Metal Detectors

Everyone knows what a metal detector is. For some it’s a device of inconvenience that beeps even when you’ve emptied all your pockets. That is the moment when an official says ‘step this way please’ and everyone looks at you as if you just got caught cheating at your High School test. For others, which is the majority by the way, it is a device that secures facilities, locates concealed weapons and identifies hidden metallic objects. In other words, this device is directly responsible for saving thousands of lives every day.

Metal detectors may use different technologies and come in different shapes and sizes but all of them are used to achieve the same goal i.e. to detect the presence of a metal.

Different Types of Metal Detectors

A wide variety of these detectors is available in the market. These include:

  • Hand Held

    These come with a handle and are used to sweep the ground or body scan individuals. Hand held detectors are portable and are commonly used in office buildings and schools.

  • Walk Through

    Generally used in airports and shopping malls, these are door shaped. If an individual has a hidden weapon such as a knife or a gun, the detector may sound an alarm alerting the authorities.

  • Underwater

    This device may use either the PI or VLF technology. These detectors are designed to meet the needs of divers and archeologists interested in underwater explorations.

Different Technologies

Present day detectors use several advanced technologies. These include:

  1. Very Low Frequency (VLF) Technology - More commonly known as induction balance, devices that come with this technology use two coils; transmitter coil and receiver coil. This technology is mostly used in hand held models.

  2. Pulse Induction (PI) Technology - These detectors are designed to send short but powerful pulses of electrical current through the coil, creating an electromagnetic field to detect a nearby metallic object. This technology is also commonly used in hand held models.

  3. Beat Frequency Oscillation (BFO) Technology - A BFO model uses two coils and thousand of pulses are created by an oscillator connected to both coils. These pulses create radio waves. The presence of a metallic object is detected due to the change in radio wave frequency.  The BFO technology is commonly utilized in walk through detectors.

Did you know?

The main component of a metal detector is an oscillator. The oscillator is responsible for creating a magnetic field by producing an alternating current that passes through a coil. If this magnetic field comes in contact with a piece of metal, the device alerts either by a sound or a vibration.

Metal Sensor Components

It is made up of different components that include the following:

  • Battery – The battery is designed to provide power.

  • Control Box – This is where the input and output signals are processed.

  • Search Coil – This is designed to transmit electromagnetic field into the area under observation.

  • Stabilizer – This stabilizes the unit as the handler scans individuals.

  • Shaft – This component connects the coil and the control box.

  • Search Head – This is where the search coil is located.

The use of metal detectors has increased in recent years. Here are some relevant statistics,

A report issued by the National Centre for Education Statistics estimated that one percent of public schools in 2008, made it mandatory for students to pass through a metal detector every morning and this percentage has increased ever since. The report also said that a higher percentage of high schools than middle schools required students to pass a daily check.

The use of such detectors in your office building, shopping malls, schools and industrial facilities may help avoid tragedies. As their use becomes more common, some homeowners are also using this technology to protect themselves and their loved ones better.


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