Patent GB-191009634-A (GB)
Title: Circuits for Registers in Automatic Telephone Exchanges.
Filed: 1910-04-20
Granted: 1910-11-10
Abstract: 9634. Siemens Bros. & Co., [Siemens & Halske Akt.-Ges.]. April 20. Automatic exchange systems.-The register of a calling subscriber is included in the test lead of his individual preliminary or group selector, and is actuated when a change of resistance in this lead is brought about by the closing of a contact in the connector. The potential in the test lead is so adjusted that it also controls the release of the preliminary or group selector. The invention is described as applied to a system in which preliminary selectors are used, and in which the call is registered when a connexion is made with the desired line, but the arrangements may be such that a call is registered when the called subscriber replies. Preliminary selector. Assuming that subscriber No 133 wishes to call subscriber No. 655, he removes his receiver and proceeds to send sets of six, five, and five impulses in the usual way, the impulse-sender being arranged to earth the b-line at e during the interruption of the a-line at k. The removal of the subscriber's receiver energizes his line-relay AR<133>, which closes at r<2> the circuit of the actuating-magnet D<133> through an interrupter U. As soon as the selector moves from its normal position, the contacts i', i<3>, i<4> move into the position shown. When the wiper v<1> engages the earthed test-lead c' of an idle group selector, current passes from the terminal m of the battery G over a contact r<1>, winding 1 of the relay T<133>, lead C', resistances w<1>, w<2>, and contact f<1> to earth. The relay T<133> is thus energized, and (1) connects the calling-lines over the contacts t<4>, t<5> to the leads a<1>, b<1>, and relays A, B of the group-selector GW, at the same time disconnecting the line-relay AR<133>; (2) connects the test-lead c<1> over the contacts i<2>, t<2>, winding 2 of the relay T<133>, and winding z<2> of the register to the negative pole of the battery ; (3) connects the lead c' over the contacts i<2>, t<2>, i<3> and winding z<1> of the register to the battery terminal m. The various resistances in these circuits are so proportioned that the potential of the lead c<1> is slightly higher than that of the battery lead m, so that the test-relay of any other preliminary selector testing the lead c<1> cannot be energized. The registering magnet is not energized because the currents through the unequal windings z<1>, z<2> oppose each other, but the relay T<133> remains energized because the current through the winding 2 is greater than that through the winding 1. Group selector. When the calling subscriber turns his impulse-sender, the earthing of the b-line upsets the balance of the differential relay X, which closes a contact x<3> so that current passes from the negative pole of the battery over the contact x<3>, and then divides, part passing through the relay B to earth, and part through the winding 2 of the relay X to earth at the sub-station. The relays B, X are thus energized independently of the a-line, so that its subsequent interruptions do not affect them. The relay X also closes at x<4> a circuit through the side-switch magnet S, which does not move the side-switch until subsequently de-energized. The interruptions of the a-line are repeated by the relay A to the lifting-magnet H, which raises the selector to the desired level. When the impulse - sender returns to zero, the contact e is opened, with the result that the relay X is de-energized, and opens the circuit of the magnet S, which moves the side-switch into its second position, in which the rotary magnet D is connected over the arm h7 to the interrupter U. During the rotary movement of the selector, the magnet S is included in a local circuit including a resistance and the arm h<9>, but when the wiper c engages an idle line, which is connected over a contact f<5> to the high-tension pole of the battery, a feeble current flows in the reverse direction through the magnet 8, which releases its armature and allows the side-switch to move into its third position. The relays A', B' of the connector are thus energized by current flowing through the sub-station, and relay B<1> by closing a contact b<4> brings the testing-lead C<III> into a circuit which includes the relays V, Z', wiper c, contact b', and resistance w<4>. The potential in the lead C<III> is such that the testing-magnet S of any other group selector testing this lead is maintained energized. The relay V is energized and opens the circuit of the release-magnet R, but the relay Z' is not energized at this stage. Connector. The finding of the desired line proceeds in a manner similar to the operation of the g oup selector. When the earth connexion at the sub-station is removed after sending the last series of impulses, the relay X' closes a contact x<1> in the circuit of a relay P, which, if the desired subscriber is disengaged, is energized by current passing from the battery lead m through the contact i<5> of the selector VW<655>, winding 1 of relay T<655>, contact i<1>, lead c<655>, arm h<6>, and relay P to earth. The relay P (1) closes a contact p<1> so as to send an impulse from the interrupter U through the magnet S to move the side-switch into its third position, and (2) closes a contact p<2>, thereby shortcircuiting the resistance w<4> in the circuit of the relays V, Z'. The metering relay Z<1> is thus energized, and short-circuits the resistance w<1> in the test lead c<1>. The potential of the lead c<1> consequently falls below that of the battery lead m, so that a reverse current flows through the winding z', while the current through the winding z<2> is strengthened, the register magnet being thus actuated. Release. When both subscribers hang up their receivers, the relays A<1>, B<1> are de-energized, and the relay B<1> (1) closes a circuit for the releasemagnet R', and (2) opens at b<4>, the circuit of the release-relay V, which in turn (1) closes at V<4> the circuit of the release-magnet R, and (2) opens at v<5> the circuit of the test-lead c<1>. Current now flows in series through the opposing - windings of the relay T<113>, which releases its armature, thereby (1) opening the circuit of the registermagnet Z<133>, (2) disconnecting the calling-leads at t<4>, t<5>, and (3) closing at t<3> a fresh circuit for the actuating - magnet D<133> from the battery lead m through the contacts i', t<3>, magnet D<133>, and interrupter U to earth. The wipers ot the preliminary selector are thus moved into their normal position in which the circuit of the magnet D<133> is broken at the contact i<4>.