Dubovsky, George wrote:
> You will still lose torque with a pwm light dimmer. You will need something
> like an variable speed drive, where you vary the drive frequency and voltage
> simultaneously, essentially synthesizing a complete sine wave at an
> adjustable frequency. I use them on three-phase motors on my lathe and mill,
> but they are also available for single-phase motors. Not cheap, but less than
> the Hole Hawg ;-)
I noticed in one of the trade rags recently (I can't recall which) that
you can get single phase in, 3 phase out, variable frequency drives for
small motors in the $100 range. They're not the totally fancy vector
drives that use the backemf to measure torque and stuff, just a straight
V/Hz sort of drive, but still.. pretty nifty.
I would think, though, that the HoleHawg is a standard brushed universal
motor.. a light dimmer type control might work fairly well.. It's just
going to be highly nonlinear, and the triggering erratic UNLESS you put
a resistive load in parallel with the motor. Something like a 25W-100W
light bulb works well. The problem with driving an inductive load is
that the RC/diac phase control scheme for the triac doesn't switch very
well because the load current and voltage are out of phase.
If you have a phase control dimmer that uses two back to back SCRs,
rather than a triac, it will also work better.
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