GB636909A - Improvements in or relating to voltage regulators - Google Patents

Abstract

636,909. Automatic voltage control systems; rectifying. WESTERN ELECTRIC CO., Inc. July 11, 1947, No. 18480. Convention date, Nov. 25, 1942. [Classes 38 (ii) and 38 (iv)] [Also in Group XXXVII]. The output of a pair of grid-controlled rectifiers is maintained constant by (a) a saturable choke in series with the output, (b) a series resistor and a shunt connected regulating valve; (c) grid control of the rectifiers, the grid voltage being obtained from an amplifying valve and passed via a low-pass filter. The output of a full wave connected pair of gas-filled rectifiers 22, 23 is passed to a smoothing circuit including a choke 26, the inductance of which varies considerably with load current; and thence via a resistor 29 to the load 11. A bridge 60 connected across the load includes in one arm a cold cathode tube 67 which has constant voltage drop so that a variation, e.g. an increase, in load voltage unbalances the bridge and increases the negative bias on the grid of valve 61 which has its anode/cathode circuit supplied by an auxiliary rectifier 74. Valve 62, shunted across the D.C. supply, has its grid coupled to the resistor 77 in the anode/cathode circuit of valve 61, and as this grid voltage rises, so the anode current rises, increasing the voltage drop across resistor 29 to restore the load voltage. In addition, the anode voltage of valve 62 is applied via switch contacts 45, 56 and low-pass filter 84, 43 to bias the grids of rectifiers 22, 23 so as to correct any sustained changes in load condition. For about 15 seconds after first switching on, a negative bias derived from rectifier 44 is applied to the grids of rectifiers 22, 23 via contacts 45, 46 of a delayed switching device (see Group XXXVII).