The University of South China
课程设计
题 目 音响放大器设计 学院名称 电气工程学院 指导教师 黄智伟教授 班 级 通信工程071班 学 号 20074400152 学生姓名 李大龙
2010年1月
摘要：
音响放大器可以用来话音扩音、音乐欣赏、卡拉OK伴唱，其中的电子混响器使声音听起来具有一定深度感和空间立体感。 音响放大器是由话筒放大器、混合前置放大器、电子混响器、音调控制器、功率放大器几部分组成。
设计首先设计电路原理图，在multisim仿真中实现了话筒和声音的混合放大，继而在protel中制作pcb版，买好元件后在万用板上进行焊接，最终完成设计。
电路设计完成后，开始对系统进行测试：通过对系统在multisim软件下仿真测试，也对印制板进行调试。在本设计中，测试后发现系统基本能达到要求。
关键字： 混合放大 功率 LM324 MUTISIM PROTEL
Abstract:
audio amplifier can be used to voice and music appreciation, karaoke
BanChang, including electronic reverb units that sounds with certain sense of depth and space stereo feeling.
Audio amplifier is mixed by the receiver amplifiers, preamplifier, electronic reverb units, tone controller, power amplifier.
Design first, in the circuit principle diagram design multisim simulation in the microphone and sound mixing amplification, and in making PCB, protel bought in universal plate after components for welding, final design.
After the completion of the circuit design, the system is tested: through the system software simulation test in multisim under, debugging of printed circuit board. In this design, testing that the system can meet the requirements.
Key words: mix LM324 power amplifier MUTISIM PROTEL
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目录
一 系统方案设计 ··································4
1.1设计要求······························································4 1.2设计指标························································4
二 方法设计与论证··································4
2.1设计过程·········································································5 2.2 额定功率·········································································6 2.3 音调控制特性 ····································································7 2.4 频率响应·········································································7 2.5 输入阻抗·········································································8 2.6 噪声电压 ········································································8
三 单元电路设计与参数计数··························8
３．1 功率放大器························································9 ３．2 混合前置放大器 ·································································9 ３．3音调控制器·······························································10
３．4功率放大器······································································15
四 仿真过程与仿真结果······························15 五 总电路图与元器件清单···························17
５.1总原理图········································································17 ５.2、PCB板图·······································································18 ５.3元器件清单表····································································19
六 七 八 九 电路调试与分析··································20 结论与设计体会··································22 参考文献········································22 附录············································23
附录一: LM386芯片资料·······························································23 附录二：Ua741芯片资料·······························································24 附录三：LM324芯片资料··························································25
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一．系统方案设计：
1.1设计要求
1）了解集成功率放大器内部电路工作原理，掌握外围电路的设计与主要参数的测试方法。
2）掌握音响放大器的设计方法。
3）能够使用电路仿真软件进行部分电路调试。
1.2设计指标（包括原始数据、技术参数、条件、设计要求等）：
1）设计一音响放大器，要求具有音调输出控制，对话筒的输入信号进行扩音。 2）以集成功放和运放为核心进行设计 3）指标：
已知：VCC=+9V，话筒模拟输入电压为5mV，负载RL=8欧姆 频率范围：40Hz~10KHz
音调控制特性：1KHz处为0分贝，100Hz~10KHz处有上下12分贝的调节范围。 增益：大于20分贝。 额定输出功率：大于等于1W
二、方法设计与论证
2.1设计过程
根据技术指标要求，音响放大器的输入为5mV时，输出功率大于1W，则输出电压Vo>=2.8V。总电压增益AvΣ=Vo/Vi>560倍(55dB)。
话放级 AV1 8.5倍 18.5dB 42mV 混放级 AV2 3倍 9.5dB 125mV 音调级 AV3 0.8倍 –2dB 100mV 功放级 AV4 30倍 29.5dB 3V 5mV
AV?=612倍(56dB) 图一 各级增益分配图
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2.1.1 功率放大器设计
图二 LM386低电压通用型集成功率放大器
功放级的电压增益 AV4?R11RF?33R11=20K
2.1.2 功率放大器设计
如果出现高频自激(输出波形上叠加有毛刺)，可以在1脚与8脚之间加0.15?F的电容，或减小CD的值。
R31 47k? C31 0.01?F R34 47k? RP31 470k? R32 47k? C32 0.01?F ＋9V 9 4 A3 11 ＋ 2.1.3 音调控制器(含音量控制)设计
vi ＋ C34 100?F C33 470pF R33 13k? 10k? － C35 10?F C41 4.7?F ＋ 10 ＋ 10k? 8 RP33 10k? vo 音调控制器(含音量控制)设计 已知fLx=100Hz，fHx=10kHz，x=12dB。
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RP32 470k? 1 LM324 4