Patent GB-417924-A (GB)
Title: Improvements in or relating to devices for use in telephone systems for automatically transmitting and recording messages
IPC: F16N11/00
Filed: 1933-02-10
Abstract: 417,924. Sound-recording and reproducing machines. DANIEL, K., 100, Weyerthal, Lindenthal, Cologne, Germany. Feb. 10, 1933, No. 4192. Convention date, May 21, 1932. [Class 40 (ii).] In phonographic sub-station equipment comprising a transmitting record for sending a predetermined message to a calling party, and recording means for taking a message from said party, switching devices are provided whereby after the wanted party has called his substation from another sub-station, this party may record a further message on his transmitting device and also hear the messages recorded in his absence. The switching devices are operated by audio frequency currents transmitted over the line by sounding whistles, tuning forks &c., of predetermined frequencies. Incoming calling current passes to the phonographic equipment, either directly over a manually operated switch 2 or automatically through a delay switching device 4, and operates relay 10 which connects up rectified A.C. from the mains 5 and operates relay 11 which holds itself, maintains the supply circuit when 10 drops back, and completes the circuit of amplifier 14. Solenoid 19 energized by the supply over switch 18 draws up a rack 19a to bring a fresh recording cylinder 29 into position. These cylinders are mounted in a rotatable cage 28. At the same time, motor 27 is operated and solenoid 22 moves the motor about a pivot 27a so that it drives the transmitting cylinder 30. Pick-up 24 traverses the cylinder to transmit the message and eventually reaches stop 26 whereupon it closes a circuit for changing over switch 21 and returns, in a manner not described, to the starting position. Switch 21 energizes solenoid 23 to put the motor 27 into driving engagement with the recording cylinder 29 and an incoming message is recorded thereon by tool 31 used as a cutter which, at the end of the message, remains in the position it has reached. If, however, the message is too long for one cylinder, the cutter on reaching the end of the record returns to its initial position and also switches out solenoid 19 whereupon rack 19a drops since it has only a one-way driving connection with the cage 28. On reaching its lowermost position, rack 19a again switches in solenoid 19 so that rack 19a brings a new cylinder into position. The subscriber may by rotating back cage 28 bring the recorded cylinders into position for reproduction by tool 31 used as a reproducer. Important communications may be re-recorded on cylinder 32. When the subscriber calls his sub-station from another sub-station, he first hears the message on the transmitting cylinder 30, and at the termination thereof, he sounds a note by tuning fork &c. in the microphone to vibrate a tuned diaphragm 25 which operates a magnet to unlock stop 26 whereupon tool 24 pushing the stop in front of it and acting as a recording tool, records any further message that the subscriber may desire to have transmitted in his absence. When this recording is finished, the tool 24 restores to its normal position and stop 26 is re-locked in its new position. If the subscriber wishes to hear from another sub-station the messages recorded in his absence, he sounds a different note to vibrate the tuned diaphragm 17 which energizes magnet 17a to change over the switch 18. Solenoid 20 is thereby energized, and rack 20a moves automatically up and down until cage 28 is restored to the position in which the first recorded cylinder 28 comes opposite the tool 31 whereupon the recorded messages are transmitted, 31 acting as a reproducer. Amplifier 14 is controlled automatically, in known manner, to operate for either direction of transmission.