Thorens speed control

[Bazil]

Cheers Mark, circuit diagram of the speedbox or the Turntable ?

[Reid Malenfant]

The speedbox, the TT should be as simple as breaking eggs

[bobbasrah]

Didn't realise your avatar was you trying to open the last superglued pack of tobacco Mark....
Must look into that LH controller further, looks interesting.... Can it be improved as you suggested Mark?
What?

[Reid Malenfant]

Didn't realise your avatar was you trying to open the last superglued pack of tobacco Mark....
Must look into that LH controller further, looks interesting.... Can it be improved as you suggested Mark?

@ the tobacco thing

Yes I don't see why not. You see the transformer only needs to supply the relevant voltage & frequency that the control circuitry is feeding the amplifier - which feeds the transformer. Effectively the transformer is out of the feedback loop, but it could be part of it. A single or possibly dual opamp in between the frequency generator (which will have a fixed or variable voltage) & the amplifier could compare the frequency generator output & the transformer output, if they don't match then the opamp would force them to & thus the transformer would then be inside the feedback loop.

It'd probably be safe to have feedback up to 500Hz, maybe 1KHz which in reality is all that'd ever be needed as that's way above the mains frequency that you'd be feeding the synchronous motor.

I think I'd be more interested in seeing the oscillator that is generating the sine wave though & how stable it is.