Jan Steinman via EV wrote:
Is this permanent, or temporary/intermittent use?

That's important, because while most treadmill motors have high advertised horsepower; in fact, they rarely deliver even a small fraction of that.

I’d put a full-wave bridge rectifier as close to the motor as possible,
and just call it a 120 VAC motor. Put a standard plug on it. Then you
could plug it in to a wide variety of AC power control devices, as Lee

Good point! You do have to rectify the AC before it gets to the motor.

Then, it sounds like a job for a good old-fashioned variac transformer.

That would work great if it can handle the current. Small variacs (rated at a few amps) are pretty common and inexpensive used. But ones big enough to handle 15 amps continuously are quite a bit heavier and more expensive (like 20 lbs and $100).

Lee’s ideas will still produce AC, and so would work fine for a universal
(series-wound) motor, but probably not for a permanent magnet motor

Definitely not for a PM motor. For some reason, I was thinking he had a universal motor, which doesn't care whether it's running on AC or DC.

Light dimmers typically use triacs, which are AC devices. But speed controls for electric drills more often use SCRs, which do have a DC output. The circuits I mentioned from the GE SCR manual are all suitable for PM DC motors as well as shunt and series motors, because they use SCRs for control. SCRs are better suited to inductive loads.

So, rectify that puppy, and lots more options become available!

Yes. :-)

It is vanity to do with more that which can be done with less.
        -- William of Ockham
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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