一种简易毫欧电阻计的设计

Design of Simple Milliohm Resistance Meter

该文基于欧姆定律设计了一种简易毫欧电阻计,基本原理为采用精密参考电流源驱动待测电阻产生压降信号,再通过仪表放大器差分放大后,送入16 b分辨率的ADC,由单片机控制采样并显示输出测量结果。其中,待测电阻端采用四线制接法,去除接线端子的引线电阻,减小测量误差。同时采用6位半数字万用表对精密驱动电流值、仪表电路的放大系数进行校正。实验结果表明,该毫欧电阻计测量范围为0.01Ω~10Ω,分辨率可达1 mΩ,测量误差为1%,结构简单,成本低廉。

Based on Ohm＇s law,the article designed a kind of simple milliohm resistance meter. The basic principle was using precision reference current source to drive the measured resistance and generate a drop voltage signal,and then the signal was through into the instrumentation amplifier for differential amplification,sent to 16 bit resolution ADC for digital sample. The micro-process controlled the process of sampling,calculated and displayed the measurement results. Besides,the four wire method was used in the measured resistance access port for removing the influence of the wire resistance and reducing the measurement error. At the same time,the 6.5 b digital meter was used to correct the precision driving current value and the amplification factor of the circuit. The experimental results showed that the milliohm resistance meter measuring range 0.01 Ω ～10 Ω,and its resolution can reach up to 1 mΩwith 1% accuracy,having simple structure and low cost.