Abstract: Stimuli are initiated by a master oscillator, whose output is split and applied to two frequency dividers which divide the frequency by different numbers. The two frequencies thus derived are applied to waveshapers to provide a desired waveform such as a half sinewave, and also each signal is further divided by a common number. The two signals are then amplified, and applied to the body through a probe whose contacts are arranged so that the two stimuli currents are orthogonal to each other. The two high frequency signals hetrodyne within the human muscle to produce a single low frequency stimuli, useful for the production of muscle contraction, hyperemia, electroanalgesia and muscle relaxation.