Posted by Sherman in Idaho [72.47.153.163] on Tuesday, December 15, 2015 at 00:22:30 :
In Reply to: Re:How does this one work? posted by Willy-N [72.168.160.156] on Monday, December 14, 2015 at 23:03:23 :
That type is a "linear regulator". It's better than a simple resistor, because it holds the output voltage constant regardless of load. But it still dissipates the unneeded power as heat, which is why it has a large heat sink. If you're drawing, say 10 amps at 6 volts, this thing will have to drop 6 volts from 12 volts to get there, which means it will dissipate 60 watts. It can be set up to be adjustable, which is what I did (built from scratch) for the wiper control on the sno-cat, but for high power levels you have to be sure you can get rid of the waste heat. The kind I linked to on ebay is a switching device, as Jeremy said, that chops the voltage at about 10-15 thousand times a second. So long as the load (light bulb or motor) can't respond within a thousandth of a second, the chopping is no problem and it just "sees" the average voltage. Incidentally, there was a time when Dodge still had 6 volt gauges in 12 volt trucks, and they used a primitive chopper device consisting of a bimetallic strip and contact in back of the instrument panel. It "vibrated" lightly so as to provide enough voltage regulation to allow a 6 volt gas gauge to work. "Switching power supplies" are everywhere these days, at all different power levels, because they are smaller, lighter, and much more efficient than linear power supplies. They're trickier to design and they require more electronic parts, but parts are cheap and the overall device usually ends up being cheaper as well.
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