Treasure Hunting

How Do Metal Detectors Work?

Are you wondering how do metal detectors work? This question is one that many people are asking. Indeed, even we can’t help but wonder how a device can locate metals and other valuables like gold and silver.

Metal detectors may look simple devices at first glance, but the inside mechanism is extremely complicated. Today, we’ll talk about this awesome innovation and its main purpose in the industry.

What Is a Metal Detector?

When you hear “metal detector,” what is the first thing that comes to your mind? Most people would say that they think of it as a device used to look for buried coins, jewelry, or treasures. Others would think of the device used by security personnel to check our bodies and our belongings when entering malls or airports.

Basically, both are true; the devices described above are both metal detectors. You may use a metal detector to look for lost jewelry or coins around the house, or you can use it to locate metals buried underground. And, yes; those things used by security guards to scan our body are also considered metal detectors.

Parts of a Metal Detector

In order to understand how a metal detector works, we first need to get to know the basic parts that make up one. Below, we would be focusing on regular metal detectors used for treasure hunting.


Some metal detectors have stabilizers; others don’t. The main function of this part is to keep the unit steady while you are sweeping it back and forth, trying to look for coins and other metals.

Control Box

The control box is the part of a metal detector that holds the controls, circuitry, batteries, speakers, and, of course, the microprocessor.


The shaft is the part that would connect the control box and the coil. This can be adjusted to the height that you want; you can lengthen or shorten the shaft depending on your preference.

Search Coil

This is more like the antenna of the metal detector, and it is responsible for detecting the metal on the ground.

How Do Metal Detectors Work?

Metal detectors are very complicated. Although they are very easy to use, the processes that are happening inside that small device are actually very intricate. Before we find how it works, how do you use a metal detector, anyway?

Of course, the first thing you need to do is to turn the unit on. Then, move the detector slowly while walking. You can slowly bring it to a certain location, and you can sweep the coil back and forth on the ground.

An audible signal will happen if you pass it over a target object. Advanced metal detectors can actually pinpoint the metal that it has detected, and it would indicate the depth of the targeted object as well.

Pretty simple, right? This is just the basic method of using a metal detector, and it contains so many features that you would need to spend a lot of time learning about. Now, let’s proceed with the process of how these metal detectors work.

  • After turning the metal detector on, the battery would activate the transmitter circuit inside. It will then pass down the electricity through the cable from the handle towards the transmitter coil at the bottom.
  • Once the transmitter coil receives the electricity, it will then create a magnetic field around the coil. The magnetic field will serve as the antenna; it would search for metals on the ground.
  • If you try to sweep the metal detector to a certain metal, the magnetic field from the coil will seep through it. It will then create an electric flow current in the metal object that you targeted.
  • The flowing current will then create another magnetic field around the object. The signal will then be sent through the receiver coil, and it will move it up to the receiver circuit.
  • When this happens, a buzzing sound will be released by the metal detector, indicating that you found a certain metal.
Metal detecting accessories on a table

Important Features of Metal Detectors

Metal detectors have certain features that you would need when you are hunting for treasure. Your metal detector should have all these features to make sure that you won’t have a hard time searching for specific metals on the ground.

Here are some of the features that your metal detector should have:

1. Discrimination

This is one of the most important features that you want in your metal detector. The main function of this feature is to help your device to distinguish if a target is a piece of trash or a valuable metal.

You have to remember that there are so many metals that you can find buried in the ground, like bottle caps, screws, and more. You cannot simply dig continuously just because your metal detector managed to find a metal on the ground.

There are metal detectors that would auto-adjust, or you can just do this manually. The thing is that you should always check this feature on a metal detector. Although most models have this, it is better to be sure.

2. Ground Balancing

The level of mineralization in the soil can mask valuable items. This is a very important thing to know because your metal detector won’t be able to detect any valuable items if the level of mineralization in the soil is very high.

The soil contains a minute level of metal, and this will interfere with the ability of your detector to find jewelry, coins, and more. By having a ground balance feature, the detector will be able to bypass all these unnecessary items.

There are also different variations of this feature for metal detectors, such as:

  • Automatic: This type of ground balancing will automatically detect and adjust depending on the soil.
  • Preset: The manufacturer will set the ground balance on a level that would work on different types of environments.
  • Manual: This will require you to make the adjustment yourself. This is the best choice if you are looking for gold because of the changes in ground conditions.
  • Multiple: This type of ground balancing feature allows you to choose automatic or manual balancing. It means that you can balance the ground manually, or you can choose to let the metal detector do it automatically.

3. Target Identification Feature

This is the feature that you need to determine if the metal detector is detecting a valuable or trash item. Basically, this feature will produce an audible tone that would indicate if the targeted metal is valuable or not. This may differ depending on the metal detector, but usually, high-pitched tones indicate valuable items while low grunts are trash items.

There is also a certain feature that would indicate the type of metal directly on the LCD screen. An arrow will appear on the screen, indicating the type of metal that you are presently targeting.

4. Operating Frequency

Metal detectors differ depending on their operating frequency. Most of the regular metal detectors, including the ones that are made for kids, are usually operating at a lower frequency. It can scan deeper into the ground, so they provide a much better detection depth.

Higher-frequency detectors are sensitive to smaller objects and gold. This means that if you are serious with gold hunting and looking for other valuable minerals, using a higher-frequency model will help you greatly. The only problem is that they won’t be able to penetrate deep into the ground compared to lower-frequency detectors.

5. Sensitivity

Another important feature of a metal detector is sensitivity. This will determine the ability of the detector to locate metal objects from far away. If you put the sensitivity too low, you won’t be able to detect any metal at all, and if you put it too high, what you’ll find are trash metals.

Therefore, you need to have the right value for the sensitivity level. Most manufacturers will suggest a good level for certain situations. If you want to know how do metal detectors work, you will have to understand their features.

Technologies Used in Metal Detectors

To further understand how metal detectors work, you should also know the different technologies that are being used in these devices. In this way, you’d have a better understanding of how it functions the way it does.

1. Very Low Frequency (VLF)

It is commonly known as induction balance, and it is the most popular technology used on most metal detectors right now. There are two types of coils in a VLF metal detector:

  • Receiver Coil: This is the inner coil loop that has another coil of wire. It will serve as the antenna, and it will receive and amplify the frequencies coming from the target in the ground.
  • Transmitter Coil: This is the coil loop on the outside. Inside is another coil of wire, and electricity will be sent to this wire.

The transmitter coil will create an electromagnetic field. Every time the current changes its direction, the polarity will change as well. If the coil of wire is parallel in the ground, the magnetic field will push down and pull it back up to send the pulses to the receiver coil.

2. Pulse Induction (PI) Technology

This is not a common form of metal detector. PI systems use a single coil as the transmitter and the receiver, or they may also have two or three coils that work together.

If you put the metal detector over a metal target, the pulse will start creating an opposite magnetic field on the targeted object. Once the magnetic field collapses, the magnetic field from the object will make sure that the reflected pulse will take longer to disappear.

3. Beat-Frequency Oscillator (BFO) Technology

This is the most basic method of detecting metal. In this kind of system, there are also two coils of wire used. There is a large coil located in the search head, while the smaller coil is in the control box. The coils are connected to an oscillator, which would generate thousands of pulses every second.

The coil will create radio waves as the pulses actually travel through each coil. The receiver will pick up these radio waves, and it will create a series of tones. If you hear a series of tones, that just means that the metal detector found metal in the ground.

Finding Metals on the Ground

Finding metals on the ground is not as simple as you think because these metal detectors are not capable of detecting metals on the deepest parts of the ground. Most models can only detect materials eight to 12 inches below the ground, but it is affected by different factors, such as:

1. The Type of Metal Detector

The depth of the metal detector will depend on the type of technology being used. VLF detectors use higher frequencies than the others, and there are other technologies that use small and large coils.

2. Type of Metal in the Object

You should know that some metals, like iron, can create a stronger magnetic field compared to others, and it can affect the depth of your metal detector.

3. Soil

There are minerals in the soil that can actually interfere with your metal detector in that it can affect the depth that your metal detector can reach.

All these factors will affect the depth of your metal detector, so if you are disappointed with the model that you bought, you should check the area where you are trying to look for valuable metals.


Knowing how a metal detector works can help you analyze the device if it is not doing its job properly. Alternatively, how it works will also depend on what type of metal detector it is and the features that it has.

If you’re planning to buy a metal detector for yourself, make sure that you know what features you prefer and the type of technology that you need. There are some metal detectors made for leisure activities, and there are others that were created for the purpose of finding gold and other valuable minerals. You need to determine your goal and choose a metal detector based on that.