I'm trying to control a 3-pin pc fan with PWM while reading out the RPM. When the fan is powered by a 'constant' voltage (that is, not controlled by PWM) I can read out the RPM perfectly using the sketch below. But when I power the fan by a PWM signal (even when it is 255, constantly on), the RPM si…

Fan RPM readout not correct when powered by PWM

system February 24, 2012, 4:00pm 5

cool

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