Patent GB-191109577-A (GB)
Title: Improvements in or relating to Telephone Systems.
Inventor: DICKER STANLEY GORDON SINCLAIR
Filed: 1911-04-19
Granted: 1912-06-19
Abstract: 9577. Dicker, S. G. S., [Automatic Electric Co.]. April 19. Automatic and semi-automatic exchange systems.-Two-wire connectors used by operators for testing purposes or for extending a call from a manual line to an automatic subscriber are modified so that (1) the supervisory relays of the cord-circuit are directly controlled by the called subscriber, (2) the operator can ring up the wanted subscriber from her cord-circuit generator, (3) the operator can rotate the wipers on any selected level step by step at will so as to bring them into contact successively with various lines for testing purposes, and (4) the operator can extend a call to a busy line, this being effected by omitting all the parts of a connector which have to do with testing and ringing the wanted line. The connector shown in Fig. 3 fulfils the first three of the above objects, there being a direct connexion, without condensers, through from the jack J<3> to the wipers When an operator inserts the calling plug P<2>, Fig. 2, the relay 179, Fig. 3, energizes in series with the relays 173, 174, of which the relay 173 connects the battery through an inductance 176 to the tip of the plug, and the relay 174 closes the circuit of the called subscriber's supervisory lamp 175 in the usual manner. To select the desired line, the operator bridges her impulse-sender 50 across the plug P<2> by the switch S<1>, thus energizing the relay 183, and completing the circuit of the release relay 181, which locks up over its contact 180 and the armature of the relay 179, remaining in this condition as long as the plug is in the jack J<3>. The first set of selecting- impulses are repeated by the relay 183 through the private-magnet relay 188 to the vertical magnet 189. When these impulses cease, the relay '188 opens the circuit of the private magnet 191, which allows the side-switch to pass to its second position. The final set of impulses are repeated through the relay 188 and the normal contact of the relay 194 to the rotary magnet 192, thus moving the wipers to the terminals of the selected line. Busy test. If the wanted line is busy, a circuit is closed from the earthed test lead through the upper winding of the relay 194, which closes a holding-circuit for the private magnet 191 through the lower winding of the relay 194, contacts 195, 180 to ground. The side-switch is thus locked in its second position, and the busy generator O is connected over contacts 196 to the calling line. Supply of ringing-current. If the selected subscriber is disengaged, the side-switch passes to its third position, in which the relay 200 is energized and extends the connexion to the called line. The operator then rings up the subscriber by means of her cord ringing-key S<2>. When the called subscriber replies, he receives microphone current over the coil 176 and supervisory relay 177, so that he directly controls the supervisory lamp 175. Release. The release of the connector is effected when the plug P<2> is removed, thus deenergizing the relay 181, which closes the circuit of the release magnet 144. Use of the connector for testing purposes. The relay 199 and the wires 201, 202, 203 are used for testing purposes. The connector is first stepped up to the desired level in the usual manner, and the wire 201 is then earthed, thus energizing the relay 199 which (1) extends the earth connexion to the test-wiper, thus making the selected line busy 'to other connectors, (2) closes a circuit through the upper winding of the relay 194, which as before completes a holding-circuit for the private magnet 191, thus locking the side-switch in its second position as long as the wire 201 is earthed, and (3) closes a contact 208 so that the rotary magnet 192 can be repeatedly energized by interrupting the circuit of the relay 183. The wipers can thus be brought into contact with each line in succession and the line may be tested over the leads 202, 203. Trunking - connector for calling busy lines. This special connector resembles that described in Specification 1298/10 except that the busytest and riging-devices are omitted. When the calling-plug P<2> is inserted in the jack of this connector, the relay 173 is not energized owing to a high resistance connected between the jack ring and earth, so that the tip side of the cord remains grounded at G<19>, thus maintaining a holding-circuit for the connector line relay.