Triggering in the reversible half-wave magnetic amplifier

This paper describes a type of instability or triggering observed in the half-wave bridge circuit. The circuit, described in the literature by Lufcy and others, is shown schematically in Fig. 1(A).2¿5 An explanation of this triggering is presented based upon a type of reverse-slope magnetic-loop operation not previously described in the magnetic-amplifier literature (see acknowledgment). Figs. 2(A) and (B) are two commonly used models of the dynamic loops of ¿square-loop¿ magnetic-core materials. The paper shows that neither model predicts the observed triggering but that a loop having the ¿reverse slope¿ of Fig. 2(C) readily predicts the instability. In Fig. 2(C) the lower minor loop lies to the right of upper minor loop, and lines connecting their centers or flanks would have a negative or reverse slope. The reality of this reverse-slope phenomenon has been determined experimentally, and verifying data are presented. The reader is cautioned that the reverse-slope phenomenon applies only to minor hysteresis loops and not to major loops operating over the entire range from positive to negative saturation. The reader should also be aware that no model of minor- or major-loop operation can be expected to apply to other than a limited range of exciting conditions.