Silicon ChipThose wonderful op amps; they're so versatile - April 1988 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: Those wonderful op amps; they're so versatile
  4. Vintage Radio: How it Began by John Hill
  5. Feature: What is Negative Feedback? by Bryan Maher
  6. Feature: The Way I See It by Neville Williams
  7. Project: Headphone Amplifier for CD Players by John Clarke
  8. Project: Walkaround Throttle for Model Railroads by Leo Simpson & John Clarke
  9. Project: Build a Slave Flash Trigger by John Clarke & Greg Swain
  10. Serviceman's Log: Beating an intermittent by The Original TV Serviceman
  11. Project: A pH Meter For Swimming Pools by John Clarke & Leo Simpson
  12. Subscriptions
  13. Feature: Amateur Radio by Garry Cratt, VK2YBX
  14. Feature: The Evolution of Electric Railways by Bryan Maher
  15. Feature: Digital Fundamentals, Pt.6 by Louis E. Frenzel
  16. Market Centre
  17. Advertising Index
  18. Outer Back Cover

This is only a preview of the April 1988 issue of Silicon Chip.

You can view 42 of the 96 pages in the full issue, including the advertisments.

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

Articles in this series:
  • Vintage Radio: How it Began (March 1988)
  • Vintage Radio: How it Began (April 1988)
Articles in this series:
  • What is Negative Feedback? (April 1988)
  • What is Negative Feedback? (June 1988)
  • What is Negative Feedback? (July 1988)
  • What Is Negative Feedback? (September 1988)
Articles in this series:
  • The Way I See It (November 1987)
  • The Way I See It (December 1987)
  • The Way I See It (January 1988)
  • The Way I See It (February 1988)
  • The Way I See It (March 1988)
  • The Way I See It (April 1988)
  • The Way I See It (May 1988)
  • The Way I See It (June 1988)
  • The Way I See it (July 1988)
  • The Way I See It (August 1988)
  • The Way I See It (September 1988)
  • The Way I See It (October 1988)
  • The Way I See It (November 1988)
  • The Way I See It (December 1988)
  • The Way I See It (January 1989)
  • The Way I See It (February 1989)
  • The Way I See It (March 1989)
  • The Way I See It (April 1989)
  • The Way I See It (May 1989)
  • The Way I See It (June 1989)
  • The Way I See It (July 1989)
  • The Way I See It (August 1989)
  • The Way I See It (September 1989)
  • The Way I See It (October 1989)
  • The Way I See It (November 1989)
  • The Way I See It (December 1989)
Items relevant to "Walkaround Throttle for Model Railroads":
  • Silicon Chip article scan, April 1988 - Walkaround Throttle For Model Railroads Pt 1 (AUD $10.00)
  • Silicon Chip article scan, May 1988 - Walkaround Throttle For Model Railroads Pt 2 (AUD $10.00)
  • Silicon Chip article scan, April 1988 - Walkaround Throttle For Model Railroads Pt 1 (AUD $10.00)
Articles in this series:
  • Walkaround Throttle for Model Railroads (April 1988)
  • Walkaround Throttle for Model Railroads, Pt.2 (May 1988)
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:
  • The Evolution of Electric Railways (November 1987)
  • The Evolution of Electric Railways (December 1987)
  • The Evolution of Electric Railways (January 1988)
  • The Evolution of Electric Railways (February 1988)
  • The Evolution of Electric Railways (March 1988)
  • The Evolution of Electric Railways (April 1988)
  • The Evolution of Electric Railways (May 1988)
  • The Evolution of Electric Railways (June 1988)
  • The Evolution of Electric Railways (July 1988)
  • The Evolution of Electric Railways (August 1988)
  • The Evolution of Electric Railways (September 1988)
  • The Evolution of Electric Railways (October 1988)
  • The Evolution of Electric Railways (November 1988)
  • The Evolution of Electric Railways (December 1988)
  • The Evolution of Electric Railways (January 1989)
  • The Evolution Of Electric Railways (February 1989)
  • The Evolution of Electric Railways (March 1989)
  • The Evolution of Electric Railways (April 1989)
  • The Evolution of Electric Railways (May 1989)
  • The Evolution of Electric Railways (June 1989)
  • The Evolution of Electric Railways (July 1989)
  • The Evolution of Electric Railways (August 1989)
  • The Evolution of Electric Railways (September 1989)
  • The Evolution of Electric Railways (October 1989)
  • The Evolution of Electric Railways (November 1989)
  • The Evolution Of Electric Railways (December 1989)
  • The Evolution of Electric Railways (January 1990)
  • The Evolution of Electric Railways (February 1990)
  • The Evolution of Electric Railways (March 1990)
Articles in this series:
  • Digital Fundamentals, Pt.1 (November 1987)
  • Digital Fundamentals, Pt.2 (December 1987)
  • Digital Fundamnetals, Pt.3 (January 1988)
  • Digital Fundamentals, Pt.4 (February 1988)
  • Digital Fundamentals Pt.5 (March 1988)
  • Digital Fundamentals, Pt.6 (April 1988)
  • Digital Fundamentals, Pt.7 (May 1988)
  • Digital Fundamentals, Pt.8 (June 1988)
  • Digital Fundamentals, Pt.9 (August 1988)
  • Digital Fundamentals, Pt.10 (September 1988)
SILICON CHIP Publisher & Editor-In-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Regular Contributors Neville Williams, FIREE, VK2XV Bryan Maher, M.E. B.Sc. Jim Yalden, VK2YGY Garry Cratt, VK2YBX Jim Lawler, MTETIA David Whitby Photography Bob Donaldson Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 1 2 times a year by Silicon Chip Publications Pty Ltd . All material copyright (c). No part of the contents of this publication may be reproduced without prior written consent of the publisher. Kitset suppliers may not photostat articles without written permission of the publisher. Typesetting/makeup: Magazine Printers Pty Ltd, Waterloo, NSW 2017 . Printing: Macquarie Publications Pty Ltd, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rates are currently $42 per year ( 12 issues) . Out-. side Australia the cost is $62 per year surface mail or $120 per year air mail. 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. Address all mail to: Silicon Chip Publications Pty Ltd, PO Box 139 , Collaroy Beach , NSW 2097. Phone (02) 982 3935. ISSN 1030-2662 * Recommended and maximum Australian price only. 2 SILICON CHIP PUBLISHER'S LE'l-l'ER Those wonder£ul op amps; they're so versatile As you will have gathered by now, if you have been reading SILICON CHIP for a few issues, one of our major aims each month is to present electronic projects which appeal to enthusiasts with wide-ranging interests. And so it is this month, with projects aimed specifically at enthusiasts who have interests in railway modelling, photogi'aphy, high fidelity and chemistry. The latter refers to the pH meter which will be of use to people who have to maintain a swimming pool or fish tanks, or perhaps are keen gardeners. While we trust that the projects we present each month will hit the spot with readers who have specific interests, we hope that all the projects will be of general interest to a majority of our readers, merely because the circuits are interesting in themselves. · We get quite a kick out of developing these projects and consider it a challenge to get the best circuit performance for the minimum cost. For the last few weeks for example, we have been delving closely into the specifications of a number of "state-of-the-art" operational amplifiers as we develop a number of hifi-related projects. You will see the results of these endeavours over the next few months. While we were doing this research we also had occasion to review the performance of that relatively common quad op amp, the LM324. When you really look at it, this is a remarkable op amp; not necessarily state-of-the-art but remarkable nonetheless. Just consider: it can operate from single or dual supplies; it is directly compatible with logic circuitry; it has very low current drain, typically less than 800 microamps at 5V DC; and best of all, it is dirt cheap. "So what!" · you might say. Well have a look at the train controller and pH meter circuits described in this issue. By coincidence, they both depend heavily on the LM324. The pH meter uses all four op amps in one package in the same way, to obtain a circuit which compensates cleverly for the tricky parameters of a pH probe. And in the train controller circuit we use the eight op amps in two LM324 packages in four different configurations: three voltage followers, an oscillator, an amplifier and two comparators, with one interfaced directly to logic circuitry. We find it fascinating that it is possible to use such a common and cheap device (it only costs about $1.40) in such a variety of useful ways. The design of such circuitry might be way over your head but if you carefully follow the circuit description in these project articles you should eventually gain a good insight into how they work. For many people, this analysis of how circuits work is the real "buzz" of electronics; they don't wish to build 'em, just analyse 'em. Well that's great. You can enjoy electronics in a practical way by building projects; or by just reading the articles and analysing the circuits. There are few pastimes more satisfying. Leo Simpson