Patent GB-191319518-A (GB)
Title: Improved Circuit Arrangements for Automatic and Semi-automatic Telephone Systems.
Filed: 1913-08-28
Granted: 1915-06-10
Abstract: 19,518. Siemens & Halske Akt.-Ges. Aug. 28, 1912, [Convention date]. Automatic and semi-automatic exchange systems.-In systems in which trunk or other preferred calls are to be setup as well as ordinary calls, the devices necessary for the special requirements of preferred calls (special testing arrangements, repeaters, &c.) are: placed in circuits distinct from those used in the ordinary calls, but in the path by which; the trunk operator obtains access to the wanted line. Fig. 1 shows the path of an ordinary call between subscribers T<1>, T<2> set up by selectors IGW, IIGW, IIIGW, and a connector LW, and a trunk call set up by a trunk' operator F through a group selector IIIGWF, not accessible to subscribers, and the connector LW. The special testing-devices &c. RS are associated with the group selector IIIGWF. A system of this kind is shown in Figs. 2 and 3. The subscriber wanted for a trunk call may, however, be selected over a preparatory or setting route from the operator's position, and a speaking route may be established over a smaller number of selectors and the preparatory route then released. The routes for the preferred.and ordinary calls may be kept separate until they meet at a junction situated before the connectors which are used in common for both kinds of calls. The special path used for trunk calls may be provided with an improved line construction up to this junction point. Systems embodying the double route are shown in Figs. 4 to 9. Operation of connector LW, Fig. 3, for ordinary calls. When the connector LW is seized by a group selector, current over the test lead c<2> and contact 21 of a relay F, energizes a relav C<2> which connects battery to the vertical and rotary magnets H<2>, D<2> and the relay A<2>, and energizes a slow-release relay V, which by closing contacts 37, 38, connects the windings 1 of relays A<2>, B<2> to the leads a<2>, b<2>, thus energizing the relays A<2>, B<2>. The relay B<2> closes at contact 42 a circuit for a relay U, which locks up over its contact 47, and connects the vertical magnet H<2> over contact 43 to the front contact 46 of the relay A<2>. The tens impulses over the relay A<2> are thus repeated to the vertical magnet H<2>, and at the end of the impulses, the circuit of the relay B<2> is opened, thus de-energizing the relay U, so that the units impulses are repeated to the rotary magnet D<2>. The testing of the wanted line, the supply of ringing and microphone current, and the normal release of the connexion take place substantially in the manner described in Specification 22,850/13. Establishment of preferred call; operation of special group selector IIIGWF, Fig. 2. When the group selector GWF, accessible only to the trunk operator, is seized, the relays B<1>, C<1>, E are energized over the test lead c, and normal switch contacts k<1>, k<2>. The relav C<1> locks itself over contact 10 so as to be independent of contact k', and connects the impulse relay A<1> to the lead a. The relay B<1> connects its winding 2 over contacts 12<1>, 13 to the lead b, so that the relays A', B' are energized over the leads a, b. Interruptions of the a-lead are repeated to the vertical magnet H', and at the end of the impulses, the relay B' is de-energized and closes the circuit of the rotary magnet D', which rotates the wipers to find an idle connector. During this movement the relays E, C<1> are energized over contacts 10, 16<1>, w<1>. The winding 2 of relay B<1> is connected over contact 12<1> to the test wiper, so that when an idle connector is found, relay B<1> is energized and (1) cuts off the rotary magnet D<1>, (2) permanently disconnects the relay C<1>, and connects its own windings 1, 3 over contacts 16, w' to the test lead c, (3) connects battery over contacts 22, 23, 24, 25 to the relay testing-set RS, and (4) connects winding 2 of the relay E over contact 12 to the test lead c<2>, thus keeping relay E energized, and extending the leads a, b to the leads a<2>, b<2>, over contacts 13, 14 and 27, 28. Operation of connector, Fig. 3, for preferred call. The connector wipers are brought to the terminals of the wanted line in the manner previously described, but at the end of the units impulses, a special impulse is sent which maintains relay A<2> energized after B<2> has de-energized. The closing of contacts 48, 49 energizes a relay F which locks up in series with the relay C<2> over the test lead c<2>. The relay F disconnects the normal test relay P, and closes contacts 52, 53 to connect the leads a<2>, b<2> to the called line. Busy test of called line by relay set RS, Fig. 2. The connector test wiper is connected to a fourth wiper of the group selector GWF. When the relays C<2>, F are disconnected from the lead c<2>, the relay E, Fig. 2, de-energizes and connects a relay X to the leads a, b. The relay X connects a test relay Pa over contacts 55, 61 to the fourth wiper. If the wanted line is engaged in a trunk call, its test lead is earthed and the relay Pa is not energised, so that a tone transformer FV is connected to the calling line. If the wanted line is either free or engaged in a local call, the relay Pa is energized and (1) locks up over contacts 60, 65, 24, and (2) connects a less sensitive relay Pb over contact 61 to the fourth wiper. If the wanted line is engaged in a local call, relay Pb is not energized, so that the tone transformer OV is connected to the calling line. Supply of ringing-current from relay set RS, Fig. 2. If the wanted line is free, the relay Pb is energized, and closes a circuit for the ringing-relay L, which rings up the called subscriber and connects a tone transformer Fr to the calling line. When the subscriber replies, a back-bridge relay S is energized and disconnects. the original circuits and relay X. The through talking circuit is completed from the leads a, b, over contacts 14, 13 of relay B<1>, 27<1>, 28<1> of relay E, 71, 72 of relay Pb, leads a<2>, b<2> and contacts 52, 53 of relay F, Fig. 3. Release of local connexion. If the wanted line is engaged in a local call, the operator is temporarily connected over contacts 62, 63, Fig. 2, and asks the subscribers to release the local connexion. As soon as the connexion is released, the engaged potential is removed from the test lead of the wanted subscriber, so that the relay Pb, Fig. 2, becomes energized, and the call is completed in the same way as a call to a disengaged subscriber. Release of trunk connexion, Figs. 2 and 3. When the circuits over the leads a, b, c, Fig. 2, are opened at the trunk exchange, the relay B' closes the circuit of the release magnet M<1>, Fig. 2, and opens the circuits of relays F, C<2>, Fig. 3, the latter closing the circuit of the release magnet M<2>. Establishment of trunk calls over alternative route. The wanted subscriber for a trunk call may be selected over a preparatory route from the trunk operator's position, and a speaking route may be established over a smaller number of selectors, and the preparatory route then released. In the system shown in Fig. 4, the wanted line is selected over group selectors IGW, IIGW, IIIGW, and a connector LW, from an operator's position F, but the speaking route includes only the connector LW and non-numerical switches AS. In a modified system shown in Fig. 5, the preparatory route is set up from a special position B and the speaking route leads to other operators' positions F. After the wanted subscriber has been selected over group selectors and a connector LW, the speaking route is set up over the connector LW, call-finder AS, and a numerical selector LW<1>, which is actuated by the operator at position B to connect the circuit to the position FP of an operator known to be free. In the arrangements shown in Figs. 4, 5, the speaking route includes the connector serving the wanted line. but the circuits may be modifier in such a way that the connector used in the preparatory route is released and the speaking route includes the preliminary selector or call-finder associated with the wanted line. In the arrangement shown in Fig. 6, a connexion is shown from a trunk position B through selectors to wanted lines T, having preliminary selectors, the first bank terminals of which lead to group selectors for ordinary out-going calls, while the last bank terminals lead to contacts of a call-finder AS, the wipers of which lead to a trunk operator's position. The circuits for this arrangement are shown in Fig. 7. In the arrangement shown in Fig. 8, the subscribers T are provided with first and second call-finders 1AS, 2AS for out-going calls, some of the second call-finders being reserved for use in establishing the speaking route to the trunk exchange. Circuit connexions for this arrangement are shown in Fig. 9. Alternative speaking route established over wanted subscriber's preliminar selector, Fig. 7. The first bank terminals of the usual three wipers are connected to group selectors O, but the corresponding terminals engaged by a fourth arm d are all connected to a lead c'. The last bank terminals are connected to trunk operators positions F. A trunk operator at position B, having selected the wanted line over selectors GW and a-connector LW, grounds the test lead c<1> and applies such petential to the a and 6 leads as to energize the relay R. The grounding of the test lead c<1> short-circuits the test relay T, which. closes the circuit of the rotary magnet D so that the preliminary selector rotates past all the terminals leading to group selectors O, the movement continuing until an idle lead to the operator's position F is found. If the selected subscriber is the calling subscriber in an existing local call, the movement of the preliminary selector releases the local connexion. If the selected subscriber is disengaged, his preliminary selector rotates to find the earth trunk line as before. If the selected subscriber is engaged as the called subscriber in a local call, the local