I recently cracked an old pc open and from it i now have a fan and a button. My question is how can i connect the 2 and a battery? I thought just a simple circuit, but the fan has 3 wires. Help apreciated!enter image description here[enter image description hereenter image description here

  • \$\begingroup\$ For your safety, put a safety mesh behind the fan, you can use zipties to fit it at the corners. \$\endgroup\$
    – user293074
    Commented Aug 1, 2021 at 14:39
  • 1
    \$\begingroup\$ If you post images, please make sure that they are sharp and readable. \$\endgroup\$
    – StarCat
    Commented Aug 1, 2021 at 15:31

1 Answer 1


Yes, you could run the fan off a 12V battery, provided the battery can supply the required current (300mA). 2 of the wires supply power, the 3rd one is a RPM sensor that can be left unconnected.

Refer to the pinout on the left side of the picture:

Image source

The button is a momentary push-button which only makes (or breaks) contact as long as you're pushing it. You need a switch to turn the fan on without having to keep pushing the button...

Note that most computer fans are made for silent operation and have rather low airflow. This might turn out quite disappointing as a table fan.


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