Self-contained automatic recorder of the dc Josephson current

A circuit for the automatic recording of the dc Josephson current as a function of magnetic field or other variable has been designed and constructed. The apparatus requires no additional signal processing devices as have techniques for this measurement utilized in the past. Sensitivity to critical current amplitudes corresponding to the appearance of 5 mV across a sensing resistor is attained, as well as separate examination of the positive and negative halves of the zero-bias current.