数字频率计实习教程.doc

CHANGSHA UNIVERSITY OF SCIENCE TECHNOLOGY 电子技术应用实习 题目： 数字频率计的设计 学生姓名： 学 号： 班 级: 专 业： 指导教师： 年 月 日—— 年 月 日  目 录 1 实习目的及指标···································································1 2设计原理············································································2 3各模块电路的设计··································································3 3.1 时基电路··································································3 3.2显示电路···································································4 3.3 控制电路··································································5 3.4 整形电路··································································6 3.5 发挥部分··································································6 4电路的仿真和运行结果····························································8 4.1时基电路部分仿真结果···················································8 4.2闸门电路部分仿真结果···········································9 4.3显示电路部分仿真结果··················································9 4.4自检电路部分仿真结果··················································10 5 总结··············································································· 11 附录················································································· 12 附录A 数字频率计电路图····················································12 附录B 数字频率计元器件清单················································13 1实习目的及指标 1.1 实习目的 掌握数字频率计的设计，组装和调试方法； 熟悉555,74LS160及4518等集成电路的使用方法； 用74LS160组成数字频率计。 1.2 实习指标 1.2.1基本部分 (1) 被测信号的频率范围为1Hz(100KHz，分成两个频段，即1Hz(999Hz 1(100KHz。 (2) 具有自检功能，即用仪器内部的标准脉冲校准测量精度。 (3) 用3为数码管显示测量数据，测量误差小于10%。 1.2.2发挥部分 (1) 用发光二极管表示单位，当绿灯亮时表示Hz，红灯亮时表示KHz。 (2) 具有超量程报警功能，在超出当前量程挡的测量范围时，发出灯光 音响信号。 (3) 测量误差小于5%。 2设计原理 数字频率计的原理框图如图1所示，它由四个基本单元组成；可控制的计数锁存显示系统，555构成的多谐振荡器及多级分频系统，整形系统和闸门电路，换挡和自检电路。 由多谐振荡器、分级系统及控制电路得到具