How Do Metal Detectors Work?

How Do Metal Detectors Work?

You’ve probably watched TV shows where people find metallic items made from brass, tin, even silver and gold buried deep underground and maybe wondered what would you find in your own backyard if you’ve had a metal detector. Speaking of metal detectors, have you ever asked yourself how do metal detectors work?

The first thing that might pop into your mind is a metal rod powered by a magnet which reacts to the Earth’s electromagnetic field, but there’s more to it than that.

How it Actually Works

The key components of the metal detector are:

  • Search coil – It’s the most important part of the metal detector because it determines how deep the metal detector can actually detect the metallic object in the ground. The bigger the search coil, the deeper it detects, but a bigger search coil might not pick up small objects, like coins, because they can’t change the magnetic field enough to create a signal.
  • Control unit – This is the brain behind the metal detector. It consists of a battery, microprocessor, device controls, and speakers, and its purpose is to create a sound when the signal emitted from the search coil reaches it.
  • Stabilizer – The stabilizer is an attachment added to the metal detector for the purpose of better handling and more comfortable use. It stabilizes the metal detector when you move around with it so that the detector doesn’t move by itself.
  • Shaft – It’s basically a rod that connects the search coil and the control box and has other components in it as well. The shaft is often adjustable so you can adjust it to your height or maybe even elongate it if you need to reach tight spaces.

A metal detector generally consists of a search coil and a computer that processes the information given by the search coil. The search coil consists of two internal sets of cold wires – a transmitter coil and a receiver coil.

When the detector is turned on the transmitter coil generates an electromagnetic field in the surrounding space, and when the metallic object is in the magnetic field, it will create a distortion which is picked up by the receiver coil which sends a signal to the control box.

The receiver coil, also located in the search coil, detects changes in the magnetic field made by a metal object. The weaker returning magnetic field of the metallic object is amplified, and when it reaches the control box, the unit will send out a distinct audio tone.

Depending on what type of metal is detected and its purity, you will hear a different sound coming from the control unit, and also, the closer you are to the object, the more high-pitched the noise gets.

Types of Metal Detectors

Know that we know how do metal detectors work we should discuss what types of metal detectors you should buy for what purpose. Basically, there are three types of metal detectors:

  1. Very Low Frequency – Also called the VLF, this is your basic metal detector which any treasure hunter opts for in search of treasure. It’s best for detecting precious metals like gold and silver, but also other metallic objects and this is the type of metal detector you want to use if you want to search for gold in your backyard.
  • Pulse Induction – Most of these kinds of metal detectors work by only using one coil and are usually used for security at airports and municipal courts to frisk people on the entrance gate. They are extremely accurate at detecting metal objects but aren’t great at distinguishing between various types of metals, so you should stick with the VLF detector.
  • Industrial – This type of metal detectors is commonly used at doors of most shopping malls, airports, courtrooms, office buildings and so on, and almost everyone had that awkward experience of hearing something beeping behind them when they exit a store.

Side note: You can purchase a handheld pulse induction metal detector which goes well with the VFL one, especially when you start digging for the object you’ve detected as it shows you how deep the object is buried.

Best Places for Metal Detectors

We’ve explained how do metal detectors work, but we also want to give some tips on the best places to use your metal detector in order to actually find something rare and exciting.

You should try out your metal detector at places such as

  • Beaches – The shifting tides are known for dragging a lot of stuff from the bottom of the ocean.
  • Parks – People lose things at the parks all the time. If you find an object which can be traced back to the owner, be a good Samaritan and give it back to its rightful owner.
  • Old churches – Outside old churches you’re bound to find some old coins or other valuable metallic items.
  • Countryside – People have been known to find old Roman coins in the countrysides of Europe, mainly because the Roman empire was so huge that it covered nearly half of Europe.


And this is all you need to know before you start your treasure hunt.

Good luck on finding some cool and rare artefacts!

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