> >Thanks David, >If I just use a simple resistor will it ruin the tool to have it "runaway" >on start up? >Doug Most likely. Better to use a constant-voltage arrangement. Steve's method below is the right way, really. The diode trick is easy to understand and workable if you have a bunch of diodes lying around. I made up a set ladder-fashion to get variable speeds on a little muffin fan, it's got a clip lead to short out one or more diodes and raise the voltage. Junk-box science... :) david
At 20:01 8/7/2004, Steve Delanty wrote: >Doug, >I'd use a LM350. >It's a 3 amp adjustable regulator. It needs a couple external >resistors to set the output voltage. I would also use a small >ceramic capacitor from the input to ground, and the output to >ground for stability. 0.1uF @ 100volts would be a good cap >choice. > >It will NEED to be on a heatsink. If you want 3 volts at 2 amps, >it means the regulator will dissipate 12.6V - 3V= 9.6V X 2A = 19.2 watts. > >Here's a data sheet for the LM350.... >http://www.national.com/ds/LM/LM150.pdf > >Steve > > >--------------------- > >At 12:10 PM 8/7/2004, Doug in Calif wrote: > >>Hi all, >>I am looking for a good simple reliable way to run a 2.4 volt cordless >>screwdriver motor hard wired to the vanagon 12 vt system. >> >>The only thing I have found is a converter at radio shack that costs 20 >>bucks that will convert 12 vt to 3 volt at 1.2 amps. >> >>I want to run a cordeless screwdriver motor hardwired to 12 vts. I need a >>couple amps. at 2.4 or 3 vt would be okay. >> >>Any simple suggestions like using a heater blower resistor? >> >>Doug -- David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/ '84 Westy "Dutiful Passage," '85 GL "Poor Relation" |
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