An Analysis of the Modes of Operation of a Simple Transistor Oscillator

A simple transistor oscillator circuit is analyzed in an illuminating way. The analysis predicts oscillation in either of two modes and provides a means of determining the maximum frequency of oscillation in each. The two modes are identified as "three-terminal" or "two-terminal" according to whether RF current is required in the base lead to produce the oscillations. The relationship between these modes is developed and visualized in a "frequency portrait" for the transistor which serves to unify the principal results of the paper.