The article gives you information on metal detectors and how they can be used for security threats, detective work or even for fun of finding buried treasure.

House hold word after 9/11 - Metal Detectors

In case you encounter a word “metal detector” in a word association test, the first thought that comes to mind for 90% of persons is the airport security and personal security service. After 9/11 the metal detectors have become highly visible and the persons taking offence at being searched is coming down drastically. At the same time the curiosity about the metal detectors is increasing

How the metal detectors work

Metal detectors work on the principle of electromagnetic inductance or resistance. Every one knows that when electric current passes through a metal object, it offers a resistance to it and only the metallic parts allow the electric current to pass through it and thus the metals can be detected by the resistance or other electrical phenomenon. The other materials like plastics cannot be detected by metal detectors.

Types of metal detectors

You can get metal detector in various forms and working on various technologies. The usage of metal detector will determine what technology is to be used for making a metal detector. If the purpose is trying to find a booby trap in a mine field, the technology has to be more sophisticated compared to finding out a buried treasure in a treasure hunt program in a school.

Basic parts of metal detectors

If you see a into a typical metal detector you will find that it consist of 3 parts

1. Search coil: This is the biggest part of metal detector that you sweep over the area you are searching. Taking it back and fourth over the area under question will send the electrical impulses over the area and the return impulses from the area being searched are analyzed by the control unit
2. Control unit: The control unit consists of receiving unit and analyzing unit. The return impulses from the ground are given to control unit and depending the strength and frequency of the return signal the control unit gives you the information about the metal buried in ground or in the suit case under scanning
3. The Shaft: This is used to hold the metal detector and move it over the suspected area. Thus is also important unit of metal, detector as the ease of handling and therefore effectiveness depends on it.
4. Stabilizer: Optionally a stabilizer can be used along with the shaft to ease the working load on hand, so that effectiveness of the metal detector increases.

Technologies used in making metal detectors

Principally 3 technologies are being used in metal detecting. These are

• (BFO) Beat-frequency oscillation
• (PI) Pulse induction
• (VLF) Very low frequency.

Since the technical explanations of these individual are complex, they will be taken up in a separate article later on. The difference in each case is the depth of the metal being detected, the volume of the metal buried, and the like. Special metal detectors have to be built for individual applications.

It is not difficult to build a basic metal detector. Many DIY sites can help you in making a metal detector and use it for hunting a buried object. You can use them for fun on a beach or use them in a school expedition for hunting a buried treasure