I'm fairly new to using Arduino boards. I'm trying to make a fan controller for two 3-pin fans that run on 12V at 0.2 amp. I read that all I need is a power supply that will run at 12V and #of_fans * the amp of each of them, so in this case 0.4 amp. I'm having trouble finding a power supply that would work in this case and I'm confused how I would use it. Would I be running the power supply through the arduino, or would that damage the board?

Thank you.

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    \$\begingroup\$ 3 pin fans aren't really subject to control, if you want to change their speed your only option is messing with the supply voltage. \$\endgroup\$ Jun 15, 2019 at 4:16
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    \$\begingroup\$ Power the fan's, but do not involve the Arduino. Do not run the power for them through it. If you want to turn them on and off, study the schematic of 3d printers or even get an Arduino-based printer board instead of an Arduino. \$\endgroup\$ Jun 15, 2019 at 4:17
  • \$\begingroup\$ I already knew that I would have to change the voltage, I would be looking into how to do that with the arduino. \$\endgroup\$ Jun 15, 2019 at 4:18

1 Answer 1


Although computer cooling fans draw low current, you can not feed them directly with Arduino. Typically, you need a buck or buck-boost converter that can be controlled by Arduino to change the input voltage of the cooling fans. But, you can simply use a ULN2803 L293, or L298 to control the fans by PWM. The speed of the fans is controlled by the duty cycle of the PWM. Don't forget to add a free-wheeling diode and maybe a capacitor to the output.

Good luck


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