GB641567A - Improvements in and relating to voltage stabilisers for direct current supplies - Google Patents

Abstract

641,567. Automatic voltage control systems; smoothing direct currents. FURZEHILL LABORATORIES, Ltd., and SMITH & SONS (ENGLAND), Ltd., S. Nov. 28, 1947, No. 31583. [Classes 38 (ii) and 38 (iv)] In a D.C. voltage stabilizer of the type having an impedance in series with the output and a. variable impedance valve across the output, a second valve amplifies changes in current in the first and provides positive feed-back to accentuate the regulating action. A resistor 1, which may be constituted by the internal impedance of the supply, is connected in the positive line between input 12 and output 14; and a potential divider 2, 3, controls the bias applied to the grid of the regulating valve 4 connected across the output, variations in output voltage producing correcting variations in the impedance of the valve. A neon tube 5 provides a constant reference voltage in the cathode circuit, which also includes a resistor 6 which is common to a second valve 9, the grid of which is connected to the negative line, so that the voltage across resistor 6 is amplified and fed back by resistor'7 to the grid of valve 4 to augment any change in control voltage. Resistor 6 may be adjusted to give a minimum ripple voltage in the output. In a modification, Fig. 2 (not shown), the resistor 1 is replaced by an inductance, the neon tube 5 by a resistor, and the resistor 7 by a condenser, the circuit then serving to remove short period fluctuations only.