DESIGN AND CONSTRUCTION

OF

HANDHELD METAL DETECTOR

BY

AROMOYE AKEEM OLUW AFEMI

2004/18792EE

DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING

SCHOOL OF ENGINEERING AND ENGINEERING

TECHNOLOGY

FEDERAL UNIVERSITY OF TECHNOLOGY, MINNA,

NIGER STATE, NIGERIA.

A PROJECT REPORT SUBMITTED IN A PARTIAL FULFILMENT OF

THE REQUIREMENT FOR THE AWARD OF BACHELOR OF

ENGINEERING DEGREE {B. ENGR.} IN ELECTRICAL AND

COMPUTER ENGINEERING

DECEMBER, 2009

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DECLARATION

I hereby declare that this project work was conducted by me under the supervision

of Engr. J. G. kolo, Electrical and Computer Engineering Department, Federal

University of Technology, Minna.

Aromoye Akeem Oluwafemi

--fJ J I h vvV»'-U.. ·······~·:~···········O··-;·· Student's signature

Engr. J. G. Kolo

~~ ...... ........-.-.-...... ................. .... .

Supervisor's signature

E gr. Dr. Y. A. Adediran

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H. O. D's signature /

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External Examiner

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Date

Date

~A1.1(~ ........... . Date

DEDICATION

I dedicate this project to Almighty Allah for seeing me through this programme and also to my

lovely mother, Mrs. M. O. Aromoye for her moral and financial support through out my stay in

school.

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ACKNOWLEDGEMENT

I wish to express my sincere gratitude to my supervisor, Engr. J. G. Kolo for his moral

advice and intellectual support towards the completion of this project. Also, to the laboratory

technician, Mallam Umar.

My profound appreciation goes to Maolana Sheikh Ibrahim Nyass, Maolana Sheikh Nuru

Akeem, Alfa Salihu Oko-Olobi, Alhaji Ibrahim Isa Ladan, Alhaji Mohammed Isa Ladan for their

Spiritual and moral support.

To my family members, particularly my younger ones; Abdulrasheed , Saheed, Silifat.

To my friends in school; Sherif Baba, Ayan Baba, Morex Law, Sir Adams, Officer

Ayuba, Dare, Lateef physics, Azeez Mechanical, Wasiu Offa, Ganiyat Lawai (G-baby) and

others.

Finally, my sincere thanks to my dearest friends ; Mariam Ibrahim, Sherifat Mustapha,

Bola Bolaji, Ganiyat Mustapha, Helen.

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ABSTRACT

Over the years, it has become an important issue to restrict the entry of people into

certain places with weapons or instruments of harm and destruction.

This project is a design and construction of an effective means of detecting dangerous

weapons made of metal in order to reduce crime rate in the society. It lIses the principle of

electromagnetic induction and adopts a digital beat frequency technique. The system uses a

search coil to detect metallic objects at a close range and gives a visual, auditory and vibratory

indication once the metallic object is detected. The search coil forms part of an LC oscillation

circuit. The operating frequency of the LC oscillator is primarily determined by the value of

involved inductor and capacitor. In case an inductance is altered, the frequency does not remain

the same by changing its value through the introduction of a metallic object.

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LIST OF FIGURES

Figure 2.1 The block diagram of a hand-held metal detector

Figure 2.2 Schematic of a collpitts oscillator

Figure 2.3 The Symbol for an SR latch

Figure 2.4 Transistor type flip-flop

Figure 3.1 4060 pin connection diagram

Figure 3.2 4060 internal organization

Figure 3.3 The RC configuration of the 4060 astable circuit

Figure 3.4 Pin configuration of the 7806

Figure 3.5 The pin configuration of the 2SC945

Figure 3.6 The pin configuration of the 2SD400

Figure 3.7 The power unit

Figure 3.8 The power indicator circuit

Figure 3.9 The LC oscillator circuit

Figure 3.10 The Control Oscillator Circuit

Figure 3.11 The frequency counter

Figure 3.12 The relationship between the frequency from the search/LC oscillator, F1 and

active input pulse ofthe freq uency

Figure 3.l3 The SR flip-flop

Figure 3.14 The output reset unit

Figure 3.15 The output unit

Figure 3.16 The block diagram

Figure 3.17 The circuit diagram

Figure 4.1 A sketch of the casing showing carrying parts

Figure 4.2 An illustration of the test

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Cover Page

Title page

Declaration

Dedication

Acknowledgement

Abstract

List of Figures

Table of Contents

CHAPTER ONE

1.1 INTRODUCTION

1.2 Aims and objectives

1.3 Scopes of the project

1.4 Methodology

1.5 Design evaluation

1.5 .1 Merits

1.5 .2 Limitations

CHAPTER TWO

2.0 LITERA TURE REVIEW

TABLE OF CONTENTS

2.1 Historical Review of the Development of Metal Detectors

2.2 Garrett Metal Detectors

2.3 Uses of Metal Detectors

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II

III

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VII

VIII

2

2

2

3

3

3

5

5

6

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2.4 Types of Metal Detectors 8

2.4.1 Hand-held 8

2.4.2 Pinpoint 8

2.4.3 Walkthrough 8

2.4.4 Ground Search 9

2.5 Design Block Diagram Explanation and Choice of Parts 9

2.5.1 Metallic Object 10

2.5.2 Sensor/Inductor and LC Oscillator 10

2.5.2.1 Colpitts Oscillator 1 1

2.5 .3 Frequency Amplifier 13

2.5.4 The Timing Devices 13

2.5.5 SR Flip-Flop 14

CHAPTER THREE

3.0 CIRCUIT DESIGN ANALYSIS 16

3.1 Main Components Description 16

3.1.1 4060B 16

3.1.2 7806 19

3.1.3 2SC945 19

3.1.4 2SD400 20

3.2 Circuit Design 21

3.2.1 Power Circuit 21

3.2.1.1 Power Indicator 22

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3.2.2 Search LC Oscillator/Frequency Amplifier 23

3.2.3 Control Oscillator 25

3.2.4 Frequency Counter 28

3.2.5 SR flip-flop 30

3.2.6 Output Reset Timer 31

3.2.7 Alarm Indicators Unit 32

3.2.7.1 Visual Alarm Indicator 33

3.2.7.2 Audio and Vibratory Indicators 33

CHAPTER FOUR

4.0 CONSTRUCTION, TESTING AND DISCUSSION OF RESULT 36

4.1 Circuit Construction 36

4.1.1 Casing Construction 36

4.2 Testing 38

4.3 Result Discussion 39

CHAPTER FIVE

5.0 CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion

5.2 Recommendations

REFERENCES

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