How Metal Detectors Work



Metal detectors can be used for fun, if you like searching for anything – trinkets or what-have-you, or you can use these tools more seriously, if you’re after serious treasures like some elusive legendary hoard or another, and / or historical artifacts culled from the depths of time.

metal detector finds

Metal detectors are also used in security systems and military, helping to keep the world safe by uncovering hidden weapon or mines. This was, in fact, their original purpose.  It was only later that they were used for treasure hunting purposes.

Here is a metal detector being used to find a dangerous anti-tank mine.

This article has many sections, so please be sure to use the following table of contents to navigate around.

Table of Contents:

  • [ps2id url=’#1′ offset=” class=”]How do metal detectors work exactly?[/ps2id]
  • [ps2id url=’#2′ offset=” class=”]Metal detectors and electromagnetism[/ps2id]
  • [ps2id url=’#3′ offset=” class=”]What are the different parts of a metal detector?[/ps2id]
  • [ps2id url=’#4′ offset=” class=”]What can a metal detector detect exactly?[/ps2id]
  • [ps2id url=’#5′ offset=” class=”]Can metal detectors detect gold?[/ps2id]
  • [ps2id url=’#6′ offset=” class=”]How deep underground do most metal detectors detect?[/ps2id]
  • [ps2id url=’#7′ offset=” class=”]Does metal detecting really work?[/ps2id]
  • [ps2id url=’#8′ offset=” class=”]Do you need a license or special permissions to use a metal detector?[/ps2id]
  • [ps2id url=’#9′ offset=” class=”]Can you make piles of money with a metal detector?[/ps2id]
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Alright, let’s all grab our shovels and see what we can <ahem> dig up…

How Do Metal Detectors Work Exactly?

Have you ever wonder how metal detectors work? We did too, and it haunted our dreams until we set about learning the science behind it.  So, here we are now to share with you some of the interesting facts behind metal detectors and how exactly they work!

Let’s Talk About Electromagnetism


First off, it should be mentioned that we will need to talk about the concept and phenomenon of electromagnetism, which is fully at play when it comes to metal detectors.

Magnetism and electricity are like salt and pepper; they always go together (especially on chicken).

We use this magnet-electricity connection every day when we use any electric appliance. How? We use magnetism to make electricity.

And where does electricity come from?  Well, if you didn’t know, the electricity we all use day to day comes from power stations.

It is made by a generator, which is a big drum of copper wire. That wire rotates at high speed through a magnetic field, generating electricity inside. That provides power for us all to use.

Here’s a sample of how a power plant works.

So, all of the electric appliances we use are run by electric motors that work in the opposite way to generators – electricity passes into them, generating a changing magnetic field in a coil of wire that pushes against the domain of a permanent magnet, and that’s what makes the motor spin.

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With that in mind, let’s now apply this information to metal detectors themselves.

Metal Detectors and Electromagnetism

What does this have to do with metal detectors?  Everything.  A metal detector contains a transmitter coil – a coil of wire wrapped around the round head at the end of the handle.

When there is electricity flowing through the coil, it’s creating a magnetic field all around it. When you are moving, the detector over the ground, you make the magnetic field move around too.

how does a metal detector work?

If you the detector close to a metal object, its moving magnetic field affects the atoms inside it. In this way, it changes the way the electrons inside the metal moves.

Now if we are changing a magnetic field in the metal, the metal detector must induce some electricity moving inside the metal, too, because these two things always go together.

Further, if there’s any electrical activity in a piece of metal, it creates some magnetism as well.

So, in other words, when you move a metal detector over a metal object, the detector’s magnetic field causes another magnetic field to appear around the metal.

Here’s an example of someone finding something while using a metal detector.  It’s a bit long, but you can always skip to the good part (the find).

Anyway, as I was saying, this second magnetic field, around the metal, is what the detector identifies.

The metal detector has a second, receiver coil of wire in its head that’s connected to a loudspeaker. When you move the detector over the piece of metal, the magnetic field produced by the metal you make electricity flow through the receiver coil.

That causes the loudspeaker to create some sound, click or beep, telling you that you have found something.

The closer you move the detector to the object, the sound is louder, because the transmitter coil creates the stronger magnetic field in the metal, which makes everything stronger – the magnetic field the metal creates in the receiver coil, and the noise from the loudspeaker.

That’s essentially how a metal detector works – it relies on the close connection between the two components of electromagnetism. We use electricity to create magnetism, which creates more electricity that we detect.

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Now we see how electromagnetism applies to these devices, and so let’s take a look at the different components of metal detectors to see how they’re constructed.

What are the different parts of a metal detector?

fisher gold bug dp

A typical metal detector is simple and light-weight. It consists of only a few parts:

Search head, also known as search coil, antenna or loop – the crucial part that actually senses the metal.

Control box – contains the electronics, controls, microprocessor, batteries, and the speaker.

Shaft – it connects the control box and the coil. It’s often adjustable so you can set its length for comfortable using.

Stabilizer – an optional part which has the purpose of keeping the unit steady.

parts of a metal detector
Most models also have a jack for connecting earphones.

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Some more advanced detectors have more additional parts like the control box below the shaft, and a small display unit above that shows the type of the detected metal and how deep in the ground the object is located.

What can a metal detector detect exactly?

what can a metal detector detect

In general, metal detectors can detect almost all kinds of metal- iron, aluminum, nickel, gold, silver, bronze, copper, brass, aluminum, tin, and lead.

Commonly, nonspecific metal detectors can find buried metal objects, such as coins, lost or hidden jewelry. But there are different kinds of metal detectors that are better in finding certain metals.

Ferrous metals (iron, for example.) react to a detector differently from non-ferrous (like gold.), and most good metal detectors can distinguish them.

Advanced gadgets have the option of finer discrimination – it’s a process that differentiates between different metal targets or alloys. It can be handy if you are searching for a particular kind of metal.

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For example, you can set your metal detector to send sound signals that indicate metals you are interested in, such as nickel or gold, and reject other kinds.  Pretty cool, right?

Can metal detectors detect gold?

For gold hunting, you can use a general-purpose metal detector. It may happen that you stumble upon something, using this type, but it is not especially good at it.

However, there are specific metal detectors specialized for finding gold. Gold detectors are most popular among amateur treasure hunters.


By their main characteristics and purposes, these are metal detectors but specifically constructed for gold hunting.

We have already explained how a metal detector works using electromagnetism. Gold detectors do the same, but with a few additional steps – they measure inductance and conductivity.

Inductance refers to the amount of electric flows generated in the target. Conductivity refers to how easily the currents flow. By measuring their size and the speed, gold detectors can recognize a target, gold in this case.

This, unfortunately, is not a fail-safe method, but it’s certainly helpful.

Watch this amazing video for some inspiration.

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This is all good to know!  But now we need to answer yet another burning question people always ask.

How deep underground do most metal detectors detect?

The accuracy of a metal detector depends on many factors -sensitivity of the device, nature of the terrain, the condition of the soil, type of metal, size, and shape of an object.

All of that can provoke a false beeping or, on the other hand, overlooking some worth piece you are searching for.

But generally, these gadgets are pretty reliable in finding any metal objects. It’s just likely, if you are just a beginner, that you will find a lot of useless metal pieces before you uncover the mother load.

Although “How deep this metal detector can detect” is one of the most frequently asked questions, there’s no exact answer, since there are so many different types and brands of detectors.

The most simple answer is that the more sophisticated and expensive models are more powerful and do go more in-depth. But it’s far from the complete answer.

That said, the following chart should give you some idea, based on search coils of the detector.

search coil comparison chart

The condition of the soil around the target also plays a significant role in whether you will find it out.

When a metal object, a coin or artifact, is buried in the ground for some time, it creates an electromagnetic field around itself.

This effect increases over time and increases your detectors’ ability to find it until some point. After that optimal level, it decreases somewhat.

So, one of the factors that determine whether you will pick up an object with your detector is for how long it has been buried in the ground.

searching with metal detector

When the soil is extra moisture, it’s a bonus because it increases conductivity and objects are easier to detect. Use benefits from this nature’s favor whenever possible.

One more significant factor is the kind of metal that you’re detecting. Iron is the most often detected metal of them all.

Running in the “all metals” mode, without discrimination turned on, will also give you more depth. The systems used to distinguish out iron and aluminum reduces your depth range slightly.  So, turn it off if you want to increase depth.

There are also outside interference that can affect your depth capability. You may be forced to turn your sensitivity down if there are false signals because of high voltage electrical lines overhead or nearby.

Other factors that may force you to turn your sensitivity down and the depth lower are obstacles like salt water, black sand, hot rocks, and other forces of nature.

You will simply have to turn your sensitivity down to deal with these factors, and that’s why they affect the depth range.


The size of the buried object is an important factor, too. The bigger the object, the stronger the magnetic field, so in more depth you can detect it.

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Now it should be more clear why the initial question of depth is a very relative thing. It’s good to know which factors do affect the sensitivity so that you could get the most results of any metal detector.

Does metal detecting really work?

Metal detecting undoubtedly works. Electromagnetism runs them, and it’s a science in the back, not magic. You can’t doubt in magnetic fields and electricity – that’s a matter of physics, not faith. These are all scientific facts, not coincidences.

The other thing is the question will you find something using a metal detector. You can’t know it for sure. People found much amazing stuff that way, some of them worth up to thousands of millions.

metal detector find

On the other hand, some folk tried out metal detecting and realized it’s not for them. It’s up to you to see if that’s the hobby for you.

Many factors impact the quality of your experience with metal detecting. You have to try it to know if you like it. And, of course, luck is a huge factor in that game.

That, besides everything else, is what determines if someone will stumble upon something almost immediately, while someone else could hunt treasure for many years without any success.

But even in cases like that, it’s the matter of luck; you can’t blame metal detectors or suspect the science doesn’t work.

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Now, on to another matter of crucial importance…

Do you need a license or special permissions to use a metal detector?

When your first wave of excitement is gone, and it’s time for real work, you come to the question “Where to go next, where to go hunting? And am I allowed to dig there?”

It’s smart to ask those questions, before you go for treasure hunting, maybe even before you buy a metal detector.


When it comes to the question of allowed and banned metal detecting, you need to know the law, and it’s not easy at all.

What makes it difficult is that it differs not only from one country to another but also from city to city even in the same country!

Not only that, but it may happen to be allowed to hunt treasure on beaches, but not in a public park in the same city.

Even worse, it may be permitted in one public park, but prohibited in another one down the street.

The only general rule is that you should ask. Inform what’s allowed and what is not, ask for permission in advance. Visit a city’s hole, make a call to the school where you want to metal detect, read everything about the country you are going to visit.

You don’t want to end up in prison, especially not in a foreign country. Some people are willing to take a risk, but it’s certainly not recommended and may lead you to serious trouble.

Be smart, respect the land, its owner, people’s property, and the rules in general, and metal detecting will be fun as it should.

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And so, keeping in mind everything we’ve said so far…perhaps the most burning question that every newbie treasure hunter is subconsciously wondering…

Can you make piles of money with a metal detector?

Although metal detecting is a wonderful hobby for most people, some of them successfully made an income from it.

can you make money metal deecting

It certainly is possible to make money using your metal detector, but like any other serious job, it demands research and a lot of work. Here are some most common ways metal detecting can full your pockets:

Coin hunting

After any large event where were thousands of people, you’ll find a lot of coins. The good thing about that is that you’ll find them easily, on the surface, without any digging. The bad side is that you won’t get rich that way. But all adds up!

Jewelry hunting on beaches and in pools

You will need only enough patience to make money reselling things found on beaches. Here you can find anything – from trash to expensive gold jewelry. These are the places the most pieces of jewelry are lost.

Old & rare coins

Most researches dream about finding rare coins of historical value. If you are one of them, you need to do a lot of research, and then hunt in regions that have the old history – these areas have the most potential for rare discoveries to occur.

Gold nuggets

This kind of gold hunting has sense only in areas that have a natural potential to produce gold large enough to be detected.

Looking for gold nuggets is more challenging than detecting coins, but if you take time to learn enough about it, it may pay off greatly.

First, when you find one nugget, you know there are more. And second, gold is universally valued so that you can sell it easily.

Rare & collectable relics

In some areas rich in history, there are old relics found every day. Not all of them are rare and valuable, but some of them can bring money to the collector.

Areas of significant battles are particularly good for this kind of search, although wherever people have habituated long ago, you can find some valuable relics.

Cache hunting

Finding a buried treasure in any size or form is worth an effort. It doesn’t happen every day, also not to everyone, but there indeed are some buried cans with cache, gold or silver out there, and people do find them.

So, keep dreaming and experimenting with a metal detector – there is always a possibility to make a big score.

Read our article:

That about wraps it up for now!  Thanks for reading, and if you have any questions or comments, please leave them below.  We’d love to hear from you!


About the author: Patrick has the record of travelling the most out of everyone, visiting over 30 countries around the world in 15 years, and sleeping in the most tents with the least amount of blankets and cushions.  He can literally sleep anywhere! A few countries Patrick has lived in include India, Mexico, Tanzania, and Morocco, and currently he lives in Peru.

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