2 CPU fan temperature controller project

CPU fan temperature controller project jpg

This project is all about temperature controller for cooling fans in CPU and computer hardware. This temperature controller is easy to build, and materials are minimal and very cheap.
The fan controller in this project is composed of a temperature-controlled resistor (thermistor), voltage comparator and an NPN metal–oxide–semiconductor field-effect transistor (mosfet).
Initially, at 25 degrees Celsius, the controller is off the cooling fan is also off. If were are going to replace resistor R by 50K and the CPU or computer temperature reaches to 40 degrees Celsius (105 deg F), the controller turns the mosfet on, and turning the CPU fan on.
You can adjust the value of resistor R, depending on what temperature you wanted the fan controller to activate. List bellow is the possible value of R and its equivalent temperature degree Celsius

cpu temperature vs resistance

 Materials of  fan controller project is listed bellow

materials used in this temperature controller project

Controller parts
comparator used as controller

mosfet jpg

Note: this temperature controller project is functional  and tested by the author but provides no warranty in its accuracy, build and use it at your own risk.


  1. What modification is needed in this circuit to drive a 12A dc car Radiator fan with respect to temperature??

  2. just use a 12vdc 30amps relay instead of the fan, and use a diode 1n4007 parallel to this relay.