Isolation electromagnetically coupled DC and AC current sensor and detector

The paper describes an approach to the design of an isolation electromagnetically coupled DC and AC current sensor and detector. The sensor includes a magnetic multivibrator using one of the coils of a nonlinear transformer. The oscillation duty cycle in this multivibrator changes with the polarity and value of the input signal current in another transformer coil. To detect this duty cycle variation the output voltage of the multivibrator comparator is applied to an integrator and a sample-and-hold amplifier. The circuit was designed to measure the currents in the range from -2.5 to +2.5 mA. The frequency response of the circuit was flat up to 1000 Hz. A digital processor allowing one to represent measurements in a digital form was designed as well