Is it possible to make a metal detector from TV parts? Original roofing and designer roofs: Metalloiskatel. How to make a highly sensitive metal detector yourself at home from scrap materials. Assembly techniques
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 a fairly 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 operating principles; 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.
The metal detector is designed to detect a metal object (well cover, pipe section, 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 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 circuit 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. It can detect large metal objects, such as a heating battery, at a distance of up to 60 cm, while small ones, for example, a coin with a diameter of 25 mm, can be detected 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 metal detector circuit does not have any special features, it is simple and can be repeated even by novice radio amateurs. As is often written in books and magazines, with proper installation and working parts, it starts working immediately. The printed circuit board of the device is shown in the figure, it is made for SMD components, all parts are installed from the foil side, and no drilling is required. Manufacturing a search coil requires high...
The article presents a circuit diagram of a simple but powerful 1.5 volt metal detector, very easy to replicate. The generators are assembled according to a circuit that has a number of useful properties, one of which is the stability of the output voltage (both direct and alternating) when the supply voltage changes. The oscillatory circuit of the search generator on transistor VT1 includes coil L1. It operates at a frequency of about 100 kHz, which is optimal for this type of metal detector. Its frequency can be changed within small limits using a variable capacitor C2. The second generator (on transistor VT2) is exemplary and operates at a frequency of about 300 kHz.
The generator signals through resistors R2, R4 are fed to a balanced mixer, where the difference in frequencies (beats) of the third harmonic of the search generator signal and the first harmonic of the reference generator is separated. This is done to increase sensitivity - when the frequency of the search generator changes at a frequency of 10 Hz, the beat frequency changes by 30 Hz, which is more noticeable to the ear.
The signal from the output of the mixer through capacitor C8 is supplied to the input of the ultrasonic sounder and, after amplification, to the headphones BF1, BF2. Capacitor C7 suppresses signals with generator frequencies.
When the search generator coil approaches a metal object, the generation frequency changes, therefore the tone of the signal in the headphones will also change. By the nature of the change in tone, one can judge the material from which this item is made.
Most of the parts are mounted on a printed circuit board made of single-sided foil fiberglass.
You can use transistors of the KT312, KT315, KT3102 series with any letter indices. In a balanced mixer, you can use only germanium transistors of the GT309, GT313, GT322, GT346 series or earlier - P416, P422, P423 with any letter indices. In an UZMCH, the transistor should have the highest possible current transfer coefficient, for example, KT3102BM - KT3102EM, KT342BM, KT342VM - the volume of the sound signal depends on this. Power switch - any small one. Headphones are suitable with a resistance from 8 to 32 Ohms, they are connected in series. To connect them, you can install a socket on the body of the metal detector. The device is powered by a galvanic cell or AA or AAA battery, the maximum current consumption is about 12 mA.
To wind the L2 coil, a frame from the IF circuit (455 kHz) of a foreign-made receiver is used. It consists of a ferrite “dumbbell” (on which 66 turns of PEV-2 wire with a diameter of 0.06...0.1 mm are wound) and a ferrite cup covering it, the movement of which regulates the inductance of the coil. The frame is enclosed in a metal screen.
The sensitivity of the device to metal objects of different sizes depends on the size of the search coil itself. For searching for large objects (a metal sheet measuring 80x80 cm, a manhole cover for a sewer well), a coil with a diameter of about 30 cm is more suitable. With it, a maximum detection depth of such objects is achieved up to 60 cm.
For searching for small objects, a coil with a diameter of about 120 mm is better suited. Such a coil contains 56 turns of PEL wire with a diameter of 0.2...0.5 mm.
It is more technologically feasible to make a coil of an even larger diameter (for example, 300 mm) from a multicore shielded twisted pair cable, which is used for laying computer local networks. The cable must contain four such “pairs”, and the coil must contain four turns of such cable. First, wind two outer turns and fasten them in four places with insulating tape. Then two inner ones are wound and they are also wrapped with insulating tape, preferably on a fabric basis. The ends of the cable are cut so that there is an “overlap” of 5 mm...10 mm, and the outer insulation is removed from them by 15 mm, and the ends of the wires are stripped by 5 mm and tinned.
All radio components of the device are domestic and have foreign analogues:
L1 - coil
R1 - 1 kOhm
R2 - 10 kOhm
R3 - 1 kOhm
R4 - 10 kOhm
R5 - 1 kOhm
R6 - 1 kOhm
R7 - 100 kOhm
C1 - 2200
C2 - 10...240
C3 - 4700
C4 - 0.047 µF
C5 - 2200
C6 - 4700
C7 - 0.047 µF
C8 - 2.2 uF x 16 volts
VT1 - KT315B
VT2 - KT315B
VT3 - GT322B
VT4 - GT322B
Anyone can assemble such a device, even those who are completely far from electronics, you just need to solder all the parts as in the diagram. The metal detector consists of two microcircuits. They do not require any firmware or programming.
Power supply is 12 volts, you can use AA batteries, but it’s better to use a 12V battery (small)
The coil is wound on a 190mm mandrel and contains 25 turns of PEV 0.5 wire
Characteristics:
- Current consumption 30-40 mA
- Reacts to all metals, no discrimination
- Sensitivity 25 mm coin - 20 cm
- Large metal objects - 150 cm
- All parts are inexpensive and easily accessible.
List of required parts:
1) Soldering iron
2) Textolite
3) Wires
4) Drill 1mm
Here is a list of required parts
Diagram of the metal detector itself
The circuit uses 2 microcircuits (NE555 and K157UD2). They are quite common. K157UD2 - can be picked out from old equipment, which I did with success
Be sure to take 100nF film capacitors, like these, take the voltage as low as possible
Print out the board sketch on plain paper
We cut a piece of textolite to its size.
We apply it tightly and press it with a sharp object in the places of future holes.
This is how it should turn out.
Next, take any drill or drilling machine and drill holes
After drilling, you need to draw tracks. You can do this through, or simply paint them with Nitro varnish with a simple brush. The tracks should look exactly the same as on the paper template. And we poison the board.
In the places marked in red, place jumpers:
Next, we simply solder all the components into place.
For K157UD2 it is better to install an adapter socket.
To wind the search coil you need a copper wire with a diameter of 0.5-0.7 mm
If there is none, you can use another one. I didn’t have enough varnished copper wire. I took an old network cable.
He took off the shell. There were enough wires there. Two cores were enough for me, and they were used to wind the coil.
According to the diagram, the coil has a diameter of 19 cm and contains 25 turns. I’ll immediately note that the coil needs to be made of such a diameter based on what you will be looking for. The larger the coil, the deeper the search, but a large coil does not see small details well. The small coil sees small details well, but the depth is not great. I immediately wound three coils of 23cm (25 turns), 15cm (17 turns) and 10cm (13-15 turns). If you need to dig up scrap metal, then use a large one; if you are looking for small things on the beach, then use a smaller reel, but you’ll figure it out for yourself.
We wind the coil on anything of a suitable diameter and wrap it tightly with electrical tape so that the turns are tightly next to each other.
The coil should be as level as possible. The speaker took the first one available.
Now we connect everything and test the circuit to see if it works.
After applying power, you need to wait 15-20 seconds until the circuit warms up. We place the coil away from any metal, it is best to hang it in the air. Then we begin to twist the 100K variable resistor until clicks appear. As soon as the clicks appear, turn it in the opposite direction; as soon as the clicks disappear, that’s enough. After this, we also adjust the 10K resistor.
Regarding the K157UD2 microcircuit. In addition to the one I picked out, I asked one more from a neighbor and bought two at the radio market. I inserted the purchased microcircuits, turned on the device, but it refused to work. I racked my brains for a long time until I simply installed another microcircuit (the one I removed). And everything started working right away. So this is why you need an adapter socket, so that you can select a live microcircuit and not have to worry about desoldering and soldering.
Purchased chips
Many people unreasonably believe that homemade metal detectors are inferior in many respects to branded samples produced at the factory.
But in fact, structures that are correctly assembled with your own hands sometimes turn out to be not only better, but also cheaper than “factory” competitors.
Worth knowing: Most treasure hunters and local historians, in order to save money, try to choose the cheapest options. As a result, they either assemble metal detectors themselves or purchase homemade custom devices.
Beginners, as well as people who do not understand electronics, are at first intimidated by the abundance of not only special terminology, but also various formulas and circuits. However, if you delve a little deeper, everything immediately becomes clear, even with the knowledge gained in school physics lessons.
Therefore, it is worth, first of all, to understand the principle of operation of a metal detector, what it is and how you can assemble it yourself at home.
How does it work
The operating principle of this device is to use an electromagnetic field. It is created by the transmitter coil and after a collision with an object that conducts current (which is most metals), eddy currents are created that introduce distortion into the EPM of the coil.
In cases where the object is not electrically conductive, but has its own magnetic field, the interference it creates will also be captured due to shielding.
After this, changes in the electromagnetic field are sent directly to the control unit, which emits a special sound signal to notify that a person has been found, and in more expensive models displays data on the display.
It is worth examining how such devices are created following the example of a “Pirate” type metal detector.
Metal detector "Pirate"
Making a printed circuit board with your own hands
First you need to create a printed circuit board, where all the nodes of the metal detector will be located in the future. The best method is laser-iron technology or simply LUT.
To do this, it will be necessary to perform the manufacturing steps in the following sequence:
- First, using only a laser printer, you need to print the corresponding diagram created through the Sprint-Layout program. It is best to use light weight photo paper for this.
- We prepare the PCB workpiece, first sand it, and then clean it with a solution. It should have dimensions 84x31.
- Now on top of the blank we place photo paper with the diagram on the front side on which it was printed. Cover with an A4 sheet and begin ironing with a hot iron in order to transfer the marking scheme to the textolite.
- After fixing the circuit from the toner, we place it all in water, where we carefully remove the paper with our fingers.
- Next, if there are smeared areas, we correct them using a regular needle.
- Now the board needs to be placed in a solution of copper sulfate for several hours (ferric chloride can also be used).
- The toner can be removed without any problems with any solvent, such as acetone.
- We drill holes for later placement of structural elements (the drill must be very thin).
- The last stage is to lay out the board tracks. To do this, a special solution “LTI-120” is smeared on the surface, which needs to be spread over the solder of the soldering iron.
Installing elements on the board
This stage of creating a metal detector consists of installing all the elements on the created board:
- The main microcircuit is the domestic KR1006VI1 or its foreign analogue NE555. Please note that before installation, a jumper must be soldered underneath it.
- Next, a two-channel amplifier K157UD2 is installed. You can buy it or take it from Soviet tape recorders.
- After this, 2 SMD capacitors are mounted, as well as one resistor of the MLT C2-23 type.
- Now you need to solder two transistors. One must be NPN structure, and the other PNP. It is advisable to use BC557 and BC547. However, analogues will also work. It is recommended to use IRF-740 or other options with similar characteristics as a field-effect transistor.
- The capacitors are installed last. They should be taken with a minimum TKE indicator, which will increase the thermal stability of the entire structure.
Note: The hardest thing will be to get the K157UD2 amplifier out of this circuit. The reason is that it is already an old chip. That is why you can try to find similar modern options with similar parameters.
A homemade coil is created on a frame with a diameter of 20 cm. The total number of turns should be approximately 25 pieces. This indicator is based on the fact that PEV wire is used, which has a diameter of 0.5 mm.
However, there is a certain peculiarity. The total number of turns can be changed up or down. To find the most optimal option, you need to take a coin and check in which case there will be the longest distance to “catch” it.
Other elements
A signal speaker can be used taken from a portable radio. It is important that it has a resistance of 8 ohms (Chinese options can be used).
To carry out the adjustment, you will need two potentiometer models of different power: the first is 10 kOhm, and the second is 100 kOhm. To minimize the influence of interference (it will be difficult to eliminate it completely), it is recommended to use a shielded wire that will connect the circuit and the coil. The metal detector's power source must be at least 12 V.
When the entire structure has been tested for functionality, it is necessary to make a frame for the future metal detector. However, here we can only give some recommendations, because everyone will create it from the items at hand:
- to make the bar more convenient, it is worth purchasing 5 meters of ordinary PVC pipe (which are used in plumbing), as well as several jumpers. It is worth installing a special palm rest at its upper end to make it more comfortable to hold. For the board, you can find any box of the appropriate size that needs to be mounted on the rod;
- To power the system, you can use a battery from a regular screwdriver. Its advantages are low weight and high capacity;
- When creating the body and structure, keep in mind that there should not be any unnecessary metal elements in them. The reason is that they significantly distort the resulting electromagnetic field of the future device.
Checking the metal detector
First of all, you need to adjust the sensitivity using potentiometers. The threshold will be a uniform, but not very frequent, crackling.
So, he will have to “find” a five-ruble coin from a distance of approximately 30 cm, but if the coin is the size of a Soviet ruble, then from about 40 cm. He will “see” large and voluminous metal from a distance of more than a meter.
Such a device will not be able to search for small objects at significant depths. In addition, he will not be able to distinguish between the size and type of metal found. That is why, while searching for coins, you may come across ordinary nails.
This model of homemade metal detector is suitable for people who are just starting to learn the basics of treasure hunting or do not have the necessary funds to purchase an expensive device.
Their this video You will learn how to make a homemade metal detector:
Even the most serious and respectable citizens feel a slight excitement when they hear the word “treasure”. We literally walk through treasures, of which there are immeasurably many in our land.
But how can you look under the soil layer to know exactly where to dig?
Professional treasure hunters use expensive equipment, the purchase of which can pay for itself after one successful find. Archaeologists, builders, geologists, members of exploration societies use equipment provided by the organization in which they work.
But what about novice treasure hunters on a budget? You can make a metal detector at home with your own hands.
To understand the subject, consider the design and operating principle of the device
Popular metal detectors operate using the properties of electromagnetic induction. Main components:
- transmitter – generator of electromagnetic oscillations
- transmitting coil, receiving coil (in some models the coils are combined for compactness)
- electromagnetic wave receiver
- decoder that separates the useful signal from the general background
- signaling device (indicator).
The generator, using a transmitting coil, creates an electromagnetic field (EMF) around it with specified characteristics. The receiver scans the environment and compares field performance with reference values. If there are no changes, nothing happens in the circuit.
- When any conductor (any metal) enters the field of action, the basic EMF induces Foucault currents in it. These eddy currents create the object's own electromagnetic field. The receiver detects the distortion of the basic EMF and gives a signal to the indicator (audio or visual alert).
- If the object being examined is not metallic, but has ferromagnetic properties, it will shield the underlying EMF, also causing distortion.
Important! There is a misconception that the soil in which searches are carried out should not be electrically conductive.
This is wrong. The main thing is that the electromagnetic or ferromagnetic properties of the environment and the search objects are different from each other.
That is, against the background of certain characteristics of the EMF generated by the search environment, the field of individual objects will stand out.
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