Synchronous electric motor control

摘要

A synchronous electric motor for driving a record turntable is driven by an oscillator whose frequency can be varied to vary the speed of the turntable. The oscillator includes amplifier 11 with a feedback circuit including line 26. Varying resistor 29 varies the output frequency which is fed to the motor through transformer 16. Means may be provided for sensing and indicating the turntable speed.