GB611327A - Tone arm-operated electrical switching means for gramophones and like apparatus - Google Patents

Abstract

611,327. Gramophones. COMMUNICATIONS PATENTS, Ltd., and LEARNEY, L. P. April 12, 1946, No. 11306. [Class 40 (ii)] [Also in Group XXXVII] A snap-switch for starting and stopping the motor of a gramophone turntable, is operated by pivotal movement of the tone arm of the gramophone. The tone arm 6, pivoted at 10, has a pin-and-slot connection 30, 33 with a cam 21 also pivoted at 10. Rotation of the arm 6 in the direction of the arrow, Fig. 2, causes the edge 32 of the slot 33 to engage the pin 30 and so rotate the cam 21, which by engaging a roller 29 on a contact-carrying spring 23 moves a contact 27 outwards. The cam 21 also rotates a second cam 20, also pivoted at 10, through a pin-and-slot connection 34, 35, thereby stressing a contact-carrying spring 22 by means of a roller 28, until the roller rides off the edge 37 of the cam to close the contacts rapidly. When the arm 6 is rotated clockwise towards the centre of a record, the cam 21 is eventually rotated clockwise until the roller 29 rides off the edge 36 thereof, to release the contact 27 and open the circuit, the contactspring 23 engaging a hump 39 on the cam 20 restoring the parts to the Fig. 4 position. The switch may alternatively operate a brake for the turntable and may also control a muting circuit of an associated amplifier. The switch parts are mounted on a base 13 adjustably carried by the base-board of the gramophone.