How Do Metal Detectors Work?


A metal detector is an instrument that can find any instance of metal from the ground, the human body, or a parcel. But how does it work?

The operation of metal detectors is based on the principles of electromagnetic induction. Metal detectors contain one or more inductor coils that are used to interact with metallic elements. The single-coil detector is a simplified version of one used in a real metal detector.

Metal detectors work by emitting a low-frequency electromagnetic field and detecting the disturbance caused by metal objects within that field. The metal detector consists of a search coil, the circular loop of wire used to detect metal, and a control box, which contains the electronics that power the detector and process the signals.

When the search coil is passed over a metal object, it creates a disturbance in the electromagnetic field, which is detected by the control box. The control box processes this disturbance and produces an audible tone or visual display to alert the user that a metal object has been detected.

The metal detector’s sensitivity can be adjusted to detect deeper or shallower objects, and the type of metal being detected can often be identified based on the strength and frequency of the signal.

Overall, metal detectors work by emitting an electromagnetic field and detecting the disturbance caused by metal objects within that field, allowing users to locate hidden metal objects.

Do Metal Detectors Detect All Metals?

Metal detectors can detect most types of metal, including ferrous metals (such as iron and steel) and non-ferrous metals (such as copper, aluminum, and brass). However, the sensitivity of metal detectors can vary, and some may be better at detecting certain types of metal than others.

For example, some metal detectors are specifically designed to detect gold and may be more sensitive to detecting gold than other types of metal. Similarly, some metal detectors are designed to detect deeper objects and may be more sensitive to detecting deeper metals than those closer to the surface.

Additionally, the size and shape of the metal object can affect whether or not it is detected by a metal detector. Larger and more conductive metal objects are generally easier for a metal detector to detect than smaller or less conductive objects.

While metal detectors can detect most types of metal, the sensitivity and capabilities of different models can vary. Some may be better at detecting certain types of metal than others.

What Is a Metal Detector?

The very first metal detector was created in 1881 by Alexander Graham Bell to discover the bullet lodged in the body of President James Garfield when he was assassinated. The first portable version was patented in 1931 by Fischer since it has become really typical and much more widely used by treasure hunters.

A metal detector is a device to locate metal objects hidden beneath the ground or underwater. Metal detectors work by emitting a low-frequency electromagnetic field and detecting the disturbance caused by metal objects within that field.

When the search coil of a metal detector is passed over a metal object, it creates a disturbance in the electromagnetic field, which is detected by the detector’s control box. The control box processes this disturbance and produces an audible tone or visual display to alert the user that a metal object has been detected.

Metal detectors are commonly used for various purposes, including treasure hunting, detecting metal objects in construction or demolition sites, and detecting weapons or other metal objects in security screening. There are many different types of metal detectors available, and the best one for you will depend on your specific needs and the type of metal you want to detect.

What is a Metal Detector Made Out of?

Metal detectors are typically made out of a combination of metal, plastic, and electronic components. The search coil, the circular loop of wire used to detect metal, is typically made of metal, such as copper or aluminum.

The control box, which contains the electronics that power the detector and process the signals, is typically made of plastic and contains various electronic components, such as microchips, circuit boards, and batteries.

Some metal detectors are also equipped with additional features, such as a display screen, control buttons, and a speaker, which may be made of additional materials.

Overall, the components of a metal detector are designed to work together to emit an electromagnetic field and detect the disturbance caused by metal objects within that field, allowing users to locate hidden metal objects.

If you are looking for strictly gold, there are metal detectors built just for gold. If you want coins or relics, you can get a detector built for both and adjust the setting to look for one. Or turn it wide open to look for any metal items.

How Does a Metal Detector Work?

A metal detector emits a low-frequency electromagnetic field and detects the disturbance caused by metal objects within that field. The metal detector consists of a search coil, which is the circular loop of wire that is used to detect metal, and a control box, which contains the electronics that power the detector and process the signals.

When the search coil is passed over a metal object, it creates a disturbance in the electromagnetic field, which is detected by the control box. The control box processes this disturbance and produces an audible tone or visual display to alert the user that a metal object has been detected.

The metal detector’s sensitivity can be adjusted to detect deeper or shallower objects, and the type of metal being detected can often be identified based on the strength and frequency of the signal.

Overall, metal detectors work by emitting an electromagnetic field and detecting the disturbance caused by metal objects within that field, allowing users to locate hidden metal objects.

How Is The Metal Detector Built?

Metal detectors utilize the principle of electromagnetism, and the result applies to metals. The metal coil called the transmitter works on battery power and produces a magnetic field that works in the environment. Utilizing this principle, you can configure high-end metal detectors to look for particular metals.

How Deep Can a Metal Detector Detect?

The depth at which a metal detector can detect an object depends on various factors, including the size and type of the object, the sensitivity of the metal detector, and the type of soil or ground in which the object is buried. In general, most metal detectors can detect objects a few inches to a few feet deep, but some high-end models can detect objects at greater depths.

The size and type of the object being detected can affect the depth at which it is detected. Larger and more conductive objects, such as coins or jewelry, are generally easier for a metal detector to detect than smaller or less conductive objects.

The metal detector’s sensitivity can also affect its ability to detect objects at deeper depths. Some metal detectors are designed to be more sensitive and can detect deeper objects, while others are less sensitive and may only be able to detect shallower objects.

Finally, the type of soil or ground the object is buried in can also affect the depth at which it is detected. Soil or ground with a high mineral content can interfere with the signals from a metal detector, making it more difficult to detect deeper objects.

Overall, the depth at which a metal detector can detect an object can vary depending on various factors. Still, most metal detectors can detect objects a few inches to a few feet deep.

Do Metal Detectors Find Gold?

All metal detectors will find gold nuggets if they are in the ground (and big enough) – not just gold detectors. A gold metal detector is simply a detector explicitly designed to detect tiny targets in mineralized ground.

I have a Garrett AT Pro Metal Detector, and it does not do well on small gold nuggets AT ALL. While at Miss Lucy’s claim in Idaho, Rob Johnson had a shallow sandbox to show kids how to metal detect using just a few inches of sand and a small gold nugget. Rob dropped (not buried) the nugget in the sand as I was facing the other direction. He then wanted me to find it with my AT Pro.

I figured this would be easy to accomplish since the Garrett AT Pro will find gold, but it was not. In the six by six sandboxes, I could not find a small gold nugget in less than an inch of sand. I could have easily found it if it had been a nugget like the one pictured at the bottom of the post on metal detecting laws. Rob has an excellent video learning how to metal detect for gold.

Spud Diggers – How To Metal Detect For Gold – Private Lesson With The Whites 24k Goldmaster

Can Metal Detectors Detect Diamonds?

Metal detectors are not sensitive enough to detect diamonds or other precious stones. Diamonds are not metal and are not typically conductive, so they do not disturb the electromagnetic field that a metal detector is designed to detect.

However, some high-end metal detectors may be able to detect diamonds if they are set to very high sensitivity and if the diamonds are near a metal object. For example, suppose a diamond ring is buried alongside a metal object. In that case, a metal detector may detect the metal object and, as a result, the diamond ring.

Overall, while a metal detector may be able to detect diamonds in certain circumstances, most metal detectors are not designed to detect diamonds and are not typically sensitive enough to do so.

Making Your Own Metal Detector

Say ‘metal detecting’ to someone, and you will get different responses from various individuals. For example, some people think of searching a beach for coins or buried treasure. Other individuals consider airport security or portable scanners at concerts or sporting events.

A fundamental metal detector consists of an electronic box and battery case on one end, with a handle or brace for the operator’s arm. An insulated wire covers a telescoping shaft into a round plastic disk called the coil. The concept is to slowly sweep the coil end over the ground until an electronic signal is heard.

Metal detectors work on the principle of electromagnetics and their effects on conductive metals. One is a high-powered coil of metal, which uses battery power to generate a permeating magnetic field.

In 1831, Michael FARADAY observed when a magnet is moved through a closed coil of wire; a momentary current is induced into the wire. The direction of the current circulation is to create a magnetic field opposite to that of the change in the magnet’s field.

Faraday then changed the magnet with an electromagnet. Two coils were wound close together, the first being linked to a battery and the second to a galvanometer, which measures small currents.

Creating s metal detector from scratch is not overly complicated; it can be a fun DIY project for a weekend. It will certainly save you some money over buying one from a store. You will also be able to adjust and tweak it to your liking.

I will not go into details on creating your DIY metal detector, but only because Rob Johnson already has a very well laid out description on how to make your metal detector over at his site Ultimate Metal Detectors. If you follow his instructions, you should have no issues building your Detector.

How To Purchase Used Metal Detectors

OK, so you do not want to buy a new metal detector, and building one of your own from Rob’s DIY Instructions is more than you want to do. What other options do you have if you still want to go metal detecting? There are many places, such as Tates Rents, where you can spend about $30 and get a metal detector for the day. Or, with careful research, you can get your used metal detector. You might be able to find a good one on Craigslist.

Metal Detectors For Sale On Craigslist, Treasure Valley Metal Detecting Club
Metal Detectors For Sale on Craigslist

Another good place is to find a metal detecting club in your local area. An excellent place to find a local group is Facebook. Many are private groups that are not open to the general public, but you can certainly request to join, and many times you will have members in your area selling their equipment. This site was built for the Gem State Metal Detecting Club, which has its own Facebook page.

Things To Keep In Mind When Purchasing a Used Metal Detector

When you buy a metal detector, choosing whether you want a brand-new instrument or a second-hand model would be best. Here we are looking over some things to remember when purchasing a metal detector.

These things will apply to anyone buying a new or used metal detector. A used metal detector will be a better option if the budget is constrained. If you are wondering how to purchase a used metal detector, here are some beneficial tips to guide your purchase.

What Are The Types of Metal Detectors?

There is various type of metal detectors offered in the market, used for different functions. The most readily available ones are gold detectors, coin and jewel detectors, relic-searching detectors, beach-hunting detectors, and underwater metal detectors.

Keep in mind that with most modern metal detectors, you can use them underwater. Most are only rated for, on average, about 10 feet or so, but they can be fully submerged in the water without issue. Some metal detectors are considered underwater metal detectors and are built to be used in lakes and oceans and can be brought down much more significantly than 10 feet.

What Factors Should I Consider Before Buying a Used Metal Detector?

Consider the following points before your purchase:

  • The detector’s quantity of usage: If you plan to utilize it for a brand-new pastime, select an instrument offering as many features as possible.
  • Location of use: Decide if you plan to use it on the beach, underwater, or in the forest. The area does not have much of a factor outside of on land or underwater. Those two locations are going to be your two most prominent factors.
  • Decide who will utilize it: For family use, there are detectors with adjustable arm cups, and almost all detectors now have adjustable lengths to the coil to be used by anyone of any height.
  • Budget: If possible, stick to your budget and try where you can to fit all of your needs into the type of metal detector you want for what you are looking to accomplish with it.

Where should I buy it?

A previously owned metal detector from a dealership is always a good deal for your money. This is because dealers test before selling the detectors, so you know you are getting one that works. If you are buying one off Craigslist, always be careful. Make sure it has batteries, or bring some of your own. Most use 4 to 8 double-A batteries. That way, you can turn it on and ensure it works before buying it.

What are the prices of the used metal detectors?

  • All-purpose metal detectors carry a price tag of $275 to $700.
  • Underwater metal detectors come at the cost of about $500.
  • The pre-owned accessories come at a rate of $100 to $200.

 However, the only drawback is that there is no manufacturer’s guarantee to buy a used one, but purchasing from an excellent dealership will offer some safety.

If looking for a used metal detector, one thing to do is find a site like KellyCo Metal Detectors, selling many different models and manufacturers. That way, you have a chance to browse through all the different kinds and manufacturers to see what you would like to get. You can go to that manufacturer’s site if you are particular about a specific brand.

Once you have found a handful of different detectors that you would like to get and fit your needs and budget, you will have a good idea of how much that detector cost brand new. Of course, this assumes you do not just go to a site like KellyCo or a particular manufacturer and buy a used one through them.

Suppose you are looking to purchase a used detector from a local club’s Facebook group or Craigslist. In that case, you know what a new one costs, so when someone is trying to sell you three of your old detector at full price, you will learn to stay clear or counteroffer a price that is less than what it would cost you brand new. A used metal detector can be an excellent bargain for your money and a great way to start a new hobby.

A Couple of Final Questions and Answers on Purchasing a Used Metal Detector

How do you test a used metal detector?

To test, lay the metal detector on a (non-metal) table or flat surface and wave different metals in front of the coil. This can be simple nails, scrap metal, or coins from your pocket. When making big purchases through online ads (such as Craigslist), meet in a safe, public place with many people around.

A great example is Starbucks or a parking lot, such as in front of a Walmart. NOT a dark alley at night from the back of an unmarked van. Try and buy equipment with boxes as well. I know that is not always possible, as most people throw all of that stuff away.

Why are metal detectors so expensive?

Many factors could make some metal detectors more expensive than others. The main elements are:

  • Brand
  • Implemented technologies
  • Possibility to configure more settings
  • Durability
  • Capacity to operate deeper
  • Ability to detect valuable metals like gold and platinum, even in small sizes

Even with that in mind, you can still find great deals on used detectors that will not kill your budget.

How much should I spend on a used metal detector?

This is only a question you can answer based on what your budget will allow. While you can find a higher-end, better quality used metal detector for probably under $500, there is always an option of getting a basic simple one from Walmart for under $100. They will work to get you started in the hobby and get you comfortable using one. So do your research, and you can find a good deal!

Metal Detectors From WalMart, Treasure Valley Metal Detecting Club
Metal Detectors From WalMart

Are metal detectors worth the money?

Generally, this depends mainly on you! Indeed, if you love history, going outdoors, discovering new locations and territories, engaging and networking with people to get permission, finding old coins and relics, and collecting valuable items like gold from time to time. Then, Metal Detecting is worth it.

372574 KellycoTest 728x90 021519, Treasure Valley Metal Detecting Club

Jason Smith

I am a Marine who now works as a Web Developer. I have five US States left to visit. I like whiskey, wine, and coffee, soaking in hot springs or in my hot tub.

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