Self-balancing potentiometer-type magnetic amplifiers

MAGNETIC AMPLIFIER FEEDBACK circuits generally have no influence upon the effective input impedance of the control circuit, because the d-c feedback component flows through special feedback windings, “external feedback,” or in the load windings, “internal feedback” or “self-saturation.” Therefore, the effective impedance of the control circuit is determined solely by the actual total resistance of this circuit comprising the resistance of the control windings and a series resistor which is conventionally provided to increase the speed of response of the magnetic amplifier.