Patent GB-191403358-A (GB)
Title: Improvements in Machine Telephone Switching Systems.
Filed: 1914-02-09
Granted: 1915-01-21
Abstract: 3358. Western Electric Co., [Woodward, F. T., acting for Western Electric Co.]. Feb. 9. Automatic and semiautomatic exchange systems.-In a system in which a register controller receives reverting impulses from the selector which it controls, circuit arrangements are described which enable the register controller to be constructed with only ten positions, the zero position, to which the register is set when the selector is to be moved to select its zero set of terminals, being also the position in which the register normally rests. The register 35 is a power-driven switch of similar construction to the well-known sequence switch. It is set in accordance with a digit of the wanted number, either by an operator's key set or by impulses sent by a subscriber. In the course of its controlling operation, it is moved forward from its set position towards its normal position by the reverting impulses which it receives from the selector 1.55. The last impulse but one completes the restoration of the register, and a circuit is thereby closed by which the final impulse directly operates a relay 253 for opening the selector controlling-circuit and a sequence switch 200 for bringing into circuit the register 45 corresponding to the next digit. The controlling operation of the register 35 takes place in the eighth position of the register sequence switch 200, and in the fifth position of the selector sequence switch 100. As soon as the sequence switches have been brought to these positions, the selector line relay 151 is energized over the fundamental controlling-circuit in series with the register stepping- relay 251. The relay 151 energizes the power magnet 152 of the selector 155, which is thus set in motion. As the brushes 156 pass from one set of terminals to the next, an auxiliary brush 154 is intermittently connected to ground, thereby short-circuiting the relay 251 while maintaining the circuit of the relay 151.. Each of these reverting impulses moves the register 35 from one position to the next as follows. When the stepping-relay 251 de-energizes, it completes circuits through both windings of a relay 252. The circuit of the left-hand winding includes the contacts 216 top, 38, 37 and the winding of the register 35, and serves as a starting-circuit for the register. The relay 252 is differentially wound and does not become energized, but the register 35 is energized and starts moving to its next position. As soon as the register begins moving, it opens, at the contact 37, the circuit by which it was started, but the continuance of its movement until it reaches its next position is ensured by the contact 36, which is closed between each position and the next. The opening of the starting-circuit at the contact 37 has the effect, however, of energizing the differential relay 252, the left-hand winding of which is deprived of its current. The armature of this relay opens the starting- circuit at a second point, so that when the register arrives at its next position, it comes to a stop, in spite of the reclosure of the contact 37. When the stepping-relay 251 becomes energized again, at the conclusion of the impulse, it opens both circuits of the relay 252. This relay is therefore de-energized and closes its back contact. The register starting-circuit is then open only at the back contact of the relay 251, so that when the relay 251 de-energizes in response to the second impulse, the register is moved a second step. In this way, each de-energization of the stepping-relay 251 moves the register from one position to the next. Assuming that it is desired to select the fifth set of terminals in the selector 155, which correspond to the digit 4 (the first set of terminals being those which correspond to the digit 0), then the register 35 will have been set by the subscriber or operator to its sixth position (6 being the complement of the digit 4) and will regain its normal position upon receipt of the fourth reverting impulse, which is sent while the brushes 156 move from the third to the fourth set of terminals. Upon reaching its normal position, the register 35 disconnects itself at the contact 38 from the left-hand circuit of the relay 2.52, and connects this circuit through the contact 39 to a relay 2,53 and to the sequence switch 200. The final impulse, therefore, which is sent while the brushes 156 are moving from the fourth to the fifth set of terminals, does not affect the register 35, but directly energizes the relay 353 and sequence switch 200. The relay 253 opens the fundamental controlling-circuit, so that when the brushes 156 are centrally alined on the desired set of terminals, the relay 151 is de-energized and brings the selector to a stop. At the same time, the sequence switch 200 moves forward from its eighth position, disconnecting the register 35 and preparing to bring into circuit the register 45.