PWM Fan Circuit Question


#1

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: http://itp.nyu.edu/archive/physcomp-spring2014/Tutorials/HighCurrentLoads.html

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:


Flyback diode on PWM fan?
MOSFET Switching Problems
#2

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


#3

@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.

Thanks!