1、 噪音测试仪设计噪音测试仪设计 摘摘 要要：本文提出了一个噪音测试仪的设计方案，此测试仪能将外界噪声经过传声器转 换成电信号。由运放 LM324 构成三级放大电路，峰值检波网络输出直流电平反应了噪声 声压的大小。由 LM331 构成电压/频率转换电路，输出的频率信号变成 TTL 电平送给单 片机的 T0 管脚，作为 T0 的计数脉冲。系统的核心部分是单片机 AT89C51，其 3.5 引脚 接入 NE555 构成的定时器输出的方波，通过 T1 中断去控制 T0 定时计数。从 T0 端输入 的计数脉冲频率即反应了所测声压大小。最后经 CC4511 译码再驱动三位 LED 数码管显 示。本设计的优
2、点是电路简单、精度较高、实用性较强。 关键词：关键词：噪声测试仪，传声器，电压/频率，AT89C51，LED Abstract: This paper presents a design of noise tester, this tester can outside noise through the microphone into electrical signals. Posed by the three op amp LM324 amplifier, peak detector network output DC level response to the size of the no
3、ise sound pressure. Constituted by the LM331 V/F converter, the output frequency signal into a TTL level to give the microcontroller T0 pin count as the T0 pulse. Core of the system is the microcontroller AT89C51, the 3.5 pin access NE555 timer output consisting of a square wave, through the T1 T0 t
4、imer interrupt to control the count. T0-ended input count from the pulse frequency that reflects the size of the measured sound pressure. CC4511 decoding and then drive the final three by the LED digital display. This design has the advantage of simple circuit, high precision and strong practicability. Keywords: Noise tester, microphone,V/F, AT89C51, LED 第 I 页 目录目录 1 前言前言 1 2 2 整体方案设计整体方案设计 2 2.1 方案论证 2 2.2 方案比较 3 3 单元模块设计单元模块设计 4 3.1 驻极体传声器 4 3.2 集成四运放 LM324 4 3.3 峰值检波电路 5 3.4 LM331 频率电压转换器 .
