I would like to control the speed of a fan by supplying it with 12V DC and using a PWM signal from my function generator to control its speed.
I have tried using a 25 KHz switching frequency and started at 30% duty cycle with 1V RMS but was not able to control the speed.
Should I connect my generator's ground to the black lead on the fan and the positive side to the blue cable?
Also, is it ok to leave the yellow (tach) cable unused?