Patent GB-163310-A (GB)
Title: Improvements relating to automatic telephony
IPC: H04M1/38
Filed: 1921-05-12
Abstract: 163,310. Turcat, L. May 12, 1920, [Convention date]. Void [Published under Sect. 91 of the Act]. Automatic exchange systems; impulse-transmitters.-The transmitter is set to the desired number and the receiver then removed, thereby completing a circuit over one line for relays at the substation and exchange respectively. These relays complete a circuit over the other line, in-' eluding an interrupter, the selector magnet at the exchange and a sub-station magnet which steps round an arm of the transmitter until it reaches an insulating stud, thereby opening the circuit over the other line and stopping the selector. Construction of impulse-transmitter. This closely resembles that described in Specification 141,711. Selection of wanted line. Each subscriber has at the exchange five relays 62, 62<a>, 62<b>, 77, 77<a>, and a selector, represented by its magnet 72 and wipers 75, 76, 76<1>, 76<a> which normally rest upon contacts corresponding to his line. The numbersender is represented in Fig. 1 by a stepping-magnet 33, and arms 10, 14 moving over discs 7, 17 having insulating studs 11, 20. The subscriber having set his sender to the desired number, so as to move the insulating stud 11 from under the spring 10, removes his receiver, thereby locking the drum and shifting the springs 25 - - 32. The closure of springs 25, 26 completes a circuit over spring 10, relay 37, and line 82 for relays 62, 62<a> connected in parallel. Relay 62 energizes a motor to rotate interrupter 57, and the joint energization of relays 37, 62 closes a circuit through the interrupter 57, selector magnet 72, line 83, and the stepping-magnet 33. The selector and the sender rotate in synchronism until the spring 10 engages the stud 11, thereby opening the circuit of relays 37, 62, which arrest the impulse-transmitter and the selector. Busy test of wanted line. During the selecting-operation, the relay 62 energizes relays 77, 77<a> over their windings 771, 771<a>; when the relay 62 de-energizes, the relay 77a remains energized over its winding 772<a> if the wanted line is busy, and keeps the circuit of the calling line open at contacts 103, 105. Supply of ringing-current. If the wanted line is free, the relay 77 remains energized over its winding 772 and closes the calling circuit. A ringing-signal is given to the calling party over a third winding 773 of the relay 77. Talking circuit and microphone supply. The talking circuit includes the two line wires and condensers 50<a>, 95, microphone current being supplied through an impedance 114 at the exchange over line 82 and to earth at the sub-station through coil 50. Release. When the subscriber replaces his receiver, circuit is completed over contacts 25, 27, spring 14, relay 37, line 82, and relay 62, the relays 37, 62 completing a circuit over line 83, as in selection, for the selector magnet 72 and the stepping-magnet 33, so that the selector and the transmitter rotate in step until the spring 14 engages the insulating stud 20 and opens the circuit over line 82. If the selector is not properly restored, due to getting out of step, the relay 62<b> is energized over the off-normal contact 76<a> and closes a local circuit for the selector magnet 72 through the interrupter 57.