GB506542A - Improvements in or relating to thermionic amplifiers - Google Patents

Abstract

506,542. Valve amplifying circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Nov. 30, 1937, No. 33143. Convention date, Nov. 30, 1936. [Class 40 (v)] Variations in supply voltages to a pushpull .thermionic amplifier, due e.g. to large audio-frequency signal potentials and poor regulation in the supply unit, are compensated by applying the supply voltage fluctuations to the valves in parallel through a condenser. The Figure shows a push-pull amplifier 26 fed from a mains supply unit 34 and taking its input from a radio receiver 32. Grid bias, obtained from the field coil 40 of the loudspeaker 29, is applied over resistances 43 and 43a, but the decoupling condenser 49 is connected to the positive high tension lead 37. Thus any voltage variations across 37, 38 are fed 'back in reverse phase over condenser 49 to the amplifier grid circuits and are thus self-neutralizing. The amplifiers 26 in this case also operate as control or compensating valves. Specification 421,189 is referred to. The Specification as open to inspection under Sect. 91 also describes an arrangement comprising a low-frequency amplifier associated with a control valve acting as a variable shunt across a part of the voltage supply circuit, the voltage variations being applied to the grid of the control valve, Fig. 1 (Cancelled) (not shown). This subject-matter does not appear in the Specification as accepted.