Patent GB-320348-A (GB)
Title: Improvements relating to telephone systems
IPC: H04M3/60
Filed: 1928-07-09
Abstract: 320,348. Siemens Bros. & Co., Ltd., and Christian, D. A. July 9, 1928. Addition to 292,331. Semi-automatic exchange systems. - In mechanical order-wire systems the junction is assigned at the automatic office and a signal is sent over it to operate its multiple lamps at the incoming end, or it is selected by the operator and associated with the register sender by means of a hunting switch or by a switch controlled by the register sender in accordance with the number of the junction which is signalled in code over the order wire before or, as shown, after the subscriber's number. The last-mentioned system allows several order wires to be provided for each group of junctions. The hunting switch may be associated with the junction, but in the system described is associated with the sender. The systems described resemble, in other respects, that described in the parent Specification. 1st system, Figs. 1, 2; junction assigned at automatic office. The order wire is seized by the key OW, relays E - - G providing for a series of fleeting tests as described in the parent Specification, and when it is available relays T, TS lock up. At the automatic end RP energizes TP, which switches the order wire through to the register sender preselected by SF, and cuts off RP, which falls sluggishly. R pulls up in series with MA, P, (which are not operated), holds TP and energizes RR which busies the sender to other switches SF, and energizes C in the preselected junction in series with T. C grounds the incoming a-wire to energize J and light the multiple lamps at the outgoing end. C and T energize the impulse relay in the incoming selector (not shown) over the b-wire. When TP switches through, SW at the manual end releases B which cuts off a tone signal which it connected up when OW was operated. The operator then plugs into the junction and writes down the number on the strip DK. The depression of any key connects ground over the' low resistance winding SW(ii) to one or more of the wires a - - d to operate the corresponding storage relays, of which the thousands group only, MA - - MD, is shown, in series with a relay P which energizes the backstroke magnet of the digit distributor CS which thus takes a step when the key is released. When the final digit has been registered, R falls back releasing TP, and SF moves off in search of a new register sender. On the first step of CS, ST pulls up, locks itself, and makes a driving circuit over interrupter U for the sending switch magnet SSM. When the sending switch SS reaches its 9th terminals, pick-up relay S pulls up and removes a short circuit from an interrupter V connected to the b-wire. When the marked terminal is reached, stop relay FD short-circuits V, unlocks S and homes SS. In the home position of SS, FD is released, but before it falls a circuit is made for DD, which locks up and causes the operation of the 1st sequence relay AD when SS, which is again driven by interrupter U when FD falls back, reaches its 4th terminals. Relays BD, CD are operated in a similar manner after the 2nd and 3rd digits. If when a sequence relay pulls up, the digit next to be sent has not been received, a circuit exists for SP which stops the sending switch. When FD pulls up to terminate the last digit, ST is unlocked and relays AD - DD, RR fall back, the latter sluggishly. RR completes the release of the register sender and releases C, T, which respectively switch the junction through and drive SF off in search of a new junction. 2nd system, Fig. 4; junction taken by operator and associated with register sender by hunting switch. The seizure of the order wire and the registration and transmission of the number take place as in the 1st system. When the operator plugs in, the release relay in the incoming selector (not shown) connects battery to the wires c, d, and on the relapse of RP shortly after TP - switches the order wire through, X pulls up and energizes CT which makes a driving circuit for magnet JFM of JF. When the junction is found, T pulls up over T (i), locks over T (ii) in series with C, stops the switch and short circuits T (i) to allow N to pull up, busy the junction and disconnect d from C T. C interrupts the a-wire and connects the b-wire to the impulsing circuit. The sending switch driving circuit includes a front contact of T to ensure that it will not be started until the junction is found. If the number is fully registered before the junction is found, TP and X remain operated over ct2 and CS remains on its 5th terminals. Terminals 4 and 5 in bank 4 are strapped together and a circuit for an additional relay connected at the outgoing end of the conductor c of the order wire is thus maintained. This relay grounds the lower end of T to keep the order wire busy after the key OW is released. When the junction is found, the relapse of CT drives CS on one step and X, TP, and the additional relay fall back. When the number has been sent, ST falls back to release the register sender and relay C which switches through. 3rd system, Fig. 5; junction number signalled to register sender. The relay RR in addition to its functions in the systems described above, energizes an impulse relay A. ST pulls up when the junction number has been fully recorded, drives CS on one step and starts the sending switch SS. Impulses are now sent under control of the start and stop relays S, FD, and sequence relays DD, AD - - GD, operating as in the preceding systems, to relay A. The first two digits go to the magnets VM, RM of the two motion junction selector JF. As in the 2nd system, the seizure of the junction causes the incoming selector (not shown) to connect battery to the wire c, and when JF reaches the junction, T, C, N pull up as in that system. This arrange. ment makes it impossible for impulses to be sent over a busy or unseized junction. If such a provision is unnecessary, relays T, N are omitted, wiper 2 of JF is grounded over st5 and a front contact of the sequence relay BD, a further contact of BD replaces t1, and BD is made sluggish to ensure that battery is kept on! the b-wire until C has switched through after the number has been sent. Owing to the operation of C, T, the remaining digits are sent over the b-wire. When the number, has been sent, ST falls and releases the register sender as in the other systems. The relapse of RR releases A and energizes release magnet' ZM of JF.