Ammeter with the Magnetic Sensor Using Parametric Oscillation

A parametric magnetic sensor was used to develop a clamp-type ammeter capable of measuring low currents in the range from dc to high frequencies. The principle of operation is described, and results for the output of a prototype device are presented. The frequency characteristic was flat from dc to a few hundred Hz. The range of measurable currents may be adjusted by appropriate design of the magnetic core and the number of core windings.