The technology of metal detecting has been a great part of people’s lives for the past years. The metal detectors are definitely of many great uses. From leisure to safe keeping, metal detectors can be utilized. In fact, you can ask people about the use of metal detectors and you would surely hear some of them talk about metal detectors used to find coins or recyclable metals at the beach whilst others talk about the metal detectors used at the entrance of public establishments like airport and court room.

It is obvious that a metal detector can detect metals or objects that are made from metal, but how does a metal detector really work?

Parts
To understand how a metal detector works, you need to know the parts. The first part of a metal detector is the coil. This is the part that senses the metals. The second part, the control box, is the part that has the batteries, controls, circuitry, microprocessor and speaker. For consumer metal detectors, the shaft is also another part. However, this is normally absent in handheld metal detectors. You surely see metal detectors in a bar form – those that are used at malls and concert entrances. At the airport, the metal detectors are bigger and are mounted that they can stand on their own.

Technologies
There are three kinds of technology used in metal detectors: very low frequency (VLF), pulse induction (PI), and beat frequency oscillation (BFO).

VLF is also known as induction balance. It is also the most popular metal detecting technology. The coil in VLF metal detectors is of two parts: receiver coil and transmitter coil. The first one is a coil of wire. It is the inner loop and it acts as the antenna. It picks up and amplifies incoming frequency from the objects. The transmitter coil forms the outer coil. It transmits electricity. The frequency of the unit depends on the number of times the current’s direction switches in the transmitter coil. A VLF metal detector depends on this current-direction switching to distinguish inductive and resistive objects wherein metals fall on the first category.

The PI technology, on the other hand, may have one to three coils. With PI technology, powerful pulses (about 100 pulses per second) of current are sent through the coil. The pulses produce a magnetic field. But if the metal detector is near a metal, the pulses will generate an opposite magnetic field.

Lastly, the BFO technology is the most basic kind of metal detecting technology. Like the VLF, BFO metal detectors have two coils varying in size. One is larger than the other. They are also placed inside the control box. The two coils are connected to an oscillator, which produces pulses of current every second. The pulses then produce radio waves that then generate the sound. The duration and tone will change once the frequencies picked up from the objects changes. The change in the frequency happens because the pulses produced create a magnetic field. When the metal detector passes a metal object, the occurring metal field will cause the metal object to have a magnetic field that will interfere the original magnetic field.

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