基于AT89C51的金属材料电阻率测量仪
来源期刊：中南大学学报(自然科学版)2000年第6期
论文作者：Paul M D 丁家峰 曹建
文章页码：506 - 509
关键词：电阻率;恒流源;微处理器
Key words：resistivity; constant current; microprocessor
摘 要：以AT8 9C5 1微处理器为核心组成智能型微电阻测量仪 .该仪器依据四探针法原理 ,采用高稳定度的恒流源电路 ,低漂移、低噪声的直流放大器电路和自动量程转换电路构成测量回路 .恒流源采用深度负反馈技术 ,其稳定度、电压调整率和温度漂移分别小于 0 .1% ,0 .1%和 0 .0 5 % /℃ .采用了分时测量、共同一测量回路的自校准方法 ,高稳定恒电流分时通过待测试样和内置标准电阻 ,电压测量回路的输入阻抗高达 2 0MΩ以上 ,消除了试样接触电阻的影响 .通过对高精度标准电阻器组BZ 3的检测表明 ,全量程中的最大非线性误差为 0 .12 % ,对各种标号的漆包线的测量误差小于 0 .5 % ,对金属试样在腐蚀液体中的腐蚀情况能进行动态监测 ,对大试样粉末冶金样品的微小电阻也能进行精确的测量
Abstract: An instrument controlled by microprocessor AT89C51 for measuring the resistivity of metal materials was introduced. It is based on the principle of Four point probe method and has a high stable constant current power source, highly sensitive, low noise, low drift DC gain amplifier, a highly resolution A/D converter and an automatic range selector controlled by microprocessor AT89C51. The constant current power source is constructed in degenerative feedback technique. Its stability, voltage relative regulation and temperature drift are less than 0.1%,0.1% and 0.05% respectively. In measurement process, the constant current follows Rs and Rx at a time sharing process and a method of online self diagnosis was used. A serial of precise standard resisters BZ-3 was used to adjust the instrument. The results showed that the maximum error is less than 0.12%. The error is less than 0.05% in measuring the resistivity of several kinds of enameled wire. For large piece of metal samples with low resistance, the instrument can have accurate results.
