Making a metal detector for gold with your own hands: diagrams and step-by-step instructions. Powerful DIY metal detector Pirat Powerful homemade metal detector for deep searching

A metal detector is an electronic device for searching and distinguishing metals, metal objects that can be hidden at different depths under a layer of sand, earth, in the walls of rooms and various structures.

Schematic diagrams of metal detectors made on transistors, microcircuits and microcontrollers are given. A factory-made metal detector is quite expensive device, so making a homemade metal detector yourself can save quite a bit of money.

The circuits of modern metal detectors can be built according to different principles works, we list the most popular of them:

• Beat method (measuring changes in reference frequency);
• Induction balance at low frequencies;
• Induction balance on spaced coils;
• Pulse method.

Many novice radio amateurs and treasure hunters are wondering: how to make a metal detector yourself? It is advisable to start your acquaintance with assembling a simple metal detector circuit; this will allow you to understand the operation of such a device and gain first skills in searching for treasures and products made of multi-colored metals.

Now there is enough big choice multimeters, at very different prices. Now the radio amateur can not be limited to the modest set of functions of the “legendary” M-838. For not much more expensive, you can purchase a more modern device that is also capable of measuring the frequency of alternating current...

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The metal detector is designed to detect a metal object (a well cover, a piece of pipe, hidden wiring). The metal detector consists of a parallel voltage stabilizer (transistors V1 V2) at a high frequency generator (about 100 kHz) on transistor V4, an RF vibration detector (V5) and...

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The metal detector allows you to detect any metal object at a distance of up to 20 cm. The detection range depends only on the area of ​​the metal object. For those for whom this distance is not enough, for example treasure hunters, we can recommend increasing the size of the frame. This should also increase the detection depth. The schematic diagram of the metal detector is shown in the figure. The circuit is assembled using transistors operating in...

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Circuit diagram of a homemade beat-based metal detector, which is built on five microcircuits. Finds a 0.25mm coin at a depth of 5cm, a pistol at a depth of 10cm, and a metal helmet at 20cm. The schematic diagram of a beat metal detector is shown below. The circuit consists of the following components: a crystal oscillator, a measuring oscillator, a synchronous detector, a Schmidt trigger, an indication device...

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The diagram shown in the figure is a classic metal detector. The operation of the circuit is based on the principle of superheterodyne frequency conversion, which is usually used in a superheterodyne receiver. Schematic diagram of a metal detector with an integrated ULF; it uses two radio frequency generators, the frequencies of which are 5.5 MHz. The first radio frequency generator is assembled on a T1 transistor type BF494, frequency...

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This metal detector, despite the small number of parts and ease of manufacture, is quite sensitive. Large metal objects, such as a heating battery, it is able to detect at a distance of up to 60 cm, while small ones, for example, a coin with a diameter of 25 mm - at a distance of 15 cm. The operating principle of the device is based on a change in frequency in the measuring generator under the influence of nearby metals and...

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A simple compact metal detector is needed to detect various metal objects (for example, pipes, wiring, nails, fittings) in walls under a layer of plaster. This device is completely autonomous, powered by a 9-volt Krona battery, consuming 4-5 mA from it. The metal detector has sufficient sensitivity to detect: pipes at a distance of 10-15 cm; wiring and nails at a distance of 5-10...

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Scheme of a small-sized, highly economical metal detector with good repeatability and high performance characteristics, using widely available and inexpensive parts. An analysis of most common circuits has shown that they are all powered from a source with a voltage of at least 9 V (that is, “Krona”), and this is both expensive and uneconomical. So, assembled on the K561LE5 chip...

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The dream of finding treasure is increasingly being replaced in our time by a more realistic program of searching for precious metals in a natural or artificial environment.

IN modern conditions it is very important to find and extract valuable materials, who turned out to be among the waste, or in another uncontrolled environment.

Equipment is an important component of such search technology.

The search and extraction of gold and valuable metals from waste, garbage, in the natural environment is part of the recycling strategy, a technology for the effective processing of used materials, including.

Searching for them in the ground or in masses of industrial and other waste not only requires the use of equipment, but also stimulates its improvement. Are being created devices different levels and specializations. There is interest in such equipment among amateurs and enthusiasts of searching for valuable metals.

The metal detector is the most main tool manual search for metals in a chaotic natural or artificial environment.

Using such a device, you can search not only for silver, but also for silver and other precious metals.

Device principle any metal detector based on electromagnetic effects.

Here's how typical metal detecting technology works:

1. Device creates an electromagnetic field.
2. Metal an object, secretly located in a foreign environment, affects such a field when falls within its sphere of influence.
3. Device detects the impact of an object on the electromagnetic field and signals this.

A large number of metal detector models operate precisely on this principle.

Technical differences in such equipment make it possible to obtain more complete information about the fact of detecting a metal object, for example:

• estimate the mass of the find;
• obtain data on the shape, size and configuration of an object;
• specify the location, including depth.

There is a lot of information on the Internet about metal detectors of varying complexity and design. There you can also refresh your memory about the theory of the electromagnetic field, studied at school.

The simplest, primitive metal detectors (usually homemade designs for searching for gold, silver and other metals enthusiasts) assembled from ready-made devices and products operating using electromagnetic effects.

Many are familiar with the primitive, but quite workable circuit of a metal detector, in which an electromagnetic field creates a pulse element of a conventional calculator.

Reaction generated field on detected metal objects picks up the simplest household radio. The signal about such a find is audible, quite distinct and understandable.

More complex amateur and professional metal detecting devices retain the logical basis of the technology in the form of three components:

• generator electromagnetic field;
• sensor of changes in this field;
• equipment for assessing detected anomalies, signaling this.

Devices of different levels of complexity and functional potential can be divided into groups. Classification based on professionalism and user specializations – one of the generally recognized:

• amateur equipment, assembled by hand and used as a hobby tool or by beginners in metal detecting;
• semi-professional equipment necessary for enthusiastic amateurs and fanatics;
• professional metal detectors for those constantly working in this field;
• special devices for metal detectors in difficult conditions - at depth, under water, with the release of precious metals.

The distribution of search equipment is such that many devices of this type can be purchased at gardening and country supply stores.

A device for searching and detecting metal is needed not only for recycling, but also for searching for artifacts and treasures. Numerous security systems for everyone well-known frames - one of the technology versions metal search. The settings of these frames are focused on searching for weapons and similar dangerous objects.

Coil

A very important node metal detecting equipment – reel or frame. This is most often a winding of a special configuration, the task of which is to form an electromagnetic field and capture its reaction to the detection of a metal body foreign to the search environment.

In most designs the coil is placed on a long rod– a handle to move it near the search area.

For amateur production of reels, frames of the most popular types are sold. The easiest way to make such a purchase is in an online store.

Many lovers make the coil frames yourself. This is done for reasons of cost savings or in the hope of getting more quality tool author's design.

For this, improvised means are used– plastic products, plywood and even filling the assembly construction foam assembled winding.

The search operator or treasure hunter strives to find the most effective technique for working with a metal detector, choosing the desired operating modes of the electronics and the correct techniques for manipulating the coil.

Electronic circuit

The logical element of a metal detector is an electronic circuit. She performs many functions:

1. The first task of this component is in creating an electromagnetic signal of the desired format, which is converted into a field using a coil.
2. Second task electronic circuit – analysis of field changes captured by the frame, their processing.
3. The third task is giving an informing signal to the operator– sound, light, indications of indicators and instruments.

It is best if anyone who wants to assemble an electronic circuit has knowledge of amateur radio or electronic technology. Such a master can not only assemble the required circuit, but also change and improve the design.

Many electronic devices are quite simple, Even a beginner can assemble them. The resulting device will be operational without configuration if the assembler exactly followed the recommendations of the developer of such a circuit.

How to make "Pirate" yourself?

One of the most popular models of metal detectors designed for homemade amateur production is the “Pirate”.

This name, containing abbreviated details of its device and the developers' website, wittily reflects the romance of searching for precious metals.

Here the main advantages of this model:

• simplicity of device and assembly;
• low cost of parts and materials;
• sufficient operating parameters;
• recognized convenience for beginners.

The electronic circuit of this model does not require programming. In "Pirate" details available to everyone are used, Right assembled circuit fully operational.

Design and operating principle

The design and layout of the “Pirate” metal detector is traditional for equipment of this kind. It is a rod, at the lower end of which there is a coil, and in the upper part – electronic unit with battery.

The location of the electronic unit should leave room for comfortable holding of the rod by hand.

Some craftsmen prefer that sound signal The device was not supplied by a speaker, but by headphones. In this case, the headphone cable departs from the electronic unit.

The technology of operation of the device is pulsed. This allows us to provide very good sensitivity indicators for this class of equipment. Below is a diagram of an electronic unit on microcircuits.

A similar circuit can be assembled using transistors instead of microcircuits. This version may require additional settings, available only to experienced radio technicians. This is why the transistor circuit is used less frequently.

Materials, parts and blanks

In addition to those detailed and precisely indicated on schematic diagram electronic unit parts, for assembly metal detector for gold and other metals you will need to prepare some materials and blanks:

• a ready-made board for assembling an electronic circuit or foil material for it self-production;
• power source in the form of any combination of batteries or batteries with a total voltage of 12V;
• enamel wire with a cross section of 0.5 - 0.6 mm for making a coil;
• stranded copper wire for connections with a cross-section of at least 0.75 sq. mm;
• housing for the electronic unit - a plastic container of a suitable size;
• a fairly strong plastic pipe for the rod;
• coil winding frame;
• consumables - solder, heat-shrinkable casing, electrical tape, screws and fasteners, adhesives and sealants.

It is best to make a printed circuit board for assembling an electronic circuit based on designs presented on the Internet.

Below is one of these samples, suitable for assembling electronics on microcircuits.

The manufacture of the board is carried out by amateurs of homemade electronics, and even then not all of them. Most people who want to create a metal detector themselves prefer to buy such a part.

To assemble the coil you will need a frame or frame, not containing metal elements. An amateur craftsman can make such a frame from plywood, plastic, or select similar parameters from ready-made ones. plastic products, for example, dishes. The frame can be purchased ready-made or made independently

Recommended coil parameters– 25 turns of enamel wire with a diameter of 0.5 mm on a mandrel with a diameter of 190-200 mm. An increase in diameter by 30% will lead to an increase in the sensitivity of the device, provided that the number of turns is reduced to 20-21.

The plastic frame for the coil is one of the most common metal detector parts on sale.

The technology for manipulating the coil is such that this very fragile unit can suffer from impacts from uneven ground, stones, and sharp objects. To avoid this the coil on the frame is covered from below with a plastic plate. This plate not only protects the reel, but also ensures that it glides through tall grass. The search becomes more intense.

Assembly procedure and design

To successfully assemble a metal detector It is best to follow this procedure:

• printed circuit board manufacturing and electronic circuit assembly;
• choosing the right size plastic container for it and completion of the assembly of the electronic unit;
• coil manufacturing;
• manufacturing a rod of a convenient shape and attaching an electronic unit and coil to it, making connections for an electronic circuit.

Although the order of assembly is not fundamental. For those who manufacture a device for permanent long work in the field of search for non-ferrous metals and subsequent recycling (processing for reuse), ease of use is an important factor.

In this case, elaboration of the shape of the bar and the layout of the main elements of the apparatus becomes a key factor. Thus, a serious design phase appears in the creation of the device.

It is best to perform this stage of work using life-size modeling. Such modeling can be done using wooden parts suitable form, for example:

• shovel handle;
• plywood pieces of the desired shape;
• scraps from;
• temporary fasteners made from pieces of wire, nails and ropes.

Having made sure that the assembled model of the device will be sufficiently functional and convenient, you can begin the final assembly. Ready-made device, usually, does not require configuration, it is completely ready to work. You can start searching for metal by choosing the desired level of sensitivity and the correct tactics for manipulating the coil.

Assemblers who need to assemble their apparatus as quickly as possible can use ready-made sets of parts.

Purchasing such a kit allows you to significantly simplify the production of “Pirate”. There is one of the proposals.

Users of the “Pirate” metal detector who have skills in amateur radio modify the design of this device. That's just several directions such improvements:

1. Manufacturing coils with unusual parameters– in size, from special materials, for example, twisted pair cable.
2. Arrangement of additional functional systems, for example, indicating the degree of battery discharge.
3. Manufacturing models for underwater work.
4. Add-ons electronic circuit, allowing to distinguish between metals(creating a discrimination function).

A simple, inexpensive and reliable metal detector “Pirate” works properly in the most different conditions.

Homemade metal detector - pros and cons

Cheapness, basic advantage self-production of any products, relevant for a metal detector. Here are some others dignity for a homemade device:

• best match to search technology for beginners;
• the ability to create a device with a completely individual shape, design and configuration;
• the pleasure of making an effective, efficient device yourself.

Like any amateur-made device, a metal detector not without some drawbacks.

Here are the features of the “Pirate” model that users note:

• energetic charge consumption power batteries;
• no discrimination, that is, precise sensitivity to ferrous, non-ferrous and precious metals;
• limited compared to expensive models sensitivity.

Despite its shortcomings, the Pirate model is very popular. This is explained by simplicity homemade and high performance of an inexpensive device.

Experts involved in the field of recycling believe that the metal detector does not have the ability to discriminate of great importance. All metals found are so valuable that recycling them is always justified. Focusing on finding gold requires not only equipment, but also considerable experience, accompanying knowledge and, of course, Good luck.

Video on the topic

The video presents detailed guide for making and assembling a metal detector “Pirate” with your own hands:

Conclusion

When the metal detector is ready, you can begin work. You need to be aware that not even the most advanced apparatus will allow you to find only golden hidden objects.

A metal detector will help you find valuable metal, and it is very likely that it will be gold. It is best if the future metal and gold seeker has a real understanding of the search technique.

Many features of the operation of finished equipment are very important for those who develop and assemble their own models. You need to have an idea of ​​the technology in advance with such equipment - this is precisely the basis of its high-quality design.

The success of finding gold increases with experience. Here most important elements such experience:

• the correct choice of metal detector design and its high quality manufacturing with your own hands;
• ability the right choice search sites;
• ability to use the full potential of a metal detector;
• choice the right technology search in different conditions;
• modernization of the metal detector.

Properly assembled and debugged equipment will always help in the search for gold, and this valuable metal will definitely be found.

In contact with

The simplest and practical way To make a deep metal detector with your own hands is to make a deep pulse metal detector. You can take an existing pulse metal detector as a basis, or make an electronic unit for a pulse metal detector, etc. How to make these metal detectors is already described on our website. And then you need to make a deep coil for it.

In this article we will look at methods for manufacturing depth coils for pulse metal detectors. Such coils can be used with Pirate, Clone, Tracker, Koschey and other pulse metal detectors.

But it should be taken into account that with the same dimensions of the depth frame, with different metal detectors there will be different detection depths (With the Pirate, the results will be the most modest, and the best results are shown by Koschey 5IG and Koschey 4IG (TrackerPI-G) since they have a separate deep firmware!

Let's start with the mechanical designs of the depth frames for a metal detector.

No depth frames large sizes, are installed on a rod like a regular reel, but there are restrictions on weight and dimensions. Therefore, this design is suitable for frames with a diameter of up to 60-70cm. The large frame becomes too heavy and is no longer comfortable to carry this way.

Depth coil frame for metal detector made from plastic pipes, without the use of metal elements. You choose a pipe depending on the way you will connect it, and depending on the size of your frame, so that the pipe provides sufficient structural rigidity!

Small coils are usually made non-separable in the shape of a ring or square.

Here are some photos of such frames:

For large frames, the non-demountable design is already inconvenient for transportation, and it is already difficult to carry such a frame on a rod. The most common solution for large frames is a collapsible square frame with an overhead search loop or a loop passed inside the pipe frame.

In this case, the frame frame is made of plastic pipes, and search coil dangles stranded wire in isolation! THE WIRE MUST BE MULTI-CORE, since when disassembling and transporting the deep coil, the wire will bend and the single-core wire may eventually break!

Such frames are usually worn by two people:

But there are design options deep metal detector for self-carrying:

Here are some more design options for deep metal detectors and their coils:

Winding the depth frame

Table of the number of turns for depth frames of various sizes and their maximum depth detection with metal detectors PIRAT and Koschey 5I:

It is advisable, after winding the frame, to tighten the turns together with electrical tape or tape; this will reduce the interturn capacity and make the loop stronger. The wire from the frame to the electronic unit can be made from the same wire with which the frame is wound, twisting it in increments of 1 turn per 1 cm. And then crimp heat shrink tube or wrap it with electrical tape.

This is how you can easily make a depth frame for a pulse metal detector, and get a full-fledged depth metal detector that is not inferior in depth to branded metal detectors.

Finding artifacts underground is a fairly popular activity. For some, this is a profession, others are simply interested in archaeology. There are numerous groups of treasure hunters: both romantics and pragmatic treasure hunters. All these people are united by one passion: searching for metal objects hidden at various depths.

if you have accurate map indicating the location of the burial of the treasure, or plans for fighting during the war, this does not guarantee success. You can shovel tons of soil, and the desired item will calmly lie a couple of meters from the active search site.

To search for gold and less valuable metals, you will need a metal detector that you can make yourself.

Important information: The use of such devices is not prohibited by law. However, there are penalties for the consequences of such a search regarding excavations, as well as the recovery of discovered objects.

We won’t go into details; that’s the topic of another article. Simply put: if you find Golden ring on the beach, or a handful of Soviet coins in the forest - there will be no problems associated with the use of electronic search tools.

But for recovered bronze spoons that are 100 years old or older, you can get a real sentence or a large fine.

Nevertheless, devices for searching for metal objects in the depths of the earth are freely sold, and those who want to save money can make a metal detector with their own hands at home.

Operating principle of the device

Unlike ground detectors, which work using waves of different frequencies or ultrasound, a metal detector (either factory-made or home-made) works with inductance.

The coil emits an electromagnetic field, which is then analyzed by the receiver. If any object that conducts electric current or has ferromagnetic properties is in the coverage area, the field format is distorted. More precisely, under the influence of the active field of the coil, the object forms its own. This event is recorded by the receiver, and an alert is generated: the instrument needle moves, a tone sounds, and indicator lights light up.

Knowing the operating method, you can calculate the electrical circuit and create a powerful metal detector with your own hands. The complexity of the design depends only on the availability of the element base and your desire. Let's look at several popular options for assembling a homemade metal detector:

The so-called "butterfly"

This nickname was received due to the characteristic shape of the platform on which the inductors are located.

The arrangement of the elements is related to the operating principle. The circuit is made in the form of two generators operating at the same frequency. When identical coils are connected to them, an induction balance is created. As soon as a foreign object with electrical conductivity gets into the electromagnetic field, the balance of the field is destroyed.

Generators are implemented on NE555 chips. The illustration shows typical diagram such a device.

The coil for the metal detector (there are two of them, in the diagram: L1 and L2) is made by hand from wire with a cross section of 0.5–0.7 mm². Perfect option- transformer winding copper core in varnish insulation (removed from any unnecessary transformer). The characteristics do not have to be maintained with pinpoint precision, under one condition: the coils must be identical.

Approximate parameters: diameter 190 mm, each coil has exactly 30 turns. The assembled product must be monolithic. To do this, the turns are grabbed with a mounting thread and filled with transformer varnish. If this is not done, vibration of the turns will throw the circuit off balance.

Electrical diagram

There are two manufacturing options:

• given the small number of elements, you can assemble it on a breadboard by connecting the legs of the parts using conductors;
• For accuracy and reliability, it is better to etch the board according to the proposed drawing.

Any soldering “on the snot” can fail in field conditions, and you will be offended for wasting your time.

Just like a transistor metal detector, the NE555 device needs fine tuning before use. The diagram shows three variable resistors:

• R1 is designed to adjust the frequency of the generator and achieve that same balance;
• R2 coarsely adjusts sensitivity;
• Using resistor R3, you can set the sensitivity with an accuracy of 1 cm.

Information: This scheme cannot discriminate against metals. The seeker only makes it clear that the object exists. And by the tone of the signal (based on your experience) you can determine the approximate volume and depth of the deposit.

The power supply is quite universal: 9–12 volts. You can select the battery from the source uninterruptible power supply, or assemble a power supply from AAA batteries. A good option is 18650 batteries (they are also used for vaping).

Butterfly setting

The principle of operation is described above, so let’s just look at the technology. We set all resistors to the middle position, and ensure that the synchronization of the generators is disrupted. To do this, we fold the coils in a figure eight and move them relative to each other until the squeaking turns into crackling. This is a synchronization failure.

We fix the rings and rotate the resistor R1 until a steady crackling sound appears at even intervals.

By bringing metal objects to the place where the coils overlap (this is the search point), achieve a steady squeak. The sensitivity is adjusted by resistor R2.

All that remains is adjustment with resistor R3, which is used rather to correct the voltage drop in the power source.

Mechanical part

A do-it-yourself metal detector rod is made from lightweight plastic pipes or wood. The use of aluminum is undesirable as it will interfere with operation. The circuit and controls can be hidden in a sealed housing (for example, a junction box for wiring).

The butterfly finder is ready to go.

Pirate

Another popular pulse model for beginner treasure hunters is the “Pirate” metal detector. It is also easy to make with your own hands, detailed instructions in two versions:

It is advisable to bring the power supply closer to 12 volts, since the quality of operation depends on the voltage. Printed circuit boards have already been tested, both options are shown in the illustration.

Coil (in in this case one) is made from the same 0.5 mm transformer wire. The optimal diameter is 20 mm, the number of turns is 25. Since we are making the “Pirate” metal detector with our own hands, the external design fades into the background. Any materials that you were ready to throw away will do.

It is better to make the handle detachable for ease of transportation. We remember that the use of metals is unacceptable.

Sensitivity is adjusted by two variable resistors in real time while searching. No fine tuning of the generator is required.

And if you manage to properly seal the case, you can start searching for “treasures” in the beach surf, and even at the bottom of the reservoir.

It is more difficult to make an underwater metal detector with your own hands, but it will give you an undeniable advantage over your competitors.

Improved performance

You can make a deep metal detector with your own hands from a ready-made “Pirate” without additional costs. There are two ways to do this:

1. Increasing the diameter of the inductor. At the same time, downward permeability increases significantly, but sensitivity to small objects decreases.
2. Reducing the number of coil turns while simultaneously adjusting the circuit. To do this, you will have to sacrifice one coil for experiments. We remove (and cut off) turn after turn until we see that the sensitivity begins to decrease. We remember the number of turns at maximum parameters, and make a new coil for this circuit. Then we change the resistor R7 to a variable one, with similar power parameters. After conducting several experiments with sensitivity, we fix the resistance and change the variable to a constant resistor.

The Pirate metal detector can be assembled using the popular Arduino controller.

It is more convenient to use such a device, but there will still be no metal discrimination.

Having figured out how to make a metal detector with your own hands for amateur tasks, we will briefly examine several serious models.

DIY metal detector Clone PI W

In essence, this is a cheaper version of the professional finder Clone PI-AVR, only instead of an LCD display, a line of LEDs is used. This is not as convenient, but still allows you to control the depth of artifacts.

The best option for the price is the CD4066 chip and ATmega8 microcontroller.

Of course, there is also a printed circuit board layout for this solution, only the control buttons are placed on a separate panel.

Programming ATmega8 is a topic for a separate article; if you have worked with such controllers, no difficulties will arise.

Powerful metal detector Clone PI W, made by yourself, allows you to find metal no more than a meter deep, although without discrimination.

Seeker "Chance"

A similar circuit on the ATmega8 controller is called “Chance”. The principle of operation is similar, only the possibility of screening out (partial discrimination) of ferrous metals has become possible.

A printed circuit board design has also been worked out, which can be successfully replaced with a classic “breadboard” for Arduino

DIY Terminator 3

If you need a homemade metal detector with metal discrimination, pay attention to this model. The scheme is quite complicated, but your efforts pay off with the coins you find, which may turn out to be gold.

The peculiarity of the “Terminator” is the separation of the receiving and transmitting coils. A 200 mm ring is made to emit the signal. 30 turns of wire are laid for it, then it is cut, as a result we get 2 half-coils with a total capacity of 60 turns (see diagram).

The receiving coil is located inside, 48 turns with a diameter of 100 mm.

The adjustment is made using an oscilloscope; after achieving optimal amplitude results, the windings are fixed in the housing by pouring epoxy resin.

Then an experimental hands-on adjustment of the discrimination switch is performed. For this purpose, real objects from various metals, and their type is indicated on the mode switch (after checking).

Radio amateurs are working on an improved version of Terminator 4, but there is no practical copy yet.

Simple metal detectors from ready-made electrical appliances

Bottom line

Regardless of the complexity of the design, making a homemade metal detector will require a lot of time and effort from you. Therefore, out of curiosity, such devices are not made. But for professional use, this is an excellent alternative to factory copies.

Video on the topic

A deep metal detector is similar in design 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.
• Preparation pickling 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 the control unit assembly. 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’s better not to do twists, it has bad influence 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.