GB419970A - Improvements in or relating to thermionic valve circuit arrangements - Google Patents

Abstract

419,970. Valve generating and amplifying circuits. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE, 12, Hallesches Ufer, Berlin. July 24, 1933, No. 20861. Convention date, July 22, 1932. [Classes 39 (i) and 40 (v).] A valve 1 with two or more grids has the inner grid held at a substantial negative voltage, whilst another electrode, such as the second grid, exhibits secondary emission with the result that the circuit of this electrode has a negative characteristic and its current i always flows against the applied positive voltage V. The high negative bias cuts off any current to the outer electrodes until the second grid is given a positive voltage high enough to cause it to lose more electrons than it receives. Fig. 3 shows the valve and Fig. 2 its negativeresistance characteristic. For generating oscillations, Fig. 5, or for use in an amplifier, Fig. 8, the negative-resistance is connected in series in the plate circuit of a triode valve 2, the plate characteristic of which is approximately the mirror image of Fig. 2. The characteristic of the series combination is a steeply-rising curve, indicating low resistance, preferably of a negative sign. A parallel-tuned circuit 3, 4 can be sustained in oscillation even if the circuit is considerably damped. When the circuit is used as an amplifier, Fig. 8, the input is applied to the grid of the triode valve 2, the plate circuit of which includes the negative resistance device. By approximately matching the positive resistance characteristic of the triode 2 with the negative resistance characteristic of the other valve 1, high current and voltage changes in the plate circuit result from small input voltages.