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rheostat or 5v for ground?

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GeneticDrift

Registered
Joined
Sep 17, 2002
Location
ohio
which is the better way to slow a fan, obviously a rheostat has advantages because you can have variable speed.

you can also use the 12v for + and the 5v for ground which will run the fan at 7v.

doing it both ways, the 7v way is quieter but does it have any effect on the psu?

also with a rheostat you are still delivering 12v to the fan but the fan still slows............why? i understand resistance thru the rheostat but if it is still getting 12v how can it slow down?


please enlighten me :confused:
 

Carnil

Member
Joined
May 29, 2002
Location
Spokane, USA
With the rheostat, the fan gets part of the 12 volts. The rheo soaks up the rest of the 12v, and turns it into heat -- which is why people occasionally post here that their rheobus caught on fire: they didn't use parts that could take that sort of heat.