Patent GB-316651-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1928-05-02
Abstract: 316,651. Automatic Telephone Manufacturing Co., Ltd., and Taylor, R. May 2, 1928. Automatic and semi-automatic exchange systems.-In networks comprising both manual and automatic exchanges, calls from manual exchanges are passed verbally to operators in automatic exchanges over the actual circuit to be used for the connection. On being taken into use the junction is connected over a preselecting switch OF to a free relay group RG (Fig. 9) and thence over hunting switches to a free sender SN and a free operator 01, the latter not being connected up until a free sender and the calling junction have been found. The operator sets up the number on a key set and is then freed to accept other calls, the relay group and sender being released after the number has been transmitted. The embodiment shown is for a four figure exchange. Normal operation. When the distant operator connects either directly or through a hunting switch to the junction circuit (Fig. 6) relay L, in the junction relay group JR, operates followed by LZ and AS (16, 15, 14) extending the circuit to the junction finder bank JF (19, 82 and 20, 175). At 21 earth is removed from conductor 22 to mark JR selectable on the bank of JF and at 24 earth at 23 is connected to FS (Fig. 3) (33, 31, 29, 28, 27, 24, 23). Relay FS operates connecting, at 34, magnet DM2 to wiper 35. If the sender on which 35 is standing is engaged, DM2 operates and steps by self-interruption until a free circuit is reached. Similarly DM4 of JF is connected to its wiper 41 (46, 45, 43, 42) and this switch is stepped until the calling circuit is reached. Switch PF is advanced by DM3 (53, 52) until wiper 48 rests on a free operator's position but the circuit is not switched through to the position by KP until both KJ and KR have operated, i.e. when the junction finder and sender finder have both switched through. When the sender finder has found a free sender KS operates (30, 40, KS. 34, 37, DM2) and locks up over its lower winding independent of FS. Earth at 37 is connected over wiper 35 to the bank of SF to mark the sender busy and at 59 the circuit of KR is completed. KR operates preparing the extension of the storing and speaking leads. When the junction finder has found the calling line the short-circuit on wiper 41 is removed from relay KJ and this relay operates after KR pulls up (68, KJ, 46, DM4) preparing circuits for time pulse relay TY and switching relay KP. When PF has found a free position KP can operate (DM3, KP, 75, 69) extending the leads from the digit keys to the storage relays, the junction circuit to the B operator and completing a circuit for relay LO (86, 85, 83 to earth at distant exchange via supervisory relay). The operation of LO completes circuits for the position meter PM and lights the lamp PL to indicate a waiting call to the operator. The distant operator also receives a supervizory signal. The number required is set up on the key strip and is stored on storage relays MW, MX, MY, MZ &c. in the usual way. When the last digit has been stored relays DM, DC, DD, and DU have all operated disconnecting the key strip from the storage groups and releasing it for further call and preparing circuits for SS and SY. SY operates (72, 128, 127, 126, 125, 124, 123) to open-circuit FS and KS and connect another guarding earth to wiper 35. Relay KS releases followed by KR, disconnecting the B position equipment and opening circuits of KJ and KP. Relay PY pulls up (130, 136, 161, 135, 134, 133) and locks at 137. Circuit of DM1 is broken at 139 but a circuit is completed to the next bank contact at 269 allowing DM1 to operate and preselect another idle link circuit. JS (21, 22, 41, 42, 43, 142 and 141) and SS (152, 122, 151, 150, 104, 149, 148, 147, 146, 145, 144, 143) energized. JS disconnects LA from the calling circuit, locks AS at 154, completes circuit of BG at 23 and connects sending loop to group selector C over 162 and 176. PS operates (156, 13) and locks at 157 or 158 connecting busy earth to the selector at 160. The selector is held by the loop 102, 81, 82, 163, 164, 177, 109, 110, 165, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, and 167 shortcircuits the impulsing springs 166 which are impulsing at steady rate. The total call meter is operated at 179 when SS operates and at 180 a circuit is prepared for the counting relays SA, SC, SD, SE, SF, SG. Pulsing out is controlled by the counting relays without rotating switch. Two sets of impulsing springs 166 and 181 are out of phase. If springs 181 have just made when SS operates SA energizes (188, 187, 186, 185, 184, 183, 180, 182, 181) its light armature and fully when the impulse stops (189, 190, 191, 192, 102). SB energizes opening the loop but as the springs areout of phase no impulse is sent. The next impulse of 181 energizes SC and as the springs 166 open an impulse is sent. SC energizes and if only 1 impulse is required a circuit via the storage relays' operates SZ short-circuiting the loop. If more impulses are required SC prepares the circuit for SD to operate on the next impulse and SD operates SZ or the chain may continue until the required number of impulses have been sunk. CM, CC and CD operate in turn from SB to transfer the circuit in turn to the storage relay group. Release of sender. When the full number of digits have been transmitted CO operates its light armature (27, 216, 215, 214, 209, 208, 102, 103) and then operates fully (218, 91, 90, 220, 219, RR) locking up at 216. The digit set up leads are disconnected at 93, 111, 221, 147 and the holding loop is maintained at 221 and 111. Lamp 223 flickers to indicate the release condition. Relay RR pulls up in parallel with CO opening the circuits AS and JS and these release. Release of AS puts guarding potential on JF at 21 and breaks the circuit of PY releasing CO and RR. The release of JS transfers the holding circuit of the selector to JR at 81 and 155 (via I and D). Relay I operates hold BG. If the called circuit is' energized, busy flash and tone will be repeated by I to the line. If, however, the called circuit is free, relay D operates on the current reversal in the calling loop connecting LA in the circuit to provide supervisory signals to the calling operator. When the calling operator clears, relay L falls back releasing LZ, I, D, BG and PS. Partial set up. A time pulse is connected to relay TY by KJ which operates its light armature on the first pulse, operates fully on the second pulse and if the setting up has not been completed, connects the third pulse to relay SY which operates energizing MB (289, 123, 124, 125, 126, 127, 128, 131). The digit set-up leads are disconnected and marking earths connected by relays CM, CC and CD are connected to terminals 245-249. If the call is to be routed to an operator 245 is connected to 250 and the remaining terminals are joined to the sender stop leads in the sequence required. When relay PY operates, a circuit is completed via 245 and 250 to SS and the sequence required is transmitted. If partial set up are to be cleared down, 245 and 251 are connected whence PY operates CO releasing the sender as before mentioned and the call is extended to a group selector at contacts of JS. Cancelling wrong numbers.-Depression of key 253 operates MY, MW or CY, CW or DY, DW according to the number of digits set up. A cir- - cuit is thus completed to lower winding of CO and the equipment, is restored to normal. All senders engaged. SB operates over a chain circuit 264 opening the bank contacts of outlet finder and preventing unnecessary hunting. Faults. If any relays in the sender stick, relay RG<1> operates when CO releases, re-energizing CO and holding until the fault is cleared. CO connects at 225 the common exchange slow release alarm. A line fault operating L will connect the circuit to the " B " operator. After challenging the line key 77 is depressed operating SY and completing as for a faulty set-up. Specification 315,735 is referred to.