Project: Handheld Metal Detector Design and Implementation

This project proposal outlines the design and construction of a handheld metal detector. It begins with background information on metal detectors, their history, and applications, emphasizing their use in security and other fields. The proposal addresses the problem of security challenges, particularly in public places, and aims to develop a portable device to detect metallic instruments. The objectives include investigating different metal detector types, exploring technologies, designing the detector, and implementing the design. The project's scope is limited to a handheld scanner-type metal detector with an audio output upon detection. The methodology involves internet research, past research works, expert consultations, and relevant book references. The project aims to combat crime and enhance security measures. The document details the principles of a BFO metal detector, examines schematics, and explains the function of each component, along with component value choices.

PROPOSAL
1.1 PREAMBLE
Metal detectors depends on detecting one of various means that can be observed when a
metal object affects the magnetic field surrounding a coil of wire carrying an alternating current.
The major effects are: the form of the magnetic field surrounding the coil will be distorted and
the inductance of the coil will be changed. The various types of metal detectors devised utilize
these changes, electronically detecting the alteration induced in the coil by the metallic object.
Nonmetallic objects or material can also affect the coil in similar ways.
There are three basic methods used to exploit the above effect.” Induction balance” metal
detectors employ two coils, one is steered by a modulated oscillator, the other is connected to a
detector and amplifier. The two coils are gently positioned with respect to one another such that
the receiver coil picks up very little of the energy radiated by the transmitter coil when no metal
or mineral material is nearby, when the coils are brought close to a metal object, the field pattern
is distorted, greatly increasing the transmitted energy picked up by the receiver coil.
The modulated signal is detected and can be revealed by amplifying the recovered modulation to
speaker level as well as indicating it on a meter. For evident reasons, this type of metal detector
is often referred to as a “transmit-receive” or TR detector. Major advantages are good
pinpointing ability and good depth penetration and they are not sensitive to small ferrous object.
Other uses of more specialized metal detectors include usage in medicine, security etc.
Metal detectors have been used for diagnostic purposes since 1881. They have been utilized to
localize a myriad of foreign objects including bullets, intraocular metallic fragments, swallowed
coins and other foreign bodies and medical devices. Rapid detection of metallic objects may
facilitate diagnosis or treatment. Metal detectors are diagnostically useful because of their low
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expense, lack of radiation exposure and ease of use. Other uses are demining (the detection of
land mines), the discovery of weapons such as knives and guns, especially at airports,
geophysical prospecting, archaeology and 'treasure hunting'. Metal detectors are also used to
detect foreign bodies in food, and in the construction industry to detect steel reinforcing bars in
concrete and pipes and wires buried in walls and floors.
Metal detectors are finding usages all over the place has the ability to detect certain types
of materials at a distance become ever more crucial. This project will give a basic outline of the
subject and some insight into the way of approaching the challenges of creating a handheld metal
detector. The background data of the history and uses of metal detectors is showed as well as the
design standards for this particular project. The principle behind how a basic BFO metal detector
works is examined, along with the basic details of a readily available design for a detector. A
detailed examination of the chosen schematics and the function of each component is examined
and explained, as well as explanations for certain choices of component values.
1.2 PROBLEM STATEMENT
Security challenge is one of the fast rising challenges encountered in the world and
particularly in this country, loss of lives and properties occurs most especially in public places
like churches, shopping malls, cinema centers etc. without one knowing the bearers of those
dangerous metallic weapons that causes such hazards as ordinary body searches are not
sometimes very effective and may in some cases be embarrassing. Crimes in public places have
posed a major threat to humanity and has made people to live in fear. The metal detector is a
veritable means of ensuring security due to the fact that most dangerous weapons and devices,
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which have appreciable metal content can be easily detected before they are utilized. This project
aims to solve this problem by developing a portable device to detect metallic instruments.
1.3 AIMS AND OBJECTIVES
1.3.1 AIM
The aim of this project is to design and construct a handheld metal detector. It has to be battery
powered and use a commonly available and understood design. In addition to this, the circuit
design has to be relatively simple and compact so as to fit on a size limited Printed Circuit Board
(PCB).
1.3.2 OBJECTIVES
The objectives are to:
1 Investigate the various types of metal detecting devices, their uses and their capabilities.
2 Investigate the various types of technologies in the design of the device.
3 Design a metal detector.
4 Implement the design of a metal detector.
1.4 SCOPE OF THE STUDY
This project work is limited to the design and construction of a hand held scanner-type metal
detector which will detect metal on an individual and pop out a sound on detection.
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1.5 SIGNIFICANCE OF THE STUDY
This metal detector will be used as part of the security measures to combat crime and at the same
time ensure security in public places and also in some desired places.
1.6 METHODOLOGY
The methods adopted in the execution of this project will be through:
 The internet
 Past research works
 Consulting an expert in the field
 Consulting relevant books to get necessary information
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