Design and Construction of a Metal Detector
CHAPTER ONE
Objective of the Project
- To construct a walk through metal detector that is capable of detecting the presence of a metallic device.
- To the walk through metal detector world also incorporate the functionality of metallic object.
- The walk through metal detector will be capable of producing an alarm on reception of a metallic object.
CHAPTER TWO
LITERATURE REVIEW
What a Metal Detector Is
A metal detector is an electromagnetic device that is able to detect the presence of magnetic material (metals) within its range of operation. The range of operation of a metal detector is determined by the circuit design. Basically in metal detector system, a magnetic field is created using the principle of electromagnetism transmitted via a coil. When any metal is within the range of this field, an eddy current is generated by the metal creating another field or a disturbance within the transmitter. This eddy current generates a very small voltage (usually in micro Volts), which is received back amplified and sent to the output transducer which could be a speaker or a buzzer. More so, a metal detector can also be seen as a device which responds to metal that may not be readily apparent or which is hidden. The simplest form of a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field. If a piece of electrically conductive metal is close to the coil, eddy currents will be induced in the metal, and this produces an alternating magnetic field of its own. If another coil is used to measure the magnetic field (acting as a magnetometer), the change in the magnetic field due to the metallic object can be detected.
Brief History of Metal Detector Evolution
Toward the end of the 19th century, many scientists and engineers used their growing knowledge of electrical theory in an attempt to devise a machine which would pinpoint metal[1]. The use of such a device to find ore-bearing rocks would give a huge advantage to any miner who employed it. The German physicist Heinrich Wilhelm Dove invented the induction balance system, which was incorporated into metal detectors a hundred years later. Early machines were crude, used a lot of battery power, and worked only to a very limited degree. Alexanuder Graham Bell used such a device to attempt to locate a bullet lodged in the chest of American President James Garfield in 1881; the attempt was unsuccessful because the metal coil spring bed Garfield was lying on confused the detector. The modern development of the metal detector began in the 1920s[1]. Gerhard Fisher had developed a system of radio direction-finding, which was to be used for accurate navigation[1]. The system worked extremely well, but Fisher noticed that there were anomalies in areas where the terrain contained ore-bearing rocks. He reasoned that if a radio beam could bed istorted by metal, then it should be possible to design a machine which would detect metal using a search coil resonating at a radio frequency. In 1925 he applied for, and was granted, the first patent for a metal detector.
CHAPTER THREE
Design of a Metal Detector Circuit
In this project, we will demonstrate how to build a simple metal detector circuit. The device we then build will function as a metal detector that can scout out metal objects. Such as coins, nails, keys such as car keys and any metallic object you may not be able to find and even gold if you’re looking for in a bench (through this one may not have industrial strength). This metal detector can detect certain kinds of metal especially iron-containing metals, even if under a half inch of dry well or sand.
How this Metal Detector Works
How this metal detector works is that it uses an IC that generates an A.C signal that goes through a coil. Metal objects are objects which conduct electricity so a current can be induced in these metal objects. When the coil in the metal objects detector comes near a metal object, the electromagnetic field generated by the metal changes the current. The IC turns on an LED < alerting the user to the presence of metal.
CHAPTER FOUR
SYSTEM IMPLEMENTATION
The implementation of this system entails putting together all the components realized at the design stage and test running the system, the entire circuit was also tested to ensure that they are functioning well before packaging, tool used in testing was basically the ammeter, it also involved, comparing the obtained result with the expected result from the design and mathematical analysis stage.
CHAPTER FIVE
SUMMARY AND CONCLUSION
Summary of Achievements
As I browsed the internet for materials, I discovered that most readily available metal detectors are very expensive and cannot be afforded by especially people that need them. This design however is a low cost readily affordable metal detector and can easily be procured by whoever may need it. The system is also very rugged and reliable.
More so, the resulting design is easy to carry and meets with the standard of what is available in the international market. The system can also be used in teaching younger undergraduates about the principles of electromagnetism and one of its specific application (that is, Metal detection).
In the implementation of this work, a combination of bottom-up and top down design approach was used. A number of subsystems were designed, implemented and integrated to achieve the final result. These include the power supply, analogue to digital conversion, the seven segment display.
The beauty of this work is that every part of the system is working perfectly as expected and this means achieving our dream of producing a metal detector with inbuilt programmer locally. The detector is highly design and function effectively it makes the learning easy.
Furthermore this project has more features than any one available in the market today and this attests to the fact that we can produce things that are much better than those produced overseas.
REFERENCES
- Wikipedia the free encyclopaedia, Metal Detector, March, 2008, http://en.wikipedia.org/wiki/Metal_Detector.
- Graves M, Smith A and batchelor B 1998: approaches to foreign body detectionin foods, trends in food science and technology 21-27
- Wikipedia, the free encyclopaedia, Magnetism, March 2009, http://en.wikipedia.org/wiki/Magnetism
- Jackson John David(1999). Classical electrodynamics (3rd edition)
- Dr. Salman Durrani, A pulse Induction Metal Detectors, ENGN3227, Analogue Electronics.
- David K. Cheng (1992), Field and Wave Electromagnetics. Addison-WesleyPublishing Company Inc.
- Tipler, Paul (2004), W. H. Freeman. Physics for Scientists and Engineers:Electricity, Magnetism, Light, and Elementary Modern Physics 5th edition.
