Abstract: A drum for a rotatable cylinder head includes an opaque disc-shaped member having a plurality of opaque fins affixed thereto and arranged substantially normal to the disc-shaped member. A first plurality of the fins has a first width and a second plurality of the fins has a second width broader than the first width. Every fin has a distal end remote from the disc-shaped member, and an opaque circumferential ring is affixed to the distal end of each fin. The disc-shaped member, the fins and the circumferential ring form a plurality of apertures about the drum.

Abstract: A brushless DC motor system includes a multi-pole DC motor having coils and permanent magnets. Optically scannable markers are applied on the circumference of a rotating member of the motor in fixed association with the magnets. By means of a scanner, these markers are converted to signals. These signals are evaluated with respect to their phase position and moment of commutation, and as a result commutation current is supplied to the coils.

Abstract: A switch device for a turntable with a starting device which closes the switch for the drive motor on the one hand by means of a swinging movement of the pick-up arm manually during swinging-in from its support bracket onto the record, and on the other hand by means of a direct current dc low voltage solenoid which is actuated by momentary actuation of an operating service element, the latter being connected with a first contact pair, and a switch-off device which acts automatically with the arriving of the pick-up or reproducing head in the run-out groove of the record, the switch-off device opening the switch for the drive motor and containing a switch for the entire current supply of the device from the power supply mains.

Abstract: A synchronized induction motor, designed to drive a turntable of a record player, has a stator with two pole pairs spaced 90.degree. apart and a rotor with a short-circuited cylindrical body inductively entrainable by the alternating stator field. The rotor body is provided at one end with a magnetic ring peripherally subdivided into eight magnet poles spaced 45.degree. apart, these poles coacting with an armature on the stator forming two pole shoes jointly magnetizable with one stator pole pair, in line therewith, and two pairs of pole shoes jointly magnetizable with the other stator pole pair, disposed midway between the stator poles. The inductive torque exerted upon the rotor with a 50% lag of the rotor is insufficient to cause further acceleration whereby the rotor is driven synchronously by the coacting pole shoes and magnet poles.