On 6/21/2011 7:52 AM, jamesgangnc wrote:

The problem is that you can't simply continue to lower the frequency
as the lower the frequency the less effective the induction is. Also
you will find that variable frequency controllers are pricey.

Your best bet is to find a motor with brushes that you can vary the
speed of with common speed controllers.

I did find that. Cheapest VFD at a glance was $325. Although I don't see
why they should be. Maybe these things are too specialized to be made
cheaply.

It's a fan and there's little I can do about its design. It must be
quiet and that is partly why I want full control over the speed.