Comparison of directly and indirectly measured control characteristics of magnetic amplifiers with external feedback

Directly measured static control characteristics of external-feedback-type magnetic amplifiers with Silectron, Orthonol, and Supermalloy tape cores are compared with the corresponding ordinary-saturable characteristics obtained in a previous experimental study.1 With free even-harmonic conditions, minimized rectifier-reverse-current effects, and moderate ampere-turn gain (up to approximately 100) there is good agreement between corresponding characteristics. With high-ampere turn gain values (approximately 300 to 500, as obtained with nickel-iron alloy core materials) there are differences between the directly and indirectly measured characteristics which are not fully explained. They may, however, be accounted for by the variations of actual forward resistance and reverse-current effects of the feedback-rectifier elements.