Patent GB-236282-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone systems
IPC: H04Q3/58
Filed: 1924-04-02
Abstract: 236,282. Automatic Telephone Manufacturing Co., Ltd., and Saville, W. April 2, 1924. Automatic and semi-automatic exchange systems.-In a testing and trunk-offering amangement for district office systems, the junction lines used for ordinary connections are employed, for example, the two last choice lines of a group, or a single line together with a special testing and trunk-offering line. Fig. 2 shows an arrangement suitable for a large district office, in which the trunk operator's and test clerk's positions MB<1>, TD' are connected through a relay group TRG<1> to a line switch LS which selects any idle junction line AJ to the district office. Upon dialling of a special number, e.g. 99, the connection is extended to a distributor selector TOD which responds to two digits of the wanted number to select a special connector TOC<1>. The special line STJ is wired directly to the distributor TOD. Fig. 1 shows an arrangement for a smaller district office, in which the trunk operator's and test clerk's positions MB, TD are connected through relay groups RG, TRG to the last choice junction lines LCJ terminating in connectors FS. Upon dialling of a special test number, e.g. 99, or a special trunk offering number, e.g. 98, one of the connectors FS responds to transfer the connection to the special connector TOC, one of the junction lines being released in the case of trunk offering. Other slightly modified arrangements are outlined, in some of which the apparatus for testing and trunk offering is separated. First arrangement, Figs. 2, 6, 7. Testing. When the test clerk plugs into the test jack TJ<1> and throws the dialling key, sleeve relay 2 energizes, connecting the private control key PC and the connector release key CR to the hold key HK and grounding the test wire 22. Line relay 8 energizes, and the line switch. LS selects an idle line AJ in the usual manner. Switching relay 7 energizes and connects through the line and test wires 20, 21, 22. First and second selectors IS, IIS respond to the special number 99 to extend the connection to a distributor selector TOD. Line relays 101, 103 energize and connect up release. relay 102, and impulses are repeated by relay 101 to the vertical and rotary magnets 109, 110. Slow relays 105, 106 are energized during the rotary movement, and a test is made when relay 105 relapses. If the desired connector is engaged, a circuit is completed from earth on wiper P<2> through relay 106 and the upper winding of'relay' 107, which connects busy tone to the line and energizes reversing relay 100, so that polarized relay 6 in the test clerk's loop now operates and connects busy flash to lamp L. Assuming the special connector TOC<1> is idle, switching relay 108 energizes and connects up wipers P<1>, P<2>, O<1>. Line relay 152 of the connector TOC<1> energizes over wipers O<1>, O<2> and connects up release relay 153, and impulses are repeated forward at contact 139 to operate the connector. If the wanted line is engaged, reversing relay 100 energizes over wipers P<1>, 182, relay 106 being energized during the sending of impulses. The test clerk may operate the hold key HK, bridging a resistance r<1> across the line 20, 21 to hold the connection. If the wanted line is idle, wiper P<1> is grounded when relay 106 relapses, and the line switch cut-offrelay energizes. The wanted line is connected to the test jack TJ<1> over the testing line STJ upon operation of the hold key HK, which controls relay 3. Line relays 103, 101 are now connected up through the keys PC, CR, and the test clerk may.by operating the key PC release relay 103, relay 101 being held by ground on the a-wire, so that ground is removed from wiper P<1> to release the cut-off relay, and the test clerk may set up a connection over the subscriber's line switch. The test clerk mav release the connector TOC<1> by operating the key CR, whereby relay 101 is released, relay 103 being held by battery on the bwire, so that the circuit of line relay 152 is opened at contact 139. The distributor is released when the hold key HK is restored. The test clerk may withdraw his plug without releasing the connection, which is maintained over a bridge resistance r<1> upon relapse of sleeve relay 2. Trunk offering. When the operator plugs into the jack J, sleeve relay 4 energizes, lighting lamp L and grounding the test wire 22. The test clerk restores the hold key HK to release the connection, and relay 5 energizes upon relapse of relay 3 to connect the jack J to the line switch LS and to insert condensers c', c<2> in the line STJ. Modifications. The distributor TOD mav be converted to function as a single-digit selector by an additional connection X, by means of which the switch makes a single rotary step when the change-over relay 104 falls back to make connection with the connector TOC<1>. A selector may be interposed between the distributor TOD and the connector TOC'. In this case, if the connector is engaged, relay 107 is energized over its lower winding by battery on wiper P<2>, sending back a busy signal as above. Second arrangement, Figs 1, 8, 9. Testing. When the test clerk plugs into the test jack TJ<1>, provided the last choice junction lines LCS are idle, switching relays 202, 204 energize, lighting lamp TC and connecting up the junction lines. The connector FS in which the line 235, 236 terminates operates in response to the special test number 99, and a circuit is closed over the corresponding test terminal 283 for relay 205, which switches the junction lines through to the special connector TOC. Connection is made to the wanted line in the usual wav, relay 205 being locked to the test wire 299. Relay 207 energizes upon operation of the hold key HK<1>, locking relays 202, 204 independently of the jack TJ<1> and lighting " connector engaged " lamp CE. Switching relay 210 in the connector TOC also energizes over wire 234, connects the test jack TJ<1> over wires 235, 236, 233 to the line and test wipers of the connector, and completes a new holding circuit for relav 205. Trunk offering. When the operator plugs into the jack J<1>. relay 208 energizes and lights "clear for trunks " lamp CT, whereupon the test clerk releases the connection by restoring the hold key HK<1> and removing the test plug, but relay 204 is held at contact 302 of relav 208. Relay 209 energizes upon relapse of relay 207, connecting the jack J<1> to the junction line 235. 236, and causes lamp CT to flash. The connector FS operates in response to the special trunk-offering number 98, and a circuit is closed over the corresponding test terminal 284 for relay 206, which switches the junction line through to the special connector TOC. Switching relay 210 is not now energized, so that relays 211, 212 remain operated, the former serving to connect up the talking condensers 334, 335. Operation of the connector TOC directly from the positions TD. MB. In this case, wires 220, 221, 222, 223, 225 are directly connected to wires 220<1>, 221<1>, 222<1>, 298, 225<1>. and the operation is substantially as described above.