Patent GB-282426-A (GB)
Title: Apparatus for recording and reproducing telephone conversations and messages
IPC: H04M1/65
Filed: 1927-12-15
Abstract: 282,426. Vogel, K. V., and Larason, J. G. Dec. 17, 1926, [Convention date]. Manual exchange apparatus.-The circuit of the motor 15 of a phonographic apparatus for recording messages at a telephone substation during the absence of the subscriber is closed by a relay 6 which responds to ringing- current, the motor circuit including also a. time-switch 20, 21 which is driven by the motor and effects the opening of the circuit after a definite time-interval. Electric bell signals are sent back to the calling subscriber as soon as the motor is started and shortly before the circuit is opened. The arrival of ringing-curent over the line 1, 2 energizes relay 6 which in turn closes a circuit from lighting mains 10 for relay 12 and motor 15 in series with the switch 20, 21. Relay 12 locks independently of the ringing-current. The switch 20. 21 comprises a drum 19 driven by the motor and carrying a contact ring 18 wiped by a brush 17 and a helical strip 20 engaged by a spring-controlled pivoted arm 21. After one rotation of the drum 19 the arm 21 leaves the strip 20 and returns slowly under the control of a brake 49, the motor circuit being thus broken and relay 12 unlocked. The drum 19 also carries contact strips 37, 38 in the circuit of a bell 42 which is in proximity to a microphone 44 so that signals of three rings and one ring, respectively. are sent back over the line 1, 2 when the motor is started and shortly before it is stopped. Relay 12, when operated, completes the filament circuit of an amplifier 57 over insulated contacts 52, 53, and completes also the anode circuit over armature 57, contact 58, switch contacts 65, 67 and recorders 32. Speech currents from line 1, 2 pass to the amplifier over a transformer 68 and are thus recorded on the cylinder 30. For reproducing the message, receiver 66 is lifted from the hook 67 and is therebv connected in series with the recorder 32, whilst the circuit of relay 12 and motor 15 is closed by depressing spring 23<1> into engagement with contact 25. Fig. 2 shows the mechanical arrangements for changing over the sound-boxes from recording to reproducing position. The sound-boxes are mounted on a frame 73 traversed by the driving screw 31 and guided at its lower end by a rod 74. The diaphragms are united by a bar 71 connected at its mid-point to the marker 33 which as shown is in the recording position. A switch arm 81 surrounding the screw 31 is controlled by a hand lever R9 through transverse rods 92 extending the whole length of the path of movement of the frame 73. When the arm 81 is moved to horizontal position, a member 75 pivoted to the frame 73 is rocked by a pin 93 so that the marker 33 is lifted and the projection 86 rides up a slot in the guide 85, the weight 83 being at the same time lifted by a projection 95 on arm 81. In this position arm 81 is disconnected from the screw 31 and the sound-box may be moved along the record by a button 98. Further movement of arm 81 in the anticlockwise direction brings the reproducing point 96 into engagement with the cylinder 30. A pointer 99 may indicate the number of messages recorded.