Patent GB-219079-A (GB)
Abstract: 219,079. Automatic Telephone Manufacturing Co., Ltd., and Tench, F. April 16, 1923. Addition to 175,260. Semi-automatic exchange systems; impulse transmitters.-The operator's sending equipment of the parent Specification, in which a single set of digit keys is connected in succession to a number of registers, is modified by causing the registers, each of which consists of only four relays, 27 - - 30, Fig. 3, to be connected to the keys 1 - - 0, Fig. 2, by a switch S, which is moved on one step each time a key is released. When the number is completely set up, the switch S is released and then connects the registers in succession to four relays 108 - - 105 which select marking circuits for a sending switch I. A further feature consists in making the pressing of the assignment key and the plugging in by an A- operator independent of each other so that impulses are sent when both operations have been effected no matter which happens first. Registration of wanted number. The first depression of a digit key 1 - - 0, energizes one or more of the relays 27 - - 30, Fig. 3, in series with relay 12, Fig. 2, over the wipers 23 - - 26. The register relays light one of the digit lamps and lock themselves to the wire 44 which is grounded at 46, 47. Relay 12 energizes relays 11, 13 and falls back immediately since it is short-circuited by the locking circuit of the digit relays. Relay 11 locks up over the operated key and energizes the stepping magnet 49 so that when the key is released the wipers 23 - - 26 are advanced one step. Relay 13 locks up and lights the guard lamp 55 by grounding wire 54 which is common to all the trunks in the position. The remaining digits are set up similarly. Connection of sending equipment to the assigned trunk. The assignment key 65, Fig. 1, energizes relay 66 to associate the trunk shown, with the sending equipment last set. For this reason relay 66 has four armatures as each position has four'sending equipments. In the case described, relay 66 energizes relay 71 from the ground on wire 54 over a chain of contacts such as 73 belonging to the relays 71 of other trunks. Relay 71 locks up to the wire 54 direct, connects the trunk to the impulsing wires 78, 79, lights lamp 81 and breaks the chain circuit to prevent another trunk from being associated with this sending equipment in case the wire 54 is still grounded when another assignment key is pressed. Impulse transmission. When the A-operator plugs into the trunk, line relay 82 energizes busy lamp 84, and relay 86 which extends the loop and prepares starting circuits for all the sending equipments, only that completed by relay 71, of course, being operated. Relay 91, Fig. 2, energizes over the wire 90 which is now connected by relays 86, 71 to grounded wire 54 and locks up over off-normal contacts 99, energizing relay 103 and release magnet 97. Switch S restores to normal, in which position its wipers are connected to the first register and relay 103 switches over the wipers from the digit keys to the relays 105 - - 108. and locks itself to the wire 90. One or more of relays 105 - - 108 energize according to the setting of relays 27 - - 30 and pick out the appropriate marking wire for the sender I, which operates as in the parent Specification. Relay 109 under control of interrupter 110 controls the stepping magnet 113 to advance the wipers 114, 115 until the latter finds the marked terminal and energizes relay 120. At the first energization of relay 109 the trunk loop is not interrupted, relay 117 being de-energized, but thereafter impulses are sent, relay 117 being held up over wiper 114. Relay 120 in addition to releasing relay 109 and completing a circuit to drive the switch I to its next normal position. releases the stepping magnet 49 which was momentarily energized in a circuit 115, 118, 127 so that the wipers 23 - - 26 connect up to the next register. In the normal position of switch I, relay 117 falls back, releasing relay 120 so that tht next digit can be sent, the sum of the times of release of these two relays giving time for the distant switches to hunt. Release of sending equipment. When the final digit has been sent, wipers 23 - - 28 move to dead terminals so that all the relays 105 - - 108 are released, and relay 91 again energizes the release magnet 97. Since relay 101 is energized at this stage (by relay 103), relay 13 releases and the holding wires 54, 44, 40, are ungrounded when relay 97 operates. Lamp 55 therefore goes out and the storage relays and relays 101, 103 fall back. Relay 71 falls back and cuts the trunk through. Energization of electropolarized relay 85 on reply of the called subscriber shunts the upper, winding of relay 82 with a low resistance impedance 131 to give the A-operator supervision. Wiping out a wrong registration. Pressing key 132 energizes relay 133 which locks up over offnormal springs 99. Relay 133 releases the storage relays and relay 13 and energizes release magnet 97, and if the assignment key has not been pressed the whole equipment returns to normal. If the assignment key has been pressed, ground on armature 53 holds un relay 71, the impulsing loop being interrupted at 136. The operator keeps key 132 pressed long enough to allow any operated switches at the distant exchange to release.