Improved means for minimizing the sound caused by alternating currents in electronicvalves heated by alternating current

摘要

226,555. Telefunken Ges. f³r Drahtlose Telegraphie. Dec. 18, 1923, [Convention date]. Thermionic amplifiers and generators.-In a thermionic amplifier or oscillation-generator in which the anode and filament are both fed from alternating-current sources of the same frequency, provision is made for permanently adjusting the relative phase-angle of both doublefrequency disturbances, so that they mutually oppose and counteract each other. The filament current is supplied from a source c, Fig. 1, through a transformer d, the filament being shunted by a resistance e to which the centre tapping from the oscillatory circuit b is taken in known manner in order to remove the singlefrequency disturbances. The plate supply is derived from a source g through a transformer h and full-wave rectifier i. The phase relation between the two generators g and c is first set in opposition by means of a coupling k, connecting the two rotors, and the amplitudes of the doublefrequency disturbances are then equalized by adjusting the value of the smoothing condenser g across the rectifier. As shown in Fig. 2, the necessary equalizing adjustments are secured by variably coupling the grid circuit to the anode supply through coils m, n. By shunting these coils with variable condensers p, p1 and tuning the circuits so formed to the frequency of the disturbances an additional fine adjustment of phase angle is obtained. Or suitable impedance elements may be inserted for this purpose in the anode and grid circuits.