GB368152A - Improvements in or relating to thermionic valve circuit arrangements - Google Patents

Abstract

368,152. Valve circuits. ALL G E - MEINE ELEKTRICITATS-GES., 2, Friedrich Karl-Ufer, Berlin. May 23, 1931, No. 15310. Convention date, May 26, 1930. [Class 40 (v).] Disturbing voltages due to alternating or pulsating filament heating current in equipotential cathode valves are compensated by providing separate and independently adjustable means for earthing the electric centre of the heater circuit and for adjusting the compensating voltages applied to the grid. The Figure shows an arrangement in which disturbing voltages due to ohmic leakage are compensated by variable resistances 15, 16 shunted across the heater leads of an indirectly heated valve 2, the mid-point of the resistances being connected to the grid circuit. Hum due to stray capacity couplings between heating and grid circuits is eliminated by a potentiometer 12, across the heating circuit, the slider being earthed. The resistances 15, 16 may each be shunted by a variable condenser, (Fig. 1, not shown) ; the potentiometer 12 may be used to balance out hum due to leakage, that due to capacity being compensated by two variable condensers replacing the resistances 15, 16, Fig. 2, (not shown).