JPS646767A - Current detector - Google Patents

Abstract

PURPOSE:To enhance detection sensitivity, by composing a bridge circuit of an inductance element, in which an exciting coil is wound around a magnetic core in a troidal shape formed with an amorphous thin band or a thin wire, and resistors, and capturing a current to be detected at the output of the bridge circuit as the variation in inductance. CONSTITUTION:An inductance element 1, a variable resistor 2 and two fixed resistors 3 and 4 constitute a four-side bridge circuit 5. A high frequency oscillator 6 is connected to a power source terminal of the bridge circuit 5. The high frequency oscillator 6 generates a high frequency voltage so that the output is deviated in one direction from zero. The inductance element 1 is magnetized only in the positive magnetizing direction. Adjustment is performed so that the bridge circuit 5 is balanced when the current to be detected is 0 and the output becomes 0 by using the variable resistor 7. Therefore, the high frequency voltage having the low value is outputted in one current flowing direction and the high frequency voltage having the high value is outputted in the other direction at the output terminal of the bridge circuit 5 with the zero balance point as a reference. When the voltages are amplified and made to pass through a filter, the CD output can be detected.