Patent GB-315297-A (GB)
Title: Circuit arrangement for connection lines in signalling systems, and particularly in telephone systems
IPC: H04Q5/22
Filed: 1928-12-20
Abstract: 315,297. Siemens & Halske Akt.-Ges. July 11, 1928, [Convention date]. Addition to 301,828. Automatic exchange party-line systems.-In a party-line system in which the wanted partv is selected by impulses transmitted over the line, each impulse extending the line from one station to the next, the building up of the line in the case of an outgoing call takes place automatically as in the parent Specification, and is effected in the same sequences as for an outgoing call, i.e., the line is built up from the exchange end in both cases. In the system shown, outgoing calls from the party-line a2, b2, are extended over a preselector VW, and incoming calls arriving over leads a6, b6, c6, are completed over a final selector LW, the selection of the wanted subscriber being effected by dialling an extra digit, Outgoing call. When party-line subscriber Tu2 removes his receiver, a circuit is completed for relay A over relay X2 (i), contacts 3c2, 1x2, 10x1, wire a2 and contact arm dm1 of a step-bystep meter-controlling switch DM. Relays A, P, C (ii), operate the latter locking over winding (i) and relay U, and a circuit is completed over relay X (i) and wire b2 for relay X1 (ii). Relay X1 removes a short-circuit from relay C1 which extends wire b2 to the next substation. Relay X1 also opens wire a2 so that relay A releases and removes battery from wire b2 thus releasing X1. Relay A now again operates over contacts 10x1, 1x3, 3c2, the calling loop, and relay X2 (i) and holds over contacts 2x2, relay C2 also operating over lead b2 and completing the connection between the calling subscriber and the exchange. Relay P which was held during the building up of the line by relay V now releases and relay R operates over contacts 27p, 26a, 25c, 37t and coils Dr2, Dr1, and connects up the stepping magnet D1 of the preselector VW. When an idle trunk is found, relay T operates over both its windings and short-circuits its winding (ii) over an off-normal bank d1 Impulses dialled by subscriber Tu2 are repeated at contacts 26a over the outgoing loop. When the called subscriber replies, booster current over wiper c1 operates a meter connected in parallel with relay T (i) over a wiper dm3 of the switch DM which was set by relay A during the building up of the line to a position corresponding to the calling substation. When the calling subscriber hangs up, the release of relays A, C, U, closes a restoring circuit for the switch DM over wiper dm2. Incoming call. Relays A2 (i), Co, of the final selector LW operate over incoming leads a6 c6, respectively. Incoming tens impulses are repeated by relay A2 at contact 68a2 to vertical magnet H2, and at the end of the digit the relapse of relay V1 causes relay U1 (i) to operate so that the units impulses pass to the rotarv magnet D2. Relay G (i) then operates over vertical and rotary off-normal openings. If the party-line is busy, relay PI does not operate and the thermal relay Th connects a busy signal over winding (ii) of relay A2. If the party-line is idle, relay PI operates in the circuit 110co, 108v1, Q, normal contact of preselector wiper d. T. Relay Q completes a circuit 90a2, 87z, b5, 35q, 36v, for relay X (ii) which energize relay V (ii). At the first impulse of the final series, the release of relay A2 releases relay X so that at the end of the impulse relay X1 (ii) operates over contacts 34x, 31v, and relay 01 switches through. Similarly, at the second impulse relay X1 releases and at the end of the impulse relays X2, C2, operate and switch in the wanted subscriber. Ringing current RM is now supplied over the 5- second switch 5<11> and when the called party replies relay Z (i) operates and locks up over its winding (ii) in series with relay VI. Release is initiated by the de-energization of relay A2 which short-circuits relay Co. The rotary magnet D2 operates and by interaction with relay U1 rotates the line-selector wipers to the end of the bank where the shaft drops and returns to normal.