Patent GB-140053-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone systems
IPC: H04Q3/00
Filed: 1919-12-03
Abstract: 140,053. Automatic Telephone Manufacturing Co., (Assignees of Homrighous, J. H.). March 10, 1919, [Convention date]. Automatic exchange systems ; party-line systems.-Each connector at a branch exchange has a one-coordinate switch associated with it, which is actuated by the first set of number-impulses for the following purposes : (1) The connector has three sets of wipers, so as to have access to 300 lines, one set of wipers being put in circuit by the auxiliary switch. If the first digit is 1 the auxiliary switch 40 - - 43 selects the first set of wipers 44, 45, 46; if the first digit is 2 it selects the second set of wipers 47, 48, 49, (2) If the first digit is either 3 or 4 the switch 40 - - 43 selects the third set of wipers 50, 51, 52, which have access to a group of 100 party lines with two subscribers on each line, and one or other of the ringing-generators 75, 76 is brought into use according to the digit. (3) If the first digit is 5 the switch 40 - - 43 moves to its fifth or to a subsequent set of terminals to make direct connexion to an idle trunk line, such as 104, 105, leading to the main exchange, and the second &c. sets of impulses are repeated to selectors at the main exchange without actuating the local connector. Local connexion to non-party line. A calling subscriber A is connected in known manner by the line switch C to a connector D, energizing relays 25, 26. The first set of line-interruptions are repeated by relay 25 through a slow-release relay 37 to the magnet 34, which steps the auxiliary switch 40 - - 43 to select either the first or second set of connector wipers. When the impulses cease, relay 37 relapses and closes a circuit from wiper 42 through a high-resistance relay 53 in series with magnet 34, which does not respond. Relay 53 being energized, the second set of impulses are repeated through relay 37 (which now controls the side-switch magnet 67, to the vertical magnet 64, and at their termination the sideswitch 66, 72 moves to its second position. The third set of impulses is repeated through relay 37 to the rotary magnet 65, to complete the selection of the wanted line, and if this line is idle the side-switch moves to its third position. If the wanted line is busy, the self-locking relay 90 is energized in series with magnet 67 over wipers 41 and 45 or 48, so that the side-switch is locked in its second position, and a busy signal 1 is connected to the calling line. Supply of ringing-current. In the third position of the side-switch, relay 74 is energized and connects the ringing-generator 76 to the selected line in series with the upper winding of relay 85. When the called subscriber replies, relay 85 is energized and locks itself, disconnecting the ringer and connecting the called line to the backbridge relay 88. Local connexion to party line. The operation is generally the same as before, but the first set of impulses moves the switch 40 - - 43 to its third or fourth set of terminals, both of which are connected to the third set of connector wipers, and if the switch 40 - - 43 is moved to its fourth set of terminals, relay 93 is energized in series with relay 53 and connects the ringing-generator 75 in place of 76. Thus one or other of these ringing-generators is employed according as the first digit is 3 or 4. Outgoing call to main exchange. In this case the first digit called is 5, which moves the switch 40 - - 43 to its fifth set of terminals, and the grounded terminal 95 completes a circuit through wipers 41 and the side-switch (in its first position) to energize relay 96, which locks itself up and prepares a hunting-circuit for the switch 40 - 43. Thus if the first main-exchange trunk 104, 105 is busy, magnet 34 is energized in a circuit 56, 62, 55, 42, 103 and advances the switch 40 - - 43 until an idle trunk is reached. While the switch is passing over busy trunks, relay 53 is short-circuited by the grounded test wiper 42, but when an idle trunk is reached relav 53 is energized and open-circuits magnet 34, and the outgoing trunk is bridged by an inductance 113 through a circuit 59, 108, 109, 111, 113, 114, 61. Subsequent sets of impulses are repeated in this circuit by relay 25 at 114, the inductance 113 being short-circuited, while impulses are passing, by relay 37, which is energized in series with a resistance R. Incoming call from main exchange. The mainexchange trunks, such as 104, 105, have access to the local connectors, such as D, through line switches C'. Specification 1419/10 is referred to.