GB223625A - Thermionic valve circuits - Google Patents

Abstract

223,625. Lodge, Sir O. J., and Robinson, E. E. June 20, 1923. Thermionic amplifiers and detectors.-A feeble alternating potential is worked up to a stronger alternating potential of the same frequency by the use of a low-resistance resonating circuit, capable of precise, tuning and having only a single connection with the conductor in which the feeble alternations occur. This circuit is uncoupled or only coupled so that the output takes so small a current as not to interfere with its free oscillation. In the circuit shown, a single connection only is made from a receiving circuit 15 to the low-resistance resonating circuit 17 connected across a thermionic value 16. A similar connection is also shown between the output of the valve 16 and the input of valve 20 in the form of the low-resistance resonating circuit 18 which is transformer coupled to the valve 20. In a modification, the receiving circuit is, on one side, directly connected to either the grid or filament of a valve, and, on the other side, is connected to the low-resistance resonating circuit, which is connected at the opposite point to the other input electrode of the valve. In a further modification, the low-resistance resonating circuit is joined directly to the grid of a valve and stimulated by joining an opposite point in the circuit to an aerial with no earth connection. The resonating circuit may also be connected across a crystal detector. One of the Provisional Specifications describes an arrangement to amplify the effect of the resonating circuit, in which the resonating circuit is connected to the grid of an auxiliary valve, the filament of which is joined to the source of oscillations while the plate is joined through a battery to the filament of the main amplifying valve. It also states that the inductance coil of the low-resistance circuit may be in relatively adjustable halves.