turntable speed controller

[huddslad]

Hi I have a AR legend turntable that has manual speed control. This involves taking the platter of and manual putting the belt onto the appropriate pulley which is a pain the neck.
The motor runs on standard 240V ac mains. I have been looking for a speed controller that I can use to change the speed electronically but cant find one. Does anyone know of one, or has built one. I could change the motor to a 24V AC version. Has elektor published one.

Can Anyone help.

Thanks

[justin thyme]

I would have thought that the speed of the AC motor is dictated by the mains frequency, not the voltage. If so, then you'd need a circuit that can change the frequency!

[ahmedzg]

It's very complicated to control AC motor by electronics , it made of mechanical parts usually
So I think you have to use a Dc motor 12 or 24 volt with internal or external dc regulator
By altering the motor shaft pulley' diameter for the whole range and the regulator control as a fine coarse adjustment , You'll get good result

[electrosmoke]

It is not so difficult to control the speed of a synchronous turntable motor - all you need is a stable sinewave oscillator hooked to a power amp feeding the secondary winding of a small mains transformer - which should provide the "artificial" mains voltage of 230 V (or whatever) at about 4...5 W feeding the truntable motor with a constant voltage at variable frequency, thus controlling the speed.

I remember an article in Wireless World ages ago on a speed controller for a dancing studio turntable based on this idea - it used a PLL-IC (NE567?) as a generator.

[officina tron-audio]

oups sorry

[gerardoS]

It is not so difficult to control the speed of a synchronous turntable motor - all you need is a stable sinewave oscillator hooked to a power amp feeding the secondary winding of a small mains transformer - which should provide the "artificial" mains voltage of 230 V (or whatever) at about 4...5 W feeding the truntable motor with a constant voltage at variable frequency, thus controlling the speed.

I remember an article in Wireless World ages ago on a speed controller for a dancing studio turntable based on this idea - it used a PLL-IC (NE567?) as a generator.

Thank you for the information, you've been very helpful. Remember the Wireless World article? I'd like to read it.
Greetings.