PWM Fan Circuit Question

Hey guys :slight_smile: @peekay123 @ScruffR @bko

I have a quick question about the size of a Diode for the circuit below where I’m basically wanting to control the speed of an 80mm high-speed fan using PWM and an N-Channel MOSFET:

I’m powering 3 x 12v - 1 Amp Fans for a total of 30 watts.

Is the D1 Diode - The 1N4001 OK when M1 is a 3 amp fan? I think it’s perfectly fine but I wanted to ask to make sure before making a mistake :fire:

I’m following this project example:

Be sure to add the diode to your circuit correctly. The silver band on the diode denotes the cathode which is the tip of the arrow in the schematic, like so:

Yes it should be fine. You should add a 1K resistor on the output of D8 to protect the Arduino as well.

1 Like

@skottdc It worked out great after adding a 1000uF capacitor to the fan + and - line.

I did add the 1K resistor to the gate line as you suggested.

Had to attach the MOSFET to a heatsink to keep it running cool under all conditions.