[Electromedical patient protection circuit]

As protection against too high an input voltage, anti-parallel diodes have long been incorporated in the input circuit of electromedical measuring instruments. This protective principle also functions in the other direction and can be used in an appropriate circuit design to protect the patient against earth fault currents, originating from the appliance. After a short review of present electromedical protection systems, the author describes the new protective circuit and initiates a discussion about it and still open questions.