| 摘要 |
PURPOSE:To convert the extent of resistance variation into a voltage without using any bridge circuit by allowing an operational amplifier to process a resistance element output which is insensitive to an object to be detected connected to respective power sources, and a resistance element which varies in resistance value with the object to be detected. CONSTITUTION:A gauge resistance 24 which varies in resistance value R with pressure, etc., by DELTAR and a resistance 25 which has a resistance value R and is insensitive to pressure, etc., are connected between the inverted input terminal of the operational amplifier, and a positive voltage source 25 and a negative voltage source 26, and the uninverted input terminal of the amplifier 21 is gounded for biasing. The connections result in that the output voltage V0 of the amplifier 21 is a voltage proportional to a resistance variation rate DELTAR/R satisfying an equation I, and the amount of resistance variation is converted into a voltage by the simple constitution which requires no bridge circuit. In the equation, Rf is the feedback resistance value of the operational amplifier and VE is the voltages of the power sources 24 and 25.
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