Integrable, wideband, automatic volume control (a.v.c.) using Pythagoras's law for amplitude detection

The design of an a.v.c. is a simple application of control theory. The main problem in realising an integrable wideband a.v.c. is the amplitude detector. An implementation of Pythagoras's law acts magnificently in a slow a.v.c. However, in a fast a.v.c., offset will cause some 2nd-harmonic distortion.     

Semi-ideal sine oscillators (s.i.s.o.)

A class of semi-ideal sine oscillators (s.i.s.o.) featuring independent control of frequency and damping and lack of spurious responses is described.