Abstract
The project DESIGN AND CONSTRUCTION OF A 20-METRE DISTANCE REMOTELY
CONTROLLED METAL DETECTOR is used for detecting metallic objects such as phones,
bombs, and other metallic objects that are hidden from view. The design is based on the principle
of the Resonant Frequency Oscillator (RFO) metal detectors in which oscillation is a function of
parallel connection of an inductor and a capacitor operating in resonance. The project is divided
into two sections. The transmitter section acts as a remote control. This section has push buttons
and uses the microcontroller ATmega 328p for generating encoded signals which are transmitted
using radio frequency HC 12 transceiver module. At the receiver section, the HC 12 transceiver
module is used for receiving the RF signals sent from the transmitter. Another component of the
receiver section is the microcontroller ATmega 328p which is wired to the transceiver module for
decoding the signals received and hence for switching ON and OFF the metal detector circuit. The
metal detector circuit is a part of the receiver section. It is built using copper wires of gauge 26
according to the American Wire Gauge (AWG) standard and ceramic capacitor for producing
search field oscillation. The integrated circuit TDA 0161 is used together with the search field to
produce reference oscillation and it gives an output current of 10 mA when a metal is detected or
an output current of 1 mA when no metal is found by the search coil field. When a metal is detected
a buzzer emits an alarm. The complete circuit was tested and relevant parameters were measured.
When a metal is detected the detector sensor TDA 0161 output pin gives a value of 1.08 V;
however a value of 0.07 V is measured when no metal is detected. The range of operation of the
RF transceiver pair is found to be 900 metres. The project finds application in banks, shopping
malls and any security environment that requires the sensing of metallic objects.
TABLE OF CONTENTS
CONTENTS PAGE
TITLE PAGE i
DECLARATION ii
CERTIFICATION iii
DEDICATION iv
ACKNOWLEDGEMENT v
TABLE OF CONTENTS vi
LIST OF TABLES viii
LIST OF FIGURES ix
ABSTRACT x
1.0 INTRODUCTION
1.1 Background of the Study 1
1.2 Statement of the problem 2
1.3 Aim and Objectives of the Study 2
1.4 Significance of the Study 3
1.5 Scope of Study 3
2.0 LITERATURE REVIEW
2.1 Theoretical Framework 4
2.2 Conceptual Framework 5
2.2.1 Development of block diagram 6
2.3 Review of Related Empirical studies 9
2.4 Summary of Literature Review 11
3.0 CIRCUIT ANALYSIS AND DESIGN
3.1 Introduction 13
3.2 Circuit Analysis
3.2.1 Analysis of power supply 13
3.2.2 Analysis of metal detector circuit 14
3.2.3 Analysis of transmitter circuit 19
3.2.4 Analysis of the receiver circuit 20
3.3 Overview of Microcontroller (ATmega 328p) 22
3.4 Flowchart 25
3.5 Programming 27
3.6 Simulation 27
3.7 Circuit Diagram 28
4.0 CONSTRUCTION, TESTING, RESULT, DISCUSSION
4.1 Construction 29
4.1.1 Construction on bread board 29
4.1.2 Construction on vero board 31
4.2 Testing 33
4.3 Results 33
4.4 Discussion 33
5.0 CONCLUSION AND RECOMMENDATION
5.1 Conclusion 35
5.2 Recommendation 35
REFERENCES 36
APPENDICES