Patent GB-264222-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q1/38
Filed: 1925-10-13
Abstract: 264,222. Automatic Telephone Manufacturing Co., Ltd., (Automatic Electric Co.). Oct. 13, 1925. Automatic and semi-automatic exchange systems.-In a system in which the automatic switches are controlled in part over circuits using the speaking wires separately for preparing and effecting the setting, respectively, and in part over loop impulsing circuits including both speaking wires, a repeater is provided for translating control of the first kind to control of the second kind. The invention is described as applied to working over a two-way toll-line TL extending between two exchanges using the two kinds of control respectively. The translating repeater R is provided and other necessary circuit modifications are made at the near exchange in which loop dialling is employed, the supervisory and controlling apparatus being conveniently connected up over a distributing frame IDF. A call from the distant exchange employing leg dialling and supervision is extended over the toll line TL by an operator thereat, who may herself control the switches at the near exchange shown, the repeater R effecting the translation of the control, or who may signal an operator at the near exchange and ask her to set up the connection. For a call in the reverse direction, an operator plugs into a toll line jack LJ or LJ<1> at one of the two 'positions shown, thereby preparing the circuit of an associated supervisory lamp. She then rings down the toll line to signal the distant operator, or plugs a dialling cord, Fig. 2, into a dialling jack DJ or DJ<1> and impulses directly over the upper conductor 11 of the toll line to control the switches at the distant exchange. Operator at distant exchange sets up call to automatic subscriber at near exchange over toll line TL. Normally both conductors 11, 12 of the toll line are grounded at the near exchange over relays 45, 47 respectively, and are also grounded at the distant exchange. When the distant operator inserts the plug of her cord circuit into the toll line jack, ground on conductor 11 is replaced by battery causing the response of relays 45, 46. Relay 46 closes a circuit for the lower winding of polarized relay 43, and closes a bridge, including the upper winding of relay 43, across the trunk 35, 36 outgoing from the repeater R, to cause an associated line switch to extend connection to a first selector. The distant operator now connects up her dial and sends the wanted number. When the dial is moved off normal, ground on conductor 12 is replaced by battery as described subsequently in connection with a call in the opposite direction, thereby energizing relay 47 which energizes relay 48 and prepares the impulse repeating circuit by closing a direct bridge across conductors 35, 36 including armature 59 of relay 45. Relay 48 locks up, grounds lead 33 to mark the toll line busy at the jacks LJ, LJ<1>, and energizes a relay 14, which cuts off the ringing response relay 15 and operates the mechanical busy signals associated with the jacks LJ, LJ<1>. As the dial returns to normal, impulses sent over conductor 11 vibrate the relay 45 which repeats them over the outgoing loop 35, 36. When the dial reaches normal, conductor 12 is again grounded and the original bridge across the wires 35, 36 is re-made, but the impulsing circuit is again prepared when the dial is turned for the next digit. All the digits are transmitted in this manner to set up the wanted connection, and when the called party responds, the battery reversal over the trunk 35, 36 causes the response of the polarized relay 43 which applies battery to the conductor 12 to extinguish a supervisory lamp in the distant exchange as described with reference to a call in the opposite direction. When the distant operator takes down the connection, battery is removed from the conductor 11, relays 45, 46, 48, and 14 relapse, the bridge across the wires 35, 36 is opened to release the connection, and the toll trunk is marked idle. Local operator sets up call from distant exchange. In this case the distant operator, after plugging in and causing the trunk 35, 36 to be extended to an idle selector as before, rings down the toll line TL to energize relay 15, the armature of which is mechanically locked until it is tripped by the response of relay 14. Relay 15 lights a lamp at the answering jack AJ, operates the busy signals associated with the jacks LJ, LJ<1>, and energizes relay 42, which connects the conductors 11 and 12 to battery and earth over resistance 49 and relay 44 respectively, and deenergizes relays 45, 46. On plugging into jack AJ, ground on the sleeve marks the toll line busy at the jacks LJ, LJ<1> and energizes relay 14, which unlocks ringing relay 15 to extinguish the answering lamp, and closes an alternative circuit for relay 42 and the busy signals. The near operator now converses with the calling operator and sets up the call in the usual manner over her cord circuit and the toll service trunks and switches which are not shown. The near operator has supervision over the called subscriber and rings down the toll line to give the calling operator a disconnect signal. Operator at near exchange extends call to distant exchange over toll line TL. When a near operator inserts her cord plug into the jack LJ', ground on the sleeve energizes a relay 14, which cuts off the incoming ringing relay 15, energizes mechanical busy signals associated with the toll jacks LJ, LJ<1>, and completes a circuit for a relay 42, which lights a supervisory lamp associated with the jack LJ<1> and transfers the conductors 11 and 12 to battery over resistance 49 and to earth over relay 44 respectively, thereby causing a line switch at the distant exchange to extend connection to a first selector. The operator may now ring down the toll line to signal an operator at the distant exchange, or she may insert the plug P, Fig. 2, of her dial cord into the dialling jack DJ<1> and set up the connection herself. In the latter event, immediately the dial CD is moved, the closure of the off-normal springs grounds the sleeve to energize a repeater cut-off relay 41, and energizes relay 101 which connects battery to conductor 11 over the impulse. springs, and connects battery to conductor 12 over armature 103 in place of ground over relay 47, thereby preparing the distant circuits for impulse reception. On the return of the dial, impulses are sent over the conductor 11, the slow-release relay 101 holding up for a short interval in the normal position to ensure that holding battery is re-applied to conductor 11 over resistance 49 before the armature 102 falls back. In the normal position of the dial, ground is replaced on conductor 12. When the called party responds, the conductor 12 is connected to battery at the distant end causing the response of relay 44, which extinguishes the lamp associated with the jack LJ<1>. This battery is removed when the called party hangs up, the relay 44 relapses and the lamp is lighted again to give a disconnect signal. When the plug is removed from jack LJ<1>, relays 14, 42 de-energize and the removal of holding battery from conductor 11 releases the connection.