Patent GB-340567-A (GB)
Title: Improvements in or relating to cord circuit repeaters
IPC: H04M3/40
Filed: 1929-10-02
Abstract: 340,567. Manual exchange systems. STANDARD TELEPHONES & CABLES, Ltd., LOWRY, L. P., and CONNOLLY, C. G., Columbia House, Aldwych, London. Oct. 2, 1929, No. 29846. [Class 40 (iv).] In a system in which cord circuit repeaters are inserted in a connection by a repeater operator at the request of the operator controlling the call, the repeater cord circuits terminate in single plugs only, switches being associated with each end of the circuit which hunt for the connected trunks and connect balancing networks and monitoring circuits to the connection. The cord circuit repeaters are preselected, the next to be used being indicated to the repeater operator by lamp signals. When a call is received an operator connects with the calling and wanted lines, with plugs shown below the dotted line operating the relays CO. If a repeater is required in the circuit the repeater operator plugs a preselected cord circuit repeater, indicated by the lamp 1, 2, 3 or 4, into the two lines, either plug being used at the calling end, whereupon relays S, D and E energize in series. The lines are repeated in the banks of switches such as DM and when S energizes it completes a circuit for the X relay of the switch on which it appears and connects its individual contact to battery via Q. Relay D completes locking circuits for S, D and E and energizes A. Relay X energizes W and W and DM interact stepping the switch until the marked line is reached when relays Q and SY pull up and X releases. Relay SY completes a circuit for magnet DMA and this switch steps onto its next contacts completing a circuit for DD, EE and SS to energize. Operations similar to those described occur at that end of the circuit and when the called line has been found SYY energizes. The operation of SY allows G to pull up in series with XB and LB connecting, via the wipers of the hunting switch, the monitoring circuits and balancing networks to the repeater. The operation of SYY allows GG, LN and XN to energize, the relay GG performing functions identical with those of relay G. Relays SB and OB (Fig. 1) now energize in series after which SN pulls up in series with OB (Fig. 2). The OB relays substitute the repeater cord circuit for the operator's connecting circuit and the SN and SB relays complete connections to the repeater and to the monitoring circuits, the latter passing over wipers a b of the hunting switches to the operator's connecting circuit. The gain is controlled by the resistance connected to the f bank of the switches. When relay SYY operated a circuit (not shown) was completed for DMA to step to the next circuit and if this is busy a search for a free cord circuit is made. If all cord circuits are engaged relay F releases to prevent hunting. To cut into a circuit the operator plugs into a jack to operate the relay TB in the direction required. If the left hand line is connected with the resistance inserted by TB allows E to fall back and LB releases, de-energizing OB and connecting the line required to the operator. The removal of either plug releases A and SY allowing the switches to home and the circuit to be freed.