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Subject: cpu fan control: voltage control?
By: blubird302 (IP: 65.68.182.*)
Written on: 27-01-2009 07:18

Hey guys, I can say that I built the temperature fan control from the article \"Build yourself a fan temperature control\" and works exactly as it should. I have studied the mosfet transitor and for the most part understand how it works, when the resistance from the thermistor goes down it \"gradually\" increases the voltage to the fan. My question is there another component that can be added between the mosfet transistor and the fan to control when the voltage kicks in for the fan? I\'m asking because the circuit works exactly as it should, but when it\'s just to the point to start trying to spin the fan it takes a few mins to actually get the fan moving and bouncing back and forth, and I don\'t know if this is bad on the fan or would it be better to have it made to where it just kicks either on or off based on a certain voltage? I built this circuit for my home audio receiver to cool it from the top so when I turn it off after 10 mins or so the fan also turns off, does not stay running all the time. I just wasn\'t sure if the \"gradual\" supply of voltage to the fan is a good thing or not, it will start to bounce back and forth until it builds enough volts to push the blades around to keep it going, curious on this subject and any opinions would be greatly appreciated, thanks alot!

Replies:

By: Ray (IP: 86.128.78.*)
Written on: 22-03-2009 23:59

The fan not starting properly initially is a worry for me, too.
An initial 12V (or whatever) \"kick\" that instantly reduces to control voltage would be nice, as would an adjustable fan-down option.
Are there any electronics wizards out there with suggestions?
Cheers, Ray
(PS I\'ve heard the argument that fan-down is a waste of time but I\'m unconvinced.)

By: Gilligan (IP: 64.83.196.*)
Written on: 02-02-2010 17:25

Capacitor, my idea, works great.

By: Karmar (IP: 121.45.33.*)
Written on: 02-05-2010 13:28

Any info on what size capacitor and where to put it n the circuit would help for non-electrical people like myself.

Thanks

By: Adam (IP: 24.144.16.*)
Written on: 09-06-2010 07:32

I\'m not an expert, but my guess (no sure how big of a capacitor you would need, but I would think a fairly small one) would be to put the capacitor simply right before the fans. That way it would get charged before it hit the fans, and then once it does hit the fans (the voltage), the fans could \"suck\" all of it at once to kickstart it?
Any experts out there to confirm this?

Let me know if it works out for you as I am also planning on building the temp controller!