Patent GB-276067-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1926-05-17
Abstract: 276,067. Standard Telephones & Cables, Ltd., (Polinkowsky, L., and Hatton, W.). May 17, 1926. Automatic and semi - automatic exchange party line and metering systems.-A register controller for selectors having several groups of terminals in a row and arranged to send reverting impulses of ground and battery from alternate terminals is provided with an auxiliary counting chain which, during tens selection absorbs the first 8 of the impulses corresponding to movement over a group, the remaining 2 building up the tens register. The auxiliary chain controls the units setting jointly with the units register which is not built up by the impulses. If the units digit is even, the units register is made to record the next odd digit and the selector after being controlled in accordance with this setting makes one further step. The invention is described with reference to a rural office with link circuits comprising call finders and connectors, the latter comprising 3 permanently associated 100-line switches. When a subscriber calls, switches connected to the register controllers hunt for an idle link and the link seized then hunts for the calling line. Means are provided in the register controlled for controlling the selection of an idle two way trunk to a main office and of an idle line to a Private Branch Exchange. The register-controllers can be controlled by an operator in the main office (who receives a special signal if the wanted line is toll-busy) to break in on a local call. Means are provided for signalling faults to the main office. The Provisional Specification describes the operation of the register controller in setting up reverting calls on two-party lines and also routine testing equipment for testing the register controllers and selectors. Selecting idle link circuit and register. When a subscriber calls, line relay Lr, Fig. 1, a starting relay Lsr (common to a group of 50), and relays Upr, Urr common to the whole office pull up in succession. Relay Upr marks all the idle link circuits in the d arcs of the link choosers of all the registers and relay Urr energizes the common starting relay Rsr which connects ground (from Q over L to test-relays like Gtr and driving magnets LF. When one of the link choosers finds an idle link Fig. 2, its relay Gtr pulls up over the d-wiper, stops the chooser and energizes relay Gtlr which shunts the high resistance winding of relay Gtr by its low resistance winding to mark the link busy, and energizes the finder magnet PF Fig. 2, in a circuit g, H, I, Ltr (back contact of). When the calling line is found, relay Ltr pulls up over the e-wipers and cams V, N, Q, stops the finder and shunts its high resistance winding by a low resistance winding in series with relay Ltlr thus shunting out relav Lsr which releases the other starting relays. The d-terminal in the link chooser is now dead and relay Gtr falls but relay Gtlr now holds in series with relay Adr which locks itself over L, Q and energizes the magnet R which drives the sequence switch to 3. Relay Bdr now pulls up over L, Q, completes a circuit over Sur for relays Er, Cor which release relays Ltr, Lt1r, Gt1r, and connects impulse relay Isr to the line in series with a marginal relay Rcr which cuts in a compensating resistance if necessary as described in Specification 267,616. Relay Isr energizes relay Lbr which holds up relay Adr Dialling tone generated as described below goes back from DT over X. Should the selector be off-normal at this time the dialling tone circuit is opened by relay Gt1r which is energized by relay Lt1r which is energized in a circuit T, H., I, k to the selector power magnet over an offnormal contact. Hundreds selection. The hundreds digit is repeated over D to sluggish relay Lmr which drives the sequence switch to 4, and to the counting relays Acr, Bcr of which Acr 1.7 pulls up at the first impulse and locks itself in series with Bcr 17 which however is short-circuited until the end of the impulse. In response to impulses 2 - - 6 the corresponding relays Acr, Bcr are operated in a similar way, but relay Acr5 energizes relay Bxr which energizes relay Byr and releases the first four relays Acr, Bcr which are then set if necessary by impulses 7 - - 0. In position 4, relay Kcr pulls up and on the relapse of relay Lmr at the end of the digit drives the sequence switch to 5 and falls back. In 5, relay Fir pulls over T and completes the circuit .of one of the selector driving magnets PS1, PS2 &c. depending on the hundreds digit over contacts of the counting relays I, H, Ghr, Kcr, Fsr. 'The selector begins to rotate but is stopped on its first terminals by relay Fsr which pulls up in a circuit Q, 0 Fsr, j, e1, and energies relav Kcr which locks up and releases relay Fsr. Tens and units selection. At the beginning of the tens digit, which is repeated to a simple counting chain Ccr, Dcr, relay Lmr drives the sequence switch to and at the end to 8. In 7 the counting chain Acr, Bcr and relay Kcr are released and somewhat later relay Fsr is energized again and energizes relay Icr 4 of an auxiliary counting chain Icr, Jcr. The selector magnet PS1 (say) operates over its off-normal - contacts k and contacts of relays Dcr10, Ltr. The selector sends back alternately impulses of ground and battery over e1, f, ,the ground impulses shunting out relay Fsr which allows one of the Scr relays to pull up and the battery impulses re-energizing relay Fsr which energizes the next Icr relay. Thus after 8 steps (from normal) relays Icr1, Jcrl are locked up and when relay Fsr operates on the 9th step, it sends an impulse to the tens counting chain over J, Jcr1, C. The operation of the next Ccr relay releases all the auxiliary relays except Jcr1 which holds on over its left hand winding until relay Fsr falls again on the 10th step terminating the impulse to the tens chain to energize the corresponding relay Dcr. The selector has thus moved to its tenth terminals and one further pair of tens relays is operated. At the 11th step, relay Icr4 is energized again and this continues until - after 20, 30 &c. steps of the selector, the final pair of tens counting relays is energized. Relay Ccr 10 does not unlock the auxiliary counting relays and relay Dcr 10 opens the original driving circuit. The power magnet however moves the wipers one more step in a circuit I, H, and contacts of Ccr 10, Kcr, Fsr whereupon relay Fsr pulls up again and energizes relay Kcr over a contact Dcr 10. Relay Kcr locks up, opens the driving circuit and disconnects relay Fsr. Meanwhile the units digit has been building up the chain Acr, Bcr in the same way as the hundreds digit. At the beginning of the digit, relay Lmr drives the sequence switch to 9. When the units digit has been registered and the hundreds selection is complete the relays Lmr, Kcr drive the sequence switch to 11¢. Relay Ucr pulls up over M, Q and in 10 energizes relay Ehr if the units digit is odd in series with one of the relays Icr, or in the case of 9 the relay Jcr 1. The relay Icr, Jcr does not pull up in this circuit but is energized in 11¢ over direct battery at F. If the digit is even, relay Ehr is not energized and in 10¢ an impulse, operates the next pair of counting relays Acr, Bcr. In 11¢ relay Fsr is energized again over Q, O and the selector e wiper and the selector power magnet is energized again over I, contacts of Jcr 1, Ltr. Relay Fsr falls back on the first step allowing the appropriate Jcr relay to pull up and the next energization of relay Fsr operates the next Icr relay and so on. When relays Jcr 1, Icr 1 are locked the original driving circuit is opened but the selector continues to move in a circuit I, contacts of Ghr, Kcr, Fsr, which is broken after one step by relay Fsr. Relay Fsr energizes relay Kcr in series with relay Jcr1. Relay Kcr disconnects relay Fsr, and drives the sequence switch, if the digit is odd, through position 13. If the digit is even, relay Rcr pulls up in 12“ over contacts of Q, Ehr and reverses the connections of relay Fsr which falls back, releases Kcr which is unlocked between 12 and 13 and drives the selector one more step, the sequence switch stopping in 13 until, on the completion of this step, relay Fsr pulls up again and re-energizes relay Kcr. If the digit is 9, relay Jcr 1 is energized in 11¢ and the selector does not move. Busy test signal from register controller and release. The sequence switch is 11¢ releases relays Ucr, Icr 1, Jcr 1 and in 13 relays Acr, Bcr in passing 14 connects relay Str in a circuit Q. M, Str, i, to the selector test wiper cr. If the line is busy, the relay Str cannot pull up and relay Ghr disconnects relay Kcr to stop the sequence switch in 15 in which busy tone is generated as described below and sent back over BB to the line. When the subscriber hangs up, relays Isr, Lbr, Adr, Bdr fall back, the sequence switch is driven to normal and relays Er, Cor release the link circuit and the line. Supply and control of ringing current and release of register controller. If the line is idle, relay Str pulls up over the cut-off relay locks itself short circuiting resistance r<1> to mark the line busy and prevents the energization of relay Ghr so that in 14, 15 relay Kcr pulls up over C and the sequence switch runs straight on to normal. In 17 ground is connected over T to wiper h to energize relays Rcr, Lcr in the link circuit and after 18 the various relays are released, the register controller now being available for other calls. In the link circuit, relays Lcr, Rcr lock up and connect up the calling feed relay Asr. Relay Asr holds up relays Er, Cor. Relay Rcr connects relay Slr in series with the ringing starting relav D1r, Fig. 4, and ringing current generated as described below is sent out over Rgr, ringing tone leaking back over a small condenser. When the called party replies, relay Rgr releases and is released by relay Bcr which connects up the called supervisory relay Csr