Tachogenerator for record player speed control - has four stator windings at 45 degree phase intervals to double frequency

摘要

The tachogenerator with high-frequency output is particularly suitable for speed regulation of low speed mechanisms, e.g. tape recorders and record players. The generator rotor comprises a ring of magnetised material having alternate north and south poles (1) which is attached to the drive motor rotor. The stator windings are constructed on two separate thin discs (2, 3). Each disc is approx. 0.1 mm thick with a printed, serpentine winding on each side, 90 deg. out of phase with the other (2a-b). The discs are fitted together on the stator of the motor so that their respective windings are offset 45 deg. to each other. This provides an output signal whose frequency is twice that of the usual device, thus providing greater resolution of angular velocity.