GB689176A - Improvements in or relating to apparatus for playing gramophone records - Google Patents

Abstract

689,176. Driving sound reproducing machines. ELECTRICAL & MUSICAL INDUSTRIES, Ltd. Nov. 22, 1950 [Nov. 22, 1949], No. 29803/49. Class 40 (ii). In a gramophone of the kind in which a switch bar is moved from one position to another according to whether the turntable is to be revolved at slow speed for a pick-up intended for microgroove records or at normal speed for a pick-up intended for normal records, the circuit, of the motor is not completed until the correct pick-up has been lifted from its rest, which rest incorporates a switch, normally open-circuited until the pick-up is raised. When the switch bar 23 is moved to the right, as viewed in Fig. 2, for slow speed, the contact 40, Fig. 3, of switch 36 is moved to contact 42, but circuit through the switch 20 to drive motor 43 is not completed until arm 3, carrying the pick-up for micro-groove records, is raised. Similarly, when the switch bar 23 is moved in the opposite direction for normal speed, the contact 40 of switch 36 is moved to contact 41 and circuit is not completed until arm 4, carrying the pick-up for normal records, is raised and switch 44 closed. The change of speed of the turntable is accomplished by the axial movement of a jockey pulley 13 which engages the part 11 or 12 of the motor shaft depending on the position of a ramp 35 on the bar 23. During this axial movement the jockey pulley 13 is moved against the tension of a spring 33, out of contact with the motor shaft, by means of a cam 30 on the bar 23. The switch bar 23 also operates a switch 37 whereby the connections of the pick-ups to the amplifier are changed over. Specification 667,768 is referred to.