| 摘要 |
<p>748,482. Automatic exchange equipment. STANDARD TELEPHONES & CABLES, Ltd. Nov. 9, 1951 [Nov. 16, 1950], No. 28046/50. Class 40 (4). [Also in Group XL (c)] An alternating current switching circuit comprises a gas discharge tube having a priming gap and two other gaps so that when the priming gap discharges the other gaps fire and are sustained by D.C. provided to them so that an A.C. signal will pass between two 2-wire transmission circuits which are connected respectively to anodes and to cathodes of a pair of the gaps. Fig. 1 shows a switching circuit comprising a multi-gap gas discharge tube which is fired by impressing a triggering voltage on leads X, Y across the priming gap CG. Gaps G1, G2 subsequently fire and are sustained by the D.C. supply across the mid-points of repeater coils 1RC, 0RC to complete an A.C. circuit from the 2-wire transmission circuit at " Inlet A " to that at " Outlet B ". In a modification, Fig. 2 (not shown), a series of gas tubes are used so that a single incoming 2-wire transmission circuit which is multipled to all of the tubes may be connected to any one of a series of outgoing circuits which are connected each to one of the tubes. Fig. 3 shows a further modification in which by applying a priming voltage between lead X1 and a given one of leads Y1 ... YN the incoming transmission line at " Inlet 1 " may be connected to a given outgoing line " Outlet 1 " . . . Outlet N ". If the priming voltage is applied between lead X2 and a given one of leads Y1 ... YN the incoming transmission line at " Inlet 2 " may be connected to a given outgoing line " Outlet 1 " . . . Outlet N ". By the provision of additional gaps in the discharge tubes, 4-wire transmission line switching may be provided.</p> |
