Patent GB-658970-A (GB)
Title: Improvements relating to automatic telephone and like selective systems
IPC: H04Q3/42
Filed: 1948-02-06
Abstract: 658,970. Automatic exchange systems. SIEMENS BROS. & CO., Ltd., CHRISTIAN, D. A., and LONG, D.P. Feb. 6, 1948, No. 3591. [Class 40 (iv)] In an arrangement for setting a switch in accordance with the operated combination of a group of recording relays, the marking circuit comprises a number of elements, one for each recording relay, each element consisting of a wiper of the switch and a change-contact of the particular recording relay, and so avoids the use of a tree of recording relay contacts. The elements may be connected in series or in parallel, an effective marking obtaining when all or none respectively provide a through connection. Transmitting end, Fig. 1. Actuation of one of fifteen keys DK energizes a unique combination of the register relays SA ... SD in series with a start relay S. A sluggish self-interrupting relay P operates and PA follows to connect the signal current supply wires SX, SY to the outgoing trunk SW. Should SA be operated, a circuit is completed for relay YF to cause a signal pulse of " y " frequency to be transmitted. When after some delay relay P releases, PA falls back to terminate transmission of the signal, and the reverse-drive distributer switch SS steps and connects up up register relay SB. Relay YF falls back. Should SA be back a signal pulse of " x " frequency is transmitted. Relay P is reoperated three times over a circuit completed by the wiper SS3 of the distributer switch and three more " x " or " y " pulses are transmitted, depending on the condition of the individual register relays SB ... SD. Subsequent momentary actuation of a cancel key operates relay C to release the register and start relays, and PA pulls up to transmit a cancel signal of " x " frequency. Relay P steps the distributer switch SS to its eighth contact, whereon PA and C release and the switch SS homes. Receiving end, Fig. 2. The incoming " x " " y " pulses operate relays XR, YR, respectively. If the first pulse is of " y " frequency, relay RA of the recording relays RA ... RD and relay H pull up in series and if of " x " frequency H alone pulls up. At the end of the pulse a reverse-drive distributer-selector switch CS steps to connect up RB. The succeeding three pulses cause a corresponding combination of the relays RB-RD to operate. At the end of the fourth pulse, the switch CS hunts for the outlet marked by a through connection across the switch wipers CS5 ... 8 and the associated recording relay contacts RA2 ... RD2, and when this is found the test relay T stops the selector and lights one of a bank of lamps LA. When the cancel " x " pulse is received, relay XR operates slow-operating relay CO, relay H and the recording and test relays release and the switch CS homes. In a modification, twenty-six keys control two sets of three register relays and pulses of three different frequencies are utilized. The test circuit at the receiving end comprises six marking switch banks each with an associated recording relay contact and connected in parallel across the test relay to normally shortcircuit the latter, so that an effective marking is produced only at the position where all six are disconnected to remove the short-circuit.