I had a brain fart about the voltage, sheesh.

Noise might be an issue, the unit itself might make a high pitched whine apart from audio gear interference. But apart from that, a PWM controller might be an interesting project - liberating us from the restriction of *only* three fan speeds :)

alistair

On 2013-04-08, at 10:32 PM, David Beierl wrote:

>> David, know off hand what the voltage ends up being after going through the low speed resistor?
> 
> That would depend on how fast the motor is turning.  Ok, that was a uSoft answer (correct but useless) sorry.  It doesn't matter because the PWM will supply full voltage all the time, and control the power available to the motor by changing the duty cycle of the pulse train.
> 
> A possible issue with these things would be noise injection into the audio gear, dunno if it would be a problem in practice.
> 
> Yrs,
> d