http://www.outdoorlanternsonsale.com/headlight-torch/
18volt reduction to 4.5volt for rechargable torch- help please?
i am modifying my 18v rechargable torch by doing away with the hot 18v bulb and replacing it with a (12x) LED light that im using from a 4.5v headlight torch (the donor torch). so i need to cut the voltage from 18v down to 4.5v.... can i do this with aresistor, and if so, what value should that resistor be? thanks kind people!
If you don't use a solid state voltage regulator, you will waste 75% of the power in the battery in the resistors.
You can get a simple TO-3 adjustable regulator that will handle the amps although you may have to search a bit to get one that will be happy cutting down from 18 volts because that is a bit high. The whole design would be neater if you could change the wiring of the head so that it was divided into 4 sections of 3 LED's each (presumably still 4.5 volts if all 12 are in parallel) and wire those in series to get 18 volts. Of course, the head may not be built that way and if you are asking here in this way, you don't know enough to do it.
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