Inductive load instability in magnetic amplifiers

LIMITATIONS in the design of high-performance magnetic amplifiers have often been attributed to imperfections in the magnetic amplifier core and rectifier characteristics. Yet, in some instances, the useful operation of the magnetic amplifier has been the result of the existence of these same so-called imperfections. Evaluation and understanding of the parameters of the material imperfections can point the way toward utilization of the characteristics that have been regarded as the limiting factors in the amplifier performance. As an example, rectifier capacitance and leakage current tend to reduce over-all amplifier gain. At the same time, inductive loading of some circuits creates additional positive feedback and instability. By adjusting the negative feedback caused by rectifier leakage current and capacitance, these inductively loaded circuits can be made to give stable high-gain performance.