Auto speed fan according temperature

[qanba]

Hi, the title says all :P, it can be good to insert in retropie some thing to auto regulate the speed fan according the temperature of system, its so anoying to connect the fan to 5v and all the time have the MAX speed and noise with the system at 37º
its really no necessary i think can be good to put ( can be modified or not ) a range of temp to Slowly or Faster the fan.
For example: 50º start 3,3v speed , 60º start 5v speed

I hope it can be done someday.

Thanks!

[Zigurana]

@qanba
Hi, I use this script to pwm-drive an transistor, which powers a 5V fan. For me the only reason to cool the Pi is to prevent throttling (which it will once it hits 80C). I only turn on the fan when the temp goes above 60C, and only gradually.
Note: this hardly ever happens, mostly while compiling on the Pi.

[qanba]

@zigurana mi knowledges ara not so high to do that things :( , aniway is bad for raspberry to conect the 5v fan in to the 3.3v gpio?

[Zigurana]

@qanba the question is how much current the fan will draw from the GPIO pin, it can only deliver very little (like 30mA?) so it's almost never enough to power anything more than a single led.
Drawing too much power will destroy (part of) the board.

There are many tutorials out there to help you with this.

[qanba]

@zigurana its 0.20/0.25 5v fan, then its safe to connect on 3.3v gpio? thanks a lot.

[Zigurana]

@qanba not if you are going to use pwm to vary the speed.
Please read some more before you do this.

[dannydonahue]

@zigurana what transistor did you use?

[Zigurana]

Ehm, I don't recall, and I don't feel like opening up my cab right now.

But I don't think it matters much. You will need to use a transistor able to supply current needed by your fan, which likely will be most of them.
Have a look at this article for some more background.