How do metal detectors work?

How do metal detectors work?

You might be wondering about the article’s name how do metal detectors work?, as it indicates that the provided data would be technical. But this is not the case.

As our 90-95% audience is not engineers, they still want to grasp the basic concept of the metal detecting working principle. So we will cater to this problem of our audience by delivering the concept of metal detectors working in simple words.

Understanding how a metal detector works in crucial if you want to get the results you are looking for. Not understanding the technology is how most people make mistakes while metal detecting that lead to frustrations later on.

Therefore, our main focus will be on the Metal detector working principle – How do metal detectors work?

So in this article we will be explaining to you in non technical words how do metal detectors work:

Components of Metal Detector

The major parts of metal detectors are three: the control unit, the coil, and the shaft.

The Control unit

The control unit works as the brain for the metal detector, just like the CPU for the computer. All of the hardware is embedded in the control unit. The control unit has a considerable function in the metal detector.


The major component of hardware is the search coil. The coil’s work is to transfer and receive the signal from the underground, buried, or hidden metals. Coils are metallic wires.

Sometimes, the coil is connected to the wire, while in some technologies, the coil is wireless. These are embedded in physical plastic components to prevent damage from water contact and the ground. The coil must be tough against scratches.

Additionally, it should be waterproof and shockproof. The coil has a significant role in the performance of the detector. As a detectorist, you should know How to test a metal detector coil.


Lastly, the third main part of the metal detector is the shaft or support structure. The function of the shaft is to maintain the shape of the detector and make it user-friendly.

However, the shaft is not a necessary component. Some devices come without shafts. Instead, there are belts and harnesses that join with the control unit. The detectorist can easily hang the belt on their neck.

Metal detectors are based on electromagnetic induction. Now, we will describe this term in simple words:

Firstly, there is a search coil that sends electromagnetic signals underground.

Also, when the signals hit the target, it gives energy to the target and sends the energized signal back to the detector.

The coil emits signals with the same range upwards as it generates downwards. We suggest our users not wear metal items like watches, phones, or jewelry.

Metal detectors won’t work properly and may detect your watch or other metallic items.

Similarly, if there is another metal detector nearby, it will interrupt the frequency of your metal detector. So we suggest you do not perform metal detection in the presence of another detector in your area.

How do Metal Detectors Work? A Step- Stepwise Guide

  • In the first step of metal detection, the coil generates an electromagnetic field that penetrates the ground for search.
  • In the second step, the signal will target any metallic item that comes in contact with the coil’s field. The electromagnetic field charges the metal item.
  • In step three, the energized or charged metal object transmits the signals back to the search coil. The coil then receives the energized waves from the target object.
  • In the final stage, the coil transfers the charged signals to the control unit. The control unit then processes the signal and analyzes at what frequency the signal was sent and at what frequency the signal is bounced back.

There are some functions in the control unit, such as discrimination. It differentiates various metals and examines whether the detected metal is copper, iron, or gold.

Generally, detectors are incorporated with ferrous and nonferrous discrimination.

  • After the processing of signals from the control unit, the next step comprises the control unit displaying the output. The output can be in two types. One is in the form of audio, and the other is the display.

The detector produces a high-pitched sound when stumbling across precious metals. Whereas, the low-pitched volume directs the presence of nonprecious ferrous metal, i.e., iron.

With the help of tone, the detectorist can easily tell apart valuable and non-valuable metals.

The next category of output is the display output. In this grade, the control unit will display the nature of the underground metal.

Suppose there are 0-99 target IDs in the display output, and a metal is found with target ID 15, so it will be considered a ferrous metal or trash.

Quite the reverse, if the output shows 70 or 80 target IDs, it indicates the existence of nonferrous precious metals.

In general, valuable metals like gold are often associated with high numbers of IDs. Conversely, low numbers usually indicate trash like bottle caps, cans, and aluminum foil.

It is noteworthy that, depending on your locality, items will be discovered. To get rid of too much waste, use the discrimination feature to filter out unwanted metals like iron.

If your area has too many underground bullets made of brass, you can get rid of this by filtering out brass. As a result, whenever your device comes across brass, it will reject its signals.

  • The last step is deciding whether the signal is worth digging into or not.

We recommend you not activate the discriminate mode during your initial period of metal detection. You must grasp the understanding of signals first, so work on all metal modes.

Manufacturers suggest practicing near your area for 90 hours. This helps you and the detector get familiar with your ground and device.

Metal detector types and technology

VLF technology

VLF technology stands for Very Low Frequency, and it operates at low depth.

Pulse Induction

Pulse induction devices are designed for deep-seeking treasures and work at higher depths.

Learn about Pulse Induction vs VLF in depth.

Some people modified these two technologies, i.e., VLF and PI, and created a new technology with a patent.

However, the new technology produced resembles VLF and PI, such as ZVD technology and Geo Sense technology. So there are diverse categories of modified technologies extracted from basic VLF and PI.


Knowing the metal detector working principle is very important for the detectorist to use the device efficiently.

We have thoroughly covered the concept of metal detection working, from the receiving of the signal to the decision of digging. The major working components in metal detectors are the control unit and search coil.

We are confident that equipped with the right knowledge, you should now be able to hunt for treasures more effectively.

And if you have not yet purchased a metal detector and were researching for which one your need to buy. You should be able to make an informed decision on what detector might suit your needs best.

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