Feedback circuits in general, and op. amp. applications which embody feedback principles in particular, playa central role in modern electronic engineering. This importance is reflected in the undergraduate curriculum where it is common practice for first-year undergraduates to be taught the principles of these subjects. It is right therefore that one of the tutorial guides in electronic engineering be devoted to feedback circuits and op. amps. Often general feedback circuit principles are taught before passing on to op. amps., and the order of the chapters reflects this. It is equally valid...