Abstract

In an electric stimulation therapy equipment two or more stimulation current circuits for simultaneous treatment of a patient, for example for muscle training or retraining, the two stimulation circuits have individual modulators for varying the intensity of the stimulation current and a function generator is provided for producing modulation in a cyclical pattern. The function generator also delivers pulses at a defined stage of the modulation cycle which go through a frequency divider with an adjustment for determining if, and by how much, the pulses are to be counted down. The frequency divider output is converted to provide control voltages for the two amplitude modulators for oppositely switching over the amplitude modulators into alternate modes. In the case of an interference current therapy equipment, the function generator controls cycles of phase modulation which produce cycles of relative phase between alternating currents supplied respectively to the two amplitude modulators and the frequency divider outputs alternately reduce the amplitude of one of the two modulators while the other of the two has an unreduced amplitude. In the case of a medium frequency stimulation therapy equipment the continuous output of the function generator provides both modulators with a voltage for producing cycles for stimulation for the patient's tissues and the frequency divider output alternately switches off the output of each modulated in turn while the other supplies modulator periods of medium frequency electric stimulation voltage.