GB731466A - Automatic sound reproducer - Google Patents

Abstract

731,466. Gramophone circuits. ASSMANN GES., W. Jan. 16, 1953 [Jan. 17, 1952], No. 1335/53. Class 40 (4). [Also in Group XXXVIII] An arrangement for indicating an interruption in a sound transmission system of a magnetic sound reproducing apparatus employing disc-shaped records, comprises the use of an induced auxiliary voltage to the transducer while in its position of rest at the edge of the record, whereby in the absence of a signal from either the said auxiliary source, or from the sound record, for a duration of more than 15 seconds a relay is operated to produce an indicating signal. The starting of the apparatus is initiated by a calling voltage at terminals 32, Fig. 4, which operates a relay 31 to close contacts 30 in the circuit of the motor and open the contacts 29 in the circuit of a magnet 13 carrying an audio-frequency tone signal. The transducer 11 traverses the record until at the centre of the record it comes into contact with an adjustable stop to close contacts 36, and operate a relay 34 which opens switch 33 to release relay 31, whereupon motor contacts 30 open and contacts 29 close. The automatic mechanism returns the transducer 11, by means not shown, to its rest or starting position where the magnet 13 induces an audiofrequency in the transducer 11. The resulting signal, or the normal sound signal, is amplified by amplifier 25, and is received by a relay unit 27 which initiates an appropriate signal should there by an absence of any sound signal for a period longer than 15 seconds duration.