数字频率计
摘要
本文介绍了一种基于 TTL 系列芯片的简易数字频率计。数字频率计应用所学的数字电
路知识进行设计。电路由放大整形电路、时基电路、逻辑控制电路、计数锁存电路及译码
显示电路组成。能够较精准的测量幅值在 0.2V~5V 的正弦波、三角波、方波的频率。测量
范围能够达到 1Hz~9999Hz。
关键词：频率计，TTL 芯片，数字电路
Abstract
In this paper,a design of simple digital cymometer based on the TTL serises chips was
described.This design is based on the knowledge about the digital circuit we learned.It consists
of amplifier and shaping circuit , time-base circuit, control circuit, latch circuit and decoding
count show circuit.It can be used to accurately detect the frequency of sine wave, triangle wave
and square wave accurately that the amplitude is between 0.2V and 5V. Detecting range can be
achieved 1Hz ~ 9.99kHz..
Key words: cymometer, the TTL series chips,digital circuit
目录
摘要..................................................................................................................................................I
关键词..............................................................................................................................................I
Abstract ...........................................................................................................................................II
引言 .................................................................................................................................................1
1 总体方案设计 ..........................................................................................................................2
2 单元电路设计 ..........................................................................................................................3
2.1 放大整形电路................................................................................................................3
2.1.1 方案一 .................................................................................................................3
2.1.2 方案二 .................................................................................................................4
2.1.3 方案对比 .............................................................................................................4
2.2 时基电路........................................................................................................................5
2.2.1 方案一 .................................................................................................................5
2.2.2 方案二 .................................................................................................................5
2.2.3 方案对比 .............................................................................................................6
2.3 逻辑控制电路................................................................................................................6
2.4 计数器............................................................................................................................7
2.5 锁存器............................................................................................................................8
3 主要参数计算 ..........................................................................................................................9
3.1 时基电路参数................................................................................................................9
3.2 逻辑控制电路................................................................................................................9
4 总体电路设计 ........................................................................................................................10
5 仿真结果 ................................................................................................................................12
6 实物测试结果分析 ................................................................................................................14
7 体会与心得 ............................................................................................................................15
8 参考文献 ................................................................................................................................16
附录一 电路实物图 .....................................................................................................................17
附录二 元件清单 .........................................................................................................................18
引言
在电子技术中，频率是一个重要参量。应用计数法原理制成的数字式频率测量仪器具
有精确度高，测频范围宽，便于实现测量过程自动化等一系列突出特点，所以数字式频率
测量计(简称数字式频率计)已成为目前测量频率的主要仪器。
1 总体方案设计
被测信号经过放大整形整形之后变成计数器所要求的脉冲信号1。标准时间基准信号2
由时基电路提供其高电平持续时间为1s，计数器对1s时间中的脉冲计数，当1s信号结束时，
时基电路产生信号2，闸门电路关闭，逻辑控制电路产生锁存信号6是显示器上的数字稳定，
清零信号5是计数器从0开始计数。若在闸门时间1s内计数器计得的脉冲个数为N，则被测
信号频率为N(Hz)。各信号的时序图如图二所示。
图 1 组成框图
2
5
放大整形电路
锁存器
逻辑控制电路
闸门电路
译码显示器
计数器
时基电路
1
2
3
2
6
图 2 波形关系
计
数
锁
存
清
0
N
(
个
脉
冲
)
信
号
2
信
号
1
信
号
6
信
号
5
