GB432524A - Improvements in or relating to sound reproducing apparatus - Google Patents

Abstract

432,524. Gramophones. CARPENTER, C. C., 709, Old Kent Road, London. Jan. 31, 1935, No. 3166. [Class 40 (ii)] Relates to sound-reproducing apparatus comprising a number of turntables carrying disc records and adapted to operate alternately or in succession. According to the invention, a rotating member is driven at a reduced speed from one turntable spindle, and cooperates with a graduated electric contact - carrying ring to effect the closure of a circuit and thereby to initiate rotation of a second turntable when the record on the first turntable has made a predetermined number of revolutions. In the arrangement shown, each machine is provided with a switch comprising a contactarm 45 driven from the turntable spindle through reducing gear so as to rotate over contact-carrying graduated rings 7, 8. The rings are rotatably mounted in an insulating guide ring 9, and each one carries a rounded piece of insulating material in which is embedded a thin strip 14, connected to the respective ring 7 or 8. The arm 45, which carries a contact strip 51 located over the rings 7, 8, is pivoted at 44 on a beam 42, and held in contact therewith by a spring 46, Fig. 2. The beam is attached to a boss 43, which frictionally engages a spindle 4, so that the arm 45 is angularly adjustable with respect to the rings 7, 8. The spindle 4 is driven by a train of reducing gears 2 from a spindle 3, detachably connected to the turntable spindle 5. The system shown comprises two gramophones, adapted to work alternately. At a predetermined point in the rotation of the arm 45 which is associated with a machine in operation, the contact 51 engages the contact 14 on the outer ring 7, the initial setting of the arm 45 relatively to the contact 14 having been made, with the aid of the graduations, in accordance with the number of revolutions to be made by the record during playing. Engagement of the contacts 51, 14 completes a circuit through the magnet 39 of a relay 26 or 27, which thereupon closes the circuit of a motor which drives the other machine. As soon as this machine has run up to the correct speed and has begun to play (the pick-up having previously been placed at the proper position on the record), the first machine is automatically stopped by the action of the second relay 27 or 26. This operation occurs when a magnet 40 therein is energized on the engagement of the contact 51 with the contact 14 on the inner ring 8 associated with the first machine. The relays 26, 27 each comprise a mercury switch mounted in a pivoted cradle 34, Fig. 4. The cradle is biassed so that the switch moves to the circuit-opening position when it is released by the armature 37 of the magnet 40 ; momentary operation of the magnet 39 moves the switch to close the circuit. Any number of turntables may be employed.