SENSOR VARIATION DETECTING DEVICE

PROBLEM TO BE SOLVED: To obtain a sensor variation detecting circuit with high detection precision which is suitable for control over equipment having a wide temperature area to be used. SOLUTION: A sensor 2 which varies in resistance value as the circumferential environment changes and a fixed resistance 5 are connected in series and a DC voltage is applied to one end of the sensor 2 and one end of the fixed resistance 5; and the quantity of variation in the resistance value of the sensor 2 which varies as the circumferential environment changes is observed by digital equipment 1 in the form of the voltage at the connection point 6 between the sensor 2 and fixed resistance 5 and table data in the digital equipment 1 are referred to, thereby detecting the environment value. Prepared series-connected fixed resistances 3 and 4 and PNP transistors 9 and 11 are used and the resistance values of the series-connected fixed resistances 3, 4, and 5 are properly varied.