A load detecting circuit has a primary side and a secondary side with a secondary side patient load impedance input having a patient-side opto-isolator and a secondary side reference resistance load input having a reference-side opto-isolator coupled to the secondary side patient load impedance input. The circuit also includes at least one primary side output resistor, wherein the patient-side opto-isolator and the reference-side opto-isolator drive the at least one primary side output resistor and an integrator for operatively controlling the secondary side and conveying the patient load input and the reference load input to the primary side, where the patient load input and the reference load input are powered by a secondary side transformer winding.