Sensing and measurement of DC current using a transformer and RL-multivibrator

A circuit for sensing and measurement of DC current using a transformer and RL-multivibrator is proposed. The bridge multivibrator circuit is obtained, connecting the primary coil of a nonlinear transformer to an operational amplifier. The DC current that has to be measured is applied to the secondary of the transformer. It is shown that the DC voltage measured at the inverting node of the operational amplifier gives the information on polarity and value of DC current in the secondary. The transfer characteristic of such a DC current sensor is linear for small values of the measured DC current.<
>