Metal Detector

A metal detector is used to detect the presence of metal in any shape or size. Easy to operate, it is used inside, outside, or even underwater primarily by security officials and hobbyists. The first metal detector was invented in 1881 by Alexander Graham Bell. However, it was not until 1931 that a patent was issued to another individual by the name of Gerhard Fischar, who is credited with the invention of the first portable metal detector.

Use of Metal Detectors

There are three styles of metal detectors. The first is an archway type metal detector that is primarily used in office building, schools, courthouses, airports, or at concerts to alert security officials to the presence of weapons such as knives or guns. A small portable detector is often used in conjunction with an archway-type metal detector to conduct a body search. Larger hand-held metal detectors are commonly used by individuals to find metal or below the ground, in outdoor or underwater settings.

For example, archaeologists use metal detectors in their digs to assist in easily finding metal objects that may be of significance. Rather than manually sifting through the dirt, a metal detector might be used to find pieces of shrapnel, bullets, and other artifacts. Treasure hunters also use metal detectors to discover coins or jewelry that may have been buried beneath the ground or at sea for many years. The use of metal detectors by hobbyists is very popular at the beach as well.

Functions of a Metal Detector

A metal detector works by using one of three methods: beat frequency oscillation, induction balance, or pulse induction. All three methods work on the principle of electromagnetic induction through the use of inductor coils that react with the metal component in an object. The induction balance technology is the most commonly used type of metal detector. Pulse indication is the most basic of the three, and typically used for low-end metal detectors.

When a metal detector is turned on, a pulsing current is applied to the induction coils, which cause them to generate a magnetic field. When the magnetic field comes into contact with a metal object such as a piece of jewelry, electric currants are produced which in turn create their own magnetic field and signal (usually a beep) that a metal object has been detected. Metal detectors range form the very basic to extremely sophisticated, depending on the application.