I believe you'll find that home-use treadmills will typically have DC PM
motors, with rectifiers (or other semiconductors) outputting DC from about
90V to slightly higher DC voltages.
PM motors are generally significantly more compact than the equivalent HP
rating AC induction motor, and the RPMs can be much higher than many common
AC induction motors.

AC PM motors don't exist, as far as I know. Even weed string trimmer motors
will utilize one diode for DC, when a PM motor is utilized, which is all
that's required without variable speed regulation.
A rectifier/diode after a variac (for example) will provide variable speed,
but not speed regulation.

The speed control trigger switch from a corded (not cordless) variable speed
drill motor will provide variable speed in smaller universal (and likely
small, rectified DC PM) motors such as Dremel or die grinder motors.. some
of the foot-pedal speed controls use exactly the same trigger switch, rated
to about 6 amps, IIRC.

HF and other vendors have variable speed controls for routers/etc that
utilize a fairly simple triac/diac circuit (can be found at various
electronic sites online).
If choosing the router control from China, I'd recommend checking all of the
internal connections before use, as 2 of 'em that I bought had very
weak/pop-off soldered connections inside.

Universal motors (routers, grinders, corded drill motors etc) can be
operated with AC or DC, but have wound field/stator coils, not magnets, as
far as I've seen.

There were some treadmills with 3-phase AC induction motors, which use a VFD
to convert 120VAC power to 3-phase (yes, 120VAC single-phase input 3-phase
output does exist).. I have one I picked up at a hamfest, but can't remember
the name. Some A.O. Smith motors are the same type, typically for special
purpose applications - expensive.

I don't have any experience with the newer brushless DC motors other than
small fans like those used for PC case and CPU cooling fans.

If you want a seriously reliable DC PM motor for a machine application, find
a surplus new/good condition Leeson, Baldor, etc TEFC ball bearing motor
(for which spare brushes are available), and use a KB or similar DC
controller that will provide excellent speed regulation (won't slow down
with varying loads.. *and motor protection* that cheaper DC motor circuits
may not/likely not provide.

--
WB
..........


"Existential Angst" wrote in message
...
Just curious about treadmill motors.

Most treadmill motors I've seen are brushed.
Is it likely that newer ones are brushless, and if so, are the electronics
that make the motor brushless internal or external to the motor, and how
would I tell? I'd hate to find out a motor is brushless, and that I threw
away the goddamm electronics.....

Couldn't treadmills use AC permenant magnet motors? Aren't they a little
simpler than the DC?

It seems that the older DC treadmill motors, altho rated lower in power
than modern treadmill motors, pack a lot more punch to them. No
surprise.
--
EA