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Electromedical apparatus for interference current treatment

  • US 4,374,524 A
  • Filed: 08/04/1980
  • Issued: 02/22/1983
  • Est. Priority Date: 08/03/1979
  • Status: Expired due to Term
First Claim
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1. Electromedical apparatus for interference current treatment comprising at least two current circuits having current circuit output means adapted to be coupled to a patient for the purpose of interference current treatment, generator means activating the current circuits with signal frequencies of timing characteristics for effecting interference current treatment via said current circuit output means, each current circuit having a switching transistor (4, 5, 6) connected with said generator means, the transistors (4, 5, 6) having respective collector circuits for supplying collector voltages to the switching transistors, the signal frequencies from the generator means serving to operate the transistors in a switching mode such that the collector voltage of each transistor successively switches between a zero value and an operating voltage value, common control means connected with all of said collector circuits and comprising a single voltage source (23) and a common control circuit (22, 24) having an adjustable common control element means (22) for controlling the activating voltage supplied to each collector circuit so that all switching transistors (4, 5, 6) are activated on the collector side from said single voltage source (23) via said common control circuit (22, 24), and so that the magnitudes of the collector output signals of all of the switching transistors (4, 5, 6) are synchronously adjustable in dependence upon the setting of the common control element means (22), the common control element means being a potentiometer (22) connected with said single voltage source (23), said common control circuit further comprising an operational amplifier (24) having feedback circuit means providing an output-to-input current path and thereby providing a low-resistance output from said operational amplifier connected with all of said collector circuits, said operational amplifier having an amplifier input means connected with said potentiometer (22), said amplifier input means being connected with said single voltage source (23) under the control of said potentiometer (22), said current circuits further having low pass filters (10, 11, 12) having filter inputs connected with the collectors of said transistors (4, 5, 6) and having filter outputs connected with said current circuit output means for supplying sinusoidal signals in accordance with the frequency and phase of the signal frequencies.

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