Patent GB-263168-A (GB)
IPC: H04Q3/00
Filed: 1926-12-15
Abstract: 263,168. Automatic Electric, Inc., (Assignees of Stehlik, R. F.). Dec. 21, 1925, [Convention date]. Automatic exchange partyline systems.-In a partyline system employing code ringing determined by the transmission of an additional digit, dead-number calls are routed to a special operator by means of a relay, the circuit of which includes a fourth wiper and bank contact of the connector, a wiper of the code-selecting auxiliary switch, and a jumperwire at a distributing frame. If the called line is busy, the busy tone is only transmitted after it has been determined that the wanted party is in service. When a calling line has been routed to the special operator the called line is freed so that calls to other parties on the line may proceed. Call to subscriber A' (station digit 1); called line busy. During the rotary movement of the connector H, relav 12 energized in parallel with the rotary magnet 18 completes a circuit for the upper winding of a twostep relay 15. On the release of relay 12, relay 15 operates, completely closing a circuit for relay 228 and transferring the impulsing circuit to magnet 120. The additional (station) digit 1 therefore operates the auxiliary switch MS and during this operation relay 12 connects relay 10 over contacts 44, 56, 64 to the test wiper 71. If the called line is busy, relay 10 operates and connects the upper winding of a second twostep relay 14 to lead 154. This lead is earthed bv a multi-contact relay 201 which is periodically operated (in turn with other multi-contact relays 202 - - 204, one for each station on the party-line) by an interrupter INT. At the first operation and release of relay 201 after the operation of relay 10, relay 14 operates, and at the second operation and release, a third two-step relay 11 energizes and connects busy tone to the lower talking conductor. The time interval introduced by relays 14, 11 permits the transfer relay 16 to test whether the wanted party is in service, as will be described in a succeeding paragraph. Called line idle. If terminal 75 is not earthed, switching relay 13 operates at the end of the rotary movement over its lower winding and contacts 44, 56, 64, 71 and locks up. The station digit passes to switch MS as before, and on the release of relay 12, relay 10 is operated over the interrupter " pick-up " wire 147 and closes the ringing circuit from lead 145 over wiper 124 (which has two arms spaced at 90‹ as shown), lead 129, and the a-wire 101 to ground over the bell at the substation A<1>, the uppermost cam of the interrupter INT determining the transmission of the correct ringing-code. When the called party replies, the ringing-circuit is extended over wire 102, contacts 40. wiper 125, to the lower winding of relay 9 which energizes to cut off the ringing current and to complete the talking connection. If the called line is busy when the first test is made at the end of the units digit but falls idle during the dialling of the station digit, relay 13 will operate when relay 12 falls back and the call will be completed. Wanted party out of service. When any party on a line is disconnected, a jumper wire 213 is connected at a distributing frame DF between a terminal 215 connected to a fourth terminal 76 of the line and a terminal 216 associated with that one of the relays 201 - - 204 which corresponds to the particular station which has been disconnected. When, therefore, relay 12 falls back after the setting of the switch MS in the case of a call to a disconnected station, relay 16 is energized over a circuit including armature 206, jumper 213, terminal 76, wiper 123, and armature 205, as soon as the interrupter energizes relay 201. Relay 16 locks up and (1) connects the talking leads to the bank of finder F; (2) places earth on lead 151; (3) disconnects wipers 70 - - 73 so that the called line is freed for calls to other stations; (4) completes a circuit for the starting relay 231 of the call-finder F; and (5) in the case of a busy line, completes a circuit for relay 13 which opens the locking circuits of relays 14, 11 to prevent the transmission of busy tone. When the calling line has been found, relay 232 operates over lead 151 in series with magnet 233 which remains energized independently of its interrupter contacts. Relay 232 lights lamp L, and the special operator on seeing this throws key K<1>, which completes a holding circuit for relay 232 over both its windings and operates relay 252. The latter completes a metallic loop for the ring-cut-off relay 9, and also operates relav 251 which connects the calling subscriber to the operator's head-set. A kick-off key K is provided to release relay 232 and magnet 233 and so step on the finder F in case the lead 151 becomes permanently earthed.