How Does Metal Detector Work?

How Does Metal Detector Work?

Explaining How a Metal Detector Works 1Nothing can be more exciting than finding a buried treasure. Have you ever wondered how a metal detector, which is used by millions of people around the world to uncover priceless relics, works? The same technology used in this device is also used by the police, military and other security services to keep the world safe by detecting weapons and buried mines. The following sections focus on explaining how a metal detector works.

A metal detector is based on the principle of electromagnetic induction. It contains a coil of wire (the transmitter coil) wrapped around a circular head at the end of the handle. Whenever electricity flows through the coil, a magnetic field is created around it. As you sweep the device on the ground, you also move the invisible magnetic field around.

When the detector is swept over an object made of metal, the magnetic field in motion affects the atoms in the metal altering the way in which the electrons move. Now, according to Maxwell’s rule, the changing magnetic field induces an electric current in the metal. However, Maxwell also proved that the electricity moving in a metal object also creates some magnetism. Simply put, the magnetic field produced in the metal detector creates an additional magnetic field around the metal.

The detector has an additional coil of wire called the receiver coil near its head. It picks up the second magnetic field which is induced in the metal. Once the detector is swept over a metal piece, the magnetic field induced in the metal cuts through the coil causing an electric current to flow through it, again according to the Maxwell’s rule. The receiver coil is connected to a loudspeaker which makes a beep sound due to the current flow. As the transmitter coil is moved closer and closer towards the metal object, the noise becomes louder. Learn more about metal detecting and read metal detector reviews at


Most metal detectors provide a numeric display which shows the target’s possible identity. This feature is called Visual Discrimination Indicator (VDI). It allows us to make informed decisions about which targets to choose to dig instead of relying solely on the instrument’s audio discriminator to do the job.


Explaining How a Metal Detector Works 2This feature allows the instrument to respond to the targets within a certain range and rejects targets outside the range. Sophisticated detectors come with features that allow you to set multiple accept or reject responses.


They can be classified into the VLF (Very Low Frequency) type and the PI (Pulse Induction) type. The VLF detectors come with the technology that is discussed above. A PI detector’s search coil is different from that of a VLF detector as a single coil is used in it for both the transmitter and receiver. Although it isn’t suitable to hunt for metallic objects in urban areas (as they contain iron trash), they are perfect for relic hunting in rural areas where ferrous trash is non-existent. They are also used in extreme search conditions such as highly mineralized ground or salt-water beaches to search for objects buried very deep.

Owning one of these devices can be fun. Hunting for valuables that that are buried under the ground can be a fantastic hobby provided that you know how to use a metal detector.

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