This document describes the design and implementation of an audio transmission system using infrared technology. It includes block diagrams that show the main components of the transmitter and receiver, including a condenser microphone, transmitting laser, photodiode, and loudspeaker. The document also provides schematic diagrams of the transmitter and receiver circuits and describes the operation of key components such as operational amplifiers, capacitors, integrated circuits, and LEDs. It discusses the printed circuit board design and fabrication, construction, testing, and applications of the infrared audio transmission system.

1. CONTENTS
Acknowledgement.…………………………………………………………………………..…i
Preface………………………………………………………………………………………....ii
Table Of Figure……………………………………………………………………………….iii
List Of Table………………………………………………………………………………….iv
CHAPTER 1. INTRODUCTION……..…………………………………….1-3
1.1 Project Definition…..……………………….…………………………………………2
1.2 Project Overview…........………………………………………………………………3
CHAPTER 2. BLOCK DIAGRAM AND ITS DESCRIPTION………….4-7
2.1 Basic Block Diagram..………………………………………………………………...5
2.2 Block Diagram Description…….…………………………………………………...6-7
2.2.1 Condenser Microphone………………...……………………………………………6
2.2.2 Transmitting Section...………………………………………………………………6
2.2.3 Laser Torch………….………………………………………………………………6
2.2.4 Receiving Section…..……………………………………………………………….7
2.2.5 Loudspeaker……….……………………………………………………………...…7
CHAPTER 3. SCHEMATIC DIAGRAM………………………………...8-12
3.1 Transmitter Circuit……………...………………………………………………...9-10
3.2 Receiver Circuit……………………………………………………………………...11
3.3 Microphone………………………………………………………………………….12
Chapter 4. Hardware Design And Description………………………….13-16
4.1 Working……………………………………………………………………………..15
4.2 List Of Component..…………………………………………………………….…...16

2. CHAPTER 5. DESCRIPTION OF COMPONENT…………………….17-42
5.1 Operational Amplifier………..………………………………………………..18-22
5.1.1 IC-741……………………………………………………………………….…...19
5.1.2 Negative Feedback Control…………………………………………………..20-21
5.2 Variable Resistance………………………………………………………………..22
5.3 Capacitor……………………………………………………………………….23-26
5.3.1 Fixed Capacitor……………………...……………………………………….24-26
5.3.1.1 Polyester……………………………………………………………………….24
5.3.1.2 Mica…...……………………………………………………………………….25
5.3.1.3 Ceramic.……………………………………………………………………….25
5.3.1.4 Electrolyte.…………………………………………………………………25-26
5.4 Digital Voltmeter………………………………………………………………27-28
5.5 Battery (9volt)……………………………………………………………………..29
5.6 Laser Torch………………………………………………………………………..30
5.7 Microphone…………………………………………………………………….30-32
5.7.1 Condenser Microphone……………………………………………………....31-32
5.8 Integrated Circuit………………………………………………………………….32
5.9 Photodiode………………………………….………………………………….32-35
5.9.1 Principle Of Operation…………………………………………………………..34
5.9.2 Applications...……………………………………………………………………35
5.10 Phototransistor………………………………………………………………..35-37
5.11 Light Emitting Diode (Led)…………………………………………………..37-42
5.11.1 Advantages……………………………………………………..........................40
5.11.2 Seven Segment Display…………………………………………….............41-42

3. CHAPTER 6. PCB DESIGN AND FABRICATION…………………...43-47
6.1 PCB Design………………………….…………………………………………….44
6.2 PCB Fabrication……………………….…………………………………………..45
6.3 Printed Circuit Board Layout………….………………………………………46-47
CHAPTER 7. LIST OF REQUIRED TOOLS AND INSTRUMENT…48-49
7.1 Required Tools And Instrument…….…………………………………………….49
CHAPTER 8. COMPONENT REQUIRED……………………………..50-52
8.1 Component Required For Transmitter…………………………………………….51
8.2 Component Required For Receiver.………………………………………………52
CHAPTER 9. CONSTRUCTION AND TESTING…………………….53-55
9.1 Construction……………………….………………………………………………54
9.2 Testing……………………………….……………………………………………55
CHAPTER 10. SETTING UPLINK AND PRECAUTION…………….56-59
10.1 Setting uplink……………………….……………………………………………57
10.2 Precautions…………………….………………………………………………....58
CHAPTER 11. ADVANTAGES AND DISADVANTAGES…………...59-60
11.1 Advantages……………………….………………………………………………60
11.2 Disadvantages……………………….…………………………………………...60
CHAPTER 12. PROBLEM FACED……………………………………..61-62
12.1 Problem Faced………….…………………………………………......................62
CHAPTER 13. APPLICATIONS………………………………………..63-64
13.1 Applications Of Projects………….………………………………………….......64
CONCLUSION……………………………………………………………….65
REFERENCES………………………………………………………………..66
APPENDIX………………………………………………………………..67-76