| 摘要 |
PURPOSE:To perform measurement without using a large-capacity battery by supplying a variable-frequency AC current, superposed upon a DC current, to a resonating circuit having unknown inductance, and by detecting the peak frequency of its output voltage. CONSTITUTION:When a measurement start signal is sent from a microcomputer 21 to a saw-tooth wave generator 23, a voltage-controlled oscillator 15 starts oscillating. Its oscillation output is superposed upon a DC current I through a transformer 13, and the resulting current is applied to the parallel resonating circuit having unknown inductance Lx and known capacitances C0 and C1. The terminal voltage of the resonating circuit is applied to a peak holding circuit 25 through a voltage amplifying and shaping circuit 24 and when a peak-value detection signal is sent out of the circuit 25, a frequency measuring instrument 26 holds a current frequency f0. Then, an operator 27 calculates inductance L from the value of the capacitance C0 and the value of the frequency f0. Thus, large-capacity inductance is measured economically without using a large-capacity battery. |
