Patent GB-267606-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04M3/32
Filed: 1925-12-17
Abstract: 267,606. Automatic Telephone Manufacturing Co., Ltd., Passmore, W. O., and Simpson, L. M. Dec. 17, 1925. Automatic and semi-automatic exchange systems.-Routine testing equipment for use at a semi-automatic exchange of the kind described in Specification 229,765 is associated automatic. ally in turn with each impulse sender by means of switches in tandem. Key sets are provided on which are set up a test number which is transmitted to the sender under test, and the number which should be received back from the sender. If these agree, the test is applied to the next sender, but if not, an alarm is given and the test is stopped. Means are provided for testing the translation of an exchange designation into a routing number, and for testing the sending of code impulses. In all cases the received number is displayed on a lamp indicator, and apparatus is provided for testing the pause between digits. While each sender is under test, the next one is marked busy, so that it shall be available for testing when the first sender is released. By means of special keys, connection may be made with any particular sender, which may then be tested a number of times. According to one of the Provisional Specifications, a key may be provided to enable each sender to be tested twice. Routine test. Assuming that the number used for the test is Holborn 2345, and that the exchange designation HOL, which is equivalent to 465, is translated into the routing number 230468, the operator sets up these digits on the keysets, and presses start key SK, which energizes relays 129, 135. Magnet 58 is connected up, and its circuit is opened again when sluggish relay 106 pulls up, advancing the group switch GS one step into engagement with the first distributing switch DS1. A circuit is closed through relay 54 and wire 62 for lamp 159, which indicates the impulse sender under test. Relay 106 also locks relay 129 and connects up relay 91. Assuming that the first impulse sender is idle, relay 100 energizes and grounds wire 65 to mark the sender busy. If the second sender is busy, ground on wire 66 operates relay 118, which disconnects relay 120 until the sender becomes idle. When relay 120 energizes, it grounds wire 66 to prevent the next sender being taken into use. The banks of wipers 31, 37 of the distributing switches are multipled together with a slip of one terminal as shown. At contact 101, ground is connected momentarily over wire 75 to relay 50 until sluggish relay 140 pulls up. Relay 50 locks and magnet 39 now interacts with sluggish relays 45, 48 to step the impulse switch PS, which connects the input number keysets in turn over wires such as 17 - - 20 to wipers 23 - - 26 and thence to the storage relays in the sender. In the 15th position of the switch, the relay 160 energizes, locks to ground in the sender over wire 65, which it extends to wire 74, and connects wipers 24, 25 over wires 188, 189 to impulse relay 407, which energizes and connects up relay 405 over wire 187. If the digits have been properly registered, ground is connected over wipers 23, 13 and wire 76 to energize relay 152, which locks to wire 74, grounds locking wire 202 and wiper 22 to start the transmission of impulses in the sender. At the next step of the switch PS, relay 41 energizes and completes the homing circuit for magnet 39. The first train of impulses from the sender are repeated by relay 407 to magnet 415 of the minor switch M1, and sluggish relays 403, 401 fall back in turn at the end of the train, causing two-step relay 409 to energize, and transfer the impulsing circuit to magnet 419 of the next minor switch M2. The terminals of wiper 417 are connected through lamps to the first code output keyset, and if the correct code digit has been received, the appropriate lamp lights. The succeeding digits are checked in a similar manner, and relay 308 energizes in the lamp circuit for the last digit, putting a further ground on locking wire 202 and connecting up interrupter 324 which sends out ground impulses once every four seconds. The first impulse causes two-step relay 319 to pull up, extending the impulse circuit to wire 205. If the impulse sender is operating correctly, it has released by this time, removing ground from wire 65, so that relays 152, 160 release. Wire 205 is therefore connected to wire 204, and the next ground impulse energizes relay 315, which locks and connects up the release magnets of the minor switches over wire 325 and sluggish relay 313, which holds up relay 308 during the restoring movement. On the relapse if relays 313, 308, relay 315 is disconnected, but before it falls back, a momentary circuit is closed over wires 201, 69 for magnet 56 with slowrelease relay 104 in parallel, causing the switch DS1 to advance one step into engagement with the next impulse sender, and relav 91 to fall back for an instant. The next sender, even if it was in use when originally tested over wiper 37, should now be free, and relay 100 energizes and starts the impulse switch PS as before. If however this sender is still busy, relay 96 energizes over wire 65, disconnects relay 100 to stop the test and connects up a four-second interrupter to energize relays 146, 142 in turn. The latter relay locks and lights the sender busy alarm lamp 181. The circuit of the 25th indicating lamp 158 includes relay 116, so that when ground is connected to wire 201 at the conclusion of the test of the 25th sender, it is extended over wire 67 to magnet 58 to advance the switch GS into engagement with the second distributing switch. When all the senders have been tested, relay 111 energizes over wiper 28, disconnects relay 106 and rings a bell over wire 115. Incorrect number transmitted by the sender. Assuming for example that the first digit received is 1 instead of 2, the switch M1 is advanced one step only, and a circuit is closed over wires 426, 194 and the first key of the set for relay 301, which locks, and closes an alarm circuit over wire 307. In addition, interrupter 324 is dis. connected to hold up the test, wire 74 is extended over wire 203 to ground at release key RK to prevent release of the sender, and a further ground is placed on wire 202 to prevent the display lamps being cleared down. The circuits remain in this condition until key RK is pressed. Sender does not release properly. In this case, ground is not removed from wire 65 and relay 152 remains operated, so that when interrupter 324 is connected to wire 205, relay 142 energizes and locks, lighting the cut-off failure lamp 182. Since no circuit is closed for relay 315, the test is held up. Pause testing apparatus. As shown, the switch PT registers only the pause between the first and second code digits. When the minor switch M1 has been set by the first digit, interrupter 427, which sends 20 ground impulses per second, is connected over wires 424, 199 to two-step relay 164, which energizes and connects the interrupter to magnet 175 to step the switch PT. When thesecond series of impulses come in, a branch of the circuit of magnet 419 extends over wire 200 to relay 170, which energizes at the first impulse, locks and disconnects magnet 175 to stop theswitch. If the pause between the digits is incorrect, a circuit is made over wiper 178 for one of the lamps 179, 180, according as it is too short or too long, in series with relay 301, which operates as before to give an alarm and stop the test. The switch PT is restored by the releaseof relay 164 on the removal of ground from wire- 74. Testing the transmission of code impulses. The attendant operates the keys as before for the required input and output numbers, and then one of the keys K1-4, which control the insertion of the correct resistance in the loop circuit for operating relays 241, 243, 245 corresponding with the resistance automatically inserted in the impulse sender. When the six routing digits have been received, the two-step relay associated with the minor switch M6 energizes and closes a circuit over wire 191 for relay 211, which transfers the impulsing loop to relay 221 over resistances 276, 277, 278, assuming key K2 has been operated, and removes ground from wire 187 to prevent any further operation of the minor switches. A four-second interrupter is connected up and relays 224, 215 energize. Relay 215 locks, extends the impulsing loop to relays 241, 243, 245 and connects up relays 247, 265. The disconnection of battery through relay 221 starts the sending of code impulses, which operate relays 241, 243, 245 in various combinations. The first digit is registered as in Specification 229,371 in the relay set 261-264, the contacts of which are connected up to control the display lamps in the same way as the terminals of the minor switches. Relay 253 transfers the operating circuits of the next relay set similar to 261-264. When the last digit has been received, relay 279 connects up relay 250, which grounds wire 282 to light the display lamps. If the transmission has been effected correctly, relay 308 energizes as before and initiates the testing of the next sender, while, if this is not the case, relay 301 energizes and gives an alarm. Incomplete number of digits transmitted. When relay 215 energizes, the four-second interrupter is connected to relay 227, which prepares a circuit for relay 230, which is normally opened' by relay 250, but if the full four digits are not transmitted, relay 230 energizes, locks and grounds wire 282 to light the display lamps. The code transmission failure lamp 183 lights, and since the fourth digit is not received, relay 308 fails to energize and holds up the test. Stepping the distributor switches over blank terminals. The 25th position of the switch DS1 is shown blank, and in this position, a circuit is closed over wiper 31 for relay 123, which locks relay 106, connects up relay 104 and connects an interrupter first to relay 149 and then over wire 69 to magnet 56, whic