Electronics > Beginners

PWM Fan frequency and motor speed controllers

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The good thing with PWM control is that the fan itself takes care of the regulation. E.g. if you want to run at 25% speed, a DC control (switchmode or linear) would probably have to give the fan a short "boost" of a slighly higher voltage to get the fan spinning, then settle for the voltage that corresponds to 25% of max speed; with PWM control the fan itself takes care of this startup scenario.

AFAIK, 25 kHz PWM frequency was chosen as to be outside the audible band to make switching noise unaudible (to humans).

At 3 amps, there will be some power losses, quite high if linear regulating, less so for switchmode. This regulation is moved to the fan itself with PWM control - and the fan is a very good cooler.


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