毕业论文：数字式电容测试仪的设计.doc

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4、LinesToPoctionParagraSelec摘要本设计是基于555定时器，连接构成多谐振荡器以及单稳态触发器而测量电容的。单稳态触发器中所涉及的电容，即是被测量的电容。其脉冲输入信号是555定时器构成的多谐振荡器所产生。信号的频率可以根据所选的电阻，电容的参数而调节。这样便可以定量的确定被测电容的容值范围。因为单稳态触发器的输出脉宽是根据电容值的不同而不同的，所以脉宽即是对应的电容值，其精确度可以达到0.1%。然后在电路中加入一个由LM741以及一个电容和一个电阻构成的阻容平滑滤波器，将单稳态触发器输出的信号滤波，使最终输

5、出电压与被测量的电容值呈线性关系。最后是输出电压的数字化，将输入到7448译码器中翻译成BCD码，输入到LED数码管中显示出来。关键词：:电容，555定时器，滤波器，线性，译码器，LED数码管SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSp

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