Patent GB-170282-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1921-10-06
Abstract: 170,282. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Ray, A. J.). Oct. 15, 1920, [Convention date]. Addition to 134,193. Automatic a n d semi-automatic exchange systems. - In working between a manual and an automatic exchange, a control and supervisory circuit is employed which can be connected at each end to either ground or battery, as described in the parent Specification. In 'the system shown in the drawings, a manual main exchange is connected over twowire trunks to a small automatic private branch exchange. Each trunk 40, 41 terminates at the branch exchange in a repeater E and can be connected by a line switch C to an idle connector H to select a wanted subscriber A<1>. The connectors H can also be seized by the line switches C<1> of the branch exchange subscribers and operated either to make a local connection or, when raised to the tenth level, to hunt for an idle trunk to the main exchange. The control and supervisory circuit between the exchanges is a simplex circuit comprising the two trunk wires 40, 41 in parallel and terminates in wires 21, Fig. 1, and 86, Fig. 2, which are connected through controlling relays to ground or battery. Call from manual. exchange to automatic branch exchange. When the operator plugs into the jack J<1> a bridge relay 27 and sleeve relay 24 are energized and the wire 21 of the simplex circuit is connected to batterv through the upper winding of relay 26. The wire 86, Fig. 2, at the other end of the simplex circuit is normally grounded through the upper winding of relay 56, so that relays 26, 56 are energized in series. Relay 26 opens the bridge circuit to de-energize relays 27, 11 and to light the lamp L<2>. Relay 56 energizes relay 55, which grounds the trunk test wire 43 and bridges the upper winding of an electropolarized relay 59 across wires 90, 92 to energize the line relay 93 of the switch C, which operates in known manner to find an idle connector H. The switching relay 98 is then energized to extend the circuit 90, 92 to the connector, energizing relays 122, 123. The operator throws a key K<1> to connect her impulse sender S in the simplex circuit and dials the wanted number. The impulses are repeated by relay 56 to relay 122 and by relays 122 to the vertical magnet 129 and series relav 124. The first impulse passes through normal contact 144, 142 and subsequent impulses through off-normal contact 144, 143 and locking contact of relay 124. Relay 124 relapses at the termination of the digit and remains de-energized (since its original circuit is open at contact 144, 142) during the transmission of the second digit, the impulses of which are therefore repeated to the rotary magnet 131. Relay 127, energized in series with magnet 131, connects the test relay 126 to wiper 171, so that if the wanted line is busy, relay 126 becomes energized and locks itself, and on the de-energization of relay 127 a busy tone device B is connected to the calling line. On the other hand if the wanted line is idle relay 126 is not energized and the de-energization of relay 127 closes a circuit for the lower winding of relay 128 in series with relay 80. Relay 128 locks itself through its upper winding, grounds the test wiper 171, and completes a ringing circuit including the upper winding of relay 125. When the called subscriber answers, relay 125 becomes energized and locks itself up, breaking the ring- ing circuit and completing the talking circuit, so as to energize the back-bridge relay 121, which reverses the current in the wires 104, 106 to energize the electropolarized relay 59. Supervisory signals; release. The energization of relay 59, when the call is answered, closes a holding-circuit through the lower winding of relay 56 and energizes relay 58, which disconnects the simplex circuit 86 from its ground connection through relay 56 and connects it to battery through relay 57. Assuming that the operator has restored the key K<1>, the other end of the simplex circuit is also at this time connected to battery through relay 26, so that relay 26 is deenergized and restores the bridge connection through relay 27 so as to energize relay 11 and extinguish the lamp L<2>. After conversation, when the called subscriber disconnects himself, the de-energization of the back-bridge relay restores the current in the upper winding of relay 59 to its normal direction, relays 59 and 58 become de-energized, and the simplex circuit 86 is again connected to ground through relay 56. The relay 26 is therefore again energized and causes the lamp L<2> to glow. When the operator takes down the plug, the de-energization of relay 24 connects the simplex wire 21 to ground through relay 25. Both ends of the simplex circuit being now connected to ground, relay 56 relapses and releases the connection by opening the contact 77. Even if the called subscriber fails to disconnect himself the operator can release the connection by withdrawing the plug. In this case the grounding of the simplex circuit through relay 25 results in the energization of relay 57, which opens the holding circuit through the lower winding of relay 56, which relapses and releases the connection. In this case the momentary energization of relay 25 in series with relay 57 flashes the lamp L<3>, which indicates to the operator that the circuits have released properly. Call from automatic branch exchange to manual exchange. The line switch C<1> operates in known manner to extend a calling line A<1> over wires 107, 108, 109 to an idle connector H, energizing relays 122, 123. In response to the digit O, the vertical magnet 129 is operated as before described to raise the wipers to the tenth level, at which a grcup of springs 132 - - 135 is operated to prepare circuits for the relay 120 and rotary magnet 131 and to energize the test relay 126, which locks itself. The de-energization of relay 124 at the conclusion of the digit de-energizes relay 126 ar.d completes the circuit of the rotary magnet 131 and relay 127. Relay 127 connects wiper 171 through contact 153 of the rotary magnet to relay 126, so that rotary motion continues in the usual manner until an idle line 42, 43, 44 is reached. Relay 127 then relapses and energizes the lower winding of relay 128 in series with relay 50, Fig. 2. Relay 128 locks itself and energizes relay 120, which extends a clean metallic talking circuit, free from all bridge or relay connections, from the calling line through the switches C<1>, H to the wires 42, 44. Relay 120 at contact 137 locks itself in parallel with relay 128 to wiper 171, which is now grounded over wire 43 as described below. Relay 50 connects the wires 42, 44 through windings of repeater R<1> to relay 52, which becomes energized over the calling line and energizes relay 53, which grounds the wire 43 to lock relays 50, 120, 128, and 180. Calling and supervisory signals; release. Relay 53 also connects the simplex wire 86 to battery through relay 57, thereby energizing relay 25 at the other end of the simplex circuit so as to light the calling lamp L<3>. When the operator inserts the answering plug, relays 27, 24 are energized and the simplex wire 21 is connected through relay 26 to battery, de-energizing relay 57 which energizes the customary reversing relay 51. When subscriber A disconnects himself the de-energization of relay 53 unlocks relays 120, 128, 180 to release the switches H, C<1>, and connects the simplex wire 86 to ground through relay 56, energizing relay 26 which controls relay 11 to light the lamp L<2>. The operator then takes down the cord.