How Metal Detectors Work: The Basics of Detecting Metal

How Metal Detectors Work

Wondering how metal detectors work? Today we will go over the basic fundamentals of understanding how metal detectors detect metal. Knowing this will greatly help you understand a bit more on how to decide which the right metal detector for you might be!

Understanding the Parts of a Metal Detector

There are many different types of metal detectors, but they all mostly work the same way. The difference of course depends on mostly the technology used and the type of equipment you may be considering.

You have a lot of options to choose from, with many different brands of metal detectors. While they all have different features, most metal detectors for hobbyists all have common parts and components.

The Anatomy of a Metal Detector

anatomy of a metal detector

Seeing the different parts of a metal detector can better help you understand exactly how it works. Most units consist of 4 basic parts, although the different way these parts are assembled and work together can sometimes vary.

The Stabilizer: This is the part which you use to hold the metal detector. This is what keeps it steady as you are sweeping your machine back and forth over the ground.

The Control Box: The control box of every unit is what contains the controls, speakers, microprocessors, batteries, and electronic circuits. Some control boxes are quite simple and only use dials. Other control boxes have adopted modern technology to show advanced controls and LCD screens.

The Coil: The coil is the part of the machine which is swept over the ground.  This is the part of the machine which will actually be detecting where the buried treasure might be!

Coils can come in different sizes and shapes, and many machines offer the benefit of being able to swap different coils for different uses. Being able to switch between a small coil and a large coil can give you a lot of adaptability when metal detecting in various locations.

The Shaft: The shaft is the part which connects the control box to the search coil. Most shafts on a majority of machines can be adjusted to the desired height which is comfortable for the user. This part is sometimes also wrapped with a visible cord which is what connects the electrical components from the coil to the control box.

Headphones: Headphones are not always required while metal detecting, though many people do find them quite useful, especially when detecting in loud areas such as the shores of the beach where wind and waves may make it difficult to carefully discern between signal sounds.

How Metal Detectors Work

how metal detectors work

Once you understand the basics of the anatomy of the machine, you are ready to begin to understand how the metal detector actually detects metals underground.

Contrary to popular belief, a metal detector is NOT a magnet. A magnet would only be able to find ferrous metals. Ferrous metals are quite common and generally are of very low value.

For example, rusty nails are a ferrous material. You would need thousands of these rusty old nails to take to the scrap yard and make enough to even buy a cup of coffee.

Needless to say, ferrous targets aren’t exactly the “treasure” you may be hoping to find!

Instead, metal detectors function based on the principles of electromagnetic induction. It sounds a bit technical and complicated, but it is actually easy enough for even the non-scientific or non-tech person to understand.

The coil of the metal detector creates an electromagnetic field around itself when a current passes through it. This current is controlled by the control box of your machine when you turn it on.

Most mid-level detectors will give you some ability to adjust the electrical current depending on the environment. Other detectors may have automatic settings which do this for you without the need to adjust the controls.

When there is metal present around this could that is conducting the electric current, it changes the electromagnetic field. This induces new electric currents, which are called eddy currents in the metal object you discover.

This eddy current has its own magnetic field and creates an opposite current in the coil. At this moment when this happens, you will hear a signal from your machine which suggests a difference in the current. This change in sound and signal on LCD screen control boxes will alert you that metal is present near the coil.

This is the most fundamental and basic explanation of how a metal detector works. Of course, we could get into the more specific and technical details, but my hope is to explain it in the simplest of ways so that anyone can understand how it might work.

Once you understand the most basic fundamentals of how metal detectors detect metal, this can help you in your research on choosing which metal detector might be right for you.


Important Things to Know About Metal Detecting

If you are new to metal detecting, or simply curious to learn more, there are a few good resources to learn the secrets of finding good treasures.

#1. Know What You Want to Find and Be Prepared!

There are many things you can find while metal detecting. The most popular things people like to find are these:

  • Old Coins
  • Relics and Artifacts
  • Jewelry, such as rings, necklaces, bracelets and more
  • Gold nuggets

Finding gold rings along the beach requires a different type of metal detecting shovel than you would use if you were digging up old Civil War relics on an old battlefield! It’s very important you use the right tools for the job!

Another thing to consider is some metal detectors are better for finding things like gold. There are many gold prospecting metal detectors, though many are a bit in the higher end range. Fortunately, even with a decent mid-range metal detector and lots of practice, you will be able to find most gold jewelry that is not buried too deep quite easily.

#2. Think About Where You Will Be Detecting Most Often!

Once you know what type of materials you wish to find, the next thing to consider is where you will be metal detecting. There are many places to go metal detecting, such as the woods, in a field, or even along the shores of a beach. The main difference between these places is the type of shovel for metal detecting you might want to bring!

As you can imagine, metal detecting at a beach can be very different than metal detecting in a field or in the woods. Making sure you have the right type of gear will largely influence the results you may have.

If you are in a saltwater environment, it’s very important to choose a machine suitable to go underwater and not be affected by the salt water, since this can change the signal readings of the electromagnetic field of your coil on the machine.

Need inspiration for places to metal detect? See our article on where to go metal detecting for some great ideas!

#3. The other important thing? You must practice!

You cannot expect to pick up a metal detector for the very first time and find something valuable if you are not yet even able to know how to operate the machine well enough to understand whether it is signaling that gold or coins would be present!

One of the easiest ways to practice is to set some targets in your yard, and see what your metal detector does when it goes over them. For example, a metal detector will make a much different sound over a piece of jewelry than it would over a rusty nail.

You may want to practice with a number of different materials you already have at home to begin to understand the signals of your machine and its sensitivity to different metals.


Metal detectors are quite fascinating, and really a lot of good fun. Learning how one works makes it a lot easier for you to decide on which metal detector might be best for you. This will definitely help you know which ones are going to give you the very best possible experience when you first start.

Do you have any questions on how a metal detector works? Are you curious about learning more about metal detecting? What metal detecting experiences do you have that you might like to share? Tell us your thoughts in the comments section below!

1 thought on “How Metal Detectors Work: The Basics of Detecting Metal”

  1. Hi, I wanted to know what makes the signals/VDI readings more stable? is the achieved by a lower current? and also is there a way to increase the conductivity of targets in the ground as I remember seeing a product by garret called bloodhound that you place metal prods into the ground and pump electrical current through the ground. Thank you

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