Patent GB-412722-A (GB)
Title: Improvements relating to automatic telephone systems
IPC: H04Q3/42
Filed: 1933-03-30
Abstract: 412,722. Automatic exchange systems. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, HUMPHRIES, H. E., 61, Rochester Way, Blackheath, both in London, and LONG, D. P., 3, Ingleby Way, Chislehurst, Kent. March 30, 1933, No. 9568. [Class 40 (iv).] A single-motion final selector adapted for P.B.X. hunting and controlled by marking from a digit switch which marks all the lines of a P.B.X. group when hunting is required, is provided with separate marking banks for numbered lines, that is, lines which can be called individually, and unnumbered lines, that is, lines of P.B.X. groups other than the first. Thus a night service line is capable of being marked in one bank as an individual line or in another bank as one line of the group to be searched. The two markings may correspond to the same outlet from the selector, or to different outlets which lead to the same line circuit. The invention is applied to a final selector having two sets of double-ended wipers, the ends of which come into operation in turn. In Fig. 1, numbered lines are wired to the full line banks and are selected in accordance with one of 50 markings applied by the digit switch DS to the single-ended wiper bank FS 7, wiperswitching relay WS being operated if the tens digit is 5-9 to discriminate between the two sets of 50 lines, while unnumbered lines are wired to the dotted line banks and are marked in one of the single-ended wiper banks FS 8, 9 dependent on WS. Night service lines have two outlets from the selector corresponding to the marking contacts in the bank FS 7 and in the bank FS 8 or 9. In Figs. 2, 3, for numbered lines the digit switch DS applies one of 100 markings to the double-ended wiper bank FS 7 and wiper-switching relay WS is dependent on a discriminating signal from a previous switching stage. Unnumbered lines are wired to the dotted line banks and are marked in one of the single-ended wiper banks FS 8, 9 dependent on WS. Each night service line has a single outlet from the selector, the two marking contacts in the bank FS 7 and the bank FS 8 or 9 being in corresponding positions. First arrangement, Fig. 1. The final selector tests free due to absence of earth on wire P, relay JB being normally operated. The associating relay K energizes in series with line relay A, and upon operation of release relay B, the digit switch DS moves to its first position, in which JB falls back and busies all the selectors of the group. The digit switch steps in response to the tens digit and one or more of relays W, X, Y operate to connect up one of the five wipers DS 4-8, while wiperswitching relay WS energizes if the digit is 5-9. Dialling relay C relapses, and the digit switch moves automatically to position 12 in which relay E(i) pulls up, whereupon the digit switch responds to the units digit. Upon the relapse of relay C, latch magnet LM operates and the final selector rotates under the control of the electric motor DM, one or more outlets being marked over one of wipers DS 4-8, the same marking being applied for the pairs of tens digits 1 and 6, 2 and 7, &c. When an idle marked outlet is reached, test relay T energizes over FS 7, 8 or 9 and FS 5 or 6, followed by TA, which connects relay E(ii) to FS 1 or 2. If the seized outlet corresponds to a spare number, battery over FS 1 or 2 holds E(ii) and NU tone is applied. Otherwise, E falls back and connects up switching relay H(i) which connects earth to wire BS to initiate ringing at a preceding feed bridge circuit, and releases the common apparatus. If no idle marked outlet is found, test relay T energizes in the last position of the selector and a busy signal is sent back, since in this case switching relay H(i) is shunted by the circuit over T. Second arrangement, Figs. 2, 3. The final selector tests free due to battery on wire P, relay JB being normally inoperative. Line relay A energizes either over the negative wire or over the loop in series with discriminating relay P(i), and upon operation of release relay B, JB pulls up and allows the associating relay K to energize over wire P. Wiper-switching relay WS operates if P is up. Dialling relay C energizes, connects up relay R and closes a self-stepping circuit over wiper DS1 for the digit switch DS, which however is controlled by circuits over front contact a2 in each odd position of wiper DS2 and over back contact a2 in each even position, with the result that the switch takes two steps for each impulse of the tens digit after the first. One or more of relays W, X, Y operate to render one of the five wipers DS 4-8 effective for marking. When relay C falls back, E(i) energizes and the digit switch steps automatically to position 11 or to normal according as the tens digit was 1-5 or 6-0 in readiness for receiving the units digit. In this case the switch takes one step per impulse since it is controlled by a circuit over back contact a<2> in both odd and even positions of wiper DS2. Dialling relay C upon operation connects up F, TK(i) and disconnects R, and upon its relapse at the end of the digit, latch magnet LM operates and allows the final selector to rotate. A statistical meter connected to wire TM1 or 2 is actuated as FS 8 or 9 passes over a special contact before R falls back, the selectors associated with the common apparatus being arranged in two groups. When the selector moves off-normal, relay K(i) is held in series with H(i), which is inoperative. Testing takes place as in Fig. 1, and the relapse of E connects up booster battery to operate switching relay H(i). If no idle marked outlet is found, test relay T energizes when the normal position is reached again over FS 5 or 6, FS 7 and P(ii), which operates together with TA. Relay E(ii) holds over FS 1 or 2 and busy flash and tone are transmitted through TK(ii). Toll offering. If the connection has been set up by an operator, she may offer the call by applying booster battery and earth alternately to the positive wire in phase respectively with the earth and battery on wire BT. The windings of TK are then in opposition and the relay releases. Relays T, P fall back and a circuit is prepared for stopping the selector on the line marked over FS 7, the selector being restarted by the relapse of TA. Test relay T now operates in series with TL, which prepares for the operation of TA should the line become idle and connects through the speaking and test wires. If the wanted line is engaged in a toll call, the operator hears toll busy tone. On the release of an existing local connection, TA energizes over FS 5 or 6 and disconnects E, allowing switching relay H to operate as in a normal call.