GB736142A - Improvements in or relating to electric discharge tube circuits - Google Patents

Abstract

736,142. Discharge-tube gating circuits. STANDARD TELEPHONES & CABLES, Ltd. Dec. 7, 1951 [Dec. 12, 1950], No. 30363/50. Class 40 (6). A " one " or " all " gate circuit comprises a cold-cathode gas-filled discharge tube having two or more identical gaps so arranged that a predetermined change in potential on one gap will result either in a change of potential in the output circuit or in a change of potential in the output circuit only if the potentials across all the gaps are less than a predetermined value. Fig. 2 shows a coincidence circuit comprising a cold-cathode discharge tube of the type described in Specification 736,143, [Group XL (a)], having an anode A and discharge gaps G1-G4. Normally the cathodes are at earth potential except for G 1 which may be for example at - 10 volts so that discharge takes place only across gap G1. If 50-volt positive pulses are applied at P1 then the discharge will transfer to any other cathode which is at earth potential but if the voltage at points P1-P4 is raised simultaneously to 50 volts then the discharge will cease and a positive output pulse will appear at lead OP. In a modification, Fig. 3 (not shown), two such discharge tubes are operated in parallel so that an output pulse is obtained only when coincidence occurs in both tubes simultaneously. In a further modification, Fig. 4 (not shown) two discharge tubes have their inputs parallelled and driven from the anode of a similar tube, coincidence on either of the former two tubes resulting in an output pulse at its respective anode. The output pulse on coincidence may be produced across a highresistance cathode load resistor, Fig. 5 (not shown), or several outputs may be taken from across the loads of several cathodes, Fig. 6 (not shown). Fig. 8 shows one stage of a multiple coincidence circuit in which coincidence of all the voltages applied at the cathodes P1-P5 of any one of the fifteen discharge tubes such as CT8 results in a positive pulse across the common load resistor R7 and the firing of tube TRIS. Fig. 9 shows the combination of a coincidence circuit comprising discharge tube D1 with a mixer of " one " type gating stage comprising tube D2. The priming cathode PC of the coincidence tube D1 maintains a small auxiliary discharge and in the presence of positive pulses applied simultaneously at inputs 1-6 a positive output pulse is produced at the anode. This pulse is applied to an anode of tube 12 and the outputs of other similar coincidence tubes are connected to corresponding anodes so that when coincidence occurs on any tube a positive output pulse is produced across the cathode load resistor. The tube D2 comprises a tube such as D1 in which the common electrode is used as cathode and the individual electrodes as anodes. Specification 636,700 also is referred to.