Patent GB-134193-A (GB)
Title: Improvements in or relating to Automatic or Semi-automatic Telephone Systems.
IPC: H04Q3/00
Filed: 1919-06-04
Abstract: 134,193. Automatic Telephone Manufacturing Co., (Assignees of Wicks, J.). Oct. 23, 1918, [Convention date]. Automatic and semi-automatic exchange systems.-Arrangements are described for phantomcircuit working on the inter-exchange trunks of automatic and semi-automatic systems. In setting up a connexion, the automatic switches at the distant exchange are controlled entirely over one wire of one of the two trunks X, Y, Fig. 3, one wire of each trunk being allotted to the control of the connexion of the trunk, and one of the remaining two wires to the control of the superimposed phantom-circuit connexion. Thus the phantom-circuit connexion shown in Figs. 2, 3, 4, and 5 is controlled over the circuit 51, Fig. 2, 53, Fig. 3, 55, Fig. 4. The setting-impulses are repeated over this circuit by repeater sets E, Fig. 2, F, Fig. 4, and the supervisory or metering operations and the release of the connexion are controlled over the same circuit by switching one or other end of the circuit from ground to battery, or vice versa. The repeater sets are organized to act correctly when seized by standard two-wire selectors. Connexions can be set up over the trunks X, Y, and X + Y in either direction; the establishment of a phantom-circuit call from left to right will first be described. Repeater E, Fig. 2, and repeater-selector F. Fig. 4. The calling-subscriber's line is extended to the leads 300, 301, 302 of the repeater E by a preliminary selector and first selector operating as described in Specification 132,226. Relay 38 is energized by a ground impulse over the test wire 302 and connects the calling-line to relay 40, which energizes relay 41. which puts a locking- ground on the test wire 302. Relay 41 also connects the upper winding of relay 45 to the out-. going operating-circuit 51, 53, 55, energizing this relay in series with relay 60, Fig. 4, the upper winding of which is connected to the other end of the circuit. Relay 60 energizes relay 74, which puts a busy ground on the test wire 202 to mark the switch F non-selectable for calls in the other direction. Relay 74 also closes a circuit through the upper winding of relay 77, but without energrizing this relay, which only responds to the added effects of both its windings. The numerical interruptions of the calling-line are repeated by relay 40 to the circuit of relays 45, 60. During the passage of each set of impulses, a slow-release relay 49 is energized and closes a low-resistance shunt round relay 45. The first series of impulses delivered to the relay 60 energize the vertical magnet 68 in series with a. slow-release relay 69, which energizes a relay 84, which locks itself. At the termination of the series, relay 69 relapses and completes the circuit of the rotary magnet 85. The selector now rotates to find an idle trunk in the selected level, the magnet 85 and relay 84 opening and closing each other's circuits in turn until the test-wiper 80 comes on to the ungrounded terminal of an idle connector H, Fig. 5, whereupon a high-resistance relay 93 (being no longer short-circuited through the testwiper) becomes energized in series with relay 84, which is wound so as not to be energized by this circuit. Relay 93 locks itself to the test-wiper 80, switches the talking-circuit to the selector wipers, and bridges.the lower winding of relay 77 across the repeater condenser, so as to energize relays 105, 106 in the connector. Relay 77 still does not respond, the effects of its two windings being opposed. Relay 106 grounds the incoming test wire to mark the connector busy and to keep relay 93 locked independently of relay 74. Connector H, Fig. 5. The next series of interruptions is repeated by relay 60 over the outgoing talking conductors to relay 105. During the passage of the impulses, relay 94 is energized and short-circuits the resistance 99 and the lower winding of relay 77 in the outgoing impulse circuit. Relay 105 now controls the vertical magnet 116 to raise the connector to the wanted level. At the first step, the original circuit of the vertical magnet is opened at the normal contacts O N, but a second locking-circuit is maintained by a slow-release relay 115 in the same circuit. At the termination of the series of impulses, relay 115 relapses and prepares a circuit for the rotary magnet 121. The next series of impulses energize the magnet. 121, which rotates the connector to the terminals of the wanted subscriber. Busy test and signal. A slow-release relay 122, energized in parallel with the rotary magnet 121, connects the test-wiper 120 to a relay 123 and maintains this connexion for an instant after the final impulses have ceased, so that if the wanted line is busy, relay 123 becomes energized. Relay 123 connects a busy signal apparatus to the calling-line and closes a circuit by which it remains energized when relay 122 relapses. Supply of ringing-current. On the other hand, if the wanted line is idle, the relapse of relay 122 closes a circuit through the lower winding of relay 124 and the called-subscriber's cut-off relay. Relay 124 locks itself through its upper winding, grounds the test-wiper 120, and connects a ring- ing-machine R to the called line. Supervisory or metering signal when called sub- .scriber answers. When the called subscriber answers, a relay 125 is energized, which locks itself through its lower winding, disconnects the called line from the ringing-machine, and connects it to a bridge relay 126. Relay 126 reverses the connexions of the line relay 105, reversing the direction of the current in the lower winding of relay 77, Fig. 4, which now energizes for the first time, both its windings assisting each other. Relay 77 locks the relay 60 and transfers the conductor 55 from the grounded upper winding of this relay to the upper winding of relay 127, which is connected to battery. This de-energizes relay 45, Fig. 2, at the other end of the circuit 55, 53, 51, and the relapse of relay 45 energizes relay 44, which reverses the connexions of the relay 40 with regard to the calling-line. This reversal may operate a meter or an operator's supervisory signal in known manner. Release. The release of the connector is delayed until both subscribers have disconnected, but the rest of the connexion is released under control of the calling-subscriber. When the calling-subscriber opens his line circuit, the preliminary selector and first selector are released, and relays 40, 41, 38, Fig. 2, are de-energized. Relay 41 transfers the conductor 51 from its connexion to battery (through the upper winding of relay 45) to the grounded upper winding of relay 130, which becomes energized in series with relay 127, Fig. 4, at the other end of the circuit 51, 53, 55. Relay 127 opens the circuit of relay 74, which energizes the magnet 131 to release the switch F. This de-energizes the connector relays 105, 106 and the bridge relay 77, Fig. 4, which transfers the conductor 55 again to the grounded upper winding of relay 60, de-energizing relay 130, Fig. 2, at the other end of the circuit 55, 53, 51. When the called subscriber also hangs up his receiver, relay 126 is de-energized and completes the release circuit of the connector. All switches and relays are now at normal. Calls in the reverse direction. The repeaterselector F, Fig. 4, which, in this case, acts only as a repeater, is seized by a selector over the trunk 200, 201, 202, and repeats the subsequent impulses over the circuit 55, 53, 51 to operate the repeater E, Fig. 2, which controls a selector or connector over the trunk 217, 218, 219. The operation of the circuits is generally similar to that already described and need only be indicated briefly. Relay 77, Fig. 4, is energized over the test wire 202 and relay 98 over the calling-line. Relay 98 energizes relay 204, which applies a holding-ground to the test wire 202 and switches the circuit 55 to the lower winding of relay 127. Relay 130, Fig. 2, which is energized in series with relay 127 at the other end of the circuit 55, 53, 51, energizes relay 215, which marks the repeater E busy to calls in the other direction, energizes the lower winding of relay 216, and bridges the outgoing circuit 217. 218 through the upper winding of relay 216. This relay, however, does not respond, the effects of its two windings being opposed. The subsequent impulses are repeated by relay 98, Fig. 4, over the circuit 55, 53, 51 to relay 130, Fig. 2, which repeats them again to the outgoing circuit 217, 218, to operate the switches which complete the connexion. When the called subscriber answers, the current in the upper winding of relay 216 is reversed, and this relay becomes energized, energizing relay 232, which switches the conductor 51 to battery through relay 45, de-energizing relay 127, Fig. 4, which energizes relay 203 to reverse the current in the calling-line. When the calling-subscriber hangs up, relays 98, 204, 77 are de-energized, and the circuit 55 is transferred to ground through relay 60. Relays 45, 60 are now energized in series in the circuit 51, 53, 55 and initiate the release of the connexion.