GB298277A - Improvements in or relating to apparatus for the electrical transmission of sound from gramophone records - Google Patents

Abstract

298,277. Pearson, L. H. April 7, 1927. Multiple machines, mechanical. -In the reproduction of sound by electric pick-ups from records on separate turntables. switch means for connecting the pick-ups to an amplifier and loud speaker are automatically operated to effect reproduction from the records in succession and open the circuit of one pick-up before closing the circuit of the other. Pick-ups P', P<2>, as for example those described in Specification 293,483, [Class 40 (iv), Telephones &c.], co-operate with turntables G<1>, G<2> separately driven by motors M<1>, M<2> controlled by switches MS<1>. MS' which in the position shown cause the turntable G<1> to be driven. As the pick-up P<1> traverses the record, a contact TA<1> cairried by the arm TA supporting that pick-up moves up to a contact C<1 >and completes a circuit through a relay RY which moves the switches MS<1>, MS<2>, to cut out the motor M<1> and start the motor M<2>, the pick-up P<2> having previously been positioned manually at the starting point of the record on turntable G. A switch S<3> is simultaneously closed to start the secondary of the transformer T' in the output of the pick-up P' so that reproduction therefrom is cut off. In addition, the secondary is also short-circuited during speeding-up and stopping of the turntable G<1> by a switch GC<1>, GC<2> controlled by a governor GC driven from the turntable drive so that reproduction from pick-up P<1> is stopped when the turntable rotates below a predetermined speed. A relay, switches and governor control corresponding to RY, MS<1>, MS<2>, S<3> and GC is provided in connection with the turntable. G<2> which is traversed by the pick-up P<2> acting on completion of playing to bring a contact TA<2> up to a contact C<2> whereby the motor M<2> is cut out and the motor M<1>; or a third motor and turntable, started. Adjustable resistances V<1> V<2> control the volume of the output from the respective pick-ups.