A new type of electron-optical voltmeter

An electronic instrument is described for measuring peak voltages in the range of 2¿20 kV, direct or alternating current, to an accuracy of 3%. It has a low capacitance (9 cm) and can be used in some circuits up to frequencies of 1 Mc/s or over. Its action is based on he proportionality theorem for a triode electron-optical system, in that the angle of the beam is denned by the ratio of two voltages: the anode voltage and the voltage of the modulator grid. The beam angle emains constant when both terms of this ratio are multiplied by the same factor, the modulator bias voltage being directly proportional to the voltage to be measured when the latter is applied to the anode. A high voltage is thus measured in terms of a low voltage, the instrument constituting an electron-optical potentiometer. The range of measurement can be extended as desired. The same principle can also be applied to the construction of high-voltage tubes so that they act as their own voltage-measuring instruments.