Patent GB-191024995-A (GB)
Title: Circuit suitable for use in connection with Automatic Telephone Systems.
Filed: 1910-10-27
Granted: 1911-12-27
Abstract: 24,995. Western Electric Co., [Telephon Apparat Fabrik E. Zwietusch & Co.]. Oct. 27. Automatic e x c h a n g e systems. - The selectors are adjusted by varying the resistance of the line circuit, and the connexions are switched to the succeeding selector &c., by opening the line circuit. The invention is described as applied to a system u s i n g impulsestorers of the kind described in Specification 26,079/10, in which the line impulses are received and stored by an easilyoperated switching-device, which afterwards repeats them to the selectors. The circuits of the impulse-storer and of the selectors are controlled by sequence switches of the kind described in Specification 20,840/09, and the connector is of the kind described in Specification 16,867/11, in which ten sets of latched brushes co-operate with ten rows of fixed terminals, the particular set of brushes required being released by means of a separate brush selector. In the system shown in Fig. 1, the selecting and switching circuit includes one line wire with an earth return, but in a modified system, the second line wire may form the return. Subscriber's impulse-transmitter. The contacts Z<100>, Z'‹, Z' of the impulse sender NS iutermittently short-circuit a resistance w<2> during the return of the hundreds, tens, and units disks to zero, the contact f<4> being opened after the transmission of each set of impulses. The contact f<1>-f<2> is closed while all the impulses are transmitted, and serves to earth the b-line and line relay LR during the selecting process. Call-finder. The removal of the receiver, before the adjustment of the impulse-sender, energizes the relays AR, LR, the relay AR setting in action the power magnet SM of the call-finder LF. When the test wiper b<3> reaches the contact grounded by the relay LR, the relays BR, TR are energized, and disconnect the magnet SM and the relay AR. The relay LR is maintained over a relay CR. Impulse-storer and repeater. The impulsestorer comprises hundreds, tens, and units ratchetdisks RG<100>, RG<10>, RG', set by .the magnets W<100>, W<10>, W<1>, and returned to their normal position by the magnets U<100>, U<10>, U<1>. The circuits are controlled by a sequence switch, represented by its power magnet TM and contacts m ... z. The setting of the impulse transmitter NS closes a contact f<1>-f<3>, which short-circuits the relay CR, thereby energizing the power magnet TM over the contact m and the armatures of relays CR, BR. The sequence switch thus moves into its second position, in which the relays WR, UR are connected through a ballast resistance wi to the line a in circuit with the contact f<4>, and resistance w<3>. The relay WR responds only to strong currents, while the relay UR responds to weak currents also. During the return of the hundreds disk of the impulse-sender, the resistance w<2> is intermittently short-circuited, thereby causing the relay WR to repeat these impulses to the actuating-magnet W<100> of the hundreds ratchet RG<100>, which is rotated, the off-normal contact i<5> preparing a circuit for the relay R<100>, which is closed when the relay UR relapses at the end of the first set of impulses. The relay R<100> locks-up, substitutes the magnet W<10> of the tens ratchet for the magnet W<100>, and closes a circuit over contact o for the power magnet TM, which moves the sequence switch into its third position, the second set of impulses being then repeated by the relay WR to the magnet W'‹. At the end of this set of impulses the relay R<10>, acting like the relay R<100>, moves the sequence switch into its fourth position, in which the units impulses are received by the magnet W<1>, and finally the relay R<1> moves the sequence switch into its fifth position. Group selector. In the third, fourth, and fifth positions of the sequence switch, the relay SR, controlling the power magnet GM of the selector, is energized over contact j and the returning- magnet U'‹‹ of the hundreds disk. As the selector rotates, a notched disk Sg, on its shaft, intermittently short-circuits the magnet U<100>, thus returning the disk RG<100> step-by-step to its normal position, in which the spring i<3> earths the magnet TM, thereby moving the sequence switch into its sixth position, and arresting the selector. No provision is made in the Figure for the usual hunting operation, it being assumed for the sake of simplicity that only a single connector is provided for each group of subscribers. Connector. The delivery of the tens set of impulses commences as soon as the sequence switch moves into its sixth position, in which a circuit is closed from the controlling-relay GR of the brush chooser BC, through the contacts h<1>, m<1> of the connector sequence switch, contacts x, i, and magnet U<10> to earth. The power magnet BM causes the brush chooser BC to rotate, the notched disk Sf on its shaft intermittently short-circuiting the magnet U<10>, thus returning the disk RG<10> to its normal position, in which a apring k<3> earths the power magnet TM, thereby moving the sequence switch into its seventh position, and de-energizing the relay GR. The excitation and de-excitation of the relay GR moves the connector sequence switch first into its second and then into its third position, in which the controlling-relay FR of the connector shaft is energized over contacts y<1>, m<1>, x, v, and the magnet U<1>. During the rotation of the connector, the magnet U<1> is intermittently short-circuited by a notched disk Su, and when the disk RG<1> reaches its normal position, the selector sequence switch moves into its eighth or conversation position, de-energizing the relay FR, and arresting the connector. The excitation and de-excitation of the relay FR move the connector sequence switch first into its fourth and then into its fifth positions. When the called subscriber removes his receiver, the relays LR<1> and SRx are energized, the latter moving the connector sequence switch into its sixth or conversation position. The calling subscriber is supplied with microphone current through the relays LR, SU. Release. When the calling subscriber hangs up, the relay LR opens the circuit of the cut-off relay BR, thus leaving the call-finder free to respond to another call. The call-finder has no particular normal position. The de-energizing of the relay SU earths the power magnet TM, thus returning the selector sequence switch to its normal position ; in its passage through its ninth and tenth positions, the power magnet GM is energized through its offnormal contact ON, and the selector is then rotated into its normal position. When the called subsubscriber replaces his receiver, the relay SRx earths the magnet SS, moving the connector sequence switch into its normal position, in which the power magnet FM is energized over its offnormal contact ONs.