GB502586A - Improvements in and relating to electric recording and reproducing devices - Google Patents

Abstract

502,586. Electric recording and reproducing apparatus. RYSICK, A., and KOSMOGRAPH DIKTIERMASCHINENFABRIK GES. March 14, 1938, No. 7839. [Class 40 (iv)] In an electric recording and reproducing device including a microphone, an amplifier, a loud-speaker, and a pick-up having both recording and reproducing members, the change-over switching arms are operated by relays and are arranged in a chamber at a substantial distance from the other parts of the device. The pick-up 14, Fig. 4, is shown twice, acting as a reproducing device on the left and as a recorder on the right. The microphone 112 is connected to a battery 118 provided with a charging device. The loud-speaker is shown at 126. The amplifier includes three valves 34, 35 and 38, the valve 35 being for rectifying purposes. When recording, the switches 15, 69, 90, 100, 119 and 123 are all in the position shown in dotted lines, and when reproducing they are in the positions shown in full lines. The switch 15 is operated by hand, and the others by relays 92 and 91, controlled by the switch 15. The switch 90 connects the transformer 58 either to the loudspeaker 126 whilst reproducing, or to the pickup 14, rectifier 129 and milliammeter 132 when recording. The milliammeter may be adapted to be used as a voltmeter to show the condition of the battery 118, the necessary connections being controlled by a switch, not shown. Instead, of charging the battery 118 only when reproducing, the switch 123 may be dispensed with and the battery may be charged on the buffer principle by means of the circuit shown in Fig. 4a, including a rectifier 120, a choke 143 and condensers 144.