TIMER CONVERSION David W. Doty After converting most of our home's lighting and general purpose outlets to inverter power, we were faced with the dilemma of those 24 hour/day loads (clocks, timers, answering machine, VCR, etc.). We solved these problems in several different ways. First, we added extra power switches to the TV, VCR, and computer to eliminate these as 24 hour/day loads. Second, we purchased a nice "School House" style wind-up clock for the living room. Our next problem was the telephone answering machine. Because our battery bank is located in a detached garage, we didn't have a nearby source of 12 VDC to power the items that could be converted to low voltage. To solve this, I installed a second solar system with the batteries located out on the deck. This system was intended to run only small 12 volt loads like the answering machine and a car stereo. Later, we added a pair of reading lamps for our bed, an area light (PL-13), and a small 12 volt color TV. We get a tremendous amount of pleasure and utility out of this small system. After all this, we still had one obstacle, the alarm clock. I just couldn't find a battery operated or wind-up clock that I liked. I finally stumbled across a seven day electronic programmable timer at Radio Shack. This timer was designed for 110 volt use, but is easily converted for 12 volt applications. After completing the conversion, I connected the timer to our 12 volt stereo and presto, we had a seven day, programmable, alarm clock/stereo. The timer we used is a Radio Shack cat. # 63-889, and sells for $32.95, but we got one on sale for about $25. This unit has a control console with a LCD display attached to a plug-in relay/power supply unit. The relay/power supply unit is easily disassembled to bypass the transformer for 12 volt operation. The relay has a rating stamped on it of 16A@240V, 1/3HP, 16A@24VDC. There are also provisions for two "AA" batteries for memory back-up. To convert this timer, simply remove the four screws that hold together the plug-in relay/power supply unit. Make sure you use a screwdriver that fits properly, because the heads on these screws strip-out quite easily. After opening the case, you need to remove or by-pass the transformer. I chose to remove the transformer completely on mine using a desoldering tool. Then add jumper wires where the transformer was. Polarity is not important at this point, because the bridge rectifier is still in the circuit. After you reassemble the case, the conversion is done. You can now plug the unit into 12 VDC and have the timer control the outlet on the cube. CAUTION !! Do not try to plug this unit into 110 volt AC after this conversion--it will smoke instantly if you do. If you wish to control a 110 volt load with this timer while using 12 VDC to run the clock, you may do so by isolating the relay contacts from the source that runs the timer. To do this, do not add the jumper wires after you remove the transformer. Instead, connect a length of two conductor, 18 gauge wire to the spot were the transformer was connected to the bridge rectifier. Drill a small hole in the case for the wires to pass through. You may now power the timer from your 12 volt batteries using these wires, and use the relay to control a separate 110 volt load. Access David W. Doty, 14702 33rd. Ave. N.W., Gig Hatbor, WA 98335 ¥ 206-851-2208.