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Last updated on: February 7th, 2020
Best metal detectors are the sort of item that you automatically assume you have to purchase in a store if you want one. Fortunately, this isn’t the case. Making your own basic metal detector is relatively simple, and can be done with items that are easy to obtain. You probably already have everything you need in your home.
How to Make a Metal Detector
The best part about making your own metal detector is you can customize it to your personal preferences, instead of settling for something manufactured by a large company.
While homemade metal detectors aren’t as powerful as commercial models, they can still be used to find all sorts of hidden metal objects.
Here are step by step instructions you can follow to make your own metal detector using items you likely already have around your house.
Materials You’ll Need:
- Radio (AM/FM frequency)
- Broomstick or mop handle
- A small piece of wood. (This is piece may or may not be needed, depending on how your radio and calculator interact. You can also substitute any other flat, non-metal material for the wood.)
Step 1 – Collect Your Materials
The calculator and the radio will form the main part of your metal detector. For this project, you don’t need a fancy calculator. A regular calculator will work just as well as, for example, a graphing calculator.
Also, you don’t need to purchase one that beeps. The noise made by the metal detector is caused by fluctuations in the frequency, not the calculator.
Be sure the radio is capable of receiving Amplitude Modulation (AM) transmissions. It should also be small enough that you can comfortably carry it around, but large enough that you can easily access the settings for frequency and volume. A radio that is too large or heavy will quickly become cumbersome and may fall off the shaft.
The shaft of the metal detector is made from the broomstick or mop handle. Any long piece of wood or plastic can be used to make the shaft as long as it will hold on to tape. Obviously, a metal handle is a poor choice as it will throw off the signal from the radio.
In terms of tape, it doesn’t matter what kind you use. Masking tape is a great choice, since it provides a strong grip. This kind of tape can also easily be removed if you find you need to make adjustments to your setup.
Step 2 – Prep Your Calculator and Radio
Together, the calculator and the radio form the search head. This is the heart of the metal detector, and is the part of the tool that picks up on the presence of metal and alerts the user. It is the main part of the entire project, and as such, it requires the most attention and precision.
To start, turn on the radio. Move the frequency as high as the radio will go and turn the volume to the highest setting. Make sure it is set to AM, not FM, as these are different types of modulation of radio signals. The FM setting won’t be able to pick up the signal from the calculator.
Now that you have set your radio to AM and have turned it up all the way, all you should be able to hear is static. If you can hear anything other than static, you are still picking up a transmission. The most likely cause is that your dial is partially set to a station.
Tip: If your radio has a dial that you turn manually to adjust the frequency, you may find that when you move the radio the dial adjusts itself. You can solve this problem by taping the dial in place. Once the dial is set to the highest frequency, cover the dial in tape so it can’t move.
Step 3 – Put the Calculator and Radio in Place
Turn on the calculator and place it back to back with the radio. You will need to adjust the exact position of the calculator so that you can hear a consistent tone coming from the radio. This tone should be fairly dull, rather than high-pitched. Try a few different angles to get the strongest tone. You may also need to set the calculator and radio apart a few inches. The best set up will depend on several factors, including the type of radio and calculator and the size of the radio.
Once you hear a constant hum coming from the radio, tape the calculator in place. If you found the tone was the strongest when the calculator and radio were on an angle, you will need to tape the items together on the same angle. Try placing the radio on a piece of wood and taping it in place before you attach the calculator. This gives the radio something sturdy to sit on while you attach the calculator.
Tip: Be sure to tape the calculator and the radio very securely. If it moves during the next step, you’ll need to start over.
Step 4 – Attach the Handle to the Search Head
The main part of the metal detector can now be secured to the shaft. Prop up the material you will be using as the shaft, and attach the calculator-radio combo to the end using the same kind of tape you used to attach the calculator to the radio. If you taped the calculator and radio to a piece of wood – or another kind of flat surface – you can attach that extra piece to the shaft.
The shaft is intended to make it easier to hold the search head. It does not impact how the metal detector works, so you don’t have to worry about exactly how the search head is connected to the shaft.
Tip: When you are connecting the handle, keep in mind that you are taping the tech to the bottom of the shaft. Since you will be turning the whole thing upside down to use it, it is incredibly important to make sure the whole thing is secure.
Step 5 – Take Your Metal Detector For a Test Run
As soon as your tech is secured, you are ready to go. Make sure both the calculator and the radio are turned on and move about the area. When you get close to something with metal, you will hear a beeping sound. The closer you get, the more persistent the beeping will be.
An easy test is to place a piece of cutlery on the floor. Slowly move your metal detector closer to the cutlery so you can hear the sound it makes when metal is nearby. Once you know what it sounds like you’ll know when you’ve found something metal.
Remember that the beeping you will hear won’t sound exactly like the sound that comes from commercial metal detectors. Since this design is so much more simple, it won’t emit the same kind of sound. In some cases, you may hear a fluctuation in the frequency rather than a distinct beep. Each design will turn out slightly differently since each person will be using different materials.
How it Works
This simple design also has a simple explanation. The circuit board in the calculator emits a signal, which bounces off anything metal. Normally, this signal is not audible because humans are not capable of hearing this frequency. However, the radio picks up the signal when it bounces off a metal surface. The interaction between the high AM frequency and the calculator’s circuit is what causes the change in the sound coming from the radio.
Is a Homemade Metal Detector Worth Trying?
As with any item you make yourself, there are pros and cons. Making your own metal detector is no different, and there are some factors you should consider.
Whether or not a homemade metal detector is worth it for you depends in part on why you want to use it.
Building your own metal detector is significantly less expensive than purchasing one. In part, this is because you likely already have everything you need to build one. However, even if you were to buy each piece, the cost would still be lower than buying a premade metal detector. You can save up to a few hundred dollars by making your own version.
Some commercial metal detectors can cost a couple thousand dollars. Anyone who wants to use a metal detector professionally may find that this is a reasonable cost, but the average user doesn’t want to spend that much.
Commercially designed metal detectors have a much stronger signal than the one you can make at home. This is because they contain much more complicated circuits in the search heads, which boosts the frequency. As a result, commercial metal detectors can find metal that is much further away. At this point we recommend reading our guide on How to choose a metal detector.
A homemade version will still be able to detect metal up to a couple feet away, however, it won’t be able to find metal that is buried deep underground. If your goal is to develop a metal detector for a weekend hobby, a homemade version will likely be sufficient.
A homemade metal detector is not as durable as a store bought one, for the simple reason that your DIY version is held together with tape. Commercially designed metal detectors are intended to last a long time and they are put together using high-quality materials.
You can increase the durability of your homemade metal detector by using higher quality materials, but it won’t meet the standards set by commercial models.