电子技术课程设计：正弦波发生、频率测量显示电路设计

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1、电子技术课程设计实验报告学院：物联网工程学院班级：自动化1204姓名：XXX学号：1070412428同组成员：XXX二〇一四年六月目录一、实验名称··············································3二、实验任务和要求········································3三、实验电路（a）系统框图·········································3（b）总电路原理图·····································4（c）总电路管脚图··············

2、·······················5四、单元电路及原理分析（1）+5V电源电路·····································5（2）正弦波发生及波形变换电路·························6（3）单稳态定时电路···································7（4）频率计数显示电路·································7（5）超量程指示电路···································8（6）控制电路····························

3、·············9五、元器件列表···········································10六、安装与调试1、使用仪器仪表······································102、安装·············································103、调试·············································114、调试中出现的故障、原因及排除方法·················14七、收获和体会·····························

4、·············15-2-一、实验名称正弦波发生、频率测量显示电路二、实验任务和要求正弦波振荡频率100～1000Hz，输出信号幅度5±5％V；（1）用3位数码管显示振荡频率；（2）能自动连续测量、显示频率，测量周期为4S；（3）用中规模集成电路实现。三、实验电路（a)系统框图图1-1正弦波发生电路组成框图（b)总电路原理图-3-原理图分析：正弦波振荡器自激振荡产生正弦波输出信号，波形变换电路将正弦波变换成方波，方波输入到计数器中，由计数器对输入方波信号进行计数，计数器的计数结果在译码显示中显示；控制电路部分输出定时触发信号、超量程复位信号和清零信号，定时触发信号输入到单稳态

5、定时电路中，单稳态定时电路将定时触发信号给计数器，计数器在定时周期内对方波信号进行计数；超量程复位信号和计数器输出的超量程指示同时控制超量程指示电路部分，发光二极管发光进行超量程指示；清零信号输入到计数器中，在计数超过量程时计数器清零。-4-（c)总电路管脚图五、单元电路及原理分析（1）+5V电源电路参考电路中所用芯片有±12V和+5V几种，+5V电源可由+12V电源降压获取，电路如图1-2所示。图1-2+5V电源电路-5-（2）正弦波发生及波形变换电路因振荡频率要求不高，故采用RC文氏振荡器。考虑到要数字显示振荡频率，需对正弦波进行波形变换以便计数。正弦波发生及波形变换电路如图1-3

6、所示。图1-3正弦波发生及波形变换电路（3）单稳态定时电路为了便于测量换算，设计一个1S定时电路，在该定时范围内所测得的脉冲个数即为振荡频率。定时电路及单稳态输出波形如图1-4所示。-6-图1-41s定时电路（4）频率计数显示电路计数器选用MC14553芯片，这是一片3位BCD加法计数器芯片，由选择端DS、DS、DS控制每一时刻只输出一位BCD码。123显示译码器选用CD4511芯片，该芯片具有BCD七段锁存/译码/驱动功能。计数及译码显示电路如图1-5所示。-7-图1-5计数及译码显示电路（5）超量程指示电路当计数器MC14553计到1000个脉冲时，“OF”端会输出一个正脉冲，该信

7、号连到超量程指示电路，驱动发光管发光，表示信号频率超范围需调整。超量程指示电路如图1-6所示。-8-（6）控制电路控制电路实际上是一低频信号发生器，振荡周期为4S，精度要求不高，用其产生方波和尖脉冲信号，分别用来触发单稳态电路、超量程指示电路复位和计数器清零。电路如图1-7所示。图1-6超量程指示电路图1-7控制电路-9-五、元器件列表元器件名称参数数量元器件名称数量０.４７ｋΩ１ＵＡ７４１１１ｋΩ１ＨＡ１７７４１２２ｋΩ２三极管ＮＰＮ２９１ｋ