|
|
Posted by David Sherman [216.18.131.86] on Friday, January 29, 2010 at 12:29:58 :
In Reply to: windshield voltage reducer - hope it helps posted by mannyc [68.165.89.2] on Friday, January 29, 2010 at 09:42:56 :
All that is is a standard resistor, worth much less than $15, with the value markings erased from the top of it. It may indeed be a value that's suitable for making a 6 volt wiper run on 12 volts, subject to the limitations I already described when using a plain resistance rather than a voltage regulator. Or it may be the value that one guy tried and found worked okay with his particular setup. As I said, the current that wipers draw fluctuates all over the place. To say that it's a "12 volt to 6 volt reducer" is only true at one exact and constant value of load current. The way he describes it is simply dishonest. It's a resistor, pure and simple, and can't do any other magic, any more than a partially-clogged pipe can "regulate" pressure.
Based on the size of it, it looks like a 10 or 25 watt unit, but remember for those extruded aluminum cased power resistors, they only achieve that power level if they're mounted against a heat sink, preferably with some heat sink grease on the mounting surface. I used one on one of my sno-cats, with the instrument panel as the heat sink, but it's fairly thick aluminum which conducts heat better than steel. Bottom line is you'd do just as well to dig an old ignition ballast resistor out of your junk box, or even buy a new one, and try it as to pay $20 including freight for this resistor of unknown value. When I get to my office I'll look up those resistors in the electronic supply catalogs and see what they really cost these days. I'm thinking $5 or less in single-piece quantities. Of course he did do a little "work" on them by erasing the markings, thus transforming a mere resistor into a voltage reducer.
Follow Ups: