An electronic wave analyzer designed primarily for classroom teaching in electronics is described in detail. The analyzer is essentially a two-stage audio amplifier which contains series resonance loads tunable to frequencies between 300 and 2000 c/sec. Its purpose is to demonstrate Fourier's theorem visibly; namely, to show that any periodic voltage or current wave can be resolved into sinusoidal waves of various amplitudes and phases, whose frequencies are integral multiples of the lowest frequency present. Other electronic principles are demonstrated and a method for producing amplitude-modulated waves is shown.