GB774830A - Improvements in or relating to electric control circuits - Google Patents

Abstract

774,830. Supply systems depending on the use of a plurality of sources. DECCA RECORD CO., Ltd. Nov. 10, 1955 [March 30, 1955], No. 9338/55. Class 38 (4). A circuit for the control of a high direct voltage, say for the reflector electrode of a klystron, comprises a potentiometer network 10-16 connected across a high voltage source B, E and of which the adjustable resistor 16 is at the earthed, or low potential, end of the network, there being a grid-controlled valve 18 in series with a load resistor 17 and a stabilized lower voltage source D, E connected in shunt across the potentiometer network with the grid of the valve energized from a point on the potentiometer network, so that the output voltage, which appears between terminals C, E, can be controlled by the resistor 16. Resistors 15, 16 may be remote from the rest of the apparatus, being connected to the other elements of the potentiometer by a single lead 30 and earth. The preset resistors 12, 14 determine the range of control provided by the adjustable resistor 16. A second valve 20 cathode-coupled to valve 18 and having an anode load 21, 22 equal to load resistor 17 may maintain the loading on the stabilized source constant as resistor 16 is varied. The second valve is biased over resistors 23, 24. A changeover switch 25, which permits the output terminal C to be connected to either of the two valves, provides for alternative output voltages for a given setting of resistor 16. The circuit shown is for controlling a voltage which is negative with respect to earth, but it may be re-arranged for controlling a positive voltage.