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Advertising Index Altronics.................................. 64-67 Bitscope Designs......................... 57 Blamey & Saunders Hearing.......... 9 Circuit Labs Ltd............................ 13 HB Wireless Sales & Service......... 3 Emona Instruments...................... 25 Grantronics................................... 95 Hare & Forbes.......................... OBC High Profile Communications....... 95 Instant PCBs................................ 95 Jaycar .............................. IFC,45-52 Ask SILICON CHIP . . . continued from p94 circuit operation indefinitely while the Sun shines. If this is the case, the 12V rail needs clamping to 15V or 16V to protect a PIR detector, when fitted. On another point, I found the potentiometer “timer” control to be very tedious to use. As a modification, I have incorporated switched potentiometers using 12-position switches and resistor strings to make convenient and far more accurate timer settings. I have also considered modifying the PIC software to enable the use of hex code digital switches or 12-pole DIL switches to set the timer delay. Finally, one of my systems is used to keep my ride-on mower properly charged and as an added bonus I use the battery to run some garden lights. In this way, the battery is kept healthy by constant cycling and the life has been significantly extended compared to the usual mode of “ride-on” use. I look forward to your comments on the lighting circuit. (B. T., via email). • It is true that removing the battery and operating the PIR directly via the solar panel is not ideal but after all, it was designed for use with a battery, firstly so that the lights can be used at night and secondly so that the PIC will have a power supply. Without the battery supply, the PIC is powered via the solar panel but the PIC supply is dependent on Mosfet switching. It is a chicken and egg situation and this control loop is possibly unstable. If you don’t want a battery in the circuit, then the PIR detector should be operated from the solar panel supply via a series dropping resistor and 12V zener diode. Additionally, the solar panel should be connected in the 96  Silicon Chip DOWNLOAD OUR CATALOG at www.iinet.net.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au Notes & Errata Barking Dog Blaster (September 2012): the Fig.2 overlay diagram shows the LED package (LED1) with the incorrect orientation. The anode marking (A) is in the correct position but the LED flat side should be toward the lower edge of the PCB. Classic-D Amplifier Speaker Pro­ tector (November & December 2012): The 4.7µF capacitor shown on the circuit and in the parts list should be 47µF. The overlay diagram and PCB is correct. USB Power Meter (December 2012): in Fig.2 (p40), the component shown below IC3 should be a 100Ω resistor, not a 100nF capacitor. Keith Rippon................................. 95 Kitstop.......................................... 19 LED Sales.................................... 95 Linkwell........................................ 12 Mastercut..................................... 79 Matrix Multimedia......................... 55 Microbee Technology................... 79 Microchip Technology..................... 5 Mikroelektronika........................... 11 Oatley Electronics...................... IBC Ocean Controls.............................. 8 Ozcommfile.................................. 12 Prime Electronics......................... 19 Qualify Pty Ltd.............................. 31 Quest Electronics......................... 95 Radio, TV & Hobbies DVD............ 93 RF Modules.................................. 96 Sesame Electronics..................... 95 Silicon Chip Binders................ 61,95 Silicon Chip Bookshop................. 77 Silicon Chip Order Form............... 85 Silicon Chip Partshop................... 84 Silicon Chip Subscriptions........... 53 Splat Controls............................... 95 Tekmark Australia......................... 13 Television Replacements............. 95 battery position rather than the solar panel position so that the circuit can run correctly. The timer is not meant to be absolutely precise and is there to switch the lights off after a period that is not critical. The 2-25s and 4m to 480m settings are available. This timer setting would normally be done once to suit the application. We did not use hex code switches for the timer selection or complex 12-position switches as these are rather Tenrod Pty Ltd.............................. 15 Truscotts Electronic World............ 95 Verbatim Australia........................ 17 Wiltronics..................................... 6,7 Worldwide Elect. Components..... 96 expensive and the analog trimpot to set the time out is much simpler and cheaper, especially since it is unlikely the settings will be changed once they SC are set. siliconchip.com.au