GB658167A - Improvements in or relating to valve amplifiers - Google Patents

Abstract

658,167. Valve amplifying circuits. BRITISH THOMSON-HOUSTON CO., Ltd. July 1, 1949, No. 17485. Convention date, July 1, 1948. [Class 40 (vi)] An A.C. operated push-pull amplifier is arranged to discriminate against signals occurring in quadrature with the supply by employing as bias for the valves either a large A.C. in phase with the supply plus a large D.C. or rectified A.C. in quadrature with the supply. The circuits are particularly applicable to systems employing amplifiers where the desired signal varies in amplitude but is either in phase or 180 degrees out of phase with the supply. The valves 1, 2, Fig. 7, are given a large negative bias by battery Ec which is neutralized by a corresponding alternating potential developed across the secondary of transformer 24. The valves are thus sensitized only near the peak of the anode potential, Figs. 8, 9 and 10 (not shown). In a modification, Fig. 11 (not shown), the alternating potential across the secondary of the transformer is rectified to supply the D.C. bias. In a further modification, Fig. 12, the A.C. fed to transformer 30 is in quadrature to that used for the anode supply. The valves 1, 2 are thus sensitized at the peak of the cusps formed by the diodes 35 conducting, which occur at the peaks of the anode supply, Fig. 13 (not shown).