Voltage Measurements in the Presence of Strong Fields

A description is given of an apparatus capable of measuring instantaneous voltages in the presence of heavy current discharges. The basic advantages of the system are (1) a single ground connection which is independent of the two points of the desired voltage, (2) cancellation of induced voltages in measuring circuit by electronic means with bandpass depending only upon amplifiers used, (3) the cancellation of the measuring circuit pickup is insensitive to large changes in the geometry of the measuring circuit.