| 摘要 |
PURPOSE:To effect the stable oscillations without any influence from the leak resistance at the base side of a sensor, which guards two pins, by constructing a resistance-frequency converter with the use of the sensor and two amplifiers. CONSTITUTION:In the surface of a base 17 for supporting the two pins of a sensor 12, the housing the base to enclose the respective pins is enclosed by a guard ring condutor 18, which is connected with a grounding pin 16. The sensor 12 thus constructed is inserted as a resistor, which is operative to determine the frequency of a resistance-frequency converting circuit, into this circuit. This circuit is composed of two amplifiers 21 and 22. Thus, even if leak resistors 26 and 27 are changed, a sensor resistor 20 is left invaried. And, the resistor 26 can be neglected because the output impedance of the amplifier 22 is low. Moreover, the resistor 27 is also neglected because the impedance taken from the inverted input terminal of the amplifier 21 is high. Thus, the stable operations can be performed without any influence from the leak resistance of the sensor 20. |
