Hi, "world-wide brain" :)

I am using an old washing machine motor to drive my small metalworking
lathe, using a very simple U2008- and triac-based speed controller,
which does not work too well. Lathe is not used too often, so I am not
going to invest lots of time or money in that, but anyway, I am
thinking of a better controller.

I have checked several different appnotes and docs about universal
motors, and general conclusion is to use DC drive with PWM, which
should not be extremely difficult.
But I have not seen any docs that would talk about steering the field
winding separately from the collector. Lathe requires a lot of torque
at low speeds, so probably I could get some advantage with higher
current in field winding, when voltage on collector is low.
By default field winding is connected in series with collector, so it
gets less power, when voltage is reduced for lower rpm's.
Any thoughts?


--=20
KPL
--=20
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