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some advice would be great

curlz

Oct 17, 2014
2
Joined
Oct 17, 2014
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would i be able to use a standard (100/200 ohm) adjustable potentiometer to alter the speed of a 12v dc fan or would i need some sort of voltage regulator and resistors to "help" it out

thanks for any advice
 
Last edited:

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
8,393
Joined
Nov 28, 2011
Messages
8,393
You need something to boost the current capability of the potentiometer. There are several options, many of which are nicely presented and described at this page:

http://www.pcsilencioso.com/cpemma/ef.html

Those options are all "linear" regulators - a transistor conducts more or less, to adjust the output voltage. This forces the pass transistor to dissipate power, which means it needs a heatsink. Usually, power dissipation is worst when the fan is running at about half of the supply voltage. If the fan draws more than a few watts, it may be worthwhile using PWM (pulse width modulation) to avoid the heat dissipation.
 

curlz

Oct 17, 2014
2
Joined
Oct 17, 2014
Messages
2
thanks alot. i wasn't really expecting such a quick and informative response.
i will have a look through the link.

thanks again
 
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