Silicon ChipNicad Cell Discharger, May 1993 - July 1993 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: Old textbooks & data books are valuable
  4. Feature: The Keck Optical Telescope Pt.1 by Bob Symes
  5. Order Form
  6. Review: Tektronix TDS 320 100MHz Digital Scope by Leo Simpson
  7. Feature: Programming The Motorola 68HC705C8 by Barry Rozema
  8. Feature: Data: The ISD1016 Voice Recorder IC by Darren Yates
  9. Subscriptions
  10. Project: Build A Single Chip Message Recorder by Darren Yates
  11. Project: Light Beam Relay Extender by Darren Yates
  12. Serviceman's Log: When it looks easy, it often ain't by The TV Serviceman
  13. Project: Build An AM Radio Trainer; Pt.2 by Marque Crozman & Leo Simpson
  14. Project: Windows-Based Digital Logic Analyser; Pt.2 by Jussi Jumppanen
  15. Product Showcase
  16. Project: A Low-Cost Quiz Game Adjudicator by Darren Yates
  17. Feature: Remote Control by Bob Young
  18. Feature: Amateur Radio by Garry Cratt, VK2YBX
  19. Vintage Radio: In the good ol' days of my childhood by John Hill
  20. Back Issues
  21. Notes & Errata: Nicad Cell Discharger, May 1993
  22. Market Centre
  23. Advertising Index
  24. Outer Back Cover: Nilsen Instruments

This is only a preview of the July 1993 issue of Silicon Chip.

You can view 37 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:
  • The Keck Optical Telescope Pt.1 (July 1993)
  • The Keck Optical Telescope Pt.1 (July 1993)
  • The Keck Optical Telescope; Pt.2 (August 1993)
  • The Keck Optical Telescope; Pt.2 (August 1993)
Articles in this series:
  • Programming The Motorola 68HC705C8 (July 1993)
  • Programming The Motorola 68HC705C8 (July 1993)
  • Programming the Motorola 68HC705C8 (October 1993)
  • Programming the Motorola 68HC705C8 (October 1993)
  • Programming The 68HC705C8 Microcontroller (December 1993)
  • Programming The 68HC705C8 Microcontroller (December 1993)
Items relevant to "Build A Single Chip Message Recorder":
  • Single-Chip Message Recorder PCB pattern (PDF download) [01104931] (Free)
Items relevant to "Light Beam Relay Extender":
  • Light Beam Relay Extender PCB pattern (PDF download) [03106931] (Free)
Items relevant to "Build An AM Radio Trainer; Pt.2":
  • AM Radio Trainer PCB Pattern [06107931] (Free)
Articles in this series:
  • Build An AM Radio Trainer; Pt.1 (June 1993)
  • Build An AM Radio Trainer; Pt.1 (June 1993)
  • Build An AM Radio Trainer; Pt.2 (July 1993)
  • Build An AM Radio Trainer; Pt.2 (July 1993)
Articles in this series:
  • Windows-Based Digital Logic Analyser; Pt.1 (June 1993)
  • Some customers can be a real pain (June 1993)
  • Windows-Based Digital Logic Analyser; Pt.1 (June 1993)
  • Some customers can be a real pain (June 1993)
  • Windows-Based Digital Logic Analyser; Pt.2 (July 1993)
  • Windows-Based Digital Logic Analyser; Pt.2 (July 1993)
Items relevant to "A Low-Cost Quiz Game Adjudicator":
  • Low-Cost Quiz Game Adjudicator PCB pattern (PDF download) [08106931] (Free)
Articles in this series:
  • Remote Control (May 1993)
  • Remote Control (May 1993)
  • Remote Control (June 1993)
  • Remote Control (June 1993)
  • Remote Control (July 1993)
  • Remote Control (July 1993)
  • Remote Control (August 1993)
  • Remote Control (August 1993)
Articles in this series:
  • Amateur Radio (November 1987)
  • Amateur Radio (November 1987)
  • Amateur Radio (December 1987)
  • Amateur Radio (December 1987)
  • Amateur Radio (February 1988)
  • Amateur Radio (February 1988)
  • Amateur Radio (March 1988)
  • Amateur Radio (March 1988)
  • Amateur Radio (April 1988)
  • Amateur Radio (April 1988)
  • Amateur Radio (May 1988)
  • Amateur Radio (May 1988)
  • Amateur Radio (June 1988)
  • Amateur Radio (June 1988)
  • Amateur Radio (July 1988)
  • Amateur Radio (July 1988)
  • Amateur Radio (August 1988)
  • Amateur Radio (August 1988)
  • Amateur Radio (September 1988)
  • Amateur Radio (September 1988)
  • Amateur Radio (October 1988)
  • Amateur Radio (October 1988)
  • Amateur Radio (November 1988)
  • Amateur Radio (November 1988)
  • Amateur Radio (December 1988)
  • Amateur Radio (December 1988)
  • Amateur Radio (January 1989)
  • Amateur Radio (January 1989)
  • Amateur Radio (April 1989)
  • Amateur Radio (April 1989)
  • Amateur Radio (May 1989)
  • Amateur Radio (May 1989)
  • Amateur Radio (June 1989)
  • Amateur Radio (June 1989)
  • Amateur Radio (July 1989)
  • Amateur Radio (July 1989)
  • Amateur Radio (August 1989)
  • Amateur Radio (August 1989)
  • Amateur Radio (September 1989)
  • Amateur Radio (September 1989)
  • Amateur Radio (October 1989)
  • Amateur Radio (October 1989)
  • Amateur Radio (November 1989)
  • Amateur Radio (November 1989)
  • Amateur Radio (December 1989)
  • Amateur Radio (December 1989)
  • Amateur Radio (February 1990)
  • Amateur Radio (February 1990)
  • Amateur Radio (March 1990)
  • Amateur Radio (March 1990)
  • Amateur Radio (April 1990)
  • Amateur Radio (April 1990)
  • Amateur Radio (May 1990)
  • Amateur Radio (May 1990)
  • Amateur Radio (June 1990)
  • Amateur Radio (June 1990)
  • Amateur Radio (July 1990)
  • Amateur Radio (July 1990)
  • The "Tube" vs. The Microchip (August 1990)
  • The "Tube" vs. The Microchip (August 1990)
  • Amateur Radio (September 1990)
  • Amateur Radio (September 1990)
  • Amateur Radio (October 1990)
  • Amateur Radio (October 1990)
  • Amateur Radio (November 1990)
  • Amateur Radio (November 1990)
  • Amateur Radio (December 1990)
  • Amateur Radio (December 1990)
  • Amateur Radio (January 1991)
  • Amateur Radio (January 1991)
  • Amateur Radio (February 1991)
  • Amateur Radio (February 1991)
  • Amateur Radio (March 1991)
  • Amateur Radio (March 1991)
  • Amateur Radio (April 1991)
  • Amateur Radio (April 1991)
  • Amateur Radio (May 1991)
  • Amateur Radio (May 1991)
  • Amateur Radio (June 1991)
  • Amateur Radio (June 1991)
  • Amateur Radio (July 1991)
  • Amateur Radio (July 1991)
  • Amateur Radio (August 1991)
  • Amateur Radio (August 1991)
  • Amateur Radio (September 1991)
  • Amateur Radio (September 1991)
  • Amateur Radio (October 1991)
  • Amateur Radio (October 1991)
  • Amateur Radio (November 1991)
  • Amateur Radio (November 1991)
  • Amateur Radio (January 1992)
  • Amateur Radio (January 1992)
  • Amateur Radio (February 1992)
  • Amateur Radio (February 1992)
  • Amateur Radio (March 1992)
  • Amateur Radio (March 1992)
  • Amateur Radio (July 1992)
  • Amateur Radio (July 1992)
  • Amateur Radio (August 1992)
  • Amateur Radio (August 1992)
  • Amateur Radio (September 1992)
  • Amateur Radio (September 1992)
  • Amateur Radio (October 1992)
  • Amateur Radio (October 1992)
  • Amateur Radio (November 1992)
  • Amateur Radio (November 1992)
  • Amateur Radio (January 1993)
  • Amateur Radio (January 1993)
  • Amateur Radio (March 1993)
  • Amateur Radio (March 1993)
  • Amateur Radio (May 1993)
  • Amateur Radio (May 1993)
  • Amateur Radio (June 1993)
  • Amateur Radio (June 1993)
  • Amateur Radio (July 1993)
  • Amateur Radio (July 1993)
  • Amateur Radio (August 1993)
  • Amateur Radio (August 1993)
  • Amateur Radio (September 1993)
  • Amateur Radio (September 1993)
  • Amateur Radio (October 1993)
  • Amateur Radio (October 1993)
  • Amateur Radio (December 1993)
  • Amateur Radio (December 1993)
  • Amateur Radio (February 1994)
  • Amateur Radio (February 1994)
  • Amateur Radio (March 1994)
  • Amateur Radio (March 1994)
  • Amateur Radio (May 1994)
  • Amateur Radio (May 1994)
  • Amateur Radio (June 1994)
  • Amateur Radio (June 1994)
  • Amateur Radio (September 1994)
  • Amateur Radio (September 1994)
  • Amateur Radio (December 1994)
  • Amateur Radio (December 1994)
  • Amateur Radio (January 1995)
  • Amateur Radio (January 1995)
  • CB Radio Can Now Transmit Data (March 2001)
  • CB Radio Can Now Transmit Data (March 2001)
  • What's On Offer In "Walkie Talkies" (March 2001)
  • What's On Offer In "Walkie Talkies" (March 2001)
  • Stressless Wireless (October 2004)
  • Stressless Wireless (October 2004)
  • WiNRADiO: Marrying A Radio Receiver To A PC (January 2007)
  • WiNRADiO: Marrying A Radio Receiver To A PC (January 2007)
  • “Degen” Synthesised HF Communications Receiver (January 2007)
  • “Degen” Synthesised HF Communications Receiver (January 2007)
  • PICAXE-08M 433MHz Data Transceiver (October 2008)
  • PICAXE-08M 433MHz Data Transceiver (October 2008)
  • Half-Duplex With HopeRF’s HM-TR UHF Transceivers (April 2009)
  • Half-Duplex With HopeRF’s HM-TR UHF Transceivers (April 2009)
  • Dorji 433MHz Wireless Data Modules (January 2012)
  • Dorji 433MHz Wireless Data Modules (January 2012)
Life, lawns & the Woofer Stopper Your Woofer Stopper in the May 1993 issue gives me renewed hope and I certainly intend obtaining one. However, my main trou­ ble with “mutts” and “moggies” is their nocturnal fouling of lawns and gardens. Some time ago I installed a passive IR floodlight unit primarily as a safety device, but find that it readily detects and to some extent scares animals bent on messing up the place. This in combination with a slightly modified Woofer Stopper should completely overcome the problem. My thoughts are: (1) since the flood unit has an adjustable timer (a few seconds to 15 minutes), it should be possible to delete the out, the amplifier has been loaded with a total of about 60W in speak­ers (to the 100V line outputs). Something that seems odd with the design in that you say the amplifier output should be loaded with an output transformer that presents a 4Ω load, but on checking the data in the Altron­ics catalog, the wiring configuration you suggest gives a 16Ω load. Could this be the problem? (D. W., East Gresford, NSW). • We think the most likely reason why the output resistors are burning out is that the 4.3µH inductor in parallel with those resistors is open circuit. That would explain why it takes an hour or two for the resistors to fail and also why your amplifier does not appear to be delivering full power. You can easily check whether the inductor is open circuit (or not properly soldered into circuit) by measuring across the three paralleled 12Ω resistors with your multimeter. The reading should be zero ohms but if it reads four ohms, then the inductor is open circuit. You are not the first person to be confused by the data in the Altronics catalog. The data is incorrect. The transformer should be connected as indicated in the circuit on page 28 of the December 1988 issue; ie, with 94  Silicon Chip Woofer Stopper timing function and switch it on/off with the floodlights; (2) Power a small PSU from the 240V at the lamps (easily accessible) to provide a suitable common DC supply for the modified circuitry. The flood unit is rated 300W maximum – I use two 100W lamps. There must be many garden enthusiasts who would appreciate such a gadget. Would you please consider publishing a modified circuit and description of such a unit? (A. B., Chittaway Bay, NSW). • There is no reason why the system would not work (technical­ly) but whether it would stop dogs defacing your lawn we do not know. If the idea receives sufficient reader interest, we shall consider a version along the lines you suggest. primary windings in series and the secondary windings in series. That connection “reflects” a load of close to 4Ω to the amplifier’s output and allows it to deliver maximum power. Building the FM subcarrier adaptor I wish to build the FM Radio Receiver described in the November 1992 issue of SILICON CHIP. In doing so, I wish to add on a subcarrier adaptor circuit detailed recently in another electronics magazine. This will allow me to receive the increas­ing number of ACS (known as SCA in the USA) transmissions being piggy-backed onto the FM broadcasts in our capital cities, in the subcarrier range of 67-92kHz. However, I have a slight problem in that the adaptor cir­cuit I have states that it should be connected to the FM receiv­er’s detector output, straight after the discriminator but before any filtering and obviously before the stereo decoder. The arti­cle further suggests that this point could be found (in the event that you lack a circuit diagram for the radio) by looking for audio signals in the high frequency range around 50kHz near the discriminator IC or coil, with a level of around a 100mV or so. It doesn’t seem to matter whether this signal has some DC present as it is AC coupled at the input of the adaptor. This sounds fine if you happen to have a CRO but I don’t and I also don’t want to go out and buy your circuit and the adaptor only to find that it will not work. Can you suggest the ideal point to get these signals for the adaptor on the FM Receiver you de­scribed in the November article? Having described my problem, you might like to know that the adaptor in question requires a fair amount of basic construc­tion and I am not aware of any kit resellers that intend to sell this kit complete. This brings up another point. Would SILICON CHIP be interested in producing a full ACS FM receiver in a future issue? An FM receiver along the lines of the November 1992 circuit, modified so that it could receive ACS or normal FM broadcasts at the flick of a switch, would be great. What would the readers think of this? I believe that you produced a sub­ carrier adaptor back in January 1988 but I don’t have the article and besides no-one that I am aware of produces the kits. I’ve also heard that it requires a slight modification to its twin-T filter circuit capacitors in order to receive signals such as the BBC, etc. Wouldn’t it be great to combine an FM receiver and the adaptor all in one? (P. F., Camberwell, Vic). • The FM Receiver described in our November 1992 can be used as a source for the SCA adaptor, as you suggest. Just take the output directly from pin 2 of IC1. The SCA adaptor we described in January 1988 is no longer available in kit form but the parts are readily available, including the PC board. It is quite simple to modify it to suit the BBC signals. All you have to do is change the capacitors in the twin-T filter from 0.0022µF to 0.0015µF. No other changes to the circuit should be necessary. Notes & errata Nicad Cell Discharger, May 1993: transistor Q2 is incor­rectly labelled on the circuit diagram (Fig.1) as a BC328. It should be a BC338 NPN type, as shown in the parts list. The parts list should also be amended to show 1 x 2.7kΩ resistor and 2 x 1.5kΩ (not 1 x SC 1.5kΩ) resistors.