Quote:
Originally posted by bigben2k
I ran the numbers once...
You need a minimum of 1/4 of the power than you're trying to control. In your case, that would be 3 Watts. Of course you want a little bit more, vbecause you don't want to run a rheostat at maximum power, so I'd go with a common 5 watt unit.
Now where's that thread...
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Ummm, could be wrong here but if he has a 12watt fan he will want about 1/4 MORE of a rated rheostat. Say 14-16 watts. A rheostat is basically a variable resistor. If you turn it down the extra load is dumped by heat output. So if he used a 5watt rehostat and turned it down to say 6watts then the rheostat would have to dump 6 watts of load. If the thing is only rated at 5 watts then expect a fire. Seriously, been there done that.
You have to think backwards with rheostats. The more you turn it down the more load it is handling. The higher you run it the less load it is handling. Or maybe I just missed something...:shrug: