown in our June and July issue are polemounted and commonsense dictates that any such mounting should be quite substantial and that concrete should be used. The dish shown in our August issue is supplied with its own free-standing mount, designed to be anchored to any horizontal surface. In this instance, as the height above ground of the dish is low, we feel there is little chance of it being moved by strong winds. In fact, practical experience confirms this. Some councils do require planning permission for installation of domestic dish antennas and have established guidelines for screening them with shrubs. You would be wise to check with your local council. As far as we know, there are no current satellite TV magazines. This is no doubt the result of the downturn in satellite television activity in the US market, due to broadcasters scrambling many previously unencoded satellite signals. Likewise, we are not aware of any active groups for satellite TV enthusiasts. Notes & errata Battery Charger For Solar Panels, November 1991: inductor 11 should be wound with 56 turns of 0.4mm wire, not 200 turns as stated in the text. Also, one 680Q resistor has been omitted from the parts list. SC - - ORDER FORM ______ ,,_, USE THIS FORM FOR ALL YOUR SILICON CHIP PURCHASES SILICON CHIP BINDERS: Yes! Please rush me _ _ _ SILICON CHIP binder(s)<at> $A14.95 each including postage. (Overseas orders please addA$3.00 each for postage). 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ISSUE YEAR YEAR ISSUE ISSUE YEAR ISSUE YEAR TOTAL$A SUBSC RIPTIONS: RATES □ NEW SUBSCRIPTION: Month To Start Start In □ RENE WAL:SubNo. (PLEASE TICK ONE) Australia □ GIFT SUBSCRIPTION: Month To Start Your Details Mr/Mrs/M s: Address: Postcode 2 years (24 issues) 1 year (12 issues) O$A84 O$A42 Australia with Binder(s) O$A105 O$A53 NZ & PNG (Airmail) O$A130 O$A65 Overseas Surface Mail O$A130 O$A62 Overseas Airmail O$A240 O$A120 Daytime telephone number. _ _ _ _ _ _ __ Gift Subscription Details Enclosed is my cheque/money order for $_ __ or debit myO □ 111111 □ rmn Message: _ _ _ _ _ _ _ _ _ _ __ Mr/Mrs/Ms: _ _ _ _ _ _ _ _ _ _ _ _ __ 11 I I Card expiry date Signature _ _ _ _ _ _ _ _ _ _ _!_ _ 0'.Z&UWJLl (02) 979 6503 ~ Fax the coupon with your Credit Card details 24 Hours, 7 Days a Week 4a Address: _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _Postcode_ _ __ (02) 979 5644 9am - 5pm Mon-Fri. Please have your Credit Card details ready. Mail coupon to: FREEPOST25 Silicon Chip Publicat ions PO Box 139 Collaroy Beach NSMT 2097 No stamp required in Australia MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. r------------- ------------, CLASSIFIED ADVERTISING RATES ANTIQUE RADIO 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. To run your classified ad, print it clearly on the lines 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. 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) 726 1613 AH. FOR SALE Enclosed is my cheque/money order for $._ _ __ O Bankcard O Visa Card or please debit my O Master Card I I I I I I i I I I Signature_ _ _ _ _ _ _ _ _ _ _ _ Card expiry date.___ /_ __ I I Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ I I Street _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ __ I I Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode._ _ _ __ _ L _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ JI Card No. 94 L______L__~I .___I~~I L_Ij_______J____L__JI .___I~~ 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 postage. Only from M. Delahunty, 42 Villiers St, New Farm, 4004 Old. Phone (07) 358 2785. KIT REPAIRS Kits repaired from all magazines. Switchmode power supplies repaired, design work from start to finish computer software consultancy. Ring anytime 9am-9pm Mon-Sun. EEM Electronics, 10 Bouverie Place, Epping, Vic. 3076 Phone (03) 401 1393 Direct CAD PCB design From your schematic, rough PCB,to ink plot negat i ve for prototype or one-off in s i ng I e or daub I e s i ded w i th s ii k screens & so I der resist. NC and photoplot options avai I able on Floppies. r Prices at December 1, 1991 SIMM 1MB x 9 1MBx8 4MB x 9 256 X 9 (For SIP Phone (02)807 6916 O or wr I te 0 ( ~ .C ~ G. F . & M. Hughes ~ PO Box 37, Ryde PCB ART NSW, 2112 1 J~ SATELLITE DISH ANTENNA: Videosat 2.1-metre, AZ/EL, Gold Band LNC, 60metre cable. 1.8-metre free-standing mount. Complete unit ready to go. Used once. Under cost $1500. Lawson Radio, 298 Great Western Highway, Lawson , NSW. Phone (047) 59 1254. COMPONENTS SPECIALS available until end April 1992. MC14433 digital panel meter chip $15.00 (new stock). MC45512 memorytelephonediallerchip $10.00. 4001, 4011 , 4071 , 4081 $0.40 ea for 1O up. 4013, 4017, 4024, 4040 $0.80 ea in lots of 10 up. 7805, 7808, 78L05, 78L08 $0.40 ea. 1N914 $0.05 ea, 1N4004 $0.07 ea. 2114 static RAM chips $1.50 ea, data available. P&P on components $4.00 up to order value of $200.00. Ring for postage rates on higher order values. CTOAN Electronics, PO Box 33, Condell Park, NSW 2200. Phone (02) 708 3763. DIGITAL SPEEDO kit $50.00. Digital tacho with 10RPM resolution $49.00. Memory telephone dialler with single button dialling $30.00. 40kHz crystals $12.00. Hall effect sensors $4.00. Certified P&P $5.00. CTOAN Electronics, PO Box 33, Condell Park, NSW 2200. Phone (02) 708 3763. $115 OFF THE WOR LD'S FIRST MSDOS Pocket PC. Australia's best price on Atari Portfolio $380 incl. tax, postage and insurance. 80C88 CPU, video cassette size. Lowest prices on accessories. For more info, send a 43c stamp to: Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043 CHEAPEST LASER EVER? We have a good supply of some new & near new laser heads with minor beam geometry problems. They produce outputs from 1-2mW. We can provide our universal 12V laser power supply kit & one of "' MEMORY EXPANSION 100ns 80ns 100ns 80ns sons sons add $1) DRAM-DIP 1MB x 1 sons 256 X 4 100ns sons 41256 120ns 100ns sons 55.00 57.00 48.00 53.00 225.00 16.00 6.40 6.30 6.50 1.80 2.00 2.20 COPROCESSORS 80387-DX 25 80387-SX 16 80287 10MHz 80287 To 20 173.00 142.00 95.00 156.00 FLOPPY DRIVES 3.5 Panasonic 1.44 3.5 Teac 1.44 5.25 Panasonic 1.2 80.00 86.00 92.00 EXPANSION CARDS LS 866N 32Mb OK 240.00 AST RAM plus 8Mb 350.00 BOCA AT plus 8Mb 250.00 PELHAM Tel (02) 980 6988 SPECIALS Sun SLC Sharp 6220 Sharp 8081 PS/2(ALL) PS/2(ALL) Mac FX/NIX Laser Printers 4Mb 1Mb 1Mb 2Mb 4Mb 4Mb 2Mb 250.00 160.00 100.00 150.00 295.00 230.00 206.00 SOCKETS Simm Sockets 30 x 1 Vert Simm Sockets 30 x 2 Ang Simm Sockets 30 x 2 Vert 1.70 3.50 3.20 Sales Tax 20%. Overnight Delivery. Credit Cards Welcome 1 st Floor, 100 Yarrara Road, Pennant Hills, NSW 2120. \.. DIGI-CART DSP BOARD For 16-bit IBM compatibles. Broadcast quality 44.1 kHz/16-bit stereo audio with audio recorder software. $1 599 + tax Custom software service for applications available. PC Computers (08) 332 6513 36 Regent St, Kensington SA. these heads for only $89. Oatley Electronics, PO Box 89, Oatley, .NSW 2223. Phone (02) 579 4985. Fax (02) 570 7910 BARGAIN PRICED LASER! A bigger laser! This SPECIALLY priced LASER KIT includes a brand new LARGE 3-5mW HE-NE LASER tube and a high quality potted 12V laser power supply to suit. Use them for effects, surveying, holography, healing, etc. Definitely not for kids! - laser light and high voltage dangers. The price is an incredible $199 for the tube and a power supply. Certified p&pAustralia $6; NZ (airmail) $10. Major credit cards accepted with phone & Fax (02) 980 6991 ~ FIX-A-KIT KIT REPAIR & CONSTRUCTION 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION TECHNICAL ASSISTANCE HYCAL ELECTRONICS Design, Manufacture & Repair of Electronic Equipment · (02) 633 5477 TRANSFORMER REWI NDS ALL TYPES OF TRANSFORMER REWINDS TRANSFORMER REWINDS Reply Paid No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 76 1291. Fax: (065) 76 1003. fax orders. Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. Fax (02) 570 7910 LCD DISPLAY MODULES: high quality LCD display modules with LSI driver circuitry included , at a small fraction of their real prices: 24-character x 2-line display (24 x 2) - $24; 16 x 2 display - WANTED: YOUR CIRCUIT & DESIGN IDEAS Do you have a good circuit idea languishing in the ol' brain cells? If so, why not sketch it out, write a brief description & send it to us Provided your idea is workable & original, we'll publish it in Circuit Notebook & you'll make some money. You'll also help save us from the dreadful "circuit burnout" syndrome which afflicts anyone who has to generate too many circuit ideas in too short a time. We'll pay up to $60 for a really good circuit (not too big please). So transfer your circuit to paper & send it to Silicon Chip Publications, PO Box 139, Collaroy Beach, NSW 2097. FEB RUARY 1992 95 r----- -- -----------------, X SILICON CHIP BINDERS Protect your valuable issues with a special binder from SILICON CHIP. Our binders feature heavy board covers, are made from a distinctive two-tone green vinyl, and have the SILICON CHIP logo printed in gold-coloured lettering on the spine and front cover. They hold up to 14 issues and will look great on your bookshelf. Price: $A 11.95 + $A3 p&p or buy a subscription and get a discount on the first binder (see the subscription order form in this issue).To order, simply fill in & mail this coupon or phone orfaxyourorderto Silicon Chip Publications. Yes! Please send me _ _ _ SILICON CHIP binder(s) at $A11.95 plus $A3 p&p each (NZ $A6 p&p). Enclosed is my cheque/money order for $._ _ _ __ or please debit my D Bankcard Card No. O Visa Card O Master Card L_____L__~I '--1~____,I '--1~ ____,I ~I~____, Signature_ _ __ _ _ _ _ __ _ _ Card expiry date_ _~/_ __ Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Street _ _ __ _ _ _ __ _ _ _ _ _ _ _ _ _ _ __ _ __ SILICON CHIP PUBLICATIONS PO Box 139, Collaroy Beach, NSW 2097, Australia. Fax: (02) 979 6503. L _________________________ J $16; 16 x 2 display with backlighting $22.50. All modules are supplied with information and we have a backlighting inverter kit available: $9. Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. Fax (02) 570 7910 PCVOICE RECORDER SOFTWARE: turn your computer into an audio recorder, $25 + $3pp {VGA/EGA/CGA/ MONO). MS-DOS required. Also available: PC TALKING VOLTMETER software. For project published in SILICON CHIP, Oct/Nov 1991. Plugs into the printer port of any IBM PC/XT/AT/386 or compatible. Displays voltages up to ±128V on screen, takes voltage samples over time, has 8-bit accuracy to within 1%. Combines with the PCVOICE RECORDER project to give a talking voltmeter. Available on 5¼-inch 360Kb disc plus documentation and instructions for $30 plus $3pp. Send your cheque or money order to Darren Yates, PO Box 134, French's Forest, NSW 2086. 96 SILICON CHIP Altronics .. ........ ..................... 48-49 Antique Radio Restorations .... .. 94 Av-Comm ...................... ..... ... .... 70 David Reid Electronics .. .............. 3 Dick Smith Electronics .... ..... 15-17 EEM Electronics .......... .. ........... 94 Electronic Components Shop ... 55 Electronic World .. .. .................... 53 Emona Instruments .. .. ... ............ 61 Geoff Wood Electronics ............ 83 G. F. & M. Hughes .... ..... .. .......... 95 Harbuch Electronics ... ... ............ 59 Hycal Instruments ..................... 95 Jaycar Electronics ...... 29-32,65-68 J.V. Tuners ............... ................. 59 Mark One Communications ... ..... 9 Oatley Electronics ................ 91,95 Patex Systems .......................... 63 PC Computers .......... .. ...... ...... .. 95 PC Marketplace ....... ............. 41,81 Pelham ............... ....... ... ... .. 95,0BC Peter C. Lacey Services .... .. .. ... 59 Philips .. .. ...... .. ... .... .. .... ............ IBC Preston Electronics ......... ....... ... 54 Protel Technology .. .... ..... .. ........ 60 RCS Radio .... ... ........... .. ........ .. .. 55 Suburb/town _ _ __ _ _ _ _ _ _ _ _ Postcode_ _ _ _ __ Phone (02) 979 5644 Advertising Index Resurrection Radio .... .. ..... ... ..... 21 Rod Irving Electronics .. .... .... 22,23 .................................. . 74,75,86,87 Forty pages of dreams! z CD ~ Scan Audio .. .... .... ... ......... .. ...... . IFC Stewart Electronics .. .... .... .. ....... 96 St Lucia .. ... .. .. .. .. ... .. .. .. .. .. .. .. .. 11 ,14 Transformer Rewinds ................ 95 Yokogawa ............... ........... ..... ... .. 5 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Electronic Toy Services, 2/ 111 Glynville Drive, Hackham West, SA 5163. Phone (08) 382 8919. • Jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 356 5555. • Marday Services, PO Box 19-189, Avondale , Auckland, NZ. Phone 88 5730. Name: Address: ......... .. ...... .. .. ................ ...... . Call sign: .. ......... Post Code: ... Stewart Electronic Components P.O. Box 281 Oakleigfi 3166 phone (03)543-3733 fax (03)543-7238 P/L • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491 . FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT e Introducing ScopeMeter PHILIPS TM There's More Than One Reason to Reach for It Built to Take It In face there's every reason to reach for ScopeMeter. Because only ScopeMeter combines the expertise of Fluke and Philips to bring you a dual-channel digital scope along with everything you've come to expect from Fluke digital multimeters. The result, an integrated scope-and-multimeter that lets you see a waveform and digital meter display at the same time from the same input Dr switch between high-precision Scope and Meter functions with the touch of a key. That makes it faster and easier than ever to capt/Jre, store and analyze precisely what you 're looking for. At aprice that looks good, too. To get your hands on a ScopeMeter, contact your Philips sales office or your nearest authorized Philips/Fluke distributor. ■ ScopeMeter Now there's only one to reach for Double Duty ■ Simply Easy Integrated 5D MHz digital storage scope and 3000-count (3- 2/J digit) multimeter. ■ Precision Min/Max Record and 40 ns Glitch Capture make ,r easy to troubleshoot intermittent failures. ■ Simultaneous waveform and digital display on a backlit screen you can read across the room. ■ Completely sealed against water, dust and contaminants. ■ EM! protected and measures up to 600 volts rms. ■ Rugged construction with shock-resistant holster. ■ Three-year warranty. ■ ■ ■ lnt11itive front panel layout for simple, straightforward operation. Pop-up menus and five function keys for easy control Autoset key automatically sets voltage, time and trigger functions. Goes Wherever You Go Runs on rechargeable NiCad Batteries, standard C-cells or the included line voltage adapterIbattery charger. ■ Adjustable tilt-stand comes in handy as a hanger, too. ■ Compatible with a wide range of mu/timeter and scope accessories. Be No. 1with Fluke and Philips For further information please contect your /ocai Philips Test & Measurement Organisation: SYDNEY /02/ 888 0416 MELBOURNE /03/ 881 3666 PEHTH /09/ 277 4199 WELLINUTON /04/ 88 9788 PHILIPS BRISBANE /07/ 844 0191 ADELAIDE /08) 348 2888 AUCKLAND /09/ 89 4160 Our factory is ISO-9O01 certified