Patent GB-191006964-A (GB)
Title: Connections for Semi-automatic Telephone Exchanges.
Filed: 1910-03-19
Granted: 1910-08-25
Abstract: 6964. Siemens & Halske Akt.-Ges. March 20, 1909, [Convention date]. Semi-automatic exchange systems.-In a semiautomatic telephone exchange system of the kind described in Specification 9055/09, in which a calling subscriber is connected by a preliminary selector at the exchange to an idle connector of the Strowger-switch type which is actuated by the operator to connect the desired subscriber, the connector is itself provided with an automatic switch of the preliminary-selector type to connect the connector to the leads of an idle operator. Otherwise the leads of each operator may have a separate service selector which attaches itself to a calling line, and passes on other calls to the next selector. The calling subscriber No. 33 is connected by the preliminary selector VW<33> to the leads a', b<1> of an idle connector LW<1>, the circuit of the holder-on relay T<33> being completed from the battery G, over winding t, lead c<1>, contacts b<2>, b<3> and the interrupter U'. The relays A, B at the connector are brought in circuit with the battery G over the subscriber's leads a<33>, b<33>. The relay B, by breaking the contacts b<2>, b<3> and making contacts b<2>, b<1>, directly earths the hold-on relay T<33>. The relay A, by closing contacts a<1>, a<2>, completes a circuit for the magnet Dh of the selector HW from the positive pole of the battery G over contacts f<1>, f<2>, contacts a<1>, a<2>, contacts v<2>, v<1>, magnet Dh, and interrupter U'. When the testing-lead c<z> of an idle operator is reached, a circuit is made from earth over position 1 of switch h, lead c<2>, magnet V, contacts v<4>, v<5>, contacts b<4>, b<3>, and contacts f<4>, f<3> to the lead m. The magnet V cuts-out the driving-magnet Dh at the contacts v<1>, v<2>, connects the operator's leads a<z>, b<z> to the leads a', b<1> of the calling subscriber, and completes a holding-on circuit for itself over the contacts v<4>, v<3>. This holding-on circuit proceeds from the positive pole of the battery G over a resistance w<4>, contacts u<1>, u<2>, and lead f. The testing-lead c<z> is now busy to other selectors on account of the potential on it being equal to that of the lead m. After enquiry, the operator actuates the switch shaft W to connect subscriber No. 55 to the points f<1>, f<2> of the leads a', b<1>. By moving the switch h<1> to position 3, the relay B is cut out of its former circuit, but the differential relay X is now actuated, and, by closing contacts x<1>, x<2>, completes a hold-on circuit for the relay B, and closes the contacts x<3>, x<4> in a circuit including the relay U. The relay U cuts off the leads a', b<1> from the connector during the operation of the switch shaft W, but when the earth connection is broken by the operator the relay U is de-energized. By further moving the switch h into the position 3, the operator breaks the circuit of the relay V, and the connector is disengaged from the operator's line. When the leads of each operator's position are connected to a service selector which finds the calling line, the hold-on magnet of the selector apparatus closes a contact which connects the common lead from the connectors to the next selector. The circuit of the holding-on magnet includes a relay at the connector which cuts off the connector from the common calling lead of the selectors. In a modification, the calling connectors may be connected in turn to the next disengaged operators by means of a rotary switch of the kind described in Specification 8648/01.