Dmitry wrote...

>Can that circuit be used for 115 AC fan control? ;)

It might work, but probably not very well.

For one thing, MOSFETs rated for high voltage usually don't have very
low Rds(on) so they are likely to get rather hot.  The circuit works
well for low-voltage AC like with Dale's 12V yard lights, because you
can get MOSFETs with extremely low ON resistances; but the same isn't
true for high voltage.

The other problem is that I don't think AC induction motors do very well
having their speed controlled only by voltage reduction.  Without
reducing the AC frequency as well, they are forced to run in a high-slip
condition which causes them to overheat and have very low torque.  I'm
no motor-control expert, so that might not be correct; but I think
that's what happens.

Dave

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