PATH SWITCH OVER SYSTEM GUIDE WIRE CONTROLLED MULTISTAGE CROSSPOINT NETWORK

1,115,754. Automatic exchange system. INTERNATIONAL STANDARD ELECTRIC CORPORATION. 11 Nov., 1966 [17 Nov., 1965], No. 50568/66. Heading H4K. In a multi-stage reed-relay switching network wherein each crosspoint relay winding is connected in series with one of its own make contacts and a diode is connected between the junction of the winding and contact and a marker, the marking voltages used in each stage differ from those in the preceding or succeeding stage by an amount equal to the sum of a crosspoint relay's operating voltage and a marking diode's breakdown voltage. As shown, the marking voltages are determined by the Zener diode chain Z. In operation, and after a route finding operation which is not particularly described, the marker stage KStA closes its contact, e.g. R1, corresponding to a selected junctor VS1, and also its contact as1 corresponding to a selected column of relays KPA1 of one A-stage matrix (and similar columns in other A matrices) whereby KPA1 comes up. Thereafter contact bs1 in marker stage EStB is closed whereby KPB1 operates in series with diodes GB1 and GA1, the latter diode breaking down due to the choice of marking potentials. When the transients which occur at operation have ceased, diode GA1 recovers and relay KPB1 then holds in series with KPA1. Similar processes occur for each stage of the network, the chosen path finally being held, when the marker is released, by battery in the line circuit (on the left side of the network but not shown) and earth in the junctor. Reference has been directed by the Comptroller to Specification 1,040,651.