GB156330A - Improvements relating to amplifying devices for use in wireless telegraphy and telephony - Google Patents

Abstract

156,330. Bolitho, J. B. Oct. 6, 1919. Thermionic amplifiers and detectors.-In a " trigger " relay, oscillations initiated by incoming signals are periodically quenched by a second valve which intermittently neutralizes the reaction between the grid and anode circuits of the triggered " valve. In the arrangement shown, the potential of the grid 2 of the " trigger " valve is brought to the required value by means of the battery 10 and potentiometer 11, and impulses induced in the grid reaction coil 9. from the coil 33 in the signal circuit, raise the potential of the grid 2 sufficiently to cause the valve 1, 2, 3 to oscillate. A condenser 34 mav be shunted across the coil 9 to tune the circuit 34, 9 to incoming signals. A second valve 12, 13, 14 is employed to neutralize periodically the reaction between the grid and anode circuits of the valve 1, 2, 3 by means of a coil 22 having a reversed reaction and included in the plate circuit of the valve 12, 13, 14. The filaments 3, 14 are connected in parallel, whilst the grids 2, 13 are joined with or without arrangements for applying a different potential to the grid 13 as compared with the grid 2. An oscillating potential is applied to the plate 12 by coupling the plate circuit to an oscillating valve circuit 23. When the potential of the plate 12 -becomes sufficiently positive, a current flows through the coil 22, the reaction of which balances out the reaction of the coil 4. The oscillations initiated in the valve 1, 2, 3 by incoming signals are thus intermittently damped out at a frequency equal to the frequency of the oscillations produced by the source 23, which should be low compared with that of the incoming signal. An indicating or recording device 7 is included in the plate circuit of the first valve. Any source of oscillations cr impulses may be used in place of the oscillating valve 23.