Introduces some instruments used to accurately measure the low level DC voltage of low level DC current ,this paper analyzes the characteristics it need ,and put forward a feasible method of designing ammeter and voltmeter .% 介绍了低电平情况下精确测量直流电流、电压的一些工具，分析其中所具备的特性，提出了可行的电流计、电压计的电路设计方法。
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