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使用热电阻的多路测温系统中,为了高分辨地测出电阻的变化量,需考虑切换开关的接触电阻等不确定量的影响。本文提出一个简易可行的采样及△R_t-△V转换电路。图示的电路能自动对消这些因素的影响,配用高输入阻抗的运算放大器,能对BA_2铂热电砠在窄量程范围内做到分辨力0.01℃(流经热电阻的电流2.5mA)。文中对此电路作了详尽的分析和精确的计算。
Multi-channel temperature measurement using thermal resistance system, in order to detect high-resolution changes in resistance, the need to consider the switch resistance of the contact resistance and other uncertainties. This paper presents a simple and feasible sampling and △ R_t- △ V conversion circuit. The illustrated circuit automatically counteracts the effects of these factors. Equipped with an op amp with high input impedance, the resolution of 0.01 ° C (2.5mA through the thermal resistor) is achieved over a narrow range of BA_2 platinum thermocouples. This article made a detailed analysis of the circuit and accurate calculations.