Patent GB-191115133-A (GB)
IPC: H04M3/62
Abstract: 15,133. Derriman, W. H., [Automatic Electric Co.]. June 28. Automatic and semi-automatic exchange systems; metering systems. - In systems having lines of different character, for example, lines with call-registers and lines without them. means are provided for indicating to the operator the character of the calling or called line. The indication may be an audible one, given when the operator answers the call, or it may take the form of an additional call-lamp which only lights up when calls are received from lines of certain character. The invention is specially applicable to semi - automatic systems and is described in connexion with two such systems, in one of which a calling-line is automatically connected by line and master switches to an idle plug-cord, the connexion being completed by the operator inserting the plug in the jack of the desired subscriber. In the other system, a similar manual exchange is modified so as to allow of interconnecting its subscribers with those of a distant automatic exchange. In this system, if a manual subscriber desires connexion with a distant automatic subscriber, the subscriber releases his connexion with the operator, who uses a two-way cord-circuit, inserting one plug in the jack of the calling subscriber and the other in the jack of a trunk leading to the automatic exchange, and the automatic subscriber is selected by the manual operator through numerical selectors in the usual way. If an automatic subscriber desires connexion with a manual subscriber, he extends connexion to a manual-operator's trunk, and gives the required order, giving also his own number. The automatic subscriber next hangs up his receiver, breaking connexion with the operator's trunk. The manual operator then calls back to the calling line by means of a cord-circuit and another trunk to the automatic exchange, and inserts the other plug in the jack of the required manual subscriber. The latter system is shown in Figs. 1 to 6, Fig. 1 showing the means by which a manual subscriber is connected to an idle cord-plug P; Fig. 2 the cord-circuit used for interconnecting manual and automatic subscribers; Figs. 4 and 5 the selector F<1>, repeater E<1>, and connector L used by the manual operator in selecting an automatic subscriber; and Fig. 6 an automatic subscriber with the repeater E used in obtaining connexion with a selector F, Fig. 3, and the operator's trunk H. Connexion of calling manual subscriber to idle cord - plug and means for indicating to the operator the character of the calling line. When the subscriber A, Fig. 1, removes his receiver, his line switch C is energized in the manner described in Specification 1419/10 and extends connexion to a secondary trunking switch C', which in turn connects the calling line to an idle cord-plug P. The closing of contact 26-27 energizes the pull-down winding 28 of the switch C<1> over the armatures of the relays 126, 128, but the movement of the armature 99 brings the two windings 28, 29 in series and in direct connexion to the battery. The operation of the switches C, C<1> bridges the battery B and relay 101 across the calling line, whereby a circuit is completed from the battery lead 90 through the secondary of a signalling transformer 112, the hold - on winding 13 of switch C, terminals 24, 111, contact 106 of relay 101, and the middle winding of this relay to ground. The relay 101 also completes the circuit of a calling-lamp 118 over a contact of the cut-off relay 131, which is energized when the plug P is raised to complete the connexion. When the operator answers the call, she receives a signal from the transformer 112, the third winding of the relay 101 serving as an inductive connexion with the speaking circuit. Tone tests of different character may be used, or the presence or absence of such a tone test may give the necessary indication. The tone signalling currents are cut off when the relay 131 is energized. Connexion with another manual subscriber. The plug P is inserted in the jack of the desired subscriber, the closing of the contact 136-137 energizing the cut-off winding 13 of the switch C of the called subscriber, thus preventing its action when the subscriber replies. The supervisory lamp 132, controlled by the relays 131, 139, is extinguished when the called subscriber replies. Connexion with automatic subscriber. The calling subscriber gives the operator his own number as well as that of the required subscriber, and releases the connexion through the switches C, C' by hanging-up his receiver. The operator then inserts the plug P', Fig. 1, of the cord-circuit O, Fig. 2, in a multiple jack of the calling subscriber, and the plug P<2> in the jack J<2> of a trunk leading to the automatic exchange, and operates her impulse - sender 141 to select the desired line. First selector. A circuit is thus closed over the trunk 147, 148, Figs. 2 and 4, and the controlling-relay 143, which energizes the slowrelease relay 159. Interruptions in the trunk circuit are thus repeated by the relay 143 through the slow-release relay 163 to the vertical magnet 165. The relay 163 is energized by these impulses, and closes the circuit of the private magnet 169, which moves the side-switch into its second position when the impulses cease. The usual mechanical connexion between the armatures of the rotary and private magnets 170, 169 is dispensed with, the private magnet being intermittently grounded over a contact 173 by the armature of the private magnet. When an idle trunk is found, the magnet 169 de-energizes, moving the side-switch into its third position, in which the relay 180 is energized over contact 178, thereby disconnecting the line-relay 143 from the trunk and extending the connexion to the repeater E<1>. Repeater. The relay 183 is thus bridged across the trunk, and energizes a slow-release relay 190 which (1) provides a new circuit for the relay 180 over the contact 195 and the righthand winding of a coil 191, and (2) supplies current to the left-hand winding of a relay 197, which, however, is not operated until both its windings are energized. The relay 183 also bridges the right-hand winding of the relay 197 and the left-hand winding of the coil 191 across the trunk 211, 212 leading to the line-relay 70, Fig. 5, of the connector. The relay 197 is still inoperative because its windings oppose each other, and this continues until the called subscriber replies, whereupon the relay 65, Fig. 5, reverses the current through its right - hand winding. The relay 197 is then energized and in turn reverses the connexions of the trunk 147, 148, thus exciting the polarized supervisory relay 40, Fig. 2. The interruptions of the trunk circuit are repeated by the relay 183 to the trunks 211, 212, the slow-release relay 222 being energized during this transmission, disconnecting the condensers 55, 56 and short-circuiting windings of the relay 197 and coil 191 so as to remove their resistance from the circuit of the connector line-relay 70. The function of the coil 191 is explained later. Connector. The relay 70, Fig. 5, which is bridged across the trunk 211, 212 through the contacts of the pole-changing relay 65, energizes the slow-release relay 215, so that the interruptions in the trunk circuit produced by the repeater relay 183, Fig. 4, are repeated over the contacts 223, 225 to the slow-release relay 226 and the vertical magnet 60. The relay 226 is energized by these impulses and closes the circuit of the private magnet 62, which moves the side-switch into its second position when the impulses cease. The final set of interruptions are thus repeated to the relay 226 and the rotary magnet 61. Busy test. The relay 226 is energized by these impulses and again energizes the private magnet 62, the circuit of which is maintained. if the selected line is busy, by current flowing over the upper winding of a relay 306, which is excited by current through its lower winding passing through the side-switch arm 68 in its second position to the grounded test terminal. The side-switch is thus locked in its second position, and the relay 306 connects the busy generator N to the calling line. The busy release is effected in the same manner as the ordinary release. Supply of ringing-current. If the selected line is idle, the private magnet releases the side-switch, which in its third position completes the circuit of the ringing-relay 64 over the contact of a relay 256 and side-switch arm 69. The ringing-generator M is thus intermittently bridged across the line until the subscriber replies, thereby energizing the back-bridge polechanging relay 65, which causes the self-locking relay 256 to disconnect the ringing-relay 64. Disconnexion of the called subscriber's lineswitch, and means for indicating to the operator the character of the called line. When the sideswitch arm 68, Fig. 5, moves into its third position, current flows from the battery lead 227, Fig. 6, through the secondary of the signalling transformer 236, cut-off winding 235 of the line-switch C<2>, test-lead 234, Fig. 5, and the right-hand winding of the back-bridge relay 65. The only function of this winding is to obtain an inductive connexion between the signalling transformer 236 and the line circuit, to which the operator can connect her speaking set. Supervisory signals. The energizing of the back-bridge relay 65, Fig. 5, reverses the current through one winding of the relay 197, Fig. 4, as previously described, thereby energizing this relay, which reverses the connexions of the trunks 147, 148 so as to operate the polarized supervisory relay 40, Fig. 2, and extinguish the supervisory lamp 41. The other supervisory lamp 265 is controlled by the relay 266, bridged across the calling line, and the relay 261 which is energized as long as the plug remains in the jack of the calling subscriber. Release. When both subscribers hang up, the lamps 41, 265 again light up, and