Abstract
The authors have already reported on an analysis of a single core balanced output magnetic amplifier proposed by Darling (Darling's circuit).
In this paper, first, the experimental results obtained on the zero drift caused by the fluctuations in the AC supply voltage and frequency, the ambient temperature and so on, are compared with the calculated results on the basis of an analysis of Darling's circuit. When these environmental conditions are stabilized well, it is experimentally recognized that the core noise or the zero-output noise caused by the fluctuations of the amount of flux in the dynamic hysteresis loop becomes detectable. The minimum allowable input level of Darling's circuit is determined by this core noise. The magnitude of core noise in Supermalloy is about equivalent to the magnitude of zero drift that is caused by the change in the ambient temperature of core from 20 to 30°C, or of diode from 20 to 21°C. Lastly, experimental studies on the core noise are performed, so that the various characteristics of core noise are made clear.
