How 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 upon 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.

Detecting anything with metal properties through sand, soil, wood, and other non-metallic items have many benefits.

Do Metal Detectors Detect All Metals?

Almost all, yes. Metal Detectors detect iron, nickel, copper, brass, aluminum, tin, lead, gold, silver, and bronze. General-purpose metal detectors can find buried metal objects such as jewelry, coins, and other metal objects. “Discrimination,” which is a settings feature on metal detectors, is a process that distinguishes between different metal targets or alloys. Stainless Steel is a metal that is very difficult to detect by any metal detector because its electric conductivity is too low in detecting it as ferrous metal.

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 ever since it has become really typical and much more widely used by treasure hunters.

What is a Metal Detector Made Out of?

The simplest form of a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field. More modern detectors have many more features and settings that can be adjusted depending on your looking. 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 the other. Or turn it wide open to look for any metal items.

How Does a Metal Detector Work?

An elementary metal detector has an electronic box and a battery on one side and a handle/arm rest to let the operator rest his arm. The operator holds the electronic box/handle end and begins sweeping the coil slowly side to side on the ground until there is an electronic signal. Once you find a signal, sweep in a much smaller area until you have pinpointed its exact location.

How Is The Metal Detector Built?

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

How Deep Can a Metal Detector Detect?

A typical good quality machine can detect six to ten inches below the ground for coin-sized objects. However, this highly depends on many factors. Mainly the ground composition and even how the item is positioned in the ground.

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 DetectorOpens in a new tab., and it does not do well on small gold nuggets, AT ALL. While at Miss Lucy’s claim in Idaho, Rob JohnsonOpens in a new tab. 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 6′ by 6′ sandbox, I could not find a small gold nugget in less than an inch of sand. If it would have been a nugget like the one pictured at the bottom of the post on metal detecting lawsOpens in a new tab., I could have easily found it. 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 will not detect non-metal items such as gemstones, diamonds, and pearls. What a metal detector can do is lead you to indicator minerals, which are used by prospectors. Prospectors follow the indicator trail back to gold or the volcanic pipe, which may contain diamonds. If the diamond is still attached, you can most definitely find diamonds generally connected to a gold ring.

Making Your Own Metal Detector

Say ‘metal detector’ to someone, and you will get completely different responses from various individuals. For example, some people think of combing a beach in search of coins or buried treasure. Other individuals consider airport security or the portable scanners at a concert or sporting event.

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 around a telescoping shaft and 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 the 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 momentay current is induced into the wire. The direction of the current circulation is to create a magnetic field opposite in direction 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 an overly complicated project, and it can undoubtedly 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 it and tweak it to your liking.

I will not go into details on creating a DIY metal detector of your own, 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 DetectorsOpens in a new tab.. If you follow his instructions, you should have no issues building a Detector of your own.

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 RentsOpens in a new tab. where you can spend about $30 and get a metal detector for the day. Or, with some careful research, you can get yourself your very own used metal detector. You might be able to find a good one on Craigslist.

Metal Detectors For Sale on Craigslist
Metal Detectors For Sale on Craigslist

Another good place is to find yourself 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 that are selling their equipment. This site was built for the Gem State Metal Detecting ClubOpens in a new tab., which has its own Facebook page.

Things To Keep In Mind When Purchasing a Used Metal Detector

As soon as you have decided to buy a metal detector, it would be best to choose whether you wish to buy a brand new instrument or a second-hand model. Here we are looking over some things to keep in mind 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 budget is a constraint. If you are wondering how to purchase a used metal detector, here are some beneficial tips to guide you in 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 into the water without issue. Some metal detectors are considered underwater metal detectors and are build to be used in lakes and oceans and can be brought down much more significant than 10 feet.

What Are The Factors That I Should 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 you can get.
  • 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 as to be used by anyone of any height.
  • Budget: If possible, stick to your budget and try where you can to fit in 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?

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 in it, or bring some of your own. Most use 4 to 8 double-A batteries. That way, you can turn it on and make sure it is working before deciding to buy 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 DetectorsOpens in a new tab., where they sell many different models and manufacturers. That way, you have a chance to browse through all different kinds and manufacturers to see what you would like to get. If you are particular to a specific brand, you can certainly go to that manufacturer site.

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 is assuming 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 a three your old detector at full price, you will learn to stay clear or counter offer 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, along with a great way to start a new hobby.

A Couple 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, coins from your pocket. When making big purchases through online ads (such as Craigslist), make sure to meet in a safe, public place with lots of people around. Starbucks or a parking lot, such as in front of a Walmart, is a great example. 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 all of 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 your comfortable with using one. So do your research, and you can find a good deal!

Metal Detectors From WalMart
Metal Detectors From WalMart

Are metal detectors worth the money?

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

Jason Smith

Former Marine, IT Guy & Builder of Websites.  I have 5 US states left to visit. I enjoy hot springs, adventures, hiking, photography, sci-fi, wine, coffee & whiskey.  I am fluent in sarcasm, name that tune, & speak in movie quotes.  I spend most of my time building websites, fixing computers, metal detecting, magnet fishing and gaming occasionally.

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