Hi all,
I am a newbie, so please go easy on me. I am connecting x6 PC fans in parallel for a GPU mining rig I am building and I would like to have the option of regulating the fan speed to control noise. The fans are simple brushless 12 V with a power input of 0.84W and a 0.07 A rated current (+/- 10%). In my calculations, I would have a 5.04 W demand in my parallel connection. Is a potentiometer the best means to control voltage and thereby fan speed? I am concerned of frying the potentiometer with 5 W and I found that I could purchase a 25W wirebound potentiometer. (see link below)

http://www.ebay.com.au/itm/High-Pow...660637&hash=item3f7b7352ba:g:L~EAAOSwjqVZCB4x

Is this overkill? I am concern that I won't get much range to control speed with this thing. Is there a different rating potentiometer that would be more appropriate or perhaps a different approach all together?

Thanks

Billy

 

A brushless fan has its speed controlled with a Pulse Width Modulation (PWM) circuit, not with a simple series resistor.
Then it can start slowly if you want and it does not waste a lot of power making heat in the series resistor.

 

You could easily make a PWM speed controller if you want. There are many 555 timer based circuits or Arduino ones on the net.
Or go for something like this..
http://www.ebay.com.au/itm/DC-6-30V...453828&hash=item2c97b9f7c0:g:ItsAAOSweW5U8Scv

 

Hi Dendad,
Thanks for your suggestion. I was very excited to see the link which is exactly what I am after, except when I read the clause 'This can NOT be used to the BRUSHLESS motor.The controller is NOT reverse-polarity protected and will be damaged if connect the supply voltage with wrong polarity.

Any suggestions?

 

If I am not mistaken, this would be suitable?

http://www.ebay.com.au/itm/5V-12V-2...155104?hash=item5d6f9773e0:g:aGQAAOSwDmBY5jw7

 

If I am not mistaken, this would be suitable?

http://www.ebay.com.au/itm/5V-12V-2...155104?hash=item5d6f9773e0:g:aGQAAOSwDmBY5jw7

That looks like it will be ok.
I think the other would too. It is not a BLDC motor controller, but as the fans have the controller internally it would work still.
As for reverse volts, check twice before switching on!

 

OK thanks. Fingers crossed this works like a charm!