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1摘要数字万用表DMM(DitalMultiMeter)采用大规模集成电路和液晶数字显示技术，具有结构简单、测量精度高、输入阻抗高、显示直观、过载能力强、功能全、耗电省、自动量程转换等优点，许多数字万用表还带有测电容、频率、温度等功能。本课题的主要内容是理解DT-830B型数字万用表的基本结构和原理，通过数字万用表的组装与调试，培养电子产品安装测试技能。关键词：数字万用表原理安装调试测试2目录第一章绪论..................................................................................................................错误!未定义书签。1.1数字万用表的概述·································································································11.3数字万用表的分析和制作意义第二章DT830B型数字万用表的结构和特点...................................................................32.1数字万用表的结构组成···························································································12.2DT830B型数字万用表的特点·················································································3第三章DT830B型数字万用表的安装与调试...................................................................63.1印制电路板元器件的安装与焊接·············································································93.1.1清点和识别元件····························································································13.1.2立式电阻、电位器立式、二极管的安装··························································13.1.3锰铜丝电阻、晶体管测试座、电池扣、保险管座和输入插座的安装················23.1.4液晶片、斑马条框架和斑马条的安装·····························································23.1.5弹簧、旋纽等的安装·····················································································23.1.6后盖安装······································································································23.2DT-830B数字万用表的调试····················································································2第四章DT830B型数字万用表的测试与使用时因注意的事项...........................................64.1数字万用表的测试·································································································14.1.1电压测量······································································································14.1.2电流测量······································································································14.1.3电阻测量······································································································14.1.4电容测量······································································································14.2使用数字万用表因注意的事项···············································································1第五章致谢..................................................................................................................错误!未定义书签。第六章总结..................................................................................................................错误!未定义书签。参考文献.......................................................................................................................错误!未定义书签。3第一章绪论1.1数字万用表的概述数字万用表是采用集成电路模/数转换器和液晶显示器，将被测量的数值直接以数字形式显示出来的一种电子测量仪表。1.2数子万用表的工作原理DT803B数字万用表是以ICL7106A/D转换器为核心的数字万用表。A/D转换器将0～2V范围的模拟电压变成三位半的BCD码数字显示出来。将被测直流电压、交流电压、直流电流、及电阻等物理量变成0~2V的直流电压。送到ICL7106的输入端，即可在数字表上进行检测。为测大于两伏的直流电压，在输入端引入衰减器，将信号变为0～2V，检测显示时再放大同样倍数。对交流电压进行检测时，必须先将被测输入信号作衰减。对它的检测过程与以上提到的电流电压的检测相同。衰减之后的交流电压还要进行精密整流，变成直流电压后才能进入A/D转换器。对直流电流的检测，必须事先将被测电流变成0～2V的直流电压，也就是实现I/V变换与衰减。衰减是由精密电阻构成的具有不同分流系数的分流器完成。至于对电阻的检测则是利用电流源在电阻上产生的压降。由于被测电4阻上通过的电流是恒定的，所以在被测电阻上产生的压降与其阻值成正比。此时只需将得到的电压信号送到A/D转换器进行检测。1.3数字万用表的分析与制作的意义在现实社会中，从事电子行业的你，无论是作为操作者还是作为管理者，不能熟练识别以及操作使用各类电器元件特性和焊接技术及其原理等，在日后的工作学习中都会有很大的困难，操作者很无知，管理者很无奈。这次给了自己一个很好的机会，来制作一个数字万用表。电子技术的进步往往预示着数字仪表研制水平的新突破。近年来各项新技术愈来愈被广泛应用，并且迅速转化为生产力。数字万用表是用来诊断电路，对一些用电产品可以维修，测量电阻，电流，电压等等的电子仪器。本次设计是对数字万用表进行分析与制作，让我更加的熟悉万用表，了解其工作原理，每个档位的作用及其工作的电路图，各元器件的认识，数字万用表与指针万用表的区别和掌握焊接电路的工艺。数字万用表的制作，锻炼了自己的动手能力，提高了自己的焊接水平，使得理论与实践相结合。像这次在万用表原有的基础上载设计一个蜂鸣档，增强了DT830B万用表的功能,也更好的了解了蜂鸣器的电路图及作用。第二章DT830B型数字万用表的结构和特点2.1数字万用表的结构组成数字万用表是由数字电压表配上相应的功能转换电路构成的，它可对交、直流电压交、直流电流、电阻、电容以及频率等多种参数进行直接测量。数字电压表通常使用一块集成电路芯片,它将A/D转换5器与能够直接驱动显示器的显示逻辑控制器集成在一起，在其周围配上相关的电阻器、电容器和显示器,组成数字万用表表头。它只测量直流电压，其它参数必须转换成和其自身大小成一定比例关系的直流电压后才能被测量。数字万用表的整体性能主要由这一数字表头的性能决定。数字电压表是数字万用表的核心，A/D转换器是数字电压表的核心，不同的A/D转换器构成不同原理的数字万用表。功能转换电路是数字万用表实现多参数测量的必备电路。电压、电流的测量电路一般由无源的分压、分流电阻网络组成；交、直流转换电路与电阻、电容等电参数测量的转换电路，一般采用有源器件组成的网络来实现。功能选择可通过机械式开关的切换来实现，量程选择可通过转换开关切换，也可以通过自动量程切换电路来实现。以DT830B为例，如下图：开关切换，也可以通过自动量程切换电路来实现。以DT830B为例，如下图：62.2数字万用表的特点（1）准确度高；（2）显示直观；（3）分辨力高；（4）测量速率快；（5）测试功能强；（6）输入阻抗高；（7）低功耗；（8）保护电路完善。第三章DT830B型数字万用表的安装与调试3.1印制电路板元器件的安装与焊接3.1.1清点和识别元件7表3电阻器元件编号元件规格数量色环编码R080.01Ω1锰铜丝电阻R090.99Ω0.5%1/4W1黑-白-白-银-绿R109Ω0.5%1/4W1白-黑-黑-银-绿R2110Ω5%1/4W1棕-黑-黑-金R11100Ω0.3%1/4W1棕-黑-黑-黑-蓝R20500-800Ω1热敏电阻R12900Ω0.3%1/4W1白-黑-黑-黑-蓝R02910Ω1%1/4W1白-棕-黑-黑-棕R139KΩ0.3%1/4W1白-黑-黑-棕-蓝R079KΩ1%1/4W1白-黑-黑-棕-棕R1490KΩ0.3%1/4W1白-黑-黑-红-蓝8R01100KΩ5%1/4W1棕-黑-黄-金R05,R22,R23220KΩ5%1/4W3红-红-黄-金R04300KΩ5%1/4W1橙-黑-黄-金R15352KΩ0.5%1/4W1橙-绿-红-橙-绿R17,R18,R19470KΩ5%1/4W3黄-紫-黄-金R16548KΩ0.5%1/4W1绿-黄-灰-橙-绿表4电容器元件编号元件规格数量元件名称C1100pF(101)1瓷片电容C2,C3,C4,C5100nF(104)4金属化电容C61uF1电解电容表5半导体器件元件编号元件规格数量元件名称D11N40071二极管Q190131三极管表6其它元器件名称数量名称数量液晶显示器1螺丝2.5*92导电胶(斑马条)2保险管座2带邦定IC线路板1晶体管输入座19保险管500mA/250V1输入插座39V叠层电池1钢珠2电池扣1滑动接触片6旋钮11/4英寸拨盘弹簧2面壳1功能面板1底壳1白凡士林1导电胶框架1焊锡丝1螺丝2*6mm3测试表笔一对1按装配图11安装元件，在没有特别指明的情况下，元件必须从线路板正面装入。线路板上的元件符号图指出了每个元件的位置和方向，普通元件安装不再介绍，下面只介绍特殊元件的安装。