GB370094A - Improvements in and relating to sound reproducing machines - Google Patents

Abstract

370,094. Gramophones. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London, and CHANTRILL, J. J., 22, Kensington Road, Carlsdon, Coventry. Feb. 2, 1931, No. 3318. [Class 40 (ii).] Relates to a sound-reproducing machine in which two sound-boxes or pick-ups are mechanically interconnected and means are provided whereby when one sound-box or pick-up becomes inoperative the other is brought into use. The pick-ups or sound-boxes may be adapted for use with a single turntable or to engage records on different turntables. As shown in Fig. 1, two pick-ups A, B are movable on pivots C in carrier arms D, E, respectively, and the arms D, E are interconnected by a link G. The arms D, E are provided with insulated contacts f<1>, f<2> which co-operate with fixed contacts e<1>, e<2>, respectively. Fig. 2 shows the supporting means for the pick-up B, which comprises a lever d<2> attached to a member g<2> rigidly secured to the pick-up. The angle between the members d<2>, g<2> is adjustable by means of a screw h. The lever d<2> has an armature k<2> which is attracted when an electromagnet b<2> is energized and this causes lever d<2>, member g<2> and the pick-up C to move about the pivots C, and a latch c<2> then engages the end of the lever d<2> to maintain the pick-up in its raised position. When the pick-up is to be lowered, an electromagnet a<2> is energized which withdraws the latch c<2> to allow the pick-up to be lowered by gravity into engagement with the record. In operation, as the pick-up A traverses the record for reproduction, the pick-up B, in its raised position, is moved towards the outer edge of the record. When the pick-up A reaches the inner groove, the contact f2, e2 engage to energize the magnets b<1>, a2. Pick-up A is thus raised from the turntable and secured by the latch c<1> while the pick-up B drops on to the turntable, as the latch c<2> is actuated, and then commences to traverse the record.