i was wondering....

If one can put fan speed controls on a condensing unit, (head pressure control),.
( i like the electronic ones that make the motor go ANY speed, compared to the cheaper pressure sensing, ON OFF ones),

Couldn't you do this with a ceiling fan?

I want to put my ceiling fan on a reostat so it would go lower than the LOW speed.

To me, this sounds like it would work.
I used to work with large freq. drives and then THEY were supposed to be a special motor to take the weird voltage / curves, but then later, after installing a device on small condenser motors that weren't DESIGNED for that, and not ever having later problems with them..