How to Make a Simple Temperature Control Fan Speed

Intro: How to Make a Simple Temperature Control Fan Speed

1 x 10K thermistor

1x IRF540n or n channel MOSFET

1 x 50 kilo-ohms potentiometer

1 x 2.2 uf 16 volts at least capacitor

This circuit uses a thermistor as a sensor, the thermistor resistance decrease when a temperature increase.

When the temperature increases the thermistor resistance decrease until the voltage set point that adjusts by potentiometer higher than Vgs threshold, MOSFET change to ON state and make a 12 volts fan start and rotating speed faster when a temperature hotter.

The capacitor that parallels with a thermistor help fan starts instantly at lowest speed when power on, The 12 volts DC fan make noise and not rotating without the capacitor(maybe a cheap Chinese power supply cause it).

I set the threshold point at 25 C, The fan start at lowest speed @ 25 C and rotating fastest @ around 38 C (I touch it and wait few munites to see the result)

Enjoy DIY!!!!