192,036. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Wicks, J.). Jan. 20, 1922, [Convention date]. Semi-automatic exchange systems.-To enable a manual exchange operator to extend connections to automatic exchanges, she is provided with a set of keys, Fig. 5, directly associated with a link circuit which terminates on the one hand in a switch SS for selecting an idle registersender and on the other hand in switches TS, TS<1>, &c. (one for each automatic exchange) for selecting an idle trunk to the wanted exchange. The operator first presses a key such as 221 individual to the wanted exchange, thus setting in action a corresponding switch TS to find an idle trunk and to light a lamp associated with the jack of that trunk at her position. The switch SS at the same time finds an idle register-sender. The operator then releases the exchange key and successively depresses numerical keys of the series 201 - - 210 to record the digits of the wanted number on relay registers, two of which are shown in Figs. 7 and 8. Finally, she plugs the connection to the marked jack, thereby initiating the operation of an impulse sender, Fig. 6, under control of the register. As soon as the number has been registered a relay 251, Fig. 5, is energized to transfer the key circuits to a second link circuit, so that the registration of a second call can be proceeded with immediately. Operation of the link-circuit switches SS, TS. The depression of an exchange key 221 energizes relav 280 which starts the switch TS to find an idle trunk, whereupon a relay 281 is energized. The relay 280 also closes a circuit through relays 267, 268 and connects the testwiper 350 of the switch SS to a point between these relays. The switch SS consists of two separate fourwiper switches, of which the stepping magnets 263, 264 are both controlled by and both control the relay 267. The two switches therefore hunt in unison like a single switch to find an idle register-sender, whereupon relay 268, being no longer short-circuited over the test wiper, becomes energized, disconnecting the test wiper from the relay 267 and connecting it to ground. As soon as both switches TS, SS have completed their operations, a circuit 275, 289, 305 is closed to light the lamp L<4>, Fig. 1, associated with the jack J<2> of the selected trunk at the operator's position. The lamps associated with the multiple jacks of the same trunk at other operator's positions are each in a different circuit, and are not lit. Meanwhile relay 281 has grounded the circuit 306 to start a switch C, Fig. 2, which hunts for an idle trunk X to the wanted exchange, whereupon relays 50, 70, 71 become energized, the upper winding of the relay 70 receiving current over the circuit 306. Registration of the wanted number. The grounding of circuit 158 by relay 268 energizes relay 103, Fig. 4, which closes a circuit through a relay 104 in series with four pairs of relays 121 - - 130 connected in series-parallel. These relays, being stiffly adjusted, do not respond, nor does the relay 104, which is differentially wound. Relay 103 also grounds a circuit 167, 420, 424 to energize relays 453, 454, which connect the circuits 141 - - 150 to relays 471 - - 480. The operator, noticing the lighted lamp L<4>, releases the exchange key 221 and successively depresses keys corresponding to the digits of the wanted number. These keys 201 - - 210 connect either ground or battery to the wires 228 - - 232, which are connected over circuits 156 - - 152 to midpoints of the pairs of relays 121 - - 130, the arrangement being such that each key energizes a corresponding relay. Thus if the operator first presses the key 204, this connects battery to the circuit 229, 155, short-circuiting the relay 123 and strengthening the current in relay 124 so that it becomes energized. At the same time relay 104 is unbalanced and becomes energized, energizing relay 102, which locks itself. The relay 124 energizes a corresponding relay 474 of the register series '471 - - 480. When the operator releases the key 204 the relay 124 relapses and opens the original circuit 144 of relay 474, but this relay remains locked in series with a relay 452, which was previously short-circuited over wire 144 but which now becomes energized. The relay 452 de-energizes relays 453, 454 and closes the circuit 524 of the corresponding relays 553. 554 of the next digit register, Fig. 8. The wires 141 - - 150 are thus disconnected from the register relays 471 - - 480 and connected to the register relays 571 - - 580, and the next key depressed by the operator causes the energization of the corresponding relay of this series, after which the wires 141 - - 150 are transferred to another digit register, and so on. Impulse transmission. After registering the wanted number the operator plugs into the jack J<2>, Fig. 1, energizing a sleeve relay 26, Fig. 2, which completes a circuit 307 to energize relay 269, Fig. 5, which first closes contact 277 to energize relay 101, Fig. 4, over circuit 157, and then operates its other armatures. Relay 101 connects the circuit 169, which is grounded in each digit register, to wire 168 to energize relays 409, 410 and to complete the circuit of a relay 407, which is intermittently energized by a cam-contact 412 -and energizes the stepping magnet 403 of the sending switch CS. At its first step off normal the switch CS energizes relay 406, which opens a contact 416, so that each subsequent energization of relay 407 removes ground from the circuit 165, 151, 279, 306 so as to de-energize relay 70, Fig. 2, which opens contact 75 to transmit an impulse over the trunk X. When the wiper 402 reaches the circuit 434 that has been grounded by the register relay 474, a relay 405 becomes energized and locks itself, open-circuiting the relay 407 to prevent the transmission of further impulses and closing a self-interrupting circuit 403, 404, 413, 401 to step the switch CS rapidly forward until it regains its normal position. A relay 451 is energized at the same time as relay 405 in a branch circuit 425. When the switch CS regains its normal position the relapse of relay 406 removes ground from the circuit 425, and a relay 450, previously short-circuited, becomes energized in series with relay 451, disconnecting ground from the circuit 441, 494, 434 and extending ground to a similar circuit, such as 523, 542, 595, 435, in the next digit register. A moment later the relay 405 relapses and re-connects the relay 407 to start the transmission of the next digit, which is controlled in a similar manner. After all the digits have been sent, ground is disconnected from the circuit 169 at all points such as 457, Fig. 7, and 557, Fig. 8, and since there is therefore no longer a ground on the wire 168 the impulse relay 407 cannot be energized again. Release of sending-equipment. The relays 409, 410 now successively relapse, and in the interval ground is momentarily disconnected from the circuit 424, so as to unlock the registers, and from circuit 158, so as to de-energize relays 102, 101, 103, and 268. The relapse of relay 268 connects the upper winding of relay 269 in parallel with its lower winding, increasing the current in circuit 307 so as to energize a marginal relay 25, Fig. 2, which locks itself, switches the connection through, and opens the circuit 307 to deenergize relay 269, causing the de-energization of relays 280, 281. All the sending-equipment is now available for fresh service. Supervisory signals. The relay 70, Fig. 2, is now energized in series with resistances 83, 84 over the two sides of the cord circuit. When the called subscriber replies, the reversal of current in the trunk X energizes an electropolarized relay 72, which bridges the relay 70 directly across the wires 63, 65, thus increasing the cord current sufficiently to energize a marginal supervisory relay 8. Wiping out incorrect registrations. This is effected 'by a key 215, Fig. 5, which energizes a relay 408, Fig. 6, to disconnect ground from the wire 424. Second link circuit. The relav 251, Fig. 5, energized by relay 269 after a call has been registered, connects the keys over wires 254 - - 261 to the operator's second link circuit. When the sending operations of the first call have been completed the relay 269 relapses, but if the operator has meanwhile taken the second link circuit into use for a second call, the relay 251 is kept energized over wire 262, independently of the relay 269, until the registration of the second call has been completed, the circuit of the relay 251 being controlled by a back contact, instead of a front contact, of the relay 269 of the second link circuit. Connection severed by operator before sending operations are completed. In this event a relay 27, Fig. 2, which was energized by the sleeve relay 26 sufficiently to attract its armature 37, becomes fully energized on the relapse of relay 26, opening the outgoing line circuit and keeping the circuit 307 closed until the sending operations are completed and the register-sender restored to normal.