Patent GB-180103-A (GB)
Abstract: 180,103. Automatic Telephone Manufacturing Cc., Ltd., (Automatic Electric Co.). March 5, 1921. Automatic and semi-automatic exchange systems; coin-freed systems; party-line systems.- A trunking operator, Fig. 1, who has established a wanted trunk connection on behalf of a substation A, Fig. 4, and has recalled the substation by setting up an automatic connection as represented in Figs. 2, 3, and 4, is provided with means for transmitting to the substation, through the selective switches, distinctive currents for assessing the charge for the trunk call, e.g. for collecting or refunding deposited coins. In the modified system represented by Figs. 1<A>, 2<A>, 3, and 4<A>, in order to enable two-wire connecting trunks to be used between the trunk and local exchanges, the assessing currents are transmitted over an auxiliary inter-exchange trunk 351, 352, 353 terminating in a special connector M, which is operated to connect itself to the talking connection. If the subscriber is busy when the operator recalls him, the operator gets a busy flash signal in addition to the usual tone. In such case the operator leaves the connection standing until the busy signal ceases, whereupon she performs an operation which initiates the automatic ringing of the line. Means are provided for giving the operator a characteristic tone signal if the substation A, Fig. 4, is of the coin-freed type. Connection of trunk operator to calling subscriber; first selector D, Fig. 1. When the wanted connection has been secured, the trunk operator plugs into the jack J<1> of an idle selector D, throws the key K to the left, and operates her dial S to recall the calling subscriber A, Fig. 4. A relay 20 is energized in the sleeve circuit and energizes a slow-release relay 21, which lights the busy lamp L<3>, and the selector impulse relay 51, which energizes relav 52. The first digit is repeated by relay 20 to relav 51 and the selector operates in known manner to select an idle trunk, denoted by an ungrounded terminal 75, associated with a repeater E, Fig. 2, and second selector F, Fig. 3, both of which may be at another exchange. Repeater E, Fig. 2, and second selector F, Fig. 3. The switching relay 50, Fig. 1, extends the impulse circuit 60 over the third wire 79 to the marginal relay 109, which does not respond, and to the impulse relay 104, which energizes relays 105, 102 and relays 151, 152, Fig. 3. The second digit is repeated by relays 20, 104 to relay 151 and the selector F operates in known manner to select an idle connector II, Fig. 4, denoted by an ungrounded terminal 175. Connector H, Fig. 4. This connector is available both for trunk calls over selectors, D, F and for ordinary local calls over terminals 301, 302, 303, Fig. 3. The switching relay 150, Fig. 3, extends the wires 142, 143 to wires 179, 180 and energizes over wire 180 the upper winding of the impulse relay 201, which energizes relay 202, which grounds the wire 305 so as to energizea low-resistance relay 207 in a circuit R<2>, 179, 143, 128, R<1>, 111. The relay 207 energizes a relay 204, which alters the connector circuits in the manner required for trunk calls. The upper winding of the relay 204, which serves as a holding winding, is in the circuit of the impulse relay 201, its impedance effect in the impulse circuit being minimized by jacketing the relay with copper. The last two digits are repeated by relays 20, 104 over wires 143, 180 to relay 201, and the connector operates in known manner to select the line A. Busy test and signal. The busy test and ring- ing arrangements are modified by the fact that the relays 204, 207 are energized, which is not the case with local calls. At the first vertical movement the ringing' cut-off relay 205 is energized by relay 203 and locks itself up, so that ringing does not commence automatically if the line A is idle. If the line is engaged the busy relay 206, which is energized in the ordinary way, locks itself to the test wiper instead of to the wire 305. The operator gets a busy tone signal from the machine Q and at the same time the supervisory lamp L<1>, Fig. 1, is intermittently flashed by the bridge relay 3, which is controlled by the relay 100, Fig. 2, which is intermittently energized over the upper talking conductor by the interrupter I. Or, if the switch P is in its alternative position, the lamp L<1> is merely extinguished. The operator opens a key K<1>, to prevent the busy tone from passing to the trunk J, and waits for the line A to become idle. Tone signal characterizing pay-station lines. As soon as the line A becomes idle the relay 206 is unlocked and energizes the switching relay 209, and the operator, noticing the cessation of the busy flash signal, operates her listening key and hears a tone signal indicating that the line A is a pay-station line. This tone is transmitted from a machine Q<1>, in the circuit of the line cut-off relay 317, to a transformer R<2>, which repeats it over wires 179, 142 to a transformer R<1>, which transfers it :o the repeater windings R. Supply of ringing current. The operator momentarily throws the key K to the right to put ringing current on the line to energize a relay 101, Fig. 2, which opens the circuit 142, 179 of the relay 207, Fig. 4, which unlocks the ringing cut-off relay 205, and ringing proceeds automatically in the usual manner, a tell-tale back-leak being provided through the condenser 299. When the subscriber A answers, the relay 205 is energized again, locks itself up and completes the talking circuits. The line A is fed with current through the relay 100, Fig. 2, which de-energizes the supervisory relay 3, Fig. 1. The operator requests the subscriber A to deposit the requisite coins, and receives the usual tell-tale signals. Collection or refund of coins. After conversation the operator depresses either the collect key CK or the refund key RK to connect a high-voltage battery B<1> or B<2> of one or other polarity to the circuit 79, so as to energize the marginal relay 109, which inserts the lower windings of the electropclarized relays 106, 107 in its own circuit. One or other of these relays is consequently energized and connects battery B3 or B4 of one or other polarity through a winding of relay 115 to the lower talking-wire, to energize the polarized sub station magnet to collect or refund the coin. A relay 110, energized by the relay 106 or 107, opens the upper talking wire. The relay 115, which is only energized if the polarized magnet circuit has been prepared by the insertion of a coin, shunts the resistance 112 with a resistance 199 to energize a marginal relay 28, Fig. 1, which lights a tell-tale lamp L<2>. If the operator should omit to press either key CK or RK, the coin is automatically collected during the release of the connection, as described below. Release. When the operator unplugs the jack J<1> the relapse of the relays 20, 21, 50 causes the release of the selector D and of the subsequent circuits. Since the relay 103, Fig. 2, is energized at this time (having been previously locked up by the relay 100) the de-energization of relay 105 energizes a relay 108, which interrupts its own circuit by unlocking the relay 103. During the moment of its energization the relay 108 connects the collecting battery B<3> to the lower talking wire. The relay 110, which was momentarily energized at the same time as relay 108, delays the release of the further part of the connection by closing contacts 139, 140 in parallel with contacts of the relay 105. Second system, Figs. 1<A>, 2<A>, 3 and 4<A>, in which connection to the calling line is set up by switches D', F, H<1> controlled over a two-wire trunk 430, 431 connecting the trunk and local exchanges, and in which a common trunk 351, 352, 353 is used for collecting and refunding coins. The operator plugs into the jack J<5>, energizing sleeve relays 420, 421, and bridges her impulse sender S<1> across the cord O<1> to control the switches D<1>, &c. The selector D<1> is operated by the first digit in the usual manner and subsequent digits are repeated by the line relay 504 of a repeater E<1> over wire 143 to control the selector F and connector H<1>, the circuits of the latter being closely similar to those of the switch H, Fig. 4. If the line A<1>, A<2> is busy, the relay 206 is energized and locks itself to the test wiper, giving the usual tone signal and grounding the wire 178 to energize relays 500, 501, Fig. 2<A>. The relav 501 locks the line relay 504 and disconnects it from line to deenergize the cord relay 406 and extinguish the lamp L<4>. When the line becomes idle, as evidenced by the re-lighting of the lamp L<4>, the operator momentarily supplies ringing current to energize the relay 521, Fig. 2<A>, so as to de-energize relay 207, Fig. 4<A>, which unlocks the ringing cut-off relav 205 and allows ringing to proceed automatica ly. Party-line code ringing. Subscribers on the same party line have different hundreds digits and are served by connectors having different code interrupters to control the ringing supply. For example, the connector H<1> gives signals composed of two rings repeated after a comparatively long pause. The ringing circuit is completed by a relay 282 which is energized and locks itself up at the first grounding of the starting-wire 285 after the relapse of the ringing cut-off relay 205. Collection or refund of coins. During conversation the back-bridge relay 500, Fig. 2<A>, energizes relay 501 to keep the cord lamp L<4> extinguished. When the called subscriber disconnects himself, the lamp L<4> lights up again and the operator plugs a special cord O<2> into the jack J<6> of an idle one of several trunks terminating in auxiliary connectors M at the local exchange. The operator then throws her listening key K<2> and, by means of a dial S<2>, transmits a two-digit number representing the trunk 430, 431 to set the connector