how to control fan speed without fan controller?

K

KSNIPPY

Limp Gawd
Joined
Nov 29, 2005
Messages
198
what can i use to control the speed of my fans without having to buy a fan controller? cant i just hook the fans into the fan plugs on the motherboard and control them from a program?
 
I know you want to do it via software, but it depends if you MB support adjustable V+ to the fan or if the fans are running off the 12+/5+ Molex or from the cpu/case 3pin fan. You can also get a potentiometer (at Radio Shack)

You can splice the (+) and put the pot there. You can wire the pot to stick out of the rear of the case.

I do not know what exact Ohm Pot you'll need, but it is doable. You'll be able to control from OFF to FULL with this.

Here's a production sample...>>CLICK<<

Somthing like this...

1MegPot.jpg


 
I also second the potentiometer for speed control. Thats how I get 100 CFM instead of 235 CFM outa my Rotron160mm fan! Otherwise it sounds like a jet plane! don't turn the dial to low or the fan will not start up agian. you can run some fans at 5V but they will not turn from a standstill at 6V.
Try a 1500 ohm pot.
 
Well, you should be able to figure out the resistance of the fan fairly easily... they have a current and voltage rating on them.

V=IR, so R=V/I, 12V/.25A = 48 Ohms.

If you wanted the potientiometer to decrease the voltage to no less than 4V, then you should use a 100 Ohm pot.

The higher pots will just drop the voltage to the fan all the way to 0V, and you'll have difficulty starting the fan again in some cases.
 
thanks for the help guys.
i just decided to get a fan controller cause i found a fairly cheap vantec on newegg that i hadnt seen on there.
 
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