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Metal Detectors: How They Work and are Used

posted by Chris Valentine

Metal detectors are used in a wide variety of purposes, from security, hobbies, and even in the food industry. It follows that different metal detectors have varying capabilities based on their specifications.

However, the basic principle behind how these devices work still holds true.


When magnetism and electricity are coupled together, incredible things happen. While it is true that electricity can produce magnetism and vice versa, both electricity and magnetism make up electromagnetism. The latter is the underlying principle behind how metal detectors work.

  • Transmitter Coil

Usually, a metal detector contains a coil of wire referred to as the transmitter coil. When electricity flows through this coil, a magnetic field is created around it. When you sweep the metal detector above the ground, the magnetic field surrounding the coil moves around too.

  • Receiver Coil

Additionally, when you move the metal detector over a piece of metal in the ground, this magnetic field coming from the metal detector causes another magnetic field to appear around the metal in the ground. The magnetic field around the metal on the ground is picked up by the detector through a second coil of wire known as the receiver coil. This coil is connected to a circuit that contains a speaker. As the metal detector is moved over the metal piece, electricity flows through the receiver coil, which makes the clicking or beeping sound.

Types of Metal Detectors

VLF Detectors. Very Low Frequency detectors are the simplest detectors, which are suitable for various kinds of general purpose metal detection and treasure hunts. These have a single and fixed frequency range, which is generally less than 30kHz.

PI Detectors.

Pulse Induction detectors use higher frequencies and pulsed signals. These have the ability to sense objects buried deeper into the ground.

FBS Detector.

Full-band spectrum detectors used multiple frequencies simultaneously, which leaves the user with the impression that he is using several slightly tuned detectors all at the same time.

Uses of Metal Detectors

Metal detectors can be used for numerous purposes. A walk-through metal detector is important, especially for security purposes, while handheld metal detectors are perfect for relic hunting. The best all round metal detectors are usually lightweight and easy-to-use. Some are even compatible with headphones, while some feature a large LCD screen.

There are also underwater metal detectors which are used to locate metallic pieces on ocean beds. Underwater construction companies use this type of metal detectors for pipeline or cable locating functions. There are even metal detectors that incorporate microprocessor technology to inspect coarse grained elements in processed food such as cornflakes, popcorn, and noodles. Generally, the price of metal detectors varies based on its specifications and capabilities.

In conclusion, it can therefore be deemed that metal detectors work based on the science of electromagnetism. As such, metal detectors can already be found in several industries, and it is no longer limited to security purposes. If you intend to use one to support your hobby, make sure to try using an inexpensive model first before investing into one with more capabilities.

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