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Advertising Index ADM Instrument Engineering....... 37 Altronics.........................loose insert Amateur Scientist CD................... 79 Circuit Labs Ltd.............................. 5 Cleverscope................................. 57 EAV Technology........................... 76 Embedded Logic Solutions............ 8 Emona Instruments...................... 55 Futurlec.......................................... 9 Grantronics................................... 95 Hare & Forbes............................. 2-3 Ask SILICON CHIP . . . continued from p94 what values would you suggest for my situation? Finally, I’d like to include some over-voltage protection just using a zener diode. How is the value of resistor chosen? It usually seems to be a low value like 10Ω. (B. W., via email). • The input capacitor for the LM317 is not critical and can be a larger electrolytic capacitor than the recommended 100nF and 1µF values. The higher value would minimise the effect of lead inductance for a long connecting lead. Typically a 10µF electrolytic capacitor would be suitable. This should be rated at 35V for the nominal 24V battery (which could reach close to 30V when charged). For added decoupling, connect a 100nF MKT capacitor in parallel with the 10µF electrolytic capacitor. A protection zener diode across the input could be used and should be a 30V type so that it clips transients and is not conducting with normal supply voltage. A 10Ω series resistor would be suitable but would need to be rated for the current drawn from the regulator. A 20W resistor would be needed for 1A. This could comprise two series 4.7Ω 10W resistors or paralleled 22Ω 10W resistors. Alternatively, for 100mA drawn from the regulator, use a larger value such as 100Ω 5W. SLA batteries cannot be rejuvenated I purchased the Battery Zapper/ Rejuvenator kit (SILICON CHIP, October 2009) with the understanding that it 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 High Profile Communications....... 95 IMP Printed Circuits..................... 12 Instant PCBs................................ 95 Jaycar .............................. IFC,45-52 Keith Rippon................................. 95 Kitstop.......................................... 93 LED Sales.................................... 95 would bring uncharged sealed lead acid (SLA) batteries back to life but on reading the instructions it says it only work for car batteries. I may have to return this kit because of this and would like some urgent help with the SLA battery issue. I’m aware of the need for a battery charger to power the circuit and just to twist the plot, can this be a solar panel instead (I have a 20W unit for experiments)? (R. S., via email). • A solar panel could be used – good idea! But sealed lead acid batteries can’t be rejuvenated. If they have been discharged below 11V, that generally SC means death. Notes & Errata PIC/AVR Programming Adaptor Board (May-June 2012): since this circuit was designed, Microchip have released a number of new PICs, many of which can be programmed using this board. This includes the PIC16F150x series (four chips). These can be programmed in mode B, not mode C as is implied by Fig.5 on page 78 of the June 2012 issue. For other new PICs, check the data sheet and compare the programming pin location and supply voltage requirements to that of other micros listed in Fig.5. Low Energy Developments.......... 95 Matrix Multimedia......................... 90 Microchip Technology..................... 7 Mikroelektronika........................... 29 Mouser Electronics................... OBC NPA Pty Ltd.................................. 70 Oatley Electronics...................... IBC Ocean Controls............................ 91 Quest Electronics......................... 95 Radio, TV & Hobbies DVD............ 78 RF Modules.................................. 96 Roland DG Australia.................... 37 Satcam......................................... 35 Sesame Electronics..................... 95 Silicon Chip Binders..................... 77 Silicon Chip Bookshop................. 89 Silicon Chip Order Form............... 83 Silicon Chip Partshop................... 82 Silicon Chip Subscriptions........... 65 Siomar Battery Engineering......... 95 Splat Controls............................... 95 Tekmark Australia........................... 9 Tenrod Pty Ltd.............................. 73 Trio Smartcal.................................. 6 Truscotts Electronic World............ 95 Verbatim Australia........................ 13 Wiltronics................................. 10,11 Worldwide Elect. Components..... 96 siliconchip.com.au