GB182839A - Telephone systems - Google Patents

Abstract

182,839. Western Electric Co., Ltd., (Western Electric Co., Inc.). Jan. 21, 1921. Automatic exchange systems.-A relay for testing the busy or idle condition of a wanted subscriber's line is connected to the test terminal through contacts of a second transiently-energized relay, the circuits being such that the test relay becomes energized immediately if the line is busy, in which case it locks up the second relay and connects busy tone to the calling line, but if the line is idle the test relay does not become energized until the relapse of the second relay, whereupon it causes ringing current to be transmitted. The invention is described in its application to a relay connector, comprising tens and units ccunting chains and tens and units series of connecting relays. The line relay 306 energizes a slow-release relay 307 which grounds the holding wire 308. The tens impulses are repeated to a relay 313 and cause the successive energization of counting relays 316, 324, &c. In response to the first impulse, relay 313 locks itself in series with relay 316, but as long as ground is connected direct to relay 313 relay 316 is short-circuited. At the termination of the impulse however this short-circuit is removed and relay 316 becomes energized, locking itself up, unlocking relay 313, and transferring the impulse circuit to the next relay 324, which accordingly becomes energized at the termination of the next impulse, and so on. As long as impulses are passing, a slow-release relay 314 is energized in series with relay 313, but at the termination of the digit, relay 314 relapses and energizes a relay 315, which locks itself up and transfers the impulse circuit to the lower series of counting relays 319, 320, &c., so that the impulses of the final digit cause the successive energization of these relays. At the termination of the final digit the relapse of relay 314 connects ground to tens and units wires, such as 325, 322, selected by the upper and lower counting chains, to energize the appropriate connecting relays 323, 326. A relay 327, controlled by relay 314, remains energized for a moment and connects the test wire 329 to the left-hand winding of a relay 311. If the wanted line is busy the relay 311 becomes energized, locking itself up, locking the relay 327, and closing the circuit of a busy-tone transformer 334. If, however, the wanted line is idle the relay 311 does not at this stage become energized, but the relapse of the relay 327 a moment later connects the test wire 329 to the grounded right-hand winding of relay 311, which becomes energized in series with the cut-off relay 328. A relay 330 is now energized and connects up a source of ringing current 332. On the reply of the called subscriber a relav 331 becomes energized, locking itself up and completing the talking connection.