Patent GB-261456-A (GB)
Title: Improvements in telephone systems
IPC: H04Q3/42
Filed: 1925-08-10
Abstract: 261,456. Standard Telephones & Cables, Ltd., (formerly Weatern Electric Co., Ltd.), (Deakin, G., and Polinkowsky, L.). Aug. 10, 1925. Semi-automatic exchange systems. - In a system in which the wanted number is displayed on a call indicator at an operator's position, several register-sets are associated with each call indicator, and after the number has been stored, the sequence switch of each register-set passes through a series of testing positions which determine the order of connection to the call indicator, only one sequence switch being able to remain in each position at one time. In the arrangement described, the register-sets are connected to the call indicator in the 16th sequence switch position, and provision is made for two waiting calls,. the register-sets remaining in the 14th and 13th positions until the call indicator becomes free. Connection to call indicator. When the operator's position is occupied, relays Cpr, Tdr are energized, and the relay Por associated with each trunk leading to the position is connected up. When the trunk 1, 2 is seized, relay Kwr energizes, locks and connects up relay Prr. Line relay Anr energizes over the a wire and connects up relay Cdr which lights lamp GL and energizes relay Csr which starts the idle finder switches OF in search of the trunk. Test relay Gtr energizes over wiper g when the trunk is engaged by one of the finders and locks over its low resistance winding in series with relay Shr. Relay Gbr energizes and advances the sequence switch R to the 2nd position. Switching relay Fitr energizes over wiper c, and connects up relays Vsr, Rar, causing relay Cdr to relapse and open the starting circuit. Relay Gbr is now connected in the fundamental circuit, and the sequence switch R moves into the third position in which the thousands register magnet is operative, revertive impulses being sent back from the corresponding interrupter to the register-controller at the originating exchange. Relay Gbr falls back when the fundamental circuit is opened, and advances the sequence switch to the 4th position, in which it re-energizes and drives the sequence switch to the 5th position. The hundreds register is then set, and the remaining registers are set in the same way in the 7th and 9th positions. Relay Glr falls back, and the sequence switch is advanced to the 12th position. Release relay Plr was energized in the 2nd position, and' is locked over contact L until the 12th position is reached. Relay Jor is bridged across wipers a, b in the 10th position, and provided the calling party has not hung up, energizes and closes a fresh holding circuit for relay Plr. Relay Olr re-energizes in the 12th position over wiper d, and drives the sequence switch to the 13th position, in which test relay Gtr is connected over contact G to common battery lead 208, and energizes provided it is not grounded over contact L of another register-set standing in the- 14th sequence switch position. Relay Shr in the locking circuit of relay Gtr connects up relay Glr, which drives the sequence switch to the 14th position. Test relay Gtr is now connected overcontact G to common battery leads 301, and energizes provided it is not grounded over contact G of another register-set standing .in the 16th position. The sequence switch R now advances to the 16th position in which the wanted number is displayed on the call indicator. Switching relay Fur releases, and interrupter CFL causes lamp GL to flash. Completion of connection, ringing and release. When the operator plugs into the wanted line, relays Bsr, Blr, Exr energize, and relay Glr is disconnected so that the sequence switch R moves into the 18th position in which the registers are restored. Relay Gbr then energized again, and advances the sequence switch to the 1st position. Relay Exr connects up relay Nbr, and connects an interrupter to ringing relay Arr. When the wanted subscriber replies, relay Sar energizes, and removes the low resistance winding- of relay Tar from the sleeve circuit, so that relay Bsr relapses and removes a short-circuit from ring cut-off relay Rhr. The supervisory lamps CL, SL ,are controlled by relays Vsr, Btr, Premature release. If this occurs while the registers are being set, relay Kwr falls back and a sluggish relay Prr is bridged across the trunk 1, 2. The register which is then being set therefor steps on to its 12th position, in which the sequence switch R is connected up at contact C and advanced to the 18th position. In the case of the units register which may make two rotations on an odd hundred, a relay Ohr becomes energized after the first rotation and causes this action to take place only after the second rotation. If the release occurs after the registers have been set, that is, in the 12th sequence switch position or later, bridged relay Jor is disconnected and releases relay Plr, and the sequence switch R moves to the 18tb position as before. Preventing additional incoming calls. If two calls come in almost simultaneously, two relays Cdr are operated, and a common relay Pdr is adapted to energize in these circumstances, disconnecting relays Tdr, Pdr to disable all the remaining trunks. Similarly, if three register-sets at the position are in use, relay Cpr is arranged to be short-circuited as in Specification 261,457 with similar results.