In designing electronic equipment for regulation of d.c. generators it is essential to know the effect on the regulated current or voltage of all possible variables in the regulating equipment as well as those in the generator proper. This paper presents, in the static case, a method of treatment which enables one to appraise quantitatively the importance of any source of possible instability in amplifier or generator. The method is applied to two types of regulating equipment, concerning which detailed information is included.