The first harmonic method is usually applied to nonlinear system analysis,
being particularly adequate for the study of oscillations. As shown in this
paper, oscillators analysis can be performed by using only basic concepts
of circuit theory. The nonlinearities present in the oscillator electric ci
rcuits are approximated, via first harmonic method, by resistance or source
-controlled equivalent circuit elements, and the resulting linear circuits
are entirely analyzed via conventional circuit theory, As a result, the ana
lysis of electric oscillators and the first harmonic method are introduced
in a comprehensible electric circuit context.