DESIGN AND CONSTRUCTION OF A FAN SPEED CONTROL SYSTEM

                       Abstract

This temperature control fan can be controlled using a microcontroller when it detects a

certain temperature that has been set. The purpose of this project is to prevent the waste of

voltage usage when it is not hot enough for fan to be needed. The temperature control fan

has three different speeds. Each speed will change according to a certain level of temperature

that is set. This project is a combination of electric supply, fan, temperature sensor and

microcontroller (ATMEL). To complete this project, there are a few steps need to be taken

which are the selections of temperature sensor, power supply, fan, design controlling using

ATMEL, developing a source code for the ATMEL and use a suitable apparatus to design

all circuit. As a conclusion, this project is to design and construct a temperature fan system

using temperature sensor which will be controlled by microcontroller. The fan speed can be

changed according to a certain level of temperature.

TABLE OF CONTENTS

Certification iiDedication ivAcknowledgment vList of Tables ixList of Figures xAbstract xi

1 INTRODUCTION 11.1 Background to the Study 11.2 Statement of the Problem 21.3 Aim and Objectives 31.4 Scope of the Study 31.5 Significance of Study 4vi

2 LITERATURE REVIEW 5

2.1 Types of Temp erature Controller 52.1.1 On/of control 52.1.2 Proportional control 62.2 Methodology 72.3 Description of the Functional Block Diagram 82.3.1 Temperature sensor 82.3.2 Error amplifier 82.3.3 Ramp generator 82.3.4 Opto-coupler 82.3.5 Power triac 92.3.6 Mains supply and load 92.3.7 Display 92.4 Theory of Components Relevant to Design 92.4.1 Silicon bandcap temperature sensor 92.4.2 Optocoupler 102.4.3 The power triode 122.4.4 Snubber network 132.4.5 Pulse width modulation (PWM) 133

DESIGN METHODOLOGY 153.1 Design Specification 153.2 Design of Power Supply 16vii

3.3 Temperature Sensor 173.4 Design of the Analog to Digital Converter 183.5 Ramp Generator 213.6 Comparator 223.7 Optocopular Driver Stage 223.8 Power Drive Circuit 243.9 Operational Principle of the Room Temperature Fan Speed Controller 254 CONSTRUCTION AND TESTING 274.1 Construction 274.2 Casing 284.3 Testing 294.4 Test Result 294.5 Bill of Engineering Measurement and Evaluation 305

CONCLUSION AND RECOMMENDATIONS 315.1 Conclusion 315.2 Recommendations 32References 33A High Level Language Codes for the Project 35B Bill of Engineering Measurement and Evaluation 45viii

LIST OF TABLES4.1 Temperature controller test result 29B.1 Bill of Engineering Measurement and Evaluation 45ix

LIST OF FIGURES2.1 Block diagram of the Room Temp erature fan Controller 72.2 LASCR 112.3 Opto - TRIAC 123.1 Power Supply schematic 163.2 LM35 Temperature Sensor and amplifier circuit 183.3 ICL 7107 analog to digital converter circuit 193.4 LED Display 213.5 A stable Multivibrator (ramp generator) 213.6 Pin layout of the µA741 op-amp 233.7 MOC3041 Optocoupler 233.8 Complete circuit diagram of the temperature controller 264.1 Circuit diagram 28