How Metal Detectors Work


An electronic instrument that can find any instance of metal from the ground, a human body or a parcel is called metal detector. It has the ability to go through the sand, soil, wood and any other non-metallic items. It can track anything metallic.

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.

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 poor to detect 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, this instrument has become really typical and much more widely used by treasure hunters everywhere.

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 setting that can be adjusted depending on what you are looking for. 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 just adjust the setting to look for one or the other. Or just turn it wide open to look for any metal items.

How does a metal detector work?
An elementary metal detector has an electronic box along with 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 till there is an electronic signal. Once you find a signal, sweep in a much smaller area until you have pinpointed it’s exact location.

How the metal detector is built?
Metal detectors utilize the principal of electromagnetism and the result it applies on 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?
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 object 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 designed specifically to detect tiny targets in mineralized ground. That’s pretty much it. I have a Garrett AT Pro Metal Detector and it does not do well on small gold nuggets, AT ALL. I was up at Miss Lucy’s claim and Rob Johnson had a shallow sandbox he was using 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, and then I had to find it with my AT Pro. I figured this would be easy to do, since the Garrett AT Pro will find gold. 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 this post on metal detecting laws, 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 to the ring then most defiantly you can find diamonds, normally attached 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 principal 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.

Michael FARADAY observed (in 1831) that when a magnet is moved through a closed coil of wire, an existing is induced in the wire. The direction of the current circulation is such as to create a magnetic field opposite in direction to that of the change in the field produced by the magnet. 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 certainly 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 am not going to 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 own metal detector over at his site Ultimate Metal Detectors. 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 Robs 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 a Tates Rents 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
Metal Detectors For Sale on Craigslist

Another good place is to find yourself a metal detecting club in your local area. A good place to find one 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 Club which has their own Facebook page as well.

Things To Keep In Mind When Purchasing a Used Metal Detector

As soon as you have decided to buy a metal detector, you need 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 buying a metal detector. This 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 an used metal detector, here are some beneficial tips, which will guide you in your purchase.

What are the types of metal detectors?
There are 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 water without issue. There are some metal detectors that are considered underwater metal detectors and are build to be used in lakes an oceans and can be brought down much greater than 10 feet.

What are the factors that I should consider before buying an used metal detector?

Consider the following points before your purchase:

  • The quantity of usage of the detector: 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. Location does not have much of a factor outside of on land or underwater, those two locations are going to be your two biggest factors.
  • Decide on who will utilize it: For a family use, there are detectors with adjustable arm cups and almost all detector now have adjustable lengths to the coil so to be used by anyone of any height.
  • Budget: Of course if at all 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 due to the fact that they test and then sell 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 you decide to buy.

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 a cost of about $500. The pre-owned accessories come at the rate of $100~200. However the only drawback is, there is no manufacturers guarantee buying a used one, but at least purchasing from an excellent dealership will offer some safety.

On thing that I would do if looking for a used metal detector, is find a site like KellyCo Metal Detectors where they sell many different models and manufacturers. That way you have a chance to browse through all different kinds and manufacturers to really see what you would like to get. If you are particular to a certain brand then you can certainly go to that manufacturer and search their site as well. Once you have found a handful of different detectors that you would like to get and fit your needs and budget. You will then have a good idea of how much that detector cost brand new. This is of course assuming you do not just go to a site like KellyCo or a particular manufacturer and just buy a used one through them. This is if you are looking to purchased a used detector from a local clubs Facebook group or from Craigslist. That way you know what I new one costs, so when someone is trying to sell you a three your old detector at full price you will know to stay clear, or are able to counter offer a price that is less that 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, simply 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. Also, 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’s not always possible as most people throw all of that stuff away.

Why are metal detectors so expensive?
There are many factors that could make some metal detectors more expensive than others. The main factors are the Brand, Implemented Technologies, Possibility to configure more settings, Durability, Capacity to operate deeper and the 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 off 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 your 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 totally 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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