This kinda relates to the mains frequency topic today -

During a clean-up this week I came across an unfinished motor
project. It was intended to be a speed control for a 250VAC
60W synchronous motor for a display turntable. I made a start on
it a few years ago but the customer never got back to me. Originally
a Mot 705K1 was the source of the drive frequency and I'd like to
update it for a PIC. That part is easy enough but where I now recall
getting stuck was the output for the motor. I got as far as rectifying
the mains via 1N4004s into a 400V 470uF cap and then chopping
that with a 2SJ1075 FET. I now realise that the motor was getting
only about half the voltage it would see on mains and/or the motor
didn't like the square wave as it hardly moved

1) does a synchronous motor need a good sine wave to run properly
2) can this be done "simply" with semis or would a low voltage high
current sine amp feeding a step-up transformer be better
3) will a synchronous motor always rotate the same way

Cost isn't too relevant, just looking for suggestions and opinions

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