Instrumental search is simply enormously popular. Adults and children, amateurs and professionals are looking for it. They are looking for treasures, coins, lost things and buried scrap metal. And the main search tool is metal detector.
There are a great variety of different metal detectors to suit every taste and color. But for many people, buying a ready-made branded metal detector is simply financially expensive. And some people want to assemble a metal detector with their own hands, and some even build their own small business on their assembly.
Homemade metal detectors
In this section of our website about homemade metal detectors, I will be collected: best metal detector circuits, their descriptions, programs and other data for manufacturing DIY metal detector. There are no metal detector circuits from the USSR or circuits with two transistors here. Since such metal detectors are only suitable for visually demonstrating the principles of metal detection, but are not at all suitable for real use.
All metal detectors in this section will be quite technologically advanced. They will have good search characteristics. And a well-assembled homemade metal detector is not much inferior to its factory-made counterparts. Basically, there are various schemes presented here pulse metal detectors And metal detector circuits with metal discrimination.
But to make these metal detectors, you will need not only desire, but also certain skills and abilities. We tried to break down the diagrams of the given metal detectors by level of complexity.
In addition to the basic data required to assemble a metal detector, there will also be information about the required minimum level of knowledge and equipment for making a metal detector yourself.
To assemble a metal detector with your own hands, you will definitely need:
This list will contain the necessary tools, materials and equipment for self-assembly of all metal detectors without exception. For many schemes you will also need various additional equipment and materials, here are just the basics for all schemes.
- Soldering iron, solder, tin and other soldering supplies.
- Screwdrivers, pliers, wire cutters and other tools.
- Materials and skills for making a printed circuit board.
- Minimum experience and knowledge in electronics and electrical engineering as well.
- And also straight hands will be very useful when assembling a metal detector with your own hands.
Here you can find diagrams for self-assembly of the following models of metal detectors:
 |
Principle of operation | I.B. |
| Metal discrimination | There is | |
| Maximum search depth | ||
| There is | ||
| Operating frequency | 4 - 17 kHz | |
| Difficulty level | Average | |
 |
Principle of operation | I.B. |
| Metal discrimination | There is | |
| Maximum search depth | 1-1.5 meters (Depends on the size of the coil) | |
| Programmable microcontrollers | There is | |
| Operating frequency | 4 - 16 kHz | |
| Difficulty level | Average | |
 |
Principle of operation | I.B. |
| Metal discrimination | There is | |
| Maximum search depth | 1 - 2 meters (Depends on the size of the coil) | |
| Programmable microcontrollers | There is | |
| Operating frequency | 4.5 - 19.5 kHz | |
| Difficulty level | High | |
The purpose of a metal detector, or, as it is also called, a metal detector, is to search for metal products using electrical or magnetic properties that distinguish them from the environment. Simply put, using a metal detector you can find metal even in the ground. However, its capabilities are not limited to this environment, since it is also used in water. This device is used by security services, criminal service, military, geologists and workers of many other specialties. But detailed instructions for assembling a metal detector with your own hands can also be useful for using the device in the home.
Area of application of the device
For those who have lost a ring or keys and know their approximate location, a metal detector will be a real salvation. Making a homemade metal detector is not that difficult, especially if there is a diagram of a homemade metal detector and a detailed description of the assembly. Most often, the assembly is carried out by amateur radio mechanics, treasure hunters, local historians and military historical associations. The device makes it possible to find a coin in the top layer of soil or large metal parts at an impressive depth of up to 1.5 meters.
Homemade devices also have these properties, but with the help of an experienced radio mechanic you can assemble a more powerful device. Many people use a metal detector for commercial purposes: when various parts are found, they sell them for scrap metal, earning a certain amount. Finds can also be more important, for example, antiques or real treasures in the form of treasure chests.
Consists in the use of electromagnetic technology. The coil creates an electromagnetic field that interacts with conductive objects, resulting in an eddy current that distorts the coil signal. Even in the absence of current conductivity, an object may have its own magnetic field, which will also create interference, thereby indicating the location of the object.
After interference arrives, the electromagnetic pulse changes and goes directly to the control unit, which emits sound signals or displays data on the display indicating the finding. Devices are divided into many groups and have a huge number of names, and they are all classified according to many parameters.
Types of detectors
General characteristics of the devices:
Discrimination is a composite parameter, since there are most likely 1 or 2 signal outputs, and there are several definitions based on the property and location of the object. However, according to the reaction of the device, taking into account the approach to the object, signals stand out:
- Spatial - you can determine the location of the object in the search location and the depth of its location.
- Geometric - the ability to figuratively form the length and width of the find.
- Qualitative - the ability to speculate about the structure of the find.
Operating Parameters
All sensitivity parameters are related to the generator frequency. Therefore, initially metal detectors are classified depending on the operating frequency:
Method of searching for metal products
There are more than 10 search methods, however, methods with digitization of signals and processing through a computer belong to professional equipment. Do-it-yourself metal detector circuits most often are made taking into account the following search methods:
- Parametric.
- Transceiver.
- Accumulation phase.
- Beating.
Without take-up reel
Parametric devices They have neither a pick-up coil nor a receiver. Detection occurs due to the influence of the object on the inductive coil of the generator. Depending on the quality factor of the coil, the frequency and amplitude of the oscillations will change, which can be recorded in different ways, for example:
- Frequency and amplitude are measured.
- The generator current is measured.
- PLL (Phase Locked Loop) loop voltage measurement.
In most cases, such devices are used as magnetic detectors. They have poor sensitivity, but are cheap and noise-resistant, and use requires a certain skill.
With built-in transmitter
Devices with receiver and transmitter are very effective, but have a complex circuit structure and require high-quality coils. Devices with one coil are called induction.
Clicking sounds after approaching an object
In metal detectors with phase accumulation, they can be with one pulse-type coil or with two generators. In a device with one coil, as pulses pass, the phase shift increases and when a certain level is reached, the discriminator is triggered and a click-type signal is sent to the headphones. The closer the object, the more often the clicks are repeated.
Double coil metal detector In terms of circuit design, it is simpler than a pulsed one, but also weaker in sensitivity, penetration is also up to 2 times less.
Metal detectors on beat
The devices are assembled with 2 generators, a reference and a working one. The working generator is adjusted to a zero beat value and, depending on the sound tone, one can judge the location of the object, its size and properties.
DIY metal detector assembly
There is an opinion that branded metal detectors are superior to homemade devices in many respects . However, the facts say the opposite: If the device is assembled correctly, then the homemade product may turn out to be not only cheaper than the factory design, but also better. Many treasure hunters purchase the cheapest types of devices, and then they either assemble the metal detector themselves or buy a custom version.
A beginner or a person who is not well versed in electronics may find the special terminology, formulas and diagrams difficult. But with a detailed analysis of all the information, it becomes clear that with at least an average level of knowledge, you can figure out how to make a homemade metal detector.
Do-it-yourself printed circuit board manufacturing
For further placement of metal detector parts, a printed circuit board is needed. To do this, it is best to use the LUT method - laser-iron technology.
Manufacturing occurs in stages in the following sequence:
At the last stage, tinning of the paths is carried out. The LTI-120 solution is spread with a soldering iron.
Installation of radio components on the board
At this stage of metal detector assembly All elements are installed in the prepared board:
In this case, an old circuit is used, but you can find and solder a similar, modern version, since the K157UD2 amplifier is currently difficult to find.
Making a device coil
A homemade reel is wound on a rigid frame with a radius of 100 mm. Need to reel approximately 25 turns. This indicator is acceptable when using PEV wire with a diameter of about 0.5 mm, but other strong material can also be used.
To select the optimal number of turns, you can conduct an experiment by testing the device to catch a coin.
Frame and additional elements
A part from a portable receiver with an Ohm resistance can be used as a signal speaker. It is allowed to use Chinese analogues with the same resistance.
For normal operation of the metal detector, need to adjust sensitivity. The threshold is determined when a uniform, but not very strong crackling is achieved. To do this, use two potentiometers with different powers. You will need one with a power of 10 kOhm, and the other with a power of 100 kOhm. To increase noise immunity, it is recommended to use a shielded cable to connect the coil to the circuit. The power source can be rechargeable batteries. The minimum voltage should be 12 V. To ensure stability of the electrical circuit, a voltage stabilizer type L7812 is installed at the output.
After making the structure and checking its functionality, you need to make the body of the portable device. Each amateur can create a frame at his own discretion from available items, but attention should be paid to the following recommendations:
- For convenience and better stability, the rod can be strengthened by purchasing several meters of PVC water pipe and several jumpers for connection. It is advisable to make a hand rest on the top part. The ideal option would be to make an armrest. In this case, it will be easier for the operator to use the metal detector.
- The board must be placed in a protected box appropriate to its size and secured to the case.
- The battery used for power supply is a screwdriver, which is lightweight and has sufficient capacity. Taking into account the parameters, some other option may be used.
- When creating the housing and the entire structure, it is necessary to take into account that the presence of foreign metal elements will greatly distort the signal of the magnetic field of the metal detector and its effectiveness will be impaired.
Device efficiency
A device made according to this design, will not be effective when searching for small objects at great depths, but some Soviet coins can be found at a depth of about 30-40 cm, and the detector senses large metal parts at a distance of about 1 meter or more.
This homemade version of a metal detector is suitable for people who are learning the basics of detecting or who do not have the opportunity to use an expensive model. For specialists or experienced treasure hunters, the effectiveness of the device may not be enough.
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! 
I can say without a doubt that this is the simplest metal detector I have ever seen. It is based on just one TDA0161 chip. You won't need to program anything - just assemble it and that's it. Another great difference is that it does not make any sounds during operation, unlike a metal detector based on the NE555 chip, which initially beeps unpleasantly and you have to guess the metal found by its tone.
In this circuit, the buzzer starts beeping only when it detects metal. The TDA0161 chip is a specialized industrial version for induction sensors. And metal detectors for production are mainly built on it, giving a signal when metal approaches the induction sensor.
You can purchase such a microcircuit at -
It is not expensive and is quite accessible to everyone.
Here is a diagram of a simple metal detector
Metal detector characteristics
- Microcircuit power supply voltage: from 3.5 to 15V
- Generator frequency: 8-10 kHz
- Current consumption: 8-12 mA in alarm mode. In search state approximately 1 mA.
- Operating temperature: -55 to +100 degrees Celsius
An old cell phone battery works well for power supply.
Coil: 140-150 turns. The diameter of the coil is 5-6 cm. Can be converted to a coil of larger diameter.
The sensitivity will depend directly on the size of the search coil.
In the scheme I use both light and sound signaling. You can choose one if you want. Buzzer with internal generator.
Thanks to this simple design, you can make a pocket metal detector or a large metal detector, depending on what you need more.
After assembly, the metal detector works immediately and does not require any adjustments, except for setting the response threshold with a variable resistor. Well, this is standard procedure for a metal detector.
So, friends, collect the things you need and, as they say, they will come in handy around the house. For example, to search for electrical wiring in a wall, even nails in a log...
Not everyone can afford to buy a metal detector. And to search for iron, it is not at all necessary to purchase an expensive device. It is enough to assemble it yourself. And he will find it too.
By the way, I will say that I saw a report on TV about how a man who had assembled a metal detector and was looking for scrap metal with it found a box of ammunition from the Civil War in the forest.
I myself have been trying to assemble such a device for a long time and it even worked! But you won’t be able to search for coins with it, since it reacts mainly to large metal objects.
And so, to assemble a simple metal detector we need:
~ two KT315 transistors or similar;
~ two 1000 pf capacitors;
~ two capacitors 10000 pf;
~ two 100 kOhm resistors.
In addition, the following will be useful: a 3.7-5 volt battery, headphones, enamel-insulated wire with a diameter of 0.5-0.7 mm.
The assembly diagram is simple!
The coils can be wound on a regular pan. After ten turns, a loop is made and the winding of the remaining twenty turns continues.
The body is made of any material, preferably sealed. The bar can be made from pipes. The coils are placed on the same plane at a distance of 10 cm.
If, when you turn on the device, a squeak appears in the headphones, then it means that you need to adjust the device - change the distance between the coils. Or customize with ferrite.
Thus, you can make money by searching for scrap metal for a good branded device. And a good deed will be done - the earth will be cleansed. Well, the metal will be reused.
The photos in the article are mine, taken back in 2014. And the first picture with the diagram is taken from open sources.
How to make a simple metal detector for searching on the beach
In this article I will tell you how to build a simple metal detector for searching for coins and jewelry on the beach. It consists of one chip - the NE555N timer, a coil and several other radio components.
Expect to spend up to 300 rubles to build this metal detector!
Required materials
To assemble the metal detector you will need:
- NE555N timer chip, in DIP package;
- resistor 47 kOhm;
- two capacitors 2.2 µF, 16 V;
- piece of contact breadboard;
- 9 volt battery, switch, battery socket;
- electromechanical sound emitter;
- 100 meters of copper wire with a diameter of 0.2 millimeters;
- some thick cardboard and glue.
Instead of an electromechanical sound emitter, you can use a 10 µF capacitor and any speaker with an 8 Ohm impedance, connected in series.
Metal detector circuit
The idea of a metal detector was taken from the book " 499 circuits on NE555 timer" I just added a switch between the battery and the chip, and I also use an electromechanical sound emitter from an old electronic alarm clock instead of a speaker.
Search coil
The most difficult part of a metal detector is its coil. I calculated that a 90mm diameter coil would have approximately 260 turns of 0.2mm diameter varnished copper wire. In this case, its inductance will be approximately 10 millihenry.
I wound the coil carefully, turn to turn. To prevent the wires from unraveling, I wrapped the winding with white electrical tape on top.
If you want to make a larger diameter coil to increase the target detection range, then there are several online calculators on the Internet with which you can calculate it.
Circuit board
I placed all the electronic components on a piece of breadboard. The connections were made using the most ordinary wire that was at hand. Soldering the board itself took no more than 15 minutes.
The size of the board turned out to be approximately equal to the size of a matchbox.
Frame
To simplify things, I decided to make the handle of the metal detector out of cardboard. The handle contains a circuit board, a switch and a battery.
All this was cut out of thick cardboard and glued together with PVA glue. After the glue had dried, I made holes in the cardboard for the board and wires.
Next, I glued the search coil to the handle with hot glue. The last step, also using hot glue, I glued the board and battery inside the handle.
Conclusion
The metal detector works as follows: as long as there are no metal objects near the coil, the sound emitter beeps at the same frequency; when a metal object is brought up, the tone of the sound changes towards a higher one.
The detection range of a large coin through the air, according to my measurements, was 5 – 7 centimeters!
Simple metal detector baby FM-2 improved
I present to your attention a diagram of a more improved metal detector Malysh FM-2. The baby fm2 metal detector is not so difficult to assemble with your own hands, despite its significant changes. This is perhaps the simplest selective metal detector that even a novice radio amateur can assemble.
You have probably heard of, and perhaps collected, such metal detectors as “Malysh” and “Malysh FM-2”. But progress does not stand still and therefore we have a diagram of a more improved metal detector Malysh FM-2. The new version adds LED indication of metals, a power-on notification function is added, the notification sound is enhanced, and the device has become much more stable in operation.
Diagram of the improved metal detector Malysh FM-2
Specifications and features:
- Supply voltage - 9 Volts
- Metal detection depth is about 15 cm.
- Selection of metals - black, non-ferrous
- LED indication of metals - black, color
- Power-on indicator
So, this printed circuit board of the Malysh FM-2 metal detector is designed to use DIP components, which would be convenient for everyone, since many novice radio amateurs have not yet encountered SMD components.
Capacitors C5-22nF and C1-100nF must be film
Voltage stabilizer AMS1117 -3.3v
This is what the finished board of the “Malysh FM-2” metal detector looks like:
View from the paths
After assembling the board, we proceed to making the coil.
A standard coil contains 150 turns, wire diameter 0.3, and wound on a frame of 150 mm. But I decided to slightly reduce the diameter to 10-11 cm so that the metal detector could better see small objects; the detection depth decreases but the sensitivity increases. I didn’t have 0.3 wire, so I wound 0.4 on a 10 cm frame, 130 turns.
So, after the coil is wound, it is necessary to tighten it very tightly with tape.
Now it is imperative to shield the coil so that the metal detector does not react to interference and there are no false alarms. Take food foil and wrap the coil tightly. Please note that the ends of the foil should not touch each other!
Then we take the wire, strip the end and wrap the coil to one edge of the screen, then tighten it and wrap it tightly with tape again.
We connect the coil to the board. The wire from the screen needs to be soldered to the minus of the board.
Now all that remains is to flash the microcontroller and that’s it, you can use it)
If you do everything correctly, the device should work without problems the first time you turn it on. Carefully check the ratings of the parts and do not forget that the capacitors C2-22nF and C6-100nF must be film, NOT ceramic!
When turned on, the device should make a characteristic sound similar to a “peep-fang”, this means that the device has turned on and is working correctly.
IMPORTANT! “According to the diagram there are 8 resistances, but in the photo there are 9” - the 9th resistor (100 Ohm) I myself installed additionally on the second LED, although it doesn’t have to be installed! The 1N4007 diode can also be omitted, as I did!
The printed circuit board, firmware, as well as a list of parts that can be bought very cheaply on AliExpress with free shipping are located below the video!
Video of the metal detector baby FM-2 v2
Good DIY metal detector
This happened several years ago. I wanted to keep my hands busy and while away the evenings as the treasure hunting season approached. It was decided to assemble a metal detector. For assembly I chose the “Pirate” metal detector circuit. Since it is not complicated, but the device itself is quite interesting. The assembly began with the search for parts. I even had to go to the workshop to get some resistors. When everything was found, it was necessary to prepare the printed circuit board, namely, etch it using the LUT method. Then it was just a matter of small things: soldering all the parts. Well, check the finished board. The first time it didn't turn on. The K157UD2 chip turned out to be faulty. After changing it, the scheme worked! 
Now you can work on the body. The body from Koschey 5I was taken as its quality, and a new front panel was made. It's up to the coil. For the coil, a frame was cut out with a jigsaw and a groove was machined along the side edge, where the coil winding was wound, and a cable with a connector was soldered. The rod was made of plastic pipes and fittings. The armrest is cut from a sewer pipe. It all turned out quite culturally. The device turned out to be light, but not rigid enough. 
The result was a working, high-quality device. Its only drawback is the lack of metal discrimination. Therefore, it can be said that it is not suitable for searching for coins. After all, both nails and coins ring the same way. 
But with its help, you can successfully dig scrap metal and hand it over to collection points, thereby earning money! There is a video with a test of this device. It was filmed by me in the spring of 2015.