Patent GB-307913-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1929-02-07
Abstract: 307,913. Associated Telephone & Telegraph Co., (Assignees of Bellamy, J. I.). March 17, 1928, [Convention date]. Automatic exchange systems.-In a register controller system in which the translation of the exchange code is accomplished by means of a cross-connecting frame common to the register controllers, the translating switch commences to hunt for the translation immediately the first digit has been stored. The terminals of the wiper banks of all the storing registers are multiplied together. The translation switch cannot rest on spare codes whilst if an unassigned code is dialled the register controller is freed and a tone is transmitted to the subscriber. The outgoing impulses are generated by a relay combination, and a correction combination ensures that the pulses transmitted are of equal duration. The selectors operated by the register controllers have double wound relays made slow-torelease by one of the windings instead of by copper slugs, whilst if the selectors have access to five or less groups the traffic is distributed over the levels by varying the normal position of the wipers on the shafts, or by arranging the register controllers in groups to transmit different translations for the same code dialled. Methods of grading the outgoing groups are indicated. Certain features of the system are claimed in Specification 327,375. Seizure and setting of register controller. When the trunk line 201 - - 203 is seized, relay 204 operates, placing guarding earth on 202 and connecting test wiper 209 of RSS to magnet 207. If RSS is standing on an engaged circuit 207 operates and moves RSS by self interruption until a free circuit is reached. Relay 206 then operates in series with 207 placing guarding earth on 209, a multiple guarding earth on 202 to maintain the line guarded whilst 204 is impulsing, and joining wipers 208, 210, 211 to the incoming circuit 201 - - 203. Relay 221 of S1 now operates over wipers 210, 211 closing a circuit for 222 in series with 223 and vertical magnet 226. Relay 222 operates but not 223 and 226 connecting guarding earth to 202, locking itself up through the vertical magnet and short circuiting the upper winding of 223. In the register sender release relay 312 energizes over wiper 208 removing earth from conductors 302, 304, 306. The first digit is repeated by 204 to register A (412, 415, 208) and the wipers of the register are moved to the terminal corresponding to the digit sent. Relay 415 operates on the first digit and falls back at the end of the train. Relay 414 pulls up with 415 and restores shortly after 415 falls back but in the interim a circuit is prepared to operate magnet 410 which slips IC on to the next contact and wiper 412 transfers the input circuit to the magnet of register B. The second and subsequent digits are stored in the registers B, C &c. and after the last digit has been received wiper 412 is stepped on to a dead contact and remains there until the switch is released. When the switch IC made its first Step wiper 411 completed a circuit to relay 443 which operated connecting the wiper of register A to relay 442. All the terminals ringed in Fig. 3 are connected to the corresponding terminals on the left of Fig. 4, and consequently if the wiper of register A rests on say the 3rd contact, the potential of the 3rd battery tap is extended through the upper contact of relay 443 to the right hand' terminal of that relay 442. Relay 442 will operate if its left hand terminal is connected to a potential different from that connected to its right hand winding by register A. If 442 operates it energizes 439 which pulls up connecting up 438 to step the switch TS one step. The switch is stepped until 442 fails to operate due to the potentials being equal at its two terminals. At the end of the second digit dialled wiper 411 moves 1 step and relays 443 and 444 are energized connecting relay 441 with the wiper of register B and relay 442 with the wiper of relay A. Relay 442 is in equilibrium and consequently will not operate. If the potentials at the terminals of 441 are not equal this relay operates moving the switch TS and the switch moves until both 441 and 442 are not energized. The third and subsequent steps of 411 connect 440 to the wiper of C. 441 to that of B and 442 to A and consequently TS moves until all three test relays are balanced. This occurs when the wipers 435 - - 437 of switch TS rest on the contacts corresponding to the digits dialled and then wipers 431 - - 434 rest on contacts which determine the translation to be transmitted. Sending of digits and correcting of impulses. When 439 falls back and remains de-energized, relay 446, which is stiffly adjusted to make it slow to operate, locking up over wiper 411, releasing relays 443 - - 445, and connecting earth to relay 407. Relay 407 energizes 406 and these two relays interact until relay 446 falls back. Each time relay 407 pulls up relays 408 and 409 energize in series connecting earth to relay 316 over 303. Relay 408 is lightly adjusted to operate relay 409. Relay 409 on operation shortcircuits the winding of 408, making it slow-torelease, and after a pause it de-energizes breaking the circuit of 316. When 408 and 407 have released, the two windings of 409 are connected in series but as the windings are mutually differential the relay de-energizes. It will be observed that the make period of the impulses transmitted over 303 are of the same duration as the release period of 408 and are of the same length h irrespective of the time of operation of relay 409 or relay 407 and of the battery potential from which the operating current is derived. The first pulse received by 316 steps the switch SS and wiper 317 completes a circuit for 313 which opens the sending loop, and energizes magnet 403 to step the output control switch OC when it subsequently de-energizes. Subsequent impulses transmitted over 303 step the wipers 317, 318 and are in addition repeated by 316 over the sending loop. Relay 315 is connected at its left hand terminal over wiper 405 to wiper 431 and at its right hand terminal to wiper 318. This relay operates when the potential on wiper 318 is higher than that on 431. In the setting shown wiper 431 is connected to the sixth battery tapping and consequently relay 315 will operate only when wiper 318 is resting on the 7th tapping and this will be after 6 impulses have been transmitted over the loop. When relay 315 operates, 314 is energized closing the loop, breaking the circuit of 403, and connecting wiper 317 to magnet 316 for stepping SS to its normal position. Relay 313 de-energizes followed by relay 314. Relay 403 releasing steps the wipers of OC one step. connecting wiper 432 to relay 315. The remaining digits of the translation are sent in a similar way. If less digits than the maximum are required for any translation the wipers 431 - - 434 not required are connected to terminal SKP. When relay 314 energizes, it connects 405 to relay 311 and when O.C. moves it connects the wipers 431 - - 434 in turn to this relay. If any of the wipers 431 - - 434 are connected to SKP, 311 energizes making a. circuit for 403 to step OC another step. When the code has been sent, the numerical registers are connected by wiper 405 to relay 315 and the numerical portion of the number is transmitted. If, due to hesitation on the part of the calling subscriber the code has been transmitted before the number has been recorded, the sending is held up, due to the maintenance of relay 314 by relay 311 (405, and wiper of Th register or H, T or U register dependent on the position of the number that has been recorded). When the full number has been transmitted wiper 405 connects relay 311 over 208 to 205 which operates looking itself to 202 and extending 201 and 203 to the selector S1. Relay 204 is disconnected and releases, de-energizing 206 which disconnects the wipers 208 - - 211 and releases the registersender selector. Relay 312 falls back earthing release conductors 302, 304, 306 to complete circuits for the operated parts of the registersender to return to normal. Spare codes on the banks of TS have the bottom conductor wired to SKP as shown. When the switch steps on to an unassigned code, relay 442 operates as the wiper of register A must be set at a potential greater than zero and consequently the switch cannot come to rest in such a position. One of the contact sets is wired as shown at UES. Should the registers A, B, C be set at an unassigned exchange code, relay 402 is operated from earth at 431 as the wipers of TS step on to this set the first time, operating 401 which locks up. The next time the wipers reach this position the earth on 431 is transmitted over unoperated contacts of 402, operated contacts of 401 and wiper 208 to energize relay 205 and the register selector sender releases as described above. The calling line is extended to SI, number unobtainable tone is supplied from 212 and the vertical magnet is disconnected at the contact of 205 to prevent the switch being stepped directly by the caller. Multiple wiring of selectors. The selector ST has access in the example to two groups respectively accessible on one or six impulses being dialled. To spread the traffic over all the levels of the switches the selectors are divided into five groups, the wipers of the groups being set in their normal position respectively below the levels 1 - - 5. If, for example, the selector with its wipers set below the 4th level is taken, connection is established over levels 4 or 9 when impulses 1 or 6 are dialled. The wipers may be set below levels 1, 3, 5 &c. and impulses 1 and 2 sent or the setting can be varied to accommodate up to five groups. Alternatively the register controllers can be arranged in groups to. transmit different translations for the same code. The outgoing trunks can be multiplied in sub groups, the l