The Utrecht 850 kV cascade generator II. The beam integrator and galvanometer

Abstract

A current integrator is described for the integration of currents from 0.01 to 500 μA with an accuracy of 0.1%. The principle used is essentially the same as that of the excellent circuit described earlier by Helmer and Hemmendinger. The modifications effected result in a considerable reduction in expense, as well as a lower input impedance. Due to increased high frequency gain much smaller condensers are necessary in order to maintain the input voltage within some hundredths of a volt of ground, at all times. The integrated current is measured as the number of output pulses, each pulse representing a fixed amount of change. Except for the condensers, no special components are used. A low-impedance electronic galvanometer for operation in series with this integra or is also described. This circuit combines the advantages of imperceptible zero drift, fixed calibration, and essentially absolute protection against burn-out