Patent GB-191309168-A (GB)
Title: Improvements in Registering Circuits for Automatic Telephone Exchanges.
Filed: 1913-04-18
Granted: 1913-09-18
Abstract: 9168. Siemens & Halske Akt.-Ges. April 18, 1912, [Convention date]. Automatic exchange systems; metering systems.-The method of registering calls on the release of a connexion by the co-operation of quick - release and slow - release relays as described in Specification 15,129/11 is modified by inserting the slow-release relay between the call-finder or pre-selector and the group selector, thereby reducing the number of relays individual to each subscriber. In the system described, the circuit of the meter Z is closed in the interval of time between the release of the armature 52 of the cut-off relay T and the release of the armature 13 of the slow-release relay V, the relays T, V being in series during a conversation. The system described operates as follows:- Call-finder. When a subscriber N' removes his receiver, the group call-relay An closes the circuit of the relay R of the first disengaged call-finder. The relay R disconnects the wire 6 leading to the relays R of other call-finders, and closes the circuit over contacts 5, 8, 9 of the operating-magnet D, which rotates the wipers until the calling line is reached, when a circuit is closed through the cut-off relay T, relay V, leads 11, 10, b, o, and contact 1. The relay T disconnects the meter Z, and connects the leads a, b to leads a', b<1>. The relay V (1) disconnects the leads 11, 10 and establishes a new circuit for the relays T, V over contact 16, lead c<2> and relay C, (2) connects the leads a<1>, b<1> to the leads a<2>, b<2>, (3) disconnects the relay R, thus extending the lead 6 to the relays R of idle call-finders, (4) disconnects the rotary magnet D, and (5) opens at contact 15 the circuit of the release magnet M of the group selector G, W. Group selector. The relay C locks up over contacts 18, 19 and connects the relays A, B over contacts 20, 21 to the calling line. The selector is raised to the required level and rotates under the control of the relay P, which, when an idle connecter is found, energizes in series with the relay C<1>, Fig. 2, and interrupts the circuit of relay C at contact 19, maintaining a circuit for the relays T, V over contact 51. The relay C extends the calling line over contacts 31, 32 to the relays A', B<1> of the connector. Connector. The connector wipers are brought to the required line in known manner and, if this line is idle. the relay P<1> energizes in series with the cut-off relay T<1>, which closes contacts 42, 43 in the line of the wanted subscriber. The relay P' short-circuits its high-resistance winding 36, and connects the battery to the called line through relays Y, Dr and contacts 37, 38. When the called subscriber answers, the relay Y energizes a relay U, which locks up over contacts 40 and closes contacts 41, thus connecting the lead a<3> to the lead a'. Busy test and busy release. If the wanted line is busy, the relay P' is not energized, and when the calling subscriber hangs up, the relay B' closes at contact 47 the circuit of the release magnet M<1>. Release and metering of call. When the called subscriber hangs up, the relay U remains energized but the relay Dr energizes a relay F, which (1) by closing contact 53, earths the lead a" over contacts 53, 41, and relay Y, and (2) opens at contact 29 the circuit of relays C', Fig. 2, and P, Fig. 1. The relay C<1> de-energizes slowly, but the relay P at once opens the circuit of relays T, V at contact 51. As the relay V releases slowly, the meter Z is energized over contacts 52, 58, 13, lead a<2>, contact 31, lead a<3> which is earthed at the connector. When relay V has fully released its armature the release magnet M is energized. When the relay C<1> has fully released its armature, the release magnet M', Fig. 2, is excited over contacts 54, 55. Interruption of local call by trunk operator in favour of trunk call. If the calling subscriber is wanted for a preferred call, the test lead c<1> is directly earthed as described in Specification 2320/12, thus maintaining the circuit of the cut-off relay T but short-circuiting the relay V, which energizes the release magnet M as before. The call is not registered, since the relay T keeps the contact 52 open.