GB769698A - Improvements in or relating to thermionic valve signal selecting circuits - Google Patents

Abstract

769,698. Thermionic distributers. CINEMATELEVISION, Ltd. March 10, 1955 [March 10, 1954], No. 6965/54. Class 40 (3). [Also in Group XL (c)] A signal selecting or gating circuit comprises a plurality of electric discharge tubes which share a common anode load the signals to be selected being applied to the respective control electrodes to which are applied gating voltages from a cold cathode gas discharge sequence tube so that the gating tubes may be controlled to pass a selected signal to the load. The Figure shows a circuit in which signals to be selected are applied at inputs 11, 21, 31, 41 to gating tubes 1-4 which have a common anode load resistor 6 and are normally biased beyond cut-off by positive voltage applied to their commoned cathodes via resistor 10. Each control grid is connected via a signal filtering circuit 14, 15; 24, 25, &c., to a cathode load resistor 16, 26, 36, 46 of a cold-cathode gas sequence tube 5 which has guide electrodes 55, 56. By application of negative control pulses to terminal 60 an anode/cathode discharge in tube 5 may be caused to travel to any selected cathode thus opening a given one of the gate tubes 1-4 and passing a selected one of the signals of inputs 11, 21, 31, 41 to the output terminal 7. The circuit may function as a distributer of the input signals by controlling tube 5 so that the gate tubes 1-4 open sequentially. Specification 747,489, [Group XXXVI], is referred to.