DIY metal detector using improvised materials. How to make a metal detector at home. Stages of making your own underwater MI

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.
Source

A metal detector is used to search for small metal objects in the soil. But a store-bought product of this kind is quite expensive. To assemble it yourself, it is enough to know the principle of its operation and have a little understanding of electrical engineering.

At the same time, the simplest scheme does not allow determining the type of metal; the discrimination function, in other words, determining the type of find, somewhat complicates the design of the metal detector, but at the same time significantly expands the owner’s capabilities when searching.

To assemble a metal detector with metal discrimination with your own hands, you need to have basic knowledge and be able to work with a soldering iron. The cost of a self-assembled device will be lower than that of a factory-made analogue.

General structure of the metal detector

Metal detectors generally operate on the principle of electromagnetic induction. The transmitting coil generates electromagnetic radiation that penetrates the ground. Reception - receives signals from metal objects located in the ground. Often the functions of both coils are combined into one - a transceiver search coil. The control circuit generates an audible signal indicating that a metal object has entered the search zone; in addition, a visual indicator in the form of a lamp or LCD panel can be used.

Metal detectors are usually assembled according to a classical design and consist of the following main parts:

• search transceiver coil;
• generator of electromagnetic radiation;
• vibration receiver;
• decoder, whose task is to isolate the noise background of an object from the general noise;
• rods on which the equipment is fixed;
• indicator system: sound and visual signaling device.

All elements of the search structure are placed on a bar; the length of the bar is selected based on the anatomical characteristics of the owner.

A discriminator, in other words, a determinant, based on the properties of the object’s material, is usually built into the control circuit; its task is to more accurately determine the characteristics of the find based on disturbances in the electromagnetic field.

Operating principle

The generator creates an electromagnetic field with predetermined characteristics around the search coil. The shape of the field and its depth depend both on the characteristics of the generator and on the shape of the coil itself.

When searching, if there are no disturbances in the electromagnetic field, nothing happens. But when a conductive object enters the electromagnetic field zone, it creates Foucault currents. When a disturbance hits the receiver, it must determine the approximate type of object and transmit information about it to the alarm device. The same story happens when an object with ferromagnetic properties appears in the search field. The characteristics of the soil affect the search field, but at the same time, with the correct settings of the characteristics of the metal detector, more precisely the radiation parameters, this interference can be minimized.

Important! Metal discrimination is one of the functions of a metal detector, which allows you to determine which category a find belongs to. It works by separating the material of an object according to the conductivity of electromagnetic waves. This will eliminate various debris and ferrous metals from the search area.

Self-assembly of a metal detector

There are several working circuits of a metal detector intended for self-assembly: from the simplest “Pirate” type to the more complex “Chance” type, with metal discrimination. The latter is worth talking about in more detail.

The main thing in any metal detector is the coil. You can use either a factory-made coil from a store or make it yourself. To work, you will need copper winding wire 0.67-0.82.

You can make a simple coil of 90 turns of winding wire for a 100-1200 mm mandrel, but with such a coil design, discrimination will not work correctly. Therefore, it is proposed to assemble a search coil from two windings: an external one with a diameter of 210 mm from 18 turns and an internal one with a diameter of 160 from 24 turns. For ease of manufacture, marking and winding of contours should be done on a plate made of non-magnetic material, for example, plexiglass or thick cardboard.

In addition, it is worth sealing the winding; for this you can use any non-magnetic materials, this will increase the resistance of the metal of the product to moisture.

We'll take the metal detector control unit from Andrey Fedorov. This scheme has already proven itself on the positive side and has been tested many times.

The printed circuit board can also be made independently: from textolite, with a foil pattern applied using the materials provided below. Usually, skills in working with printed circuit boards are sufficient for this. Drawing conductive paths according to a pre-made sketch is a fairly simple process. An iron or a hair dryer is sufficient for this purpose.

Its base is a microprocessor of the ATmega8 type, with a converter of the MCP3201 type. A microcontroller of this type is quite scarce, but despite this, it is sold in a number of online stores. Finding it and purchasing other components will not cause any special problems. Soldering of the control panel is carried out according to the diagram below.

When soldering, you need to carefully monitor the placement of parts and elements on the board. The circuit is quite complex, and the failure of one or two elements will throw all the work down the drain. Don't forget about safety precautions when soldering.

Important! It is worth clarifying that the circuit uses an ICL7660S voltage converter; the letter S indicates that this converter operates with voltages up to 12V. This is what you need to use; when using the ICL7660, the converter may fail due to overheating.

You can download a drawing of the printed circuit board and a full description of the assembly from this link www.miriskateley.com/.

Materials and equipment

To make a coil, a winding wire with a diameter of 0.6-0.8 mm is used; when winding, you need to carefully monitor its condition to prevent damage to the enamel coating. The base is a circle made of non-magnetic, electrically permeable material with a diameter of at least 250 mm.

A complete list of materials used and the possibilities of replacing them with analogues

Detail	Analogue	Quantity
NE5534		1
Converter MCP3201		1
ICL7660s converter		1
ATMega8 controller		1
Zener diode TL431		1
Voltage stabilizer 78l05		1
Quartz at 11.0592 MHz		1
Diodes 1N4148	KD522	10
Diode 1N5819	KD510	1
Diodes HER208	HER207	2
Transistors 2SC945		5
Transistors IRF9640		2
Transistors A733	2SA733	2
Capacitors, ceramics		13
Electrolytic capacitors of different ratings		8
Resistors		27
Buttons art. SWT5		6
LCD QC1602A		1

Programming the control unit

The firmware is installed via a connection to the USB port of a personal computer. Programming is carried out using the “Gromov programmer”; for firmware you need to find on the Internet the free UniProf program from Mikhail Nikolaev.

The latest version of firmware can be downloaded here radiolis.pp.ua.

Any current source with a voltage from 9 to 12 V is used to power the circuit.

Assembly

The metal detector is assembled on a rod; the control unit is conveniently placed in a housing made of high-strength plastic, on its upper part. The coil is fixed at the bottom of the device. To fix it on the rod, it will be enough to fix the coil wires on a non-magnetic base.

It should be noted that high-quality insulation of the wires and the entire control unit from moisture is necessary. The main use of this device is in the field, which is why this issue is so important.

A homemade metal detector of this type is a rather complex device, but at the same time, its assembled cost is somewhat cheaper than its industrially produced counterparts. This product is highly efficient, quite economical in energy consumption, but at the same time has all the necessary functions for finding treasures or metal objects. The discriminator is sufficient to determine metal-non-metal characteristics and identify non-ferrous metals. According to reviews, when using this type of metal detector, a small coin can be found at a depth of up to 20 cm, a steel helmet of the SSh-40 type can be found at a depth of up to half a meter.

Video

Equipment and materials

To assemble a homemade metal detector with your own hands, you will need the following components and tools:

• Chip. Both domestic, type KR1006RVI1, and its foreign analogue are suitable ( NE 555)

• Copper wire for coil winding

• Transistors of various formats ( BC 547, IRF 740, NPN, etc.)

• Finished printed circuit board or material for its manufacture

• A plastic or metal tube long enough to be used as a barbell

• The material for all body elements is durable plastic

• Consumables: any suitable fasteners, electrical tape

• Equipment: soldering iron, screwdrivers

This is the minimum set, which will be enough to assemble a simple device. This device is perfect for beginner treasure hunters.

Assembling the device

To assemble the simplest metal detector, you need to go through several steps.

PCB assembly

Electronics are traditionally the most complex part of any device. In this case, it is impossible to do without microcircuits, so it would be logical to start the assembly with a printed circuit board.

For a simple metal detector there are two PCB options:

• Chip board NE 555 (or similar domestic

• Transistor board.

Even if you assemble it yourself, it is still better to purchase a printed circuit board ready-made. They can be found in any radio electronics store. The fact is that even if the master decides to assemble a printed circuit board himself, to make it he will need to buy materials that are hardly possible to make himself, such as getinaks - pressed paper boards.

Installing electronics on the board

Next, the master’s task is to install all the electronic elements on the board. The main condition here is to strictly follow the electrical circuit diagram of the metal detector. The further operation of the entire device depends on the accuracy of soldering.

To increase the stability of the metal detector, it is recommended to additionally install film capacitors on the board. They have increased thermal stability. This is especially true for use in cold weather, for example, with frequent searches in the fall.

Power supply

Powerful circuit a homemade metal detector is provided by any power source with a total voltage of 9 to 12V. But it is believed that the sensitivity of the device is better when using a 12V power source. This can be either a battery or several batteries. You can even reuse unwanted laptop batteries.

It is worth noting that even with the simplicity of the circuit, the device ends up being quite powerful and consumes a significant amount of energy. During long-term searches, you should take care of the availability of spare batteries, and it is best to use rechargeable batteries, which will avoid troubles with the batteries draining at the most inopportune moment.

Coil assembly

Since the assembled device is a pulse device, the accuracy of the coil assembly is less important here. The best option is to use a frame with a diameter of about 200 mm. You need to wind 25 turns of copper cable. After winding is completed, the coil must be additionally wrapped with any electrical tape. This will provide additional protection from moisture.

To make the coil more sensitive, you can increase the frame diameter to 250 mm, while simultaneously reducing the number of cable turns to 21-22. After winding and insulating the coil, it must be installed on a rigid base. It is extremely important that it is made of non-metallic material. Impact-resistant plastic can be used. Such a coil will become more sensitive to non-ferrous metals, and with minor additional modifications it will theoretically be able to produce signals from precious metals that do not lie too deep in the soil.

Encapsulating the coil in a durable housing is very important because it is located at the very bottom of the boom and often comes into contact with the ground, low-growing plants, grass, rocks and debris. This way the coil is reliably protected from impacts.

The leads from the coil must be soldered to a wire, or better yet, to a twisted pair.

Device setup

If the assembly was carried out according to detailed instructions, then the metal detector does not need additional settings, since by default it will have the highest possible sensitivity. But if finer tuning is needed, you can twist the resistor R 13, achieving rare single clicks in the device's dynamics.

But if this effect can be achieved only in the extreme position, then it is better to change the resistor to R 12. Clicks in the dynamics during normal operation should occur in the middle positions. If you have an oscilloscope, this device can easily measure the frequency and speed up the setup process.

The frequency for normal operation should be approximately 130-150 Hz.

Working with a metal detector

Immediately after turning on, you need to wait a little (about 15 seconds) for the device to stabilize its operation. By adjusting the resistor R 13 until the desired state, you can proceed directly to search operations.

Make a metal detector at home

Not everyone knows how to make a metal detector with their own hands at home.The basis of the operation of any metal detectors is the transmission and response reception of electromagnetic waves. The key elements of this type of device are two coils (sometimes combined into one). The first coil is transmitting, the second is responsible for receiving the response signal emanating from detected objects.

The metal detector works on the following principle:

Power magnetic rays emanating from the device pass through metal objects, which creates an additional (secondary) magnetic field. The receiving coil detects the appearance of such a field and sends information about this to the control unit, which activates the warning system.

Based on their operating principle, such devices can be divided into:

· Simple. The cheapest devices that operate according to the banal but effective principle of “transmission-reception”.

· Induction. These are exactly the kind in which two coils are combined into one common one.

· Pulse. They work based on a pulse emanating from a transmitter. After releasing a pulse, it immediately turns off and turns on when it is necessary to generate a new pulse.

There is another classification of devices based on their technical features:

· Dynamic. A device that is simple in design and operation, continuously scanning the coverage area of ​​the created field. The key principle of working with such a metal detector is the need to constantly be in motion, otherwise the signal disappears. The disadvantage of such finders is a rather low level of sensitivity.

· Pulse devices. They have increased sensitivity, but require experience and additional configuration skills. Sometimes such a device is equipped with several coils at once, each of which is applied to different types of metals and soil in the area where the work is being carried out. Among metal detectors of this type, the most popular are electronic devices that operate at a low frequency level - around 3 kHz.

· Electronic. Such detectors are good for searching for large metal objects, having a good level of sensitivity. However, on the other hand, they can miss small artifacts, since they are often configured to ignore small signals, most often emanating from unnecessary objects, such as metal debris.

· Deep The detector is designed to search for objects located at significant depths underground. Such devices are capable of detecting a signal even at a depth of 6 meters, while others most often operate at a depth of no more than 3. This device operates on the basis of two coils, like others. But here their position relative to the earth's surface has been changed. One of them is located parallel to the ground, the second is perpendicular.

· Another option that is of less interest to search engines is stationary metal detectors. These are nothing more than frames that can often be seen at especially important objects: stadiums, metro stations. They are ways to calculate the presence of any metal products in bags and internal people who pass through the installed frame.

The simplest of metal detectors, which base their work on the “transmission-reception” principle, also have a simple design and assembly principle, so these are the devices that are best suited for making with your own hands. What is important here is only the competent selection of parts in accordance with the instructions, and the presence of minimal experience in working with radio electronics.

How to make a metal detector with your own hands

Making a metal detector from domestic parts for beginners is best considered on the basis of the “Pirate” model. This option has long been among the top homemade metal detectors. It is widely in demand among DIY enthusiasts, and in its finished form it is a device with good search depth and accuracy indicators. It allows you to detect objects at a depth of up to 1.5 meters, which can be called a good indicator for devices with such a simple design.

Among devices of this level there is another scheme based on frequency beats. But if you compare the characteristics of the “Pirate” with the devices in this diagram, the comparison will be in favor of the “Pirate”. In addition, the design of this metal detector is also easier to assemble and consists of fewer parts and components.

One of the possible disadvantages of this model is the lack of a discrimination function. A simple metal detector circuit simply cannot provide the ability to connect a discriminator. But with experience, seekers learn to independently determine which metal produces a signal from field vibrations.

Metal detector device "Pirate"

This detector is a pulse type device. To understand how to assemble such a device yourself, you need to know how a metal detector works, and then you will need to purchase:

· Long plastic tube for a barbell. All other equipment will be attached to it. PVC water pipes work well in this case.

· Material for the control unit housing. You can use any suitable size container made of durable plastic.

· Speaker. Anything, for example, a small Chinese portable radio, will do. The main condition is a resistance level from 8 to 50 Ohms.

· Headphones with jack mini-jack (3.5 mm ). Any headphones from your phone will do, mp 3-player or any similar device

· Copper cable on reel

· Electrical tape

· Transistors of various types: BC 547, IRF 740 and BC 557

· Two microcircuits: K157UD2 and NE 555

· Capacitors. It is better to use ceramic and film.

· Electrolytic capacitors, 5 pieces in total.

· Resistors of various resistance levels

“Pirate” is a metal detector based on two microcircuits. This is where the chip is used NE 555 or its domestic equivalent.

The operation of the device begins with a comparator. One of its outputs is connected to the generator (creating the electromagnetic field), the other to the receiving coil, and the third to the speaker for sound signaling.

When metal objects are detected within the created field, a signal about this from the receiving coil is sent to the comparator, and then to the speaker, which emits a corresponding sound alarm.

The finished assembled board, with the elements placed on it, is placed in a regular junction box. You can make it yourself from durable plastic, or you can buy it at any radio equipment store.

If a standard device is not enough, then there is an option to make a more advanced model for gold. The power of a device assembled according to a conventional circuit is not enough to react to gold and objects made from it, so it is easy to find an improved circuit on the Internet.

Can parts from a radio be used?

To create a signal in this model, transistors of the KT-361 and KT-215 samples are perfect. These are USSR-style parts and can be found in any old radio, or in any radio equipment from those times.

Build the Pirate finder circuit board?

You can make a printed circuit board for such a device yourself, but you won’t be able to do it from scrap materials. To make it you will need a sheet of special material - getinax. It consists of pressed slabs of thick paper impregnated with epoxy resin. Additionally, it must be covered with a special copper foil, which is used in electrical engineering.

You need to transfer all the connecting elements to such a board, mark the places for fastenings and carefully drill holes in them. All tracks must be coated with a special protective varnish, and as soon as it dries, the board must be immersed in a chlorine solution. This gives additional protection to areas where the protective layer of copper foil is thinnest.

Coil assembly

As a base, you need a ring made of any non-metallic material with a diameter of about 200 mm. Even a wooden hoop may work. Copper wire is wound onto the selected base, approximately 30 turns. To increase sensitivity, it is necessary to increase the ring diameter to 250-260 mm, and reduce the number of turns to 20-22.

It is convenient to wind on a pre-prepared board or any flat surface. The distance between the turns must be maintained approximately equal to the diameter of the base. In several places, for reliability, it is necessary to additionally strengthen the coil winding with electrical tape.

The coil is ready, it can be connected to the detector and tested for performance.

Also, the coil can be assembled from a minimal set of available tools in just a few minutes. To do this, in addition to a twisted pair of 2.5 mm cable, you will need a minimum set of tools: a soldering iron, a multitester, a sharp knife and some solder.

The procedure in this case is as follows:

· First, you need to twist the wire into two skeins, leaving about 10 cm on both sides.

· Then, clean the winding, freeing the cable cores for connection.

· Connect the wires according to the diagram; for reliability, solder them with a soldering iron and apply solder.

· Test the presence of a signal using a multitester; attach the ends of the winding to a multi-core cable with a soldering iron.

Assembling the “Pirate” metal detector from ready-made parts

Once all structural elements are ready, full assembly can begin. All parts are attached to a fairly long rod. A comfortable rubber handle is attached to the top, a control unit enclosed in a plastic case is located just below, and a coil is located at the very bottom. If everything is done correctly, no errors were made when assembling the elements - the device is ready for use, no additional manipulations will be necessary.

The design of a deep metal detector is similar to a regular one, with the exception of some technical details. It also differs in its increased sensitivity to metal objects, which makes it possible to detect them at greater depths compared to a simple metal detector. In addition, there is a selective search function, that is, the ability to find objects of a certain size without reacting to those that do not fit the parameters.

Diagram of a deep metal detector

It is quite simple, despite its apparent complexity. The metal detector consists of two parts – receiving and transmitting. The main device is a high frequency transmitter generator. Two loop antennas, one of which serves as a signal transmitter, the second as a receiver. They must be located strictly at an angle of 90 degrees to each other to prevent the receiving antenna from picking up the generator signals. When a metal object is found, the magnetic field created by the generator is distorted and subsequently picked up by the receiving antenna. In this case, the mass of a metal object is used as a source of radiation, sending the energy produced to the receiving antenna.

Metal detector receiver circuit

The transmitting device includes a thyristor with a power of 0.25 to 1 W and a sound generator with a frequency of 200 Hz. When a metal object is found, the operator hears a sound with a frequency of 200 Hz, the strength of which depends on the size of the object found and the distance to it.

A detector receiver whose oscillation circuit responds to a frequency of 120 kHz, and consists of two diodes. The amplifier can be absolutely any low-frequency generator that can be found in an old radio. An amplifier with transistors in the amount of 5-6 pieces is enough. A transistor is also used as a current amplifier for a pointer instrument, allowing the level of the received signal to be measured. That is, the device contains two types of indicators - visual and acoustic. The operating frequency is adjusted so as not to interfere with the operation of the signal receiver.

Transmitter circuit

Required parts and tools for assembly

To assemble such a metal detector, you must first prepare a set of necessary parts and tools.

In the case of a pulse metal detector, approximate parts list will look like this:

1. Electrolytic capacitors with a voltage of at least 16 V in the following capacities: 2 capacitors with a capacity of 10 μF, one with a capacity of 2200 μF, 2 pcs - 1 μF.
2. Ceramic capacitors: 1 piece with a capacity of 1 nf.
3. Film capacitors of the lowest voltage value, for example, 63 V - 2 pieces of 100 nf each.
4. Resistors of 0.125 W: 1 k - one, 1.6 k - one, 47 k - one, 62 k - two, 100 k - one, 120 k - one, 470 k - one, 2 ohm - one, 100 ohm – one, 470 ohm – one, 150 ohm – one,
5. Resistors of 0.25 W: 10 ohms - one.
6. Resistors 0.5 W: 390 ohm - one
7. Resistors 1 W: 220 ohm - one.
8. Variable resistors: 10 k – one, 100 k – one,
9. Transistors: BC 557 – one, BC 547 – one, IRF 740 – one,
10. Diodes: 1N4148 - two, 1N4007 - one.
11. Microcircuits: K157 UD2, NE555.
12. Panels for each of them.

Metal detector parts

From tools When performing work you will need:

• Soldering iron, tin, special solder, other soldering supplies.
• A set of screwdrivers, wire cutters, pliers and other plumbing tools.
• Materials for the production of printed circuit boards.

Metal detector assembly steps

The process of assembling a deep metal detector with your own hands includes the following steps:

At the first stage, it is necessary to assemble the electronic part, namely the control unit.

The step-by-step process looks like this:

• Cutting PCB to the required size.
• Preparing a PCB design and transferring it directly to the board.
• Preparing the etching solution. It contains table salt, electrolyte and hydrogen peroxide.
• Etching the board and drilling technological holes.
• Tinning the board using a soldering iron.
• Next comes the most important stage in assembling the control unit. This is the selection, search and soldering of parts directly onto the board.
• Winding a test coil. There are several options for winding it. The simplest option is to use PEV wire size 0.5 and wind it 25 turns on a suitable frame with a diameter of about 19-20 cm.

The best option would be to solder everything directly, and after the setup is complete, select the necessary connectors and adapters. It is better not to twist, as this has a negative effect on the sensitivity of the device.

The second good option would be to make such a ring from twisted pair wire. You will need about 2.5 - 2.7 m of wire.

To achieve maximum sensitivity, do the following:

1. Wind 25 turns of wire.
2. Perform a test by cutting small pieces of wire and observing the increase in sensitivity.
3. This must be done until sensitivity begins to decrease.
4. Count the number of turns, wind the final version of the coil, adding 1-2 turns. Thus, the maximum sensitivity value is achieved.

Upon completion of the main work, the control unit, coil and other parts are fixed in place on the rod. The metal detector can be turned on and checked.

Possible problems during assembly

• The assembled device does not react to metal objects. The cause may be a breakdown of the diodes or transistor. Faulty parts need to be replaced.
• Excessive heating of the transistor. You should install a resistor of lower resistance, reducing it until the heating stops.

Assembly of this type of metal detectors is not too difficult, provided all rules and instructions are strictly followed.

Many people mistakenly believe that if they make a metal detector with their own hands, it will be of much worse quality than a factory one. However, a homemade device can be not only better, but also much cheaper than models produced at the factory. Most people who like to look for various treasures are looking for cheap options to save money. Typically, they end up assembling the metal detector themselves.

Operating principles of a metal detector

Beginners at the first stages may be intimidated by various schemes and formulas when assembling them on their own. But if you look for available information on the Internet, you can easily understand all the nuances. Therefore, in order to ultimately get a good device with discrimination, it is necessary to carefully study the various diagrams, instructions and operating principles of the metal detector.

The operating principle of such a device is to use an electromagnetic field. It is created by the transmitter coil after detecting an object that conducts current (mostly all metals). The process is accompanied by characteristic sounds due to the creation of eddy currents and distortion of the EPM coil.

If the found object does not conduct current, but the metal detector still detects it, then this means that it has its own electromagnetic field.

When an object is detected, cheaper devices create a special sound after transmitting information to the control unit. But in expensive factory models, information can also be displayed on the screen.

In order to assemble the device efficiently, you must first study the detailed instructions; Making a metal detector with your own hands is not so easy. Although with the right approach it is quite possible even without special training. Moreover, it is possible to make an underwater vehicle that can search for gold and other precious metals. Although it is unlikely that it will be possible to make a deep metal detector, such devices are manufactured in factories.

The metal detector consists of:

Preparing the PCB

First you need to prepare a printed circuit board, where all the parts and components of the metal detector will subsequently be located. Basically, the method of laser-iron technology (abbr. LUT) is used for this.

At this stage To produce a board, you must follow these steps:

Installing all elements

After the PCB board is ready, it is necessary to solder the circuit elements onto it. They can be taken from old and unnecessary tape recorders, televisions, and radios. But in principle, if the list of necessary parts is ready, then you can buy everything on the radio market. They cost pennies.

The installation process is as follows:

1. First you need to install the main chip. You can use the foreign NE555 or the Soviet KR1006VI1, both will do. But problems may arise with domestic ones, since they are no longer manufactured. There should be no problems with a foreign analogue. Before installing the main part, a jumper is soldered underneath it.
2. After this, K157UD2 is installed - a two-channel amplifier. It can be found in an old tape recorder.
3. Next, capacitors and resistors are mounted.
4. At the next stage, you need to solder two transistors like BC557 or analogues.

Metal detector coil assembly

In order to make a high-quality metal detector with your own hands at home, you need to approach the assembly of the coil with great responsibility.

You can make a homemade coil from a frame with a diameter of 20 centimeters. To create such a frame, you need to take PEV wire 0.5 millimeters in diameter. 25 skeins will be enough. But in any case, the number of turns of wire can either increase or decrease. In order to understand how many of them actually need to be made, for quality work you need to use a coin. The maximum catching distance should be checked.

The speaker that produces the signal can be removed from the portable radio. An important factor is its resistance. It should not be less than 8 ohms. Alternatively, you can use cheap Chinese speakers.

Installation of additional elements

To configure the device, two potentiometer models of different power are required. One for 100 kOhm, and the second only for 10 kOhm. During operation of the metal detector, interference can often occur. To avoid this result, shielded wire is used to connect the coil and the circuit. But you need to understand that it will not be possible to completely get rid of interference. A minimum 12 V battery is used as the power source for the device.

The stability of the electrical circuit can be increased by additionally using a voltage stabilizer type L7812.

After all the electronic elements are ready, you should begin assembling the frame for the metal detector. But here it is necessary to give only general recommendations, since everyone will assemble it from improvised means.

For beginners we can advise:

• Purchase 5 meters of PVC pipe (which is used in plumbing) to create a rod, as well as a jumper. A special hand rest is installed on top of the pipe. It allows you to feel more comfortable when working. To place the board you need to find any box of appropriate size.
• The device can be powered from a regular battery from a screwdriver. The advantages of using such a battery in its small capacity.
• When creating the body of the structure, you need to take into account that there should be no unnecessary metal elements. They can negatively affect the electromagnetic field of the metal detector.

How to check functionality

A metal detector on a chip can be tested in different ways. First, sensitivity is adjusted using potentiometers. The boundary indicator will be a uniform, very strong crackling. For example, he must find a 5-ruble coin from a distance of 30 centimeters, and a Soviet ruble from 40 centimeters. Large pieces of metal should be detected from a meter or more away.

But on the other hand, he will not be able to find small objects at great depths. Moreover, he will not distinguish between the size of the detected metal and its type. Because of this, when working on such equipment, nails or pieces of unnecessary metal will be a common find.

Many who are interested in the question of how to make a homemade metal detector turn out to be novice treasure hunters who do not have the necessary funds to purchase a factory-made device.

Simple homemade designs

Today there are many ways you can make a metal detector at home, using almost only improvised means. To implement some methods, you need to have special knowledge in the field of electrical engineering, while other options can be used without any knowledge.

Metal detector made from computer disks

There is a lot of information on the Internet on how to make a metal detector from computer CDs or DVDs. The circuit is not complicated, and even a schoolchild can make such a device. To do this, you do not need to have experience with electrical engineering or special tools. Theoretically, you can also make a DIY metal detector from a phone (cell or landline) yourself.

The main material used is:

In order to To assemble a working metal detector from these parts, you need to:

• Cut off the plug from the headphones and remove the insulation by 5-10 millimeters.
• Each stripped wire must be divided into two parts. As a result, four parts should be formed.
• A disk must be attached to each wire using glue. If the disc is single-sided, then it needs to be glued to the writing side.
• Additionally, the wires must be secured with electrical tape.
• The remaining separations from the wires must be attached to the plus and minus of the battery.
• Carefully insulate the wires.
• The included calculator should be installed to the CD using electrical tape.
• Place a DVD on top and connect them with tape.
• Attach the battery to the top of the DVD disc with electrical tape.
• Testing phase.

Additionally, you can make a handle for convenient operation of the metal detector. Basically, such metal detectors are used to search for insignificant and small objects, for example, to search for a metal profile in a wall. This device is not suitable for searching for various coins and precious metals, but it is just right for home needs.

Radio receiver as a basis

In practice, they use a good and cheap way to create a metal detector from a radio receiver. This option is no worse than the previous one, but, on the contrary, has increased power.

To create such a metal detector you need:

• a box from an ordinary computer disk;
• radio receiver operating on AM frequency;
• calculator;
• scotch.

These materials should be used as follows:

As you can see from the situation, making a more or less powerful search engine will not be difficult, and will take no more than 5 minutes. This option is for novice users, since it can be done without microcircuits, drawings and the necessary experience in electrical engineering. You can also attach a handle to it for convenient use. The device is ideal for detecting old wiring or metal profiles.

This is one of the most prudent ways to create a metal detector yourself. The decision is up to everyone. On the one hand, there is an opportunity to save up to 5,000 rubles, but on the other hand, homemade devices do not always work as they should.