The nonlinear theory of a class of transistor oscillators linear differential equation of the form is developed, using the Ebers-Moll large-signal model for the transistors. Simplified versions of tuned-collector, tuned-base, and Hart ley transistor oscillators are shown to be characterized by a nonlinear differential equation of the form
![\\ddot{x} - \\mu[e^{a dot{x}} - \\kappa e^{(a+b)dot{x}}] + \\gamma dot{x} + x = 0](/images/tex/11078.gif)
where

, and

are positive constants and

. Approximate solutions of the above equation, which are derived in a very simple manner using the phase plane approach, are compared favorably with experimental results. A push-pull version of the tunedcollector oscillator characterized by the above equation with the exponential terms replaced by hyperbolic sines is discussed.