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Metal detector "Butterfly"

Metal detector

Metal detector built on the principle of disrupting the synchronization of two coils. It is because of such an interesting design that looks like a butterfly, the device got its name. Homemade easy to assemble, and all components are easy to get.

And now about the most important thing, to what depth is this miracle of technology capable of seeing. According to the author, the five-copeck coin of the USSR is found at a depth of 15 cm, which is a pretty good indicator. The device sees the metal cover from the can at a depth of already 30 cm, and the device detects such a massive object as a metal hatch at a height of 60 cm.

The metal detector can work in water, and one battery charge lasts 20-30 hours. The current consumption is 15 mA, the device weighs only 500 grams. The device can be configured for any soil. There is also a simple discriminator, the type of metal can be determined by what sound is fed into the headphones.

Materials and tools for manufacturing:
- two transistors KT315 (BC182, BC546 ...);
- two capacitors 1000 pF (1 nF or 102);
- two capacitors 10000 pF (10 nF or 103);
- stereo headphones;
- two resistances per 100 kOhm;
- one battery from a mobile to 3.7V;
- wire type PEV or PEL with a diameter of 0.5-0.7 mm in varnish insulation;
- soldering iron and other tools;
- materials for the manufacture of the housing.

The process of manufacturing a metal detector:

Step one. Device diagram
The scheme is not too rigid, so it is not necessary to strictly observe the number of turns, the rating of the parts and the power source. The most important condition is the identity of the right and left sides. Interference during operation is compensated, and the soil does not affect the quality of work. If the circuit is assembled symmetrically, it works immediately. Signals from the generators are fed to plates X and U.




The picture shows that the frequencies coincide.

In case of disruptions in the headphones, clicks begin to appear.

Now the generators are out of sync.


Step Two Board assembly

Any glue that does not conduct current is used to connect parts. The battery must always be charged and have good capacity, otherwise the setting will constantly go astray. For these purposes, you can use one or two batteries from a mobile.

Capacitors should be used mica, not sensitive to temperature extremes. If there is no textolite, the board can even be made of cardboard.






Step Three We reel
The first turn of the coil is soldered to the negative of the battery.Next you need to reel the coil, for example on a saucepan, after ten turns you need to make a loop. Here, the wire needs to be stripped and soldered to the emitter of the transistor, that is, the middle tap in the circuit. Next, you need to wind the last 20 turns, subsequently this wire is soldered to the connection of two capacitors 10000 pF and 1000 pF. In this way, you need to collect the second coil.


Step Four Metal detector housing
For the manufacture of the rod, you can use a metal-plastic water pipe, the rod must be made collapsible. Pipes 20 and 26 tightly enter one another. Coils and circuits for protection against moisture are coated with oil varnish. Coils are glued at a distance of 10 cm.

Step Five Customize the metal detector
When you turn on the metal detector, a squeak should appear in the headphones. If it so happens that the circuits are not the same, some configuration will be required. There are two ways to configure the metal detector, that is, to synchronize the generators. The first is that a large sheet of metal is brought to each coil, while under one of the coils the squeak should stop. On this coil, you need to bend the last turn inward. Or you can simply increase or decrease the distance between the coils until the sound becomes very quiet, or does not stop at all. On top of each coil, you need to glue the tubes with ferrite, then you can adjust the metal detector with a ferrite rod to complete silence.

The next method is to configure the device with a ferrite rod. A tube is glued to the coil and a rod is inserted into it. Next, ferrite must be moved until the sound in the headphones stops.

You can also adjust the device with pieces of aluminum plates that are glued inside or outside the coils. Stripes are placed on coils and move to a complete lull in the headphones. If clicks are heard in the headphones, this indicates that the metal detector is operating at the maximum level of sensitivity.

In addition to adjusting parallel to the 1000 pF capacitor, you can install a variable capacitor, which can be found in radios. That's all, after synchronization you can start searching.
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44 commentary
Guest Dmitry
I didn’t twist it, I didn’t experiment, I didn’t take it, the maximum sensitivity results are:
- large metal parts (fittings, refrigerator, etc.) - sees in a half meter;
- pliers, a roll of kitchen foil - 10-15 centimeters feels;
- a coin of 5 rubles - reacts literally when it is touched by a metal detector coil.
- others, smaller in size, do not see at all.
Summary. The product works, but there is absolutely no sense from it when searching for small products.
And where is the armored wire, now I looked, they are also glued in parts, otherwise I decided that I broke it while I pulled it out)
Pronin,
I took apart the old tv, samsung. I don’t know much about electronics. There is a baboon here, from which the armored wire departs, apparently a small transformer and some very small coil, standing in an upright position, expands from above and a little wire is wound.
Ferrite is also in the old TV - the core of the high-voltage transformer. Chop off, cut a piece
This, yes, quite a lot. In the evening I’ll throw it into the oven. Thanks for the advice.
Author
Well, probably in any radio ... I don’t know, a permanent black magnet - is this also ferrite or not? Then it can be thrown into a fire, it will cease to be a magnet.Black magnet should be found. There are even furniture, speakers, many where.
Good Lighthouse,
Is there an old TV?
Hello Dmitry! Please tell me, where can I get the ferrite, except for the radio?
Author
I dug a lot of foil, a strong signal. Antique can lid with stiffeners. Some kind of steel plate, bottle caps. But I didn’t lengthen the headphones, crawled on my head, tired quickly xaxa

Cheto, he "floats" in the settings. That squeaks evenly, then some kind of interference, but it works with any interference.
Dmitry, how did the cop go?
Author
In short, I turned the spit, and I can’t start this butterfly. I don’t understand what’s the matter, maybe the headphones or transistors are not like that.

I assembled two coils, brought them together with a figure of eight, and here it squealed everything !!!)))) xaxa There are sounds of different frequencies, set as a mosquito and glued a coil.
But the coils saw only a big target, such as an iron bowl, a car hood and so on, through the air it is 30-35 centimeters pretty clearly everything is heard.

Then I remembered about ferrite. He took the core from the radio, twisted it with a spit, and as a result experimentally found an interesting position. It is upright in the center of the coils. So, if you bring a small object to the ferrite, the device now sees it!))) He sees coins, pliers, nails, everything is small. This kind of pinpoint xaxa

On small objects, the device beeps louder and stronger; on large objects, on the contrary, the headphones can turn off altogether.
On earth, the tone of the sound rises a little, but overall not much. Right now, we've been smelling the field here, I'm going to test.

A trifle of centimeters 10, large 30-35. It will be necessary to collect everything normally with large coils. These on a 2 liter jar dangled. By the way, he sought such a buzz when the metal detector distinguished metals. The sound was really different for aluminum and steel. But it turned out to be accidentally configured. By the way, now the weakest reaction to stainless steel.
Author
pogranec,
I don’t know, I was quite happy with it. True, I don’t remember, maybe I still had 250. But I don’t remember the presence of a pinpointer there.

And who is thinking about the Terminator?
Pronin is right. 150 only for pruning. Stuffed up digging. And neither detuning from the ground, nor pinpointer.
Ace150 has practically no discrimination ... They are looking only on All metal.
That's when I got tired of digging out tin cans and iron (rusting) the wire with my PI, I began to call for a friend (Minelab) to check (target)
Author
No, they are the same in sensitivity. It’s just that 250 has a user settings discrimination and there is a pinpointer
Dima, in the video - Asya 250. (not Asya150) This is a different class! And other money. And yes, other coils are made for it.
Author
Well, the coils are different



With the standard, it is rather weak, except for the pit. I liked the discriminator in how it works, I don’t know. Good garbage filters. I cheated only on Soviet aluminum covers, but there is some kind of wise alloy. Well, on too large pieces of iron, but I collect this.
And why Asya-150? This sucks (as they say now). What bigger coil is she? And what kind of discrimination is it?
I have been doing it for a long time on a generator with filtration on quartz. Swims constantly (it is necessary to adapt). And the sensitivity is low (~ 9cm per 5kop)
Author
I am thinking of buying a Garret ACE 150 + large coil. Coins seem to be up to 40 cm, watched a video. It makes sense? I have a similar bl, I put a big plus for the discriminator, it works well there.

And here was Tesoro, so he did not see gold in gold mode))) Also an American ... also niche in depth.
There are circuits in which one generator is on the search coil, and the second is on the board, but the same principle is on beats. There is one ancient scheme, which is already half a century, with one generator (on a coil) and selection through quartz.
The lack of adjustment under the ground is one of many negative points. You can configure, but this is another scheme.
Author
Well, if so, thanks for the answer. I’ll do two ... Although I saw it on one generator. Although maybe there is a different scheme?
Author
I read that even reacts to the earth. But maybe it can be customized somehow.
It depends on what to look for. )))
The primitive scheme is unstable, and even the principle of operation on the beats cannot provide high performance.
Can you tell why this metal detector is just a toy, isn’t it so useless in finding it?
Quote: Good Lighthouse
Will a variable capacitor from the radio fit, or is it smaller than the old Soviet?
Variables are different in size, design, rating, so the main thing is not where the capacitor comes from, but its parameters. It is necessary to try, it is impossible to say exactly in absentia. Anyway, this device is a toy, nothing more.
Quote: Good Lighthouse
Is a butterfly suitable for powering a metal detector from a single battery of 3.7 volts from a mobile one, or else they write that it seems like this metal detector works fine, that it is from 3.7 volts, that is 12 volts, but only the sensitivity is less?
A battery from a mobile phone will do. Depending on the supply voltage, a selection of basic resistors is needed to ensure the normal operation of transistors.
Quote: Dmitrij
Yes, I have nothing to check.
I do not ask to measure, I ask to think: there the frequency of each of the generators is tens of kilohertz, and they will not be heard alone.
Quote: Dmitrij
Well, it should squeak, no? And when both genes are synchronized, it does not squeak. Squeak should be upon detection of metal. Or am I wrong?
Say everything correctly, and try to check one generator and hear something:
Quote: Dmitrij
Well, one coil, one transistor ... One half.
Thank you for the information!) You can also tell how there will be free time, the variable capacitor from the radio will do, or is it smaller than the old Soviet? Is a butterfly suitable for powering a metal detector from a single battery of 3.7 volts from a mobile one, or else they write that it seems like this metal detector works fine, that it is from 3.7 volts, that is 12 volts, but only the sensitivity is less? Sorry if there are a lot of questions at once, but you just briefly and clearly answer that the essence is immediately clear, like what. Thanks again for the previous answer, it helped a lot. Good luck
Author
Yes, I have nothing to check. Well, it should squeak, no? And when both genes are synchronized, it does not squeak. Squeak should be upon detection of metal. Or am I wrong?
Quote: Dmitrij
But it does not squeak.
And rightly so.)) What is the generation frequency there?
Author
Well, one coil, one transistor ... One half. Does it have to peep in the headphones? But it does not squeak. Only the thorn is quiet.
Quote: Dmitrij
Nichrome does not work, we are talking about one circuit.
What do you mean?
Author
Three times I assembled the circuit, made coils of different diameters with different wire cross-sections. Nichrome does not work, we are talking about one circuit. Just something beeped and a mustache.

Maybe the transistors are wrong. I have a mark B and some kind of round intricate sign.

Quote: Good Lighthouse
solder a variable capacitor in parallel 1000 pF for each coil or only one of them?
One, but which one, can only be determined experimentally.
Quote: Good Lighthouse
Is a tree suitable for a metal detector rod, that is, it will not interfere with the search?
A dry tree will do.
Hello! Please tell me, and solder a variable capacitor in parallel to 1000 pF for each coil or only to one of them? Is a tree suitable for a metal detector rod, that is, it will not interfere with the search? Thanks in advance for your reply.
Author
I collect on one coil. First, I wound the wire in any way, 10 turns, then another 11, turned it on, and began to squeak. And the squeak went on overclocking, like it would take off now xaxa Then the couple began to swim, like some kind of radio signals. Well, in this mode, it reacts to pliers at a distance of 20 centimeters.

I rewound the coil, put a copper wire probably 0.8 or even 1 mm. But does not want to work smiles The number of turns made correct, 10/20. Maybe Pitalova is not enough? What to try to do? Power 3.7V, tried 7.4 ...
Author
And why are there two coils and two generators, are they kind of independent? I watched the work of the metal detector, so there he sees an object precisely when he is under one of the coils.
By the way, we tried to do this with one coil, it seems to work, but weak
Quote: Dmitrij
Well, I’m not the author of homemade work), but the author says that the sound will be different. For example, steel will have a lower tone, and color higher)

Just imagine the physics of the process, then you will understand that this is not so.

Quote: Dmitrij
I had a Garrett ACE 250 metal detector, so when it detected ferrous metals it made a low sound, and if copper, aluminum and others came across, the sound went very high, sonorous. Apparently here in a similar way.

Well, you compared: a serious device based on the VLF principle and this layout to demonstrate the principle.
Author
Well, I’m not the author of homemade work), but the author says that the sound will be different. For example, steel will have a lower tone, and color higher)

I had a Garrett ACE 250 metal detector, so when it detected ferrous metals it made a low sound, and if copper, aluminum and others came across, the sound went very high, sonorous. Apparently here in a similar way.

All metals have different electrical conductivity and they all bend the magnetic field in different ways, respectively, in similar metal detectors (at the breakdown of synchronization) this can be heard in the headphones.
Quote: Dmitrij
A discriminator is a device that converts a change in an electrical signal into a change in voltage polarity. The parameters of such an electrical signal are read from the input of the discriminator, the polarity of the voltage from its output.


And this device is already built into the metal detector, its principle is such that it already has the discriminator described in the article :)

And where is it device?
And how are you going to distinguish the type of metal in sound?
Author
A discriminator is a device that converts a change in an electrical signal into a change in voltage polarity. The parameters of such an electrical signal are read from the input of the discriminator, the polarity of the voltage from its output.


And this device is already built into the metal detector, its principle is such that it already has the discriminator described in the article :)
--------------------------------------------
As for the latter, I said, I repeat once again, a few articles were used as sources, some pictures are from there and they are needed to understand what other options for schemes, elements, etc.
Quote: Dmitrij
A simple discriminator is that metal can be detected by sound,

A screen discriminator is a device, for your information, not a way. The source referred to says nothing about the “discriminator”.
Quote: Dmitrij
And about the Kander, the article is assembled from a few simple, so there are all kinds of pictures. Want to do with ordinary, ...

Just in the pictures, ordinary non-thermostable ceramics.
Quote: Dmitrij
And stop already finding fault acute

Do you think that you can write any nonsense?
Author
A simple discriminator is that the metal can be identified by sound, with different metals it is different.

And about the Kander, the article is assembled from a few simple, so there are all kinds of pictures. Do you want to do with ordinary ones, but there will be glitches when the temperature drops))

And stop already finding fault acute
There is also a simple discriminator, ...
And where is he?
Capacitors should be used mica, ...
Yes? And why are the photographs ceramic?

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