GB139867A - Improvements in the methods of using three-electrode ionic tubes, applicable for wireless telegraphy and other purposes - Google Patents

Abstract

139,867. Turner, L. B. Feb. 17, 1919. Thermionic relays.-A pair of thermionic valves have their circuits arranged so that the plate circuit of each valve is coupled by a resistance or galvanic coupling to the grid circuit of the other valve. The arrangement may be employed for wireless telegraphy and other purposes as an amplifier, rectifier, oscillation generator, or as a current limiting device for eliminating interference by " atmospherics." Fig. 3 shows an arrangement in which the input electromotive force is applied at the terminals e in the gridfilament circuit of the valve 1, which comprises a battery b' and resistance r<2>. The plate circuit of the valve 1 comprises a battery B' and resistances R<1>, r'. The grid-filament circuit of the valve 2 includes a battery b<2> and the resistance r<1> of the plate circuit of the valve 1. The plate circuit of the valve 2 reacts on the grid circuit of the valve 1 by including therein the resistance r<2>. The amplified electromotive force may be taken off across the plate and filament of one of the lamps, or, as shown in Fig. 3, across the two plates. This may be applied to the grid of a third valve 3 having an indicating-instrument, for example, a telephone T, in its plate circuit. For receiving low-frequency signals, capacitative resistance coils may be used in the valve circuits, whilst for high-frequency currents the self-capacity of resistances and batteries should be as low as possible. Batteries with constant electromotive force, for example Weston cadmium cells, are preferred for the grid circuits, or the variation of electromotive force with temperature may be compensated by suitable resistances. In adjusting the circuits, r', r<2>, b<1>, b<2> may be varied and current changes in the plate circuits observed. If the product r<1>, r<2> is too large, sudden changes in the plate currents occur as the grid potentials are varied by potentiometers. The resistance r<1 >or r<2> is then reduced until the sudden changes disappear.