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You simply won't believe how many treasures lie literally under our feet. It is clear that we do not even suspect the presence of treasure until it responds with a squeak in the metal detector. Archaeologists, geological prospectors, prospectors and builders cannot imagine working without this tool. A professional tool is expensive, so if treasure hunting is a hobby for you, you will certainly think about how to make a metal detector with your own hands. Today the editors of the site offer to study some life hacks, working diagrams and proven instructions for making this device. It is not as difficult as it seems, and even if you are a beginner radio amateur, you will cope with the task without much effort.
Treasure hunting is a fascinating hobby that requires knowledge not only in history, but also in technology and electronics.
The operating principle of the device is based on the laws of physics, which make it possible to recognize objects at a distance. The action is directed and limited. The more expensive the metal detector, the greater the radius of its operation and the sensitivity of the detector. Complex models have a metal recognition function. Each type of metal interacts in its own way with the frequency of the search circuit, and the device compares the reaction with the standard and displays information for the operator on the display or sounds a sound signal.
In another popular design, the device analyzes the phase shift in the transmitting and receiving coils. When there are no metals in the detector's coverage area, the coil transmits a signal with a small amplitude. As you approach the search object, the amplitude increases. Thus, you can distinguish between non-ferrous and ferrous metals and detect voids in the ground. The structure of the metal detector is shown in the following diagram.
Parameters of metal detectors depending on purpose and technical device
Metal detectors for amateurs are the simplest dynamic type devices. The search head of the device must constantly move; this is the only way the desired signal can appear. If you stop moving, the signal will disappear. Such simple detectors are convenient because they do not require complex settings and allow you to exclude medium soils. Disadvantages include its low sensitivity and frequent false alarms in difficult areas.
Mid-range devices have better sensitivity. In the factory configuration, this device comes with several search heads of different sizes. Setting up the detector will require certain skills. Mid-range metal detectors are capable of recognizing metals.
Computerized devices are already professional instruments with a liquid crystal screen and pointer indication. The memory of its processor is loaded with programs capable of recognizing and distinguishing a signal and classifying each detected object. Professionals independently program devices for search conditions, eliminating unwanted triggers.
Gold detecting tools work not only on coins and jewelry in the ground, but also on native metal. It is not suitable for searching for small particles such as sand. It does not recognize them, especially if the soil is highly mineralized.
Depth detectors are designed to search for objects located at impressive depths. They can detect metal at a depth of up to 6 meters, while other models “pierce” only up to 3. Such devices recognize voids and other internal soil anomalies. Depth detectors operate on two coils, one is parallel to the ground surface, the other is perpendicular.
Stationary detectors are frames installed at particularly important protected sites. They detect any metal objects in people's bags and pockets that pass through the circuit.
What types of metal detectors can you make at home with your own hands?
Detectors are divided into 5 main types based on the principle of detecting the desired object.
Let's look at which metal detectors are suitable for making with your own hands at home:
| Type | Peculiarities | Is it suitable for making it yourself? |
|---|---|---|
| Reception and transmission | Works with two induction coils. If the desired object is absent, the signal does not pass into the receiving coil. | Yes |
| Induction | Combines the functions of both coils. The signal is constant, changing when detecting the metal. | No, as a rule, difficulties arise in isolating the effective signal. |
| Based on frequency meter | The design of the device includes an LC generator that changes the frequency when metal objects are detected. Has low sensitivity. | Yes |
| With Q meter | Has an LC generator signal analyzer. Does not work well at low temperatures. | Yes |
| Pulse | Based on the transmission of eddy pulse currents. The signal changes its character depending on the type of metal detected. | Yes |
And now more about how to make a simple metal detector with your own hands using the example of the “Pirate” design.
Homemade metal detector “Pirate”: diagram and detailed description of the assembly
If you are just thinking about how to make a homemade metal detector, do not try to take on complex models. Start with a simple but effective "Pirate". The name was invented by the author of the homemade product from a combination of Pi (pulse) and Ra-t (radioscope). The name stuck, and the simple and clear assembly scheme was so loved by users that “Pirate” became one of the most popular homemade products in this area. Currently, there are already 4 modifications of the “Pirate” scheme. The metal detector is simply assembled with your own hands, without using any specific tools.
The only drawback of this device is that the DIY metal detector does not have a scheme for working with metal discrimination. But for a novice treasure hunter this is unimportant.
Parts for assembling a metal detector
To make the device you will need to purchase:
- ceramic capacitor - 1 nF;
- 2 film capacitors - 100 nF;
- electrolytic capacitors: 10 μF (16 V) – 2 pieces, 2200 μF (16 V) – 1 piece, 1 μF (16 V) – 2 pieces, 220 μF (16 V) – 1 piece;
- resistors - 7 pieces per 1; 1.6; 47; 62; 100; 120; 470 kOhm and 6 pieces for 10, 100, 150, 220, 470, 390 Ohm, 2 pieces for 2 Ohm;
- variable resistors - 3 pieces for 10 and 100 kOhm, 400 Ohm (1W);
- transistors – 3 pieces, VS557, IRF740, VS547;
- 2 diodes 1N148;
- 2 microcircuits: K157UD2 and NE555.
You will also need a plastic pipe for the rod, 9V batteries or accumulators and a PEV wire with a diameter of 0.8 mm.
For your information! Many people are interested in how to make a metal detector from a phone with their own hands. Some developers even offer programs that can be downloaded to your phone and used for this purpose. Serious radio enthusiasts can only advise you to use some spare parts - for example, a headphone input or a battery, perhaps a board to create a microcircuit.
DIY metal detector circuits
The simplest “Pirate” scheme looks like this.
The board can be placed in the body of a pocket receiver or any conveniently sized plastic box; even simple junction boxes from an electrician’s arsenal are suitable.
Important point! To get rid of possible interference when touching the device regulators, all variable resistor housings are connected to the negative side of the board.
If you want to take your experiments further, here is a diagram for making a gold-focused metal detector.
If you assembled the circuit correctly, the device will work properly. Possible problems with the microcircuit.
How to assemble a metal detector circuit board with your own hands
The metal detector circuit board circuit is quite simple. Conventionally, it can be divided into several blocks:
- search coil assembly;
- transistor sound amplifier;
- pulse generator;
- two-channel amplifier.
This is what it looks like.
The pulse generator is assembled on the NE555 timer. By selecting C1 and 2 and R2 and 3, the frequency is adjusted. The pulses obtained as a result of scanning are transmitted to transistor T1, and it transmits the signal to transistor T2. The audio frequency is amplified using the BC547 transistor to the collector, and headphones are connected.
For your information! You can make a metal detector with your own hands without microcircuits. On the Internet you will find many analog circuits using transistor oscillators. Such devices will detect metal at a depth of up to 20 centimeters in the ground and up to 30 centimeters in loose sand.
How to make a metal detector coil with your own hands
The coil is an important part of the device. It can be made from copper wire or twisted pair. More details in our master class.
Copper wire spool
| Illustration | Description of action |
|---|---|
 | Copper wire with a diameter of 0.5 mm is suitable for the coil. |
 | For winding, prepare a board with guides. The distance between the guides should be equal to the diameter of the base on which you will mount the reel. |
 | Wind the wire around the perimeter of the fastenings in 20-30 turns. |
 | Secure the winding with electrical tape in several places. |
 | Remove the winding from the base and give it a round shape. |
 | Choose a base that will hold its shape. This could be a plastic bucket lid or a wooden craft hoop. |
 | Connect the circuit to the device and test its operation. |
 | When assembled, a coil of wire may look like this. |
 | To test the operation of the device, pass metal objects over the coil at different heights. |
Twisted pair coil
| Illustration | Description of action |
|---|---|
 | Roll the wire into two coils as shown in the photo, leaving two ends of about 10 centimeters each. |
 | Strip the winding and free the wires for connection. |
 | Connect the wires as shown in the diagram. |
 | For better contact, solder the ends of the wires. |
 | Test the coil in the same manner as a copper wire coil. |
Advice! If you want to make a more powerful DIY coil for your metal detector, give it an elliptical shape.
Detailed instructions for setting up a DIY metal detector “Pirate”
For final assembly of the device you will need a plastic pipe. The assembly diagram is simple. The sensitivity of the detector is adjusted using potentiometers. Achieve the result so that it recognizes a coin from a distance of 30 centimeters. He can “hear” large metal deposits a meter to one and a half meters away. “Pirate” does not recognize non-ferrous or ferrous metals underneath you, so you just have to dig, and it is possible that you will stumble upon an old trough, and not the desired treasure. But in this case, you can take it not by quality, but by quantity, because any metal can be taken to a recycling collection point.
What the assembled “Pirate” will look like is in the next video. It only remains to note that the construction kit for making this device can be purchased on the Internet. By the way, it comes with detailed instructions on how to make a metal detector yourself at home from kit parts.
Is it possible to make an underwater metal detector with your own hands?
Searching for underwater treasures is an exciting activity. The chances of finding something valuable are not that low, especially if you have some ideas of where to look. The “Pirate” we talked about can also cope with underwater searches. You just need to slightly modify it by making good insulation from moisture and replacing the sound alarm with an LED one. How it will work in this video.
Do-it-yourself metal detector “Terminator 3”: detailed diagram and video instructions for assembly
Another modification of a homemade metal detector is the “Terminator”. DIYers are constantly improving the device, and now the third version of the device is popular, working on the principle of induction balance.
We offer you the most detailed description of the assembly of such a device from folk craftsman Viktor Goncharov.
For your information! For DIY assembly, you can choose a butterfly-shaped metal detector with two circuits. It's a little more complicated, but no less effective.
How to make a metal detector with your own hands with metal discrimination
Metal discrimination is the ability of the device to distinguish between the detected material and classify it. Discrimination is based on different electrical conductivities of metals. The detector's processor analyzes the phase shift between the signals of the two coils and not only distinguishes non-ferrous metals from ferrous metals, but can recognize whether it is copper, gold or silver. The simplest discrimination process is implemented in pulsed devices. They are able to find and distinguish non-ferrous from ferrous metal.
For your information! No matter how professional the device is, do not expect one hundred percent results from it. Many materials have similar electrical conductivity, so the machine can make mistakes.
Detailed information on assembling such a detector is in the video.
Features of deep metal detectors
A deep metal detector is attractive because it can detect objects where other devices are powerless. A good deep metal detector, made by yourself, looks to a depth of 6 meters, and is not hindered by roots, voids or other obstacles. One caveat - with its help you can only detect large objects, and this is understandable, because for the sake of a couple of coins you will not dig a six-meter hole.
And again we return to the same universal model of the “Pirate” detector. It turns out that you can make an in-depth device based on it, and it’s not at all difficult. The modification process is described in this video.
Many radio amateurs dream of making a metal detector with their own hands. It can be used to detect metal objects in the ground at different depths. On the Internet you can find many photos of metal detector circuits that are simple to use. Any beginning radio amateur can make them.
Easy assembly
For example, let's take the circuit of a simple metal detector. It is of the pulse type, but due to the simplicity of its design it is not able to distinguish between types of metals. Therefore, it will not be possible to operate such a device in areas where objects made of non-ferrous metal are found.
How to assemble the device
To assemble a simple metal detector circuit with your own hands, you will need the following tools and parts:
- Presence of KR1006VI1 microcircuit and IRF740 transistor;
- Presence of K157UD2 microcircuit and VS547 transistor;
- Copper conductor 0.5mm (PEV);
- NPN transistor;
- Housing, and various materials for it;
- Solder, flux, soldering iron.
Other details are shown in the diagram. In order for the assembled circuit to be securely fastened, a plastic case should be prepared for it.
The bar can be made using a small diameter plastic tube. A metal detecting coil will be installed in its lower part.
Beginning of work
The circuit diagram of a metal detector using transistors is a common option for many models. Assembly begins with the manufacture of a printed circuit board. Next, all radio elements are mounted on it exactly as shown in the diagram.
To ensure stable operation of the device, film capacitors are used in the circuit. This will allow you to use it in cold weather without any problems.
Power type for device
The device can operate on a voltage of 9-12 V. Due to its sufficient power, energy is intensively consumed. It is recommended to install up to 3 batteries and connect them in a parallel circuit. You can use a small battery that has a charger. Thanks to its capacity, the metal detector will work longer.
Coil installation
There are different types and schemes for the manufacture of metal detectors, but in the pulsed version, inaccuracies are allowed in the installation of the coil. When making a mandrel, the winding should be up to 25 turns, and the diameter of the ring should be 1900-200mm.
All turns of the coil must be insulated with electrical tape. Reducing the number of turns to 22, and the mandrel diameter of 270 mm will allow you to detect objects at a deeper location. The wire cross-section on the coil is 0.5 mm.
When the winding is ready, it is attached to a durable housing with sufficient rigidity, on which there should be no metal parts. Otherwise, they are able to shield the magnetic field, and the operation of the metal detector will be disrupted. The body can be made of wood or plastic, but so that it can withstand various impacts that can damage the coil.
The leads on it should be soldered to a conductor of several cores. The best option is a two-core wire.
Installation of the non-ferrous metal detector circuit is a little more complicated, and high precision must be observed in the manufacture of the coil. The number of turns reaches 100pcs, and a vinyl tube is used as the core. Foil is wound on top of the winding, which forms an electrostatic screen.
Device setup
If the installation of the circuit is done exactly, then the metal detector will not need additional settings. Its sensitivity indicators will be maximum, but fine adjustment is possible through variable resistance R13. It must be performed until rare clicks begin in the headphones.
If the adjustment fails, then the resistances must be replaced with R12. When the resistor adjustment is in the middle, this will be considered normal.
An oscilloscope is suitable for checking the device. The frequency of transistor T2 is measured on it, and the pulse should last up to 150 ms. The optimal operating frequency is up to 150 Hz.
How to use the device
You should not rush and start working immediately after turning on the metal detector. It should stabilize, so you need to wait up to 20 seconds. After adjusting the resistor appropriately, you can start looking for metal.
Note! 
Photo of the metal detector circuit
Note! 
Note! 
Among amateur radio designs, developments that help detect metal objects hidden in the ground are of particular interest. Especially if the latter are small in size, lie at a considerable depth and are also non-ferromagnetic.
Quite a few good electrical diagrams of such devices, called metal detectors by analogy with well-known military developments, and descriptions of fully functional designs have been published in various technical
Publications, but they are often designed for trained, experienced home-made workers who have a good material base and scarce parts.
But even a beginner can easily repeat and make the design we propose. Moreover, it will be quite possible to purchase the necessary parts (including a 1 MHz quartz resonator). Well, the sensitivity of the assembled metal detector... It can be judged at least by the fact that with the help of the proposed device it is easy to find, for example, a copper coin with a diameter of 20 mm and a thickness of 1.5 mm at a depth of 0.9 m.
Operating principle
It is based on a comparison of two frequencies. One of them is reference, and the other is variable. Moreover, its deviations depend on the appearance of metal objects in the field of the highly sensitive search coil. In modern metal detectors, to which the design under consideration can quite rightly be included, the reference generator operates at a frequency that is an order of magnitude different from that which appears in the field of the search coil. In our case, the reference generator (see the circuit diagram) is implemented on two logic elements ZI-NOT integrated DD2. Its frequency is stabilized and determined by a quartz resonator ZQ1 (1 MHz). The generator with varying frequency is made on the first two elements of the IC DD1. The oscillatory circuit here is formed by the search coil L1, capacitors C2 and SZ, as well as a varicap VD1. And to adjust to a frequency of 100 kHz, use potentiometer R2, which sets the required voltage to the varicap VD1.
Fig.1. Schematic diagram of a highly sensitive homemade metal detector.
Logic elements DD1.3 and DD2.3, operating on mixer DD1.4, are used as signal buffer amplifiers. The indicator is a high-impedance BF1 telephone capsule. And capacitor C10 is used as a shunt for the high-frequency component coming from the mixer.
The configuration of the printed circuit board is shown in the corresponding illustration. And the layout of radio elements on the side opposite the printed conductors is shown here in a different color.
Fig.2. Printed circuit board of a homemade metal detector, indicating the locations of the elements.
The metal detector is powered by a 9 V DC source. And since high stabilization is not necessary here, a Krona type battery is used. Capacitors C8 and C9 work successfully as a filter.
The search coil requires special precision and attention during manufacture. It is wound on a vinyl tube with an outer diameter of 15 mm and an inner diameter of 10 mm, bent in the shape of a circle 0 200 mm. The coil contains 100 turns of PEV-0.27 wire. Once the winding is complete, it is wrapped in aluminum foil to create an electrostatic shield (reduce the effect of capacitance between the coil and ground). It is important to prevent electrical contact between the winding wire and the sharp edges of the foil. In particular, “wrapping obliquely” will help here. And to protect the aluminum coating itself from mechanical damage, the coil is additionally wrapped with insulating bandage tape.
The diameter of the coil may be different. But the smaller it is, the higher the sensitivity of the entire device becomes, but the search area for hidden metal objects narrows. When the diameter of the coil increases, the opposite effect is observed.
Work with a metal detector as follows. Having placed the search coil in close proximity to the surface of the earth, adjust the generator with potentiometer R2. And in such a way that the sound in the telephone capsule cannot be heard. When the coil moves above the surface of the earth (almost close to the latter), the treasured place is found - by the appearance of sound in the telephone capsule.
When using the device discussed above to find objects hidden in the ground that are of archaeological and national cultural value, prior permission is required from the relevant authorities.
Metal detectors are used to detect invisible objects that, in their electromagnetic properties, differ from the environment in which they are located. Metal detectors are used by amateur archaeologists, geologists, and treasure hunters. These devices are also used by sappers to detect shells, builders to search for metal parts of structures (fittings, pipes...).
Most metal detectors look very similar, but in fact they differ greatly in their properties, and depending on the purpose of use. Here are some photos of commonly used metal detectors. And also a diagram of a simple metal detector.
How do metal detectors work?
The device of the metal detector is quite simple. And you can assemble it with your own hands at home. To do this, you do not need to have deep knowledge of electrical engineering. We have prepared step-by-step instructions for you that will help you assemble an amateur metal detector from available materials.
But first, let's find out what types of metal detectors exist, what properties different models have, and how to choose the right model for you. In order to choose the appropriate type of metal detector, you need to decide what technical characteristics you need.
Here are a few characteristics by which the quality of the device is judged:
Penetrating ability of the detector. To what depth does the electromagnetic field of the detector coil penetrate? This determines how deeply the device will “see” metal in the ground or other environment.
Search area covered. Typically, metal detectors examine the soil in stripes. This parameter determines the width of such stripes.
Device sensitivity. This determines whether your metal detector will detect small metal objects (for example, coins).
Detector fragmentation. This function is responsible for the detector's ability to respond only to the desired objects (for example, non-ferrous metals).
Finder immunity to interference. In addition to its own electromagnetic field, the device can enter the electromagnetic fields of other devices. (mobile devices, power lines, radio stations...). The best metal detectors are those that do not respond to fields from other sources.
Energy intensity. How many hours of searching should one battery or battery charge last?
Classification by frequency
In addition, metal detectors are classified by operating frequency. Exist:
Metal detectors operating at ultra-low frequencies. Such devices are used only by professionals. They have good technical parameters, but their operation requires tens of watts of energy. Usually installed on special vehicles with high-capacity batteries and equipment that allows you to determine the size, shape and structure of detected objects.
Metal detectors operating in the low frequency range (from 300 Hz to several thousand Hz). Easy to make. Resistant to interference, but have low susceptibility. They are also called deep detectors (“they see” metal at a depth of up to five meters).
Metal detectors with a higher operating frequency range. (up to several tens of KHz). They are more difficult to assemble than low-frequency ones. Their penetrating ability is up to one and a half meters. Detects small objects well. They are rarely used due to their low technical characteristics.
How to assemble a metal detector with your own hands at home
7 simple steps:
- In order to assemble a metal detector, we will need a Chinese radio receiver (must have a magnetic antenna, AM range), a cheap calculator, a box and double-sided tape.
- We unfold the box so that it has the shape of a book (the main part on one side, the lid on the other)
- We glue the radio and calculator to the book with double-sided tape. (the radio is attached to the lid, and the calculator is attached to the base of the box).
- We turn on the receiver and find a frequency segment that is not used by radio stations (about 1.5 MHz).
- Let's start working with the calculator. At the same time, the radio receiver begins to make loud noise.
- We begin to slowly bring the box lid closer to the main part. We need to find a position where the noise disappears.
- We fix the book in this position. Ready! You have made the simplest amateur metal. detector.
Metal detectors with metal discrimination
Among all metal detectors, devices with a discrimination function are considered especially effective. What does it mean?
The metal detector not only shows the presence of an object with a characteristic field in the ground, but also displays on the screen the approximate shape, size and material of the detected object.
Of course, with such a device, work is much more efficient (there is no need to dig the soil with each detector signal) and requires less time. But such metal detectors consume energy very quickly. Plus they are several times more expensive. For an amateur treasure hunter, a cheaper analogue is also suitable.
We hope that our article was useful to you, helped you understand the main types of metal detecting devices, and perhaps even suggested how to make your own amateur metal detector!
Photos of do-it-yourself metal detectors
Indication of device readings is carried out using an LCD indicator (VDI scale, Amplitude scale (size, location of the object), battery voltage indication (battery charge level)) and sound signals of different tones. The heart of the metal detector is the already familiar Atmega8-16PI microcontroller in conjunction with an external ADC. The use of an external ADC is due to the expansion of the set of functions of the device - the introduction of such a set of functions without an external ADC is physically impossible due to the small internal resource of the microcontroller.
I will give some characteristics of the device. Sensitivity for 5kop USSR coin up to 25cm. Selection by metals under ideal conditions: the “blacker” the metal, the lower its conductivity, and the closer to the left edge of the VDI scale the readings will be; the more “colored” the metal is, the greater its conductivity; accordingly, the readings on the scale will be closer to the right edge (the readings on the scale depend on the choice of device firmware and may change). Discrimination function: turning on one of the four masks one by one, you can tell the device not to react to “ferrous” metals to the desired extent (up to complete elimination of the influence of ferrous metal). Barrier function: at 16 levels it helps to detach from the influence of “earth” and other external factors.
To repeat Chance, first of all, you need to visit the author’s page fandy.vov.ru, where circuits, firmware, configuration bits for flashing the microcontroller, a description of the operation of the buttons and other useful information are located. The main, rare and most expensive parts of the device are the ADC chip and LCD indicator. An analogue of the ADC chip (MCP3201) is the ADS7816 chip, for which the author wrote corrected firmware (0.8.4). The next important part of the metal detector is the LCD indicator. With all the variety and current abundance of such components, the most suitable, in my opinion, are reliable and fairly cheap indicators from Winstar, which are superior in price/quality ratio to indicators from the domestic manufacturer MELT. When purchasing an indicator, you should select it based on the following instructions: character-synthesizing indicator, 2 lines of 16 characters each, Cyrillic support (the ability to use the indicator in any other development), the presence of a built-in HD44780 controller. You can view and download datasheets and pinouts on the Winstar website. The archive also contains a list of parts.
The OP37 operational amplifier can be replaced with a cheaper and more common analog NE5534P. The ICL7660S DC/DC converter can, although not advisably, be replaced with a similar one without the letter S (with the letter S at 12 volts, without it at 10 volts, it will work, but with an overload). The microcontroller is our old friend Atmega8-16PI (Atmega8-16PU, Atmega8A-PU). The controller is programmed using a simple programmer, which was used when programming the microcontroller for the Clone device. Here are the device parameters and a step-by-step description of the programming process for this controller. The most important thing here is not to forget about the configuration bits! Archive for microcontroller.
The planar coil of the metal detector is made on a dielectric frame 4 mm thick and wound with wire with a diameter of 0.65 - 0.8 mm. The coil template is shown in the figure below. The device rod is manufactured using the technology described in the article. You can assemble a metal detector on the author’s printed circuit board or use a much easier to replicate (for beginners) board from DesAlex - see the drawing on the forum. I myself remade 5 of these coils - I changed the number of turns, the thickness of the frame from 2 to 6 mm. The best result was obtained on a 4mm frame, the number of turns is the same as the author’s, the inductance is 389uH. Experiments with home-winding/rewinding did not affect the final result (noted by many who repeated this device), that is, a spread of +-10% does not affect anything. Although each result will be different from the other (diameter of the wire, quality of the wire, presence of impurities, quality of winding, waterproofing of the coil (varnish, epoxy, paint)), the quality and length of the supply cable - everything affects the quality factor of the search element.
A correctly assembled device does not require adjustment and is fully operational! In conclusion, I would like to thank the author of the metal detector (AndyF) for the excellent pulse metal detector with discrimination, as well as DesAlex for the reliable printed circuit board, without which the device would not have received such widespread popularity among radio amateurs and outdoor enthusiasts, which is the search for historical relics! Material provided by Elektrodych .
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