GB428285A - Improvements in or relating to thermionic valve and like circuit arrangements - Google Patents

Abstract

428,285. Valve circuits for wireless reception. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE, 12, Hallesches Ufer, Berlin. Oct. 10, 1933, No. 27925. Convention date, Oct. 10, 1932. [Classes 39 (i) and 40 (v)] A back-coupled valve 3, Fig. 2, or equivalent negative-resistance device, used in combination with an amplifier valve 1 is so arranged that its damping effect on a tuned circuit 2 remains independent of any change in the applied grid-bias, say for automatic volume control. Fig. 4 is a onevalve equivalent, in which the electrodes on the left-hand side of the bulb are differently designed to those on the right-hand side, so that in the former case they function as a screen-grid amplifier having a constant internal resistance over a wide range of grid bias, and in the latter as a space-charge grid valve backcoupled to introduce negative resistance. Fig. 7 is a similar two-sided arrangement comprising five grids. In Fig. 5 the right-hand half of the valve introduces negative resistance by dynatron action. In Fig. 9, the left-hand half of the valve 13 serves as a variable-mu S.G. amplifier, whilst the right-hand half acts as a space-charge grid negative-resistance device which maintains the selectivity of the tuned circuit L constant, irrespective of changes in the volume-control bias applied to the amplifier from a resistance 7 in the output circuit of the rectifier D. Specifications 423,167 and 424,792 are referred to.