The construction of a deep metal detector is similar to a conventional one, with the exception of some technical details. Its difference is also its increased sensitivity to metal objects, which makes it possible to detect them at a greater depth 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 inappropriate parameters.
Depth metal detector diagram
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 other 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 captured by the receiving antenna. In this case, the mass of the metal object is used as a radiation source, sending the generated energy to the receiving antenna.
Metal detector receiver circuit
The transmitting device includes a thyristor with a power of 0.25 to 1 W, 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 receiver. Enough amplifier on transistors in the amount of 5-6 pieces. A transistor is also used as a current amplifier for a dial gauge, which allows you to measure the level of the received signal. That is, the device has two types of indicators - visual and acoustic. The operating frequency is adjusted so as not to interfere with 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 an impulse metal detector, the approximate parts list will look like this:
- Electrolyte capacitors with a voltage of at least 16 V of the following capacities: 2 capacitors with a capacity of 10 μF, one with a capacity of 2200 μF, 2 pcs - 1 μF.
- Ceramic capacitors: 1 pc with a capacity of 1 nF.
- Film capacitors of the very minimum voltage value, for example, 63 V - 2 pcs, 100 nF each.
- Resistors 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,
- 0.25 W resistors: 10 ohms - one.
- 0.5W resistors: 390 ohm - one
- 1W resistors: 220 ohm - one.
- Variable resistors: 10 k - one, 100 k - one,
- Transistors: ВС 557 - one, ВС 547 - one, IRF 740 - one,
- Diodes: 1N4148 - two, 1N4007 - one.
- Microcircuits: K157 UD2, NE555.
- Panels for each of them.
Metal detector parts
From tools when performing work you will need:
- Soldering iron, tin, special solder, other soldering accessories.
- A set of screwdrivers, wire cutters, pliers and other locksmith tools.
- Materials for the production of printed circuit boards.
Metal detector assembly stages
The process of assembling a deep-seated metal detector with your own hands includes the following steps:
The first step is to assemble the electronic part, namely the control unit.
The step-by-step process looks like this:
- Cutting the PCB of the required size.
- Preparing a printed circuit board drawing and transferring it directly to the board.
- Preparation of the pickling solution. It contains table salt, electrolyte and hydrogen peroxide.
- Etching the board and drilling technological holes.
- Tinning the board with a soldering iron.
- Next comes the most important stage in the assembly of the control unit. This is the selection, search and soldering of parts directly to the board.
- Trial reel winding. There are several options for winding it. The simplest option is to use a PEV wire 0.5 in size 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 finishing the adjustment, select the necessary connectors and adapters. It is better not to do twisting, this has a negative effect on the sensitivity of the device.
The second good option would be to make such a ring from a twisted pair wire. It will take about 2.5 - 2.7 m of wire.
To achieve maximum sensitivity, follow these steps:
- Wind 25 turns of wire.
- Test by cutting small pieces of wire and observing the increase in sensitivity.
- It is necessary to do this until the sensitivity begins to decrease.
- Count the number of turns, wind the final coil, adding 1-2 turns. Thus, the maximum sensitivity value is reached.
At the end 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 assembly problems
- The assembled device does not react to metal objects. The reason may be a breakdown of diodes or a transistor. Defective parts need to be replaced.
- Excessive heating of the transistor. Install a resistor of lower resistance, reducing it until heating stops.
The assembly of this type of metal detector is not too difficult, provided all the rules and instructions are strictly followed.
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 in these areas to create. However, a lot of non-working, fake methods are circulating on the network, captivating with their simplicity and availability. 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 work 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 DIYers and allows you to achieve good results. It contains two microcircuits, so you 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. Below is an electronic diagram of the device and a 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 frame 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 order of 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 tuning, it is necessary to achieve rare clicks. When metal hits the area of \u200b\u200baction, you will hear a characteristic sound.
Below is a detailed video assembly instruction, which clearly shows all the stages of creating a homemade metal detector.
Metal detectors are used in order to detect invisible objects that differ in their electromagnetic properties from the environment in which they are located. Metal detectors are used by: amateur archaeologists, geologists, treasure hunters. Sappers also use these devices to detect shells, builders, to search for metal parts of structures (fittings, pipes ...).
Most metal detectors are very similar in appearance, but in fact they differ greatly in their properties, and depending on the purpose of use. Here are some pictures of commonly used metal detectors. And also a diagram of a simple metal detector.
How do metal detectors work?
The metal detector device is quite simple. And you can do it yourself at home. You don't need to have deep knowledge of electrical engineering for this. We have prepared for you step-by-step instructions that will help you assemble an amateur metal detector from available tools.
But first, let's find out what types of metal detectors exist, what properties different models have and how to choose the right model for you. In order to choose a suitable type of metal detector for yourself, you need to decide what technical characteristics you need.
Here are some characteristics by which the quality of the device is judged:
The penetrating power of the detector. How deep does the electromagnetic field of the detector coil penetrate? It depends on how deep the device will "see" the metal in the ground or other environment.
Search area covered. Usually metal detectors examine the ground in strips. This parameter determines the width of such stripes.
Device susceptibility. This determines whether your metal detector will detect small metal objects (such as coins).
Fragmentation of the detector. This function is responsible for the ability of the detector to react only to the desired objects (for example, non-ferrous metals).
The seeker's immunity to interference. In addition to its own electromagnetic field, the device can enter the electromagnetic fields of other devices. (mobile devices, power lines, radio stations ...). The best are metal detectors that do not respond to fields from other sources.
Energy intensity. How many hours of searching should one charge of batteries or accumulator be enough.
Frequency classification
In addition, metal detectors are classified according to their operating frequency. Exists:
Metal detectors operating at ultra-low frequencies. Such devices are used only by professionals. They differ in good technical parameters, but their functioning requires tens of watts of energy. They are usually installed on special vehicles with capacious batteries and equipment that allows you to determine the size, shape and structure of the objects found.
Metal detectors operating in the low frequency range (from 300 Hz to several thousand Hz). Easy to manufacture. They are resistant to interference, but have a low susceptibility. They are also called deep detectors (they "see" metal at a depth of up to five meters).
Metal detectors with an increased operating frequency range. (up to several tens of KHz). They are more difficult to collect than low-frequency ones. Their penetrating ability is up to one and a half meters. They are good at detecting small objects. They are rarely used due to their low technical characteristics.
How to assemble a metal detector with your own hands at home
7 easy steps:
- In order to assemble a metal detector, we need a Chinese radio receiver (must have a magnetic antenna, AM band), a cheap calculator, a box and double-sided tape.
- We unfold the box so that it has the shape of a book (on one side, the main part, on the other side)
- We glue the radio and the calculator to the book on double-sided tape. (the radio is attached to the lid and the calculator to the base of the box).
- We turn on the receiver and find the frequency segment that is not used by radio stations (about 1.5 MHz).
- Getting started with the calculator. In this case, the radio begins to make a lot of noise.
- We begin to slowly bring the lid of the box to the main part. We need to find a position where the noise disappears.
- We fix the book in this position. Done! Crafted Basic Craft Metal. detector.
Metal detectors with discrimination of metals
Among all metal detectors, devices with a discrimination function are considered especially effective. What does it mean?
The metal detector not only shows the presence of an object with a characteristic field in the ground, but also displays on the screen the approximate shapes, sizes and material of the detected object.
Of course, with such a device, work is much more efficient (no need to dig the ground with each detector signal) and requires less time. But such metal detectors use up energy very quickly. Plus, they are several times more expensive. For an amateur treasure hunter, a cheaper analogue is also suitable.
We hope that our article was useful for you, helped you understand the main types of metal detectors and, perhaps, even suggested how to make your own amateur metal detector!
DIY metal detector photos
The purpose of a metal detector, or, as it is also called, a metal detector, is to search for metal products using electrical or magnetic properties that distinguish them from the environment. Simply put, with a metal detector you can find metal even in the ground. However, its capabilities are not limited to this environment, since it is also used in water. This device is used by security services, criminal service, military, geologists and workers of many other specialties. But detailed instructions for assembling a metal detector with your own hands can also come in handy for using the device in a household.
Scope of the device
For those who have lost their ring or keys and know their approximate location, the metal detector will be a real salvation. Making a homemade metal detector is not that difficult, especially if there is a diagram of a homemade metal detector and a detailed description of the assembly. Most often, the assembly is done by amateurs of radio mechanics, treasure hunters, local historians and military historical associations. The device makes it possible to find a coin in the upper soil layer or large metal parts at an impressive depth of up to 1.5 meters.
Home-made devices also have such properties, but with the help of an experienced radio mechanic, you can assemble a device even more powerful. A lot of people use a metal detector for commercial purposes: when they find different parts, they rent them for scrap, earning a certain amount. Finds can be more important, for example, antiques or real treasures in the form of treasure chests.
It consists in using electromagnetic technology. An electromagnetic field is created by the coil, which interacts with conductive objects as a result of this, an eddy current is created, which distorts the coil signal. Even in the absence of conduction, the object may have its own magnetic field, which will also interfere, thereby indicating the location of the object.
After the receipt of interference, an electromagnetic pulse changes, which goes directly to the control unit, while emitting sound signals or showing data on the display indicating a find. Devices are divided into many groups and have a huge number of names, and they are all classified according to many parameters.
Varieties of detectors
General characteristics of devices:
Discrimination is a composite parameter, since there are most likely 1 or 2 signal outputs, and there are several definitions by the property and location of the object. However, according to the reaction of the device, taking into account the approach to the object, signals are allocated:
- Spatial - you can define the location of the object in the search location and the depth of the location.
- Geometric - the possibility of figurative formation of the length and width of the find.
- Qualitative - the ability to guess about the structure of the find.
Working parameters
All sensitivity parameters are related to the generator frequency. Therefore, initially metal detectors are classified depending on the operating frequency:
Search method for metal products
There are more than 10 search methods, but methods with signal digitization and processing through a computer are professional equipment. Diy metal detector circuits most often are made taking into account the following search methods:
- Parametric.
- Transceiver.
- Phase accumulation.
- Beating.
Without take-up spool
Parametric devices have neither a pickup coil nor a receiver. Detection occurs due to the influence of the object on the inductive coil of the generator. Depending on the Q-factor of the coil, the frequency and amplitude of the oscillations will change, which can be fixed in different ways, for example:
- Frequency and amplitude are measured.
- The generator current is measured.
- Measuring the voltage of the PLL loop (phase locked loop).
In most cases, such devices are used as magnetic detectors. They have poor sensitivity, but cheap and anti-jamming, and the use requires a certain skill.
With built-in transmitter
Devices with receiver and transmitter very effective, but have a complex circuit design and require high-quality coils. Devices with one coil are called induction devices.
Clicks after approaching an object
In metal detectors with phase accumulation, they can be with one pulse-type coil or with two generators. In a device with one coil, when the pulses pass, the phase shift increases and when a certain level is reached, the discriminator is triggered and a click-type signal is sent to the headphones. The closer the object is, the more often the clicks are repeated.
Double coil metal detectorb is simpler in circuitry than pulse, but also weaker in sensitivity, penetration is also less than 2 times.
Beat metal detectors
The devices are assembled with 2 generators, a reference and a working one. The working generator is adjusted to a zero beat value and, depending on the sound tone, one can judge the location of the object, its size and properties.
DIY metal detector assembly
There is an opinion that proprietary metal detectors are superior to home-made devices in many respects. ... However, the facts tell the opposite: if the device is correctly assembled, then a homemade product may be not only cheaper than a factory design, but also better. Many treasure hunters purchase the cheapest types of devices, and in the future they either assemble the metal detector on their own, or buy a custom version.
A beginner or someone who is poorly versed in electronics may find it difficult to use specialized terminology, formulas and diagrams. But with a detailed analysis of all the information, it becomes clear that having at least an average level of knowledge, you can figure out how to make a homemade metal detector.
Self-made PCB
For further placement of metal detector parts, a printed circuit board is needed. For this, it is best to use the LUT method - laser-ironing technology.
Manufacturing takes place in stages in the following sequence:
At the last stage, the paths are tinned. The LTI-120 solution is smeared with a soldering iron.
Installation of radio components on the board
At this stage in the assembly of the metal detector all elements are installed in the prepared board:
In this case, an old circuit is used, but you can find and solder a similar, modern version, since the K157UD2 amplifier is currently not easy to find.
Making a coil device
A self-made reel is wound on a rigid frame with a radius of 100 mm. Need to reel about 25 turns... This indicator is acceptable in the case of using PEV wire with a diameter of about 0.5 mm, but other strong material can also be used.
To select the optimal number of turns, you can conduct an experiment by checking the device for catching a coin.
Frame and additional elements
A part from a portable receiver with ohm resistance can be used as a signal speaker. The use of Chinese counterparts with the same resistance is allowed.
For normal operation of the metal detector, you need to adjust the sensitivity... The threshold is determined when a uniform, but not very strong crackle is reached. To do this, use two potentiometers with different powers. You will need one with a power of 10 kOhm, and the other 100 kOhm. To increase noise immunity, it is recommended to use a shielded cable to connect the coil to the circuit. The power source can be rechargeable batteries. The minimum voltage must be 12 V. For the stability of the circuit, a voltage stabilizer of the L7812 type is installed at the output.
After manufacturing the structure and checking the functionality, you need to make the case of the portable device. Each amateur can create a frame at his own discretion from improvised items, but attention should be paid to the following recommendations:
- For convenience and better stability, the bar can be strengthened by purchasing for this several meters of PVC water pipes and several jumpers for connection. It is advisable to make a palm rest on the top. The ideal option would be to make an armrest. This will make it easier for the operator to use the metal detector.
- The board must be placed in a protected box corresponding to its size and fixed to the case.
- The battery from a screwdriver is used as a power supply, which is lightweight and has sufficient capacity. Given the parameters, some other option may be used.
- When creating the case and the entire structure, it must be borne in mind that the presence of foreign metal elements will greatly distort the signal of the magnetic field of the metal detector and its effectiveness will be impaired.
Device efficiency
A device made according to this scheme, will not be effective when searching for small objects at great depths, but some Soviet coins can be found at a depth of about 30-40 cm, and the detector senses the large size of metal parts at a distance of about 1 meter or more.
Such a home-made version of a metal detector is suitable for people who are mastering the basics of searching or who do not have the opportunity to use an expensive model. The effectiveness of the device may not be enough for specialists or experienced treasure hunters.
A metal detector is a device with which you can find metal objects underground. There are many types and varieties of this device. The main differences are in scanning depth and usability. The deeper the metal detector "sees", the more expensive its cost.
Its principle of operation is based on the magnetic attraction of objects. The device generates a magnetic field that you send into the ground. As soon as an object comes across, the field is reflected from it and returns back. In this case, a find signal is emitted.
Now we will tell you how to make a metal detector with your own hands.
- 555 timer chip (SE555 / NE555);
- Resistor forty-seven kilo-ohms;
- Two 2.2 microfarad condensers;
- Battery "Krona" for nine volts;
- Buzzer;
- Copper wire 0.2 millimeters in diameter;
- Wires;
- Scotch;
- A piece of cardboard;
- Glue.
- Any discs, but double-sided is better, so the device will be more sensitive.
- Headphones.
- Calculator without solar batteries.
- 9 volt battery, crown can be used.
- Glue.
- Insulating tape.
Show all
How to make a high-frequency metal detector with your own hands?
To begin with, collect the command block. You can use a laptop or radio for this.
Tune the radio to the highest AM frequency possible. Make sure there is no radio station on this frequency.
Now we need to make a search head. To do this, cut out two circles using a thin sheet of plywood as material. One should have a diameter of fifteen centimeters, the other about ten, so that they can fit into each other.
Now cut the sticks out of the wood so that the rings are parallel to each other.
Using a quarter millimeter thick enameled copper wire, make fifteen turns from the plates.
Now you can attach the craft to the block itself.
Take the pole and attach the head to the lower end, and the radio detector to the upper end.
Turn on the frequency. If done correctly, a low sound will be heard. You can connect headphones to hear it better.
How to make a metal detector with your own hands? The easy way
You will need:
Electrical diagram
Making a coil
To make a coil with your own hands with a diameter of ninety millimeters, you need to wind two hundred and fifty turns of copper wire, and for a coil with a diameter of seventy millimeters, two hundred and ninety turns. After these manipulations, we get 10 mH.
Bobbins for bobbins can be made of cardboard and you wind wire on them.
Testing the circuit
Assemble the parts on a circuit board and test how it works.
If everything works as it should, make a printed circuit board on which you assemble all the parts.
Making a handle for the device
You can do it yourself using cardboard for the base. Cut out three identical parts in the shape of a boomerang from it, make a hole in them for the battery. Then glue all three parts to each other. Dry and cut out a spot for the switch. Attach the circuit, connect the battery, switch and glue the coil.
Checking the resulting metal detector
What you need:
Cut off the headphone plug and strip the insulation at the ends. Strip the wires ten millimeters.
Divide the stripped wires into two parts, you get four wires.
Take one end of the wires from different headphones and stick to the writing sides of both discs.
Using electrical tape, secure the wires to the drives.
Connect the two bare ends of the wires that remain to the plus and minus of the battery and also fix it with electrical tape.
Turn on the calculator and attach it to the top of one of the discs.
Place the second disc on the calculator and fasten the discs with electrical tape.
Again, attach the battery to the disk with electrical tape.
Done! You can test.
Metal finder at home
First, stock up on an empty computer disk box.
Take a small radio receiver and attach it with the back wall to one of the box doors.
You also attach a working calculator without solar panels to the other sash with your back.
Now you are setting up the device. Turn on the radio and put it in the AM reception range. Make sure there is no broadcast on this frequency. If so, adjust the scale until the broadcast is completely silent. Make the receiver sound as loud as possible, you should only hear noise.
It's time to check the performance of the made device. To do this, slowly and slowly close the box. At some point, a loud sound will be heard. So the radio has picked up the magnetic waves emitted from the calculator.
Now open the box so that the sound is low. Holding the box in this position, bring it up to a metal object and you will hear the same loud sound. This means the device is working.
This is such a simple device that it is better to use it to find lost metal products at home. It is possible in nature, but a more perfect device is needed there.
Simple and reliable metal finder
Electrical diagram
In order to make such a device, you will first need a vinyl plastic tube, the outer diameter of which is one and a half centimeters, and the inner diameter is one centimeter. It needs to be twisted into a ring twenty-five centimeters in diameter. It will serve as the base of the search coil (indicated in the diagram as L1). Do not forget to provide an exit hole, a stick will be inserted into it for holding.
Wraps the coil a hundred times with a PELSHO wire with a diameter of 02.7, wrap aluminum foil in the form of a tape on the top, it will serve as a screen for the device. It is important that you do not forget to make a small gap in the screen so that the L1 coil does not become closed.
The device is powered by a rechargeable battery or battery. You can control the frequency and sound of the signal using headphones.
