Everyone can assemble such an apparatus, even those who are completely far from electronics, you just need to solder all the parts as in the diagram. The metal detector consists of two microcircuits. They do not require any firmware or programming.
Power supply 12 volts, you can AA batteries but better battery for 12v (small)
The coil is wound on a 190mm mandrel and contains 25 turns of PEV 0.5 wire
Characteristics:
- Current consumption 30-40 mA
- Reacts to all metals no discrimination
- Sensitivity 25 mm coin - 20 cm
- Large metal objects - 150 cm
- All parts are not expensive and readily available.
List of required parts:
1) Soldering iron
2) Textolite
3) Wires
4) Drill 1mm
Here is a list of the parts you need
Diagram of the metal detector itself
The circuit uses 2 microcircuits (NE555 and K157UD2). They are quite common. K157UD2 - can be wiped out from old equipment, which I successfully did
Capacitors 100nF be sure to take film, these are the ones, we take the voltage as little as possible
We print a sketch of the board on plain paper
Cut out a piece of PCB for its size.
Apply tightly and with a sharp object push through the places of future holes
This is how it should work out.
Next, we take any drill or drilling machine and drill holes
After drilling, you need to draw the tracks. You can do this through, or simply paint them with Nitro varnish with a simple brush. The tracks should look exactly the same as on the paper template. And we poison the board.
In the places marked in red, put jumpers:
Next, we just solder all the components into place.
For K157UD2, it is better to put an adapter socket.
To wind the search coil, you need a copper wire with a diameter of 0.5-0.7 mm
If there is none, you can use another. I didn’t have enough lacquered copper wire. I took an old network cable.
He took off the shell. There were enough wires. Two veins were enough for me, they also wound the coil.
According to the scheme, the coil is 19 cm in diameter and contains 25 turns. Immediately, I note that the coil needs to be made of this diameter based on what you will be looking for. The larger the coil, the deeper the search, but the larger coil does not see fine details well. The small coil sees fine details well, but the depth is not great. I immediately wound myself three coils of 23cm (25 turns), 15cm (17 turns) and 10cm (13-15 turns). If you need to dig up scrap metal, then put a big one, if you look for small things on the beach, then the coil is smaller, well, you will figure it out yourself.
We wind the coil on anything of a suitable diameter and wrap it tightly with electrical tape so that the turns are tightly next to each other.
The coil should be as flat as possible. The speaker took the first one that came across.
Now we connect everything and try the circuit for performance.
After turning on the power, you need to wait 15-20 seconds for the circuit to warm up. We put the coil away from any metal, it is best to hang it in the air. Then we begin to twist the variable resistor 100K until clicks appear. As soon as the clicks appear, we twist in the opposite direction, as soon as the clicks disappear, that's enough. After that, we also adjust the 10K resistor.
At the expense of the K157UD2 microcircuit. In addition to the one that I picked out, I asked a neighbor for 1 more and bought two on the radio market. I inserted the purchased microcircuits, turned on the device, and he refused to work. I racked my brains for a long time until I just put another microcircuit (the one that I dropped out). And everything worked right away. So that's what a transitional socket is for, in order to pick up a live microcircuit and do not suffer with desoldering and soldering.
Purchased microcircuits
Many radio amateurs dream of making a metal detector with their own hands. It can detect metal objects in the ground at different depths. On the Internet, you can find many photo schemes of a metal detector, which are simple in the device. Any novice radio amateur can make them.
Easy assembly
Let's take a simple metal detector circuit as an example. It belongs to the impulse type, but due to the simplicity of its design, it is not able to distinguish between the types of metals. Therefore, it will not be possible to work with such a device in areas where objects made of non-ferrous metal are found.
How to assemble the device
To assemble a diagram of a simple metal detector with your own hands, you will need the following tools and parts:
- The presence of the KR1006VI1 microcircuit, and the IRF740 transistor;
- The presence of the K157UD2 microcircuit and the VS547 transistor;
- Copper conductor 0.5mm (PEV);
- NPN transistor;
- Body, 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 fixed, a plastic case should be prepared for it.
The bar can be made using a small diameter plastic tube. A metal search coil will be installed at its bottom.
Beginning of work
The circuit of a metal detector device on transistors is a common variant of many models. The assembly begins with the manufacture of the printed circuit board. Further, all radioelements are mounted on it exactly as shown in the diagram.
To make the operation of the device stable, 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 from 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 parallel. You can use a small battery that has Charger... Thanks to its capacity, the metal detector will last longer.
Coil mounting
There are different types and schemes for the manufacture of metal detectors, but in the pulse version, inaccuracies are allowed in the installation of the coil. In the manufacture of the mandrel, the winding should be up to 25 turns, and the diameter of the ring is 1900-200mm.
All turns of the coil must be insulated with electrical tape. Reducing the number of turns to 22, and the diameter of the mandrel 270mm will allow detecting objects at a deeper location. The wire cross-section on the coil is 0.5mm.
When the winding is ready, it is fastened to a sturdy case 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 shocks that can damage the coil.
The leads available on it should be soldered to a conductor of several cores. The best option is a two-wire wire.
The installation of a non-ferrous metal detector circuit is a little more complicated, and high accuracy must be observed in the manufacture of the coil. The number of turns reaches 100pcs, and a vinyl tube is used as a core. A foil is wound on top of the winding, which forms an electrostatic screen.
Setting up the device
If the installation of the circuit is done exactly, then the metal detector will not need to additional customization... Its sensitivity indicators will be maximum, but fine adjustment is possible through the 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 adjustment of the resistor is in the middle, it will be considered normal.
An oscilloscope is suitable for checking the device. It measures the frequency of the transistor T2, and the pulse should last up to 150 ms. The optimum 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 a metal detector circuit
Note! 
Note! 
Even the most serious and respectable citizens feel a little excitement at the word “treasure”. We literally walk through treasures, of which there are immeasurably many in our land.
But how do you look under the soil to know exactly where to dig?
Professional treasure hunters use expensive equipment, the purchase of which can pay off after one successful find. Archaeologists, builders, geologists, members of prospecting societies - use the technology provided by the organization in which they work.
But what about budding treasure hunters on a budget? You can make a metal detector at home with your own hands.
To understand the subject, consider the design and principle of operation of the device.
Popular metal detectors work using the properties of electromagnetic induction. Main components:
- transmitter - generator electromagnetic waves
- transmitting coil, receiving coil (in some models, the coils are combined for compactness)
- electromagnetic oscillator
- decoder that separates the useful signal from the general background
- signaling device (indicator).
The generator, with the help of a transmitting coil, creates an electromagnetic field (EMF) around it with specified characteristics. The receiver scans the environment and compares the field readings with the reference. If there are no changes, nothing happens in the schema.
- When a conductor (any metal) enters the field of action, the base EMF induces Foucault currents in it. These eddy currents create the object's own electromagnetic field. The receiver detects the distortion of the base EMF and gives a signal to the indicator (audible or visual warning).
- If the test object is not metallic but has ferromagnetic properties, it shields the baseline EMI, also causing distortion.
Important! There is a misconception that the ground in which searches are carried out should not be electrically conductive.
This is wrong. The main thing is that the electromagnetic or ferromagnetic properties of the medium and the objects of search should be different from each other.
That is, against the background of certain characteristics of the EMF formed by the search environment, the field of individual objects will stand out.
Varieties of metal detectors
Understanding the features different schemes will help not only to choose a ready-made detector. If you decide to assemble a coin detector with your own hands, you do not need to put a detector for water pipes or fittings in concrete into it.
You should initially know what the device is for, since universal metal detectors have a high cost, both when buying and when self-assembly... In addition, the narrow profile device is more compact and lightweight.
Main settings
- Search depth. Determines the penetration power for standard soils: below this band, the coil will not react to artifacts.
- Coverage: the wider it is, the less time it will take to comb. True, the selectivity and sensitivity are reduced.
- Selectivity: the selection of the desired object from a variety of objects. For example, when looking for gold jewelry on the beach, your device will not respond to steel hairpins or coins.
- Sensitivity: The higher it is, the more likely it is to find small items. However, in this case, the coil reacts to various debris, such as nails or hairpins.
- Interference immunity. The detector sensor is affected by many extraneous factors: thunderstorm, power lines, Cell phones etc. It is necessary to filter them out.
- Autonomy: this is both energy consumption and battery power reserve.
- Discrimination is the ability to distinguish artifacts by type. Let's dwell on this parameter in more detail.
A device that allows you to find metal objects located in a neutral environment, for example, soil, due to their conductivity, is called a metal detector (metal detector). This device allows you to find metal objects in various environments, including the human body.
Largely due to the development of microelectronics, metal detectors, which are produced by many enterprises around the world, have high reliability and small overall and weight characteristics.
Not so long ago, such devices could most often be seen at sappers, but now they are used by rescuers, treasure hunters, utility workers when searching for pipes, cables, etc. Moreover, many "treasure hunters" use metal detectors that they collect with their own hands ...
Design and principle of operation of the device
The metal detectors on the market work on different principles. Many believe that they use the principle of pulsed echo or radar. Their difference from locators lies in the fact that the transmitted and received signals operate constantly and simultaneously, in addition to everything else, they work at coinciding frequencies.
Devices operating on the "reception-transmission" principle register the reflected (re-emitted) signal from a metal object. This signal appears due to the effect on a metal object of an alternating magnetic field, which is generated by the metal detector coils. That is, the design of devices of this type provides for the presence of two coils, the first is transmitting, the second is receiving.
Devices of this class have the following advantages:
- simplicity of design;
- great opportunities for the detection of metallic materials.
At the same time, metal detectors of this class have certain disadvantages:
- metal detectors can be sensitive to the composition of the ground in which they are searching for metal objects.
- technological difficulties in the manufacture of the product.
In other words, devices of this type must be configured by hand before work.
Other devices are sometimes referred to as a beat detector. This name came from the distant past, more precisely from the time when superheterodyne receivers were widely used. Beating is a phenomenon that becomes noticeable when two signals with similar frequencies and equal amplitudes are added together. The beating consists in the pulsation of the amplitude of the summed signal.
The signal ripple frequency is equal to the frequency difference of the summed signals. Passing such a signal through a rectifier, it is also called a detector, the so-called difference frequency is isolated.
This scheme has been used for a long time, but nowadays, it is not used. They were replaced by synchronous detectors, but the term remained in use.
A beating metal detector works using the following principle - it registers the frequency difference from two transmitter coils. One frequency is stable, the other contains an inductor.
The device is tuned with your own hands so that the generated frequencies match or at least be close. As soon as the metal enters the zone of action, the set parameters change and the frequency changes. Frequency difference can be recorded different ways from headphones to digital techniques.
Devices of this class are distinguished by a simple sensor design, low sensitivity to the mineral composition of the soil.
But besides this, when operating them, it is necessary to take into account the fact that they have high energy consumption.
Typical design
The metal detector includes the following components:
- The coil is a box-type construction that houses the receiver and transmitter of the signal. Most often, the coil has an elliptical shape and polymers are used for its manufacture. A wire is connected to it, connecting it to the control unit. This wire transfers the signal from the receiver to the control unit. The transmitter generates a signal when metal is detected, which is broadcast to the receiver. The coil is mounted on the lower shaft.
- The metal part on which the coil is fixed and the angle of its inclination is adjusted is called the lower shaft. Thanks to this solution, a more thorough examination of the surface occurs. There are models in which the lower part can adjust the height of the metal detector and provides a telescopic connection to the rod, which is called the middle one.
- The middle boom is the node located between the lower and upper boom. Devices are fixed on it, allowing you to adjust the dimensions of the device. on the market you can find models that consist of two rods.
- The top bar is usually curved. It resembles the letter S. This shape is considered optimal for fixing it on the hand. An armrest, a control unit and a handle are installed on it. The armrest and handle are made of polymer materials.
- The metal detector control unit is required to process the data received from the coil. After the signal has been converted, it is sent to headphones or other display devices. In addition, the control unit is designed to adjust the operating mode of the device. The wire from the coil is connected using a quick-release device.
All devices included in the metal detector are waterproof.
It is this relative simplicity of the design that allows you to make metal detectors with your own hands.
Varieties of metal detectors
There is a wide range of metal detectors on the market that are used in many areas. Below is a list showing some of the variations of these devices:
Most modern metal detectors can find metal objects at a depth of 2.5 m, special deep products can detect a product at a depth of 6 meters.
Frequency of work
The second parameter is the frequency of operation. The thing is that low frequencies allow the metal detector to see at a fairly large depth, but they are not able to see small details. High frequencies allow you to see small objects, but do not allow viewing the ground at great depths.
The simplest (budget) models operate at one frequency, models that belong to the average price level use 2 or more frequencies in their work. There are models that use 28 frequencies when searching.
Modern metal detectors are equipped with such a function as metal discrimination. It allows you to distinguish the type of material located at depth. In this case, when a ferrous metal is found in the search engine's headphones, one sound will sound, and when a colored metal is found, another.
Such devices are referred to as pulse-balanced. They use frequencies from 8 to 15 kHz in their work. Batteries of 9 - 12 V are used as a source.
Devices of this class are capable of detecting a gold object at a depth of several tens of centimeters, and items made of ferrous metals at a depth of about 1 meter or more.
But, of course, these parameters depend on the device model.
How to assemble a homemade metal detector with your own hands
There are many models of devices on the market for searching for metal in the ground, walls, etc. Despite its external complexity, making a metal detector with your own hands is not so difficult and almost anyone can do it. As noted above, any metal detector consists of the following key components - a coil, a decoder and a power supply signaling device.
To assemble such a metal detector with your own hands, you need the following set of elements:
- controller;
- resonator;
- capacitors of various types, including film;
- resistors;
- sound emitter;
- Voltage regulator.
The simplest do-it-yourself metal detector
The metal detector circuit is not complicated, but you can find it either in the vastness of the world network, or in specialized literature. Above is a list of radio elements that are useful for assembling a metal detector with your own hands at home. A simple metal detector can be assembled by hand using a soldering iron or other available method. The main thing in this case, the details should not touch the body of the device. To ensure the operation of the assembled metal detector, power supplies of 9 - 12 volts are used.
For winding the coil, a wire with a cross-sectional diameter within 0.3 mm is used, of course, this will depend on the chosen scheme. By the way, the wound coil must be protected from the effects of extraneous radiation. To do this, they shield it with their own hands using ordinary food foil.
For the firmware of the controller, use special programs, which can also be found on the Internet.
Metal detector without microcircuits
If a novice "treasure hunter" has no desire to get involved with microcircuits, there are circuits without them.
There are more simple schemes based on the use of traditional transistors. Such a device can find metal at a depth of several tens of centimeters.
Deep metal detectors are used to find metals at great depths. But it is worth noting that they are not cheap and therefore it is quite possible to assemble it with your own hands. But before you start making it, you need to understand how a typical scheme works.
The circuit of a deep metal detector is not the simplest one and there are several options for its execution. Before assembling it, you must prepare the following set of parts and elements:
- capacitors different types- film, ceramic, etc.;
- resistors of different ratings;
- semiconductors - transistors and diodes.
Nominal parameters, quantity depend on the selected circuit diagram of the device. To assemble the above elements, you will need a soldering iron, a set of tools (screwdriver, pliers, wire cutters, etc.), material for making the board.
The assembly process for a deep metal detector looks like this. First, a control unit is assembled, the basis of which is a printed circuit board. It is made of PCB. Then the assembly scheme is transferred directly to the surface of the finished board. After the drawing is transferred, the board must be etched. For this, a solution is used, which includes hydrogen peroxide, salt, electrolyte.
After the board is etched, holes must be made in it to install the circuit components. After the board has been tinned. The most important stage is coming. Do-it-yourself installation and soldering of parts to the prepared board.
To wind the coil with your own hands, use a PEV brand wire with a diameter of 0.5 mm. The number of turns and the diameter of the coil depend on the chosen scheme of the deep metal detector.
A little about smartphones
There is an opinion that it is quite possible to make a metal detector from a smartphone. This is wrong! Yes, there are applications that are installed under the Android OS.
But in fact, after installing such an application, he will actually be able to find metal objects, but only pre-magnetized ones. He will not be able to search and even more to discriminate against metals.
Today, there are many different ideas on the Internet that allow you to make a metal detector with your own hands at home. Some of them require certain skills in working with electrical appliances, soldering and understanding the simplest electrical circuits, and some do not require any knowledge of these areas to create. However, a lot of non-working, fake methods are circulating on the network, captivating with their simplicity and accessibility. It is very easy for an inexperienced person to fall for the bait of deceivers - to spend time and effort on the manufacture of a knowingly inoperative device and lose all interest in this. But do not be discouraged, then readers "" will be provided with an interesting and really working scheme for creating a homemade metal detector!
Idea # 1 - Discs in motion!
Surely you have already met or heard that the simplest metal detector can be made by yourself using a CD and DVD disc as shown in the photo. The scheme is quite simple and does not require any professional tools or skills.
This instruction is the most popular due to the availability of the necessary components and the simplicity of its assembly, all you need to do is connect a pair of wires and the crown together and the device is ready. At the same time, the characteristics of this device are attributed to quite good - it finds a coin at a distance of 25-30 cm, which is quite enough for searching for coins and treasures. However, unfortunately, this instruction is fake.
The fact is that a metal detector itself is a rather complex device, its operation is based on several physical phenomena at once. Therefore, a calculator and a pair of disks cannot even remotely repeat its principle of operation, so that the creators of such instructions, who sometimes write that they even find treasures with the help of such homemade products, would not assert.
It is very easy to understand that you are being deceived even without knowledge of the laws of physics. The wires from the headphones, which must be attached to the disk, do not actually contact it in any way, since the copper is under a layer of lacquer insulation, which must be removed by firing and laboriously cleaned of carbon deposits, of course, none of the authors of the instructions does this in their devices ... Consequently, the headphones are simply not connected to any circuit, and there can be no talk of any work and even more so the search for metals.
A real metal detector works on the basis of an induction balance; its design must necessarily have at least one coil of copper wire. When a metal object enters the field of the coil, its characteristics or the received signal, depending on the design, change. These changes are recorded and amplified by the circuit, and also issued in a form understandable to a person, usually by means of sound signals.
Video instruction for assembling a metal detector from discs
Idea number 2 - Metal detector according to the "Pirate" scheme
This is a scheme that has been tested by many do-it-yourselfers and allows you to achieve good results. It contains two microcircuits, so you will have to make a small printed circuit board or assemble the device on a breadboard. But do not be alarmed, everyone can make such an option, making the necessary efforts. Provided below electronic circuit devices and printed circuit board for it.
The coil is made of enameled copper wire with a diameter of 0.5 mm. Winding should be done on a rim with a diameter of 200-260 mm, the number of turns is from 21 to 25. For reliability, it is better to install the coil in a protective plastic casing, which can then be attached to the handle made of PVC pipes.
After assembling the metal detector, it must be checked. The procedure for use is as follows: turn on the device away from metal objects for about 30 seconds so that its operation is more stable, then, by rotating the knob of variable resistors for coarse and fine adjustment, it is necessary to achieve rare clicks. When metal hits the area of action, you will hear a characteristic sound.
Below is the detailed video assembly instructions, which clearly show all the stages of creating a homemade metal detector.
