Patent GB-250680-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1925-01-17
Abstract: 250,680. Automatic Telephone Manufacturing Co., Ltd., (Automatic Electric Co.). Jan. 17, 1925. Automatic exchange systems. - The sending switch banks of a number of register controllers using a common code translating frame are multipled, each bus-bar being connected to a different point on a battery, Fig. 4, or a resistance shunting a battery, Fig. 6. In one system, Figs. 2 - - 5, terminals in the office register for which no digit is to be sent are left dead. In a second system, Figs. 7 - - 9, they are jumpered to a skip terminal which is connected to a special potential to cause the operation of a marginal relay which provides a circuit for driving the sender control switch through the blank positions. In the latter system, the release relay is held up while the sending switch is off-normal, to obviate the need for a special restoring circuit for the sending switch in the case of premature release. First system, Figs. 2 - - 6. The association of the register controller with a trunk circuit and the registration of the two office digits on a Strowger register OR and of the remaining digits on digit registers DB1 - - DR4, take place in known manner. When the register OR has been set, interrupter 109 is connected by wiper 108 of the sequence switch DD to relay 202, which thereafter oscillates its armatures until the register controller is released. The magnet 207 of the back-stroke drive sending switch SS receives impulses from 220 and advances the wipers 208, 209. At the first step, pick-up relay 203 pulls up, and connects the impulsing contact 220 to a slow-to-operate relay 206. Before relay 206 attracts its armature, test relay 205 pulls up over 209, 117, 301 to prevent the operation of the stop relay 204. Impulses are now sent over the trunk at 219, and the switch SS continues to advance, releasing 205 at each step, until wiper 209 reaches the bus-bar to which the other end of relay 205 is connected via the register wiper. Relay 205 therefore fails to operate, and an instant later, relay 206 energizes stop relay 204, which completes a homing circuit for the switch SS, completes a circuit for the magnet 111 of the back-stroke drive sender control switch SC alternative to that made for it by the pickup relay, and connects relav 205 to ground instead of to wiper 209. Relay 205 releases magnet 111 and the switch SC takes a step. When the switch SS reaches normal, relays 203, 204 fall back sluggishly in succession, after which the remaining code digits are sent in a similar manner. The terminals in the register OR for which no digit is to be sent are left dead, and when the switch SC moves to a position connected to such terminals, the relay 205 falls back and the magnet 111 receives further impulses from relay 206 until the switch SC reaches a live position. When the office code has been sent the numerical part of the number is sent under control of registers DR1 - - DR4. In case these registers have not been set when the sender is ready, the relay 205 is held energized over their normal terminals in series with the stop relay 204, and relay 204 remains energized in this circuit to delay the transmission after its locking circuit is opened by relay 203. When the number has been fully sent, ground over relay 205 is connected to the wire 80 to operate the switching relay in the trunk circuit which causes the disconnection of the wires 79, 80. Relay 205 on falling back re-energizes magnet 111 and relay 206 falling back later releases it to cause the wipers to move to their final position in which relay 205 again pulls up to prevent further stepping of switch SC. The relapse of release relay 201 operates the release magnets of the switch DD and the registers, completes a homing circuit for the switch SC, and (in the case of premature release) for the sending switch. Second system, Figs. 7 - - 10. In this system the test relay 505 is polarized and operates only when wiper 507 of the sending switch finds a higher potential than that to which the other end of the relay is connected over the register wiper. The terminals of the register OR<1> shown are jumpered to cause the number 160 to be sent. The fourth position is to be skipped and is jumpered to a much higher potential than any of the others. When the office letters have been dialled, interrupter 531 is connected by the switch DD<1> directly to the stepping magnet of the sending switch SS<1>. Pick-up relay 503 pulls up as usual and connects the polarized relay 505 over the wipers of the switch SC<1> and register OR<1> to the distributing frame DF<I>. Subsequent energizations of the stepping magnet of the sending switch interrupt the trunk circuit. Relay 505 does not pull up until wiper 507 reaches the bus-bar next beyond that to which the other end of the relay is connected, whereupon it energizes stop relay 504 which opens the circuit of the driving magnet of the switch SC<1> to cause it to advance the wipers, completes a self-interrupting circuit for the restoration of the sending switch and connects up the marginally adjusted skip relay 501 to the register wiper in place of relay 505. If a digit is to be sent from the next position this is without effect, and after the successive sluggish relapse of relays 503, 504 consequent on the restoration of the sending switch, this digit is sent in the manner just described. If, however, a position is to be skipped, relay 501 grounds the first three terminals in the path of the controlling wiper of the sequence switch SC<1>, thus causing it to advance by self-interruption past the positions to be skipped. The numerical part of the number is sent in a similar manner, the stop relay 504 being held up over normal terminals of the digit registers to delay transmission until the corresponding digit has been dialled. At the end of the number, ground over relay 501 is sent to the trunk circuit which releases relay 502 to complete a homing circuit for the switch SC<1> and operate the release magnets of the switch DD<1> and the registers. In this system the release relay 502 is held up by the pick-up relay 503 until the sending switch reaches normal and a special restoring circuit for the latter is therefore unnecessary.