Magnetic characteristics of cores in amplifiers

A METHOD of measuring the magnetic characteristics which control the manner in which cores operate in self-saturating magnetic amplifiers is necessary both for economical production and accurate design of such amplifiers. Because of the eddy-current-type effects present, even in thin gauges of the rectangular loop magnetic materials used in cores for high-performance self-saturating magnetic amplifiers, it has not been found possible to directly relate the amplifier performance to usual d-c or a-c hysteresis loop measurements.^{1, 2} When operating in an amplifier, a core will generally follow a peculiar minor hysteresis loop determined by the combination of core magnetic characteristics and conditions imposed by amplifier circuitry.² Thus to predetermine the behavior of a core, it must be tested under conditions which simulate amplifier operation.