Tubes à décharge électrique

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 conne