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Hi folks! I am trying for fun to design simple AC fan control circuit based on high frequency (> 20KHz) modulation or pulsing:

I do not want to use simple thyristor regulator, because my fan produces annoying noise. I am just trying to explore general idea of efficient, smooth and quite AC motor regulator using high frequency pulsing.

I added simple RF filter using capacitor and inductor, but I worry that I can not get rid of EMF and it can burn out rectifying bridge and transistor. What is the best way to design this kind of circuit or filter?

Thank you! :) Alex.

This might help fill in some background:

http://www.freescale.com/files/microcontrollers/doc/ref_manual/DRM039.pdf

Thank you very much! :)