Patent GB-302200-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone systems
IPC: H04Q3/00
Filed: 1927-08-09
Abstract: 302,200. Associated Telephone & Telegraph Co., and Wicks, J. Aug. 9, 1927. Automatic and semi-automatic exchange systems. - In an automatic telephone system comprising a step-by-step and a revertive-control exchange, separate register-controllers are provided in the step-by-step exchange to control inter exchange communication in opposite directions. In working between the revertivecontrol exchange RCX and the step-by-step exchange SSX, Fig. 25, a subscriber X is connected by line-finders. to a first selector R1 and a register RG. and RG controls R1 to find an idle interexchange trunk to a repeater translator RT at SSX. RT includes a counting-relay set and a pair of interrupting relays which act first to send impulses to RG and the counting set until the fundamental circuit is broken and then to the counting set and the sfep-by-step selector until the former is saturated. This is repeated for each digit, the step-by-step selectors used in any interexchange call being arranged on a similar non- decimal basis to the RCX switches. The step-bystep connector is of the 200-point type with two sets of wipers, so that arrangements are made for the counting set to operate twice over when required before becoming saturated, and for a wiper-changing relay to operate. In working from step-by-step to revertive-control, each digit dialled is registered on a separate relay counting-set which is saturated in turn by revertive impulses from the RCX selectors. The counting sets, which operate as shown in Fig. 11, are comprised in a register-controller RC connected to a repeater D in SSX reached by subscriber A through line switch LS and selector SL1. The selectors R2, R3, R4 in RCX are of the 200-point type and are arranged as shown in Fig. 6, which shows the setting up of an entirely revertive-control connection. It will be seen that for varying combinations of odd and even digits, the counting sets may require to be saturated by nine, ten, or eleven impulses. A pair of relays operated in turn by consecutive impulses during each digit and then released, discriminates between odd and even digits, and controls for each digit a relay associated with its counting set to modify the circuits controlled thereby as required. An operator may be reached by dialling a special number, through a special repeater D2 at SSX and a special selector R7 at RCX. It will be seen from Fig. 6 that if the thousands digit is 0, the counting set will receive 19 impulses in all; this is provided for by releasing the counting set after the dialled impulses are received and the nine revertive impulses are then sufficient to saturate it. Operation in case of premature disconnection or delayed dialling is described and modified connections for revertivecontrol exchanges in which the selectors are held locally instead of from the register-controllers when dialling is delayed. Preferably the registercontrollers for step-by-step to revertive-control working will be provided in common for a number of trunks, while for opposite working, they will preferably be individual to the trunks. If a revertive-control subscriber, called from the stepby-step exchange, fails to hang up, an alarm lamp will warn an operator. Inter-exchange connections with a manual exchange MX are shown on Fig. 25; this exchange is provided with keysenders. and call-indicator sets arranged for working with the revertive-control exchange, so that calls between MX and SSX will be made over identical translator or register-controller apparatus with that used between RCX and SSX. In calls local to the step-by-step exchange, selectors such as SL1, SL2, SL3 are used for the first three stages, the final selection being made throush one bank of a connector S4, or over a normal connector SL4, according as the hundreds digit is odd or even. Setting up connection from a step-by-step subscriber to a revertive-control subscriber 26249. Registration of digits. A subscriber at the stepby-step exchange is connected by a plunger-type line switch of the usual type controlled by a master switch to a first selector which is operated by the first digit dialled to find an idle trunk to a repeater D, Fig. 2. Line relay 162 energizes over the subscriber's loop and relay 163 then operates to energize the pull-down winding of the plunger-type switch E. Fig. 3, in series with the upper winding of relay 165 which is not operated. Magnet 204 locks up over both its windings in series and the remainder of the operation of the switch and its master are well-known. Switch E seizes a register. Figs. 3, 4, and 5, over wipers 250 - - 253, relay 209 energizing over lead 171 to earth conductor 232 and to connect a time-pulse lead to conductor 231. Relay 162. Fig. 2, repeats the next digit over conductor 199 and wiper 252 to relay 218, and relays 219, 220 are operated throughout the digit. The first impulse energizes two-step relay 211 of the thousands register 211 - - 215 over conductors 234, 242, and the register relays are so interconnected that their method of operation for various digits is as shown in Fig. 11. When relay 220 operates, relay 401 of the two-step input-control relays 401 - - 404, Fig. 5, operates its armature 419 from earth at 279, and when 220 releases at the end of the digit, a shortcircuit is removed from the lower winding of 401 which energizes fully to earth at 282 to transfer the impulsing circuit to the hundreds register relays 321 - - 325, Fig. 4, which lock up over 325, 491. 438, 232. If the hundreds digit is unduly delayed, relay 413 energizes to open 491 and present registration of the hundreds digit. At the end of the digit, when relay 220 releases, control relay 402 operates fully to transfer the impulsing circuit to the tens register 331 - - 335, and to hold the hundreds relays at 434 independent of relay 413. The tens digit is registered after which relay 403 transfers the impulsing circuit to units register 341 - - 345 and at the end of the units digit, control relay 404 energizes fully to open the impulsing circuit. Operation of revertive control switches. After the thousands digit is registered and relay 401 is energized, the incoming second selector R2, Fig. 7, is connected to the register controller over trunk 168, 169. Fig. 2, and conductors 172, 199, in a circuit through relavs 503, 206. 505 and contacts of sequence switch SS2, Fig. 7, in its first position, only 503 operating. Magnet 510 then energizes from earth at 517 and SS2 advances to the second position, cutting out 503, and completing a fundamental circuit in which 206, 505 energize. Magnet 508 is now energized to rotate the trip-spindle so that interrupter 513 intermittently shorts 206. Operation of 206 forms a circuit from 257 to the thousands register, in which 211, 215 have been left energized by the six impulses, so that on the first de-energization of 206, Delay 212 fully operates. It will he seen from the impulse table, Fig. 6, that in reaching the six thousand level of R2, three revertive impulses will be sent, after which relays 211, 214, 215 of the thousands register are operated, see Fig. 11, and relay 208 then energizes over 229, lower winding of 405, 239, 283, 287, 302, 316, 240, 450, conductor 232 to earth to open the fundamental circuit. Release of 505 releases magnet 508 and completes a circuit for magnet 510 to advance SS2 to position 3. Relay 505 again operates to release 510, the brush carriage magnet 509 operates and the selected brushes rotate to an idle third selector R3, Fig. 8. Relay 405 energized partially in series with 208 and pulls up fully over 448, disconnecting earth at 450 to release the thousands register. Immediately SS2 reaches position 3, relay 205 is energized in series with retarrd 502 and relay 503 over N (1, 2), J (3, 2) of SS2 to hold 208 over 256, 264 until an idle selector is found while 405 prepares an alternative locking circuit for 208 over contacts of relay 402 until the hundreds digit is registered. When R3 is reached, relays 506, 702 now operate in series, the latter forming a locking circuit over K3, 2 of SS3 and contacts 711. Relay 507 is short-circuited over the rack 512 until the brushes are properly aligned on the selected contacts when it energizes in series with the upper winding of 506 and in parallel with the lowerwinding thereof in the locking circuit of 702. Magnet 509 is then released and the holding magnet 511 energized. Magnet 510 also operates over C (3, 2) and A (1, 2) in turn to move SS2 to position 6, connecting 168, 169 to R3, and short-circuiting 205. Relay 208 is held in a circuit over 432, 449, but when the hundreds digit is registered energization of 402 releases 208, and the fundamental circuit is now extended to energize relays 206, 704. Magnet 707 now operates over 715 to step SS3 to position 2, in which trip-spindle magnet 705 is operated. At each step of the spindle, interrupter 708 shorts 206 which sends impulses to the hundreds register 321 - - 325, From Fig. 6 it is seen that in reaching the level of R3 containing 26200, eight impulses will be sent to the register and since two have already been sent, relays 321, 322, 324, 325 will then be locked. Fig. 11, and relav 208 is again operated in series with the lower winding of relay 406 over conductors 246, 247, contacts 363, 375, 378, 374, 379, conductors 350, 232 to earth. The furidamental circuit is opened so that 206, 704 de-energize, 406 energizes fully, and SS3 steps from position 2. On reaching position 3, relays 205, 701 energize in series, so that 208 is again independently locked by relays 205, 406. When SS3 position 4, relay 704 operates, and in position 5 the sequence switch stops. The brush carriage magnet 706 now operates to find an idle final selector R4, Fig. 9, when relays 703, 751 energize and lock up. Test relay 703 de-energizes 704 if the brushes are correctly aligned, releasing magnet 706 and energizing holding and sequence swi