| 摘要 |
PURPOSE:To provide a highly accurate detecting characteristic over a wide temperature range by controlling a variable capacitance circuit and a nonlinear type output voltage correcting circuit with the temperature detection output of a detecting head. CONSTITUTION:A minute DC voltage resulting from the temperature change in the coil of a detecting head is generated between the opposite terminals of the capacitor C of a resistance variation detecting circuit 2. The DC voltage is inverted and amplified by the linear amplifier IC of a DC amplifier 3 and is applied to the variable capacitance diodes D1 and D2 as an inverse voltage. Consequently, the terminal capacitances of the diodes D1 and D2 are reduced and apparently, the effective electrostatic capacitance of a high frequency circuit including the detecting coil is reduced so that the increment of the output voltage of the detecting coil is counterbalanced. The output of the linear amplifier IC is applied to the base of the transistor of a nonlinear type output voltage correcting circuit 5 and acts counterbalance the nonlinear output characteristic of the range detecting apparatus, so that a substantially linear relationship is established between the range and the output. |
