Halogen Revolt William Raynes c. 1993 William Raynes For many of us who use alternative energy, the cost of low voltage lighting is a major issue. Because these products aren't mass produced, we are forced to pay the high prices the RV and marine customers have had to contend with for years. Fortunately, some ac powered halogen and fluorescent lights can be adapted to 12 Volt use, for less money than new 12 Volt lights. If you use an inverter to run your house, your least expensive choice for efficient lighting is probably ac compact fluorescents (see Home Power #16, #20, and #30). Whereas a 13 watt 12 volt Osram compact fluorescent can set you back $50-$60, you can get a 120 vac fluorescent through a utility rebate program for under $20. I know of a man who gets these same quad Osram 120 volt units in Boston for $3 a piece. Talk about mark-up! Re-volting Halogens For those of us who use 12 Volt lighting, there is another alternative, at least in the halogen lamp market. Most of today's halogen lamps use a 12 volt bulb and a 120 volt to 12 volt transformer. Most of the units I have found are easily spotted by reading the box, where it will clearly point out the use of a 12 volt bulb. If the box doesn't specify a 12 volt bulb, a peek at the panel on the base of the display unit will tell you the output of the lamp. Many of these units, on sale, can be had for under $20. I found the one featured here for $14. When you consider the price of a 12 Volt halogen gooseneck copilot light at $30, without any base, you can easily see the savings. Remove the Guts The procedure to convert the lamp to direct 12 Volt operation is really quite simple, the only tools you need are a screwdriver, a wire cutter, and a stripper tool. You'll need a new plug to plug into your 12 Volt receptacles. Many people use automotive cigarette lighter plugs. I like to use three prong 240 vac plugs that can never be plugged in backwards or mistaken for 120 vac plugs. You'll also need an inline fuse holder and a fuse. The amperage draw of the bulb is the wattage divided by 12 Volts. Choose a slow-blow fuse with an amperage slightly higher than the bulb's draw. This is usually less than five amperes. First, remove the base of the lamp. Inside you will find a large heavy transformer Ä that's the part you don't need. You will notice that the incoming wire from the plug enters the transformer on one side and exits it on the other. Simply cut the incoming wires from the new plug and the out-going wires from the transformer and put the transformer aside for now. Rewiring Strip the ends of all the wires still in the lamp. Connect the wire that goes out from the switch to one of the wires that goes to the bulb. Now take the wire that goes into the switch, and one of the wires coming from the new plug, and connect the fuse and fuse holder between the two wires. The fuse to protects the switch, which is meant for ac use and is not usually rated for DC. Even though our house is protected by DC rated circuit breakers I like the extra insurance of the second fuse. This line is now the positive lead, and should be attached to the positive side of your new 12 Volt plug. The other incoming line is connected to the second lead that goes to the bulb. This is the negative line and should be attached to the corresponding side of the new plug. Finishing Touches All lamps are different, but most use the weight of the transformer as a kind of ballast to hold the lamp upright. If the unit is stable without this extra weight you can just leave it out and replace the bottom and you are done. If on the other hand you find you need the extra weight you have a few other options. I find some of the transformers useful in other projects so I like to replace them with a chunk of lead, although a heavy object of appropriate size and weight can be substituted. If you don't have another use for the transformer you can simply replace it in the unit and there you have it Ä a 12 Volt halogen at less than half the cost of one from a catalog. Options You may feel it necessary to replace the switch on one of these conversions with an appropriate DC rated switch. This may be appropriate, but I have not had a problem with any I have done so far, although that may just be luck. Many styles of low voltage switches are on the market and any auto parts store or Radio Shack type store will have many to choose from. I hope this article will inspire everyone living off the grid to take another look at what can be adapted around you, and ease the squeeze on your wallets. Access William Raynes, HCO 2 Box 54, Great Spruce Head Island, Sunset, ME 04683