Old Soviet and pre-revolutionary coins on the market are quite expensive. You can find them, including in abandoned old villages and towns. However, the search for such small objects, in most cases already covered with earth, without a special tool, would, of course, be extremely difficult. Therefore, modern treasure hunters use special detectors for this purpose.
There are many types of such devices on the market today. And the simplest at the same time is "Butterfly". A metal detector (its photo is presented on the page) of this design is relatively inexpensive and at the same time quite convenient to use. Therefore, the feedback from consumers, he deserved simply excellent.
Design features
This tool got its name for the presence of two coils resembling butterfly wings andlocated in the same plane. Such a metal detector works on the principle of disrupting the synchronization of frequency generators.The elements of its design are:
Microcircuits on operational amplifiers. Two of them receive coil signals. The third amplifier calculates the difference.
Speaker. It is on it that the difference of signals is displayed.
Variable capacitor. This item is designed to prevent capacitance distortion when adjusted.
Dielectric box for the circuit. Can be made from different materials.
Base for reels and rod. Its length can be 30-45 cm.
Rod made of dielectric material.
PEL wire 0.3-0.35 mm.
Batteries.
Two-wire cable.
As you can see, the design of this metal detector is really simple. That is why it has earned good reviews from consumers.
If desired, today you can purchase a Butterfly metal detector with one coil. Such models work, of course, somewhat worse than usual ones. However, some coin seekers still consider them quite promising.
Operating principle
The distance between the coils of the Butterfly tool is approximately 10 mm. As soon as any metal object, including underground, falls into the zone of action of one of them, the synchronization process of the generators is interrupted. As a result, the sound signal penetrates the earphones of the coin finder.
Metal detector "Butterfly": reviews
Of course, the Butterfly tools are inferior to most of the more complex and expensive models in terms of ease of use. However, with the help of this metal detector, you can find objects in the ground quite effectively. For example, a five-kopeck coin from the times of the USSR "Butterfly" "sees" at a distance of about 15 cm, can lids - 30 cm, hatches - 60 cm. A good opinion about this device among consumers has developed, among other things, because it can work under water.
The advantages of this metal detector are also considered by many to be long-term operation. One battery charge "Butterfly" is usually enough for as much as 20-30 hours. According to most searchers, working with this device is also convenient because it does not weigh too much - only about 500 g.
The advantages of this device, therefore, there are many. However, it also has some shortcomings. For example, many coin seekers note the fact that the coils of the Butterfly device often break their ears. In addition, such devices sometimes fray the cores in the cable. In some cases, these metal detectors may also malfunction with the standard coils themselves.
Another indirect disadvantage of this device, according to many consumers, is that in the event of a breakdown, it can be difficult to find a master to repair it. For people who do not have experience with radio electronics, this often becomes a problem. However, the device of this device is actually simple. And even if you have a minimum of skills in working with radio equipment, it will not be particularly difficult for a home master to fix such a metal detector. Moreover, all sorts of parts for it are not too expensive and you can usually find them on sale without difficulty. They are sold both in specialized and simply in hardware stores.
Metal detector device and circuit
So, there are good reviews about these devices, including because of their simple design. What device does the Butterfly metal detector have? Let's look into this in more detail.
In order for the tool to work effectively, the diameter of its coils must be at least 21 cm. There should be 30 turns of wire on them. The tap usually comes from the 10th. A rod is fixed on the basis of the device. The sensitivity adjustment system is also fixed here. Inside the rod, along with headphone outputs, a cable is stretched. The power source for metal detectors of this type is sometimes even a simple battery from mobile phone(in homemade models).
The cable inside the rod in such metal detectors is pulled along with the headphone jack. This item is for turning on/off the device. Reviews about devices of this design exist, so they are not bad also because they start working immediately after the connector is inserted into the headphones.
Above is a diagram of a simple metal detector "Butterfly" on two transistors. As you can see, it is not particularly difficult. In any case, the circuit of this device is not critical in terms of the nominal value of parts, the number of turns and power supply.
For what else the device deserves good reviews
Searching for coins with this device is actually not too difficult. Consumers also have a good opinion about Butterfly devices because they can automatically adjust to any soil. Also, the coin finder can determine the type of metal underground by the sound of the signal. In addition, due to the simplicity of the design of this device, it can be easily improved if desired. For this, of course, he also deserved excellent reviews from consumers.
In some cases, home craftsmen do not even purchase parts for the Butterfly metal detector, but simply take them from old equipment. For example, for the coils of this device, a cable from a deviating system and a TV degaussing loop is suitable. The only thing is that high-impedance headphones are usually used in such devices. And, unfortunately, they are hard to find. Ordinary audio headphones from old equipment cannot be used with this device. The sound on them during the search process simply will not be heard.
The main disadvantage of the device
Thus, according to many consumers, the inexpensive Butterfly metal detector has practically no disadvantages. This is especially true for efficiency and ease of use. This device finds coins at the same depth as the majority of rather expensive models, including imported ones.
However, in terms of ease of use, this device still has one rather serious drawback. When using the Butterfly metal detector, there is often an inconvenience in adjusting the operating frequency of the generator. It is, of course, rather difficult to search for the desired position of the rod in fractions of a millimeter in the steppe or forest.
Manufacturing nuances
Making a Butterfly metal detector with your own hands, as already mentioned, is quite simple. The scheme of this device is not particularly complex. The only thing is that when assembling it, you should make sure that its left and right parts are the same. The device board is placed in a plastic box. Glue it to the coil frame. The second board is usually supplemented with an amplifier with contact pads for three batteries and a headphone jack. Petals are cut from a tin can.
With an amplifier, the Butterfly metal detector can also be used with ordinary 30-60 Ohm headphones. This, among other things, ensures an economical mode of operation of the device.
The advantages of this device, many consumers include the fact that, as already mentioned, it can be easily improved. In addition to headphones, if desired, it will not be difficult to make a Butterfly metal detector with your own hands and more convenient in terms of fine tuning the frequency. To do this, on the board to which the petals are soldered, a variable resistor with a resistance of 100 ... 150 Ohms should be placed. Next, this board, like the first one, is placed in a box, and then the last one is attached to the rod near the handle.
How to make a Butterfly metal detector with your own hands: detailed instructions
Actually, this device is assembled as follows:
a bar is made, for example, from a 26 mm plastic pipe.
A handlebar from a bicycle is attached to one of its ends;
the base is made of plywood, polycarbonate, etc.;
the assembled circuit is attached to the base along with the coils;
a rod and a sensitivity adjustment unit are also fixed on the base;
a wire is pulled inside the rod;
the mobile phone battery is glued to the base;
the power wires of the generators and the charging connector are soldered to its contacts;
the coil and the circuit are covered with furniture varnish, and then with silicone;
a tuning unit is glued next to the coil;
an armrest is made from a water pipe.
To adjust the metal detector during operation, a plastic nut and a screw with a piece of aluminum are used. The threads of this assembly are lubricated with grease.
Instead of a conclusion
So, judging by the reviews, the Butterfly metal detector can be considered a device that is quite convenient in operation. It is easy to find coins, both small and large, as well as any other metal objects in the ground with it. Of course, this cheap device has its drawbacks. Some seekers even call it a "toy" for beginners. However, if desired, this device can always be slightly improved and made more convenient and efficient in operation.
Metal detectors can be divided into different types according to the principle of operation. One of the simplest devices is the Butterfly metal detector, the principle of operation of which is to disrupt the synchronization of frequency generators. The unit got its name because of its structure: two coils resemble the wings of a lepidopterous insect.
This type of metal detector is very simple, but if you set it up well, it will cope with the search for non-ferrous and ferrous metals. Butterfly metal detector can be made by hand.
Butterfly metal detector parts list
1. 2 transistors BC546 or equivalents
5. battery krone. 8 AAA batteries can act as a power source, but then the circuit will be large;
6.battery connector;
7.piezoelectric speaker;
8.case (may be cardboard);
9. base for coils (should be dielectric) and mount for the rod (not less than 35 and not more than 40 centimeters in length);
10. The rod can be made from any dielectric material;
11. PETV wire 60 m long and 0.3-0.35 mm in diameter;
12.foil;
13. shielded cable with cores, the number of which must be at least 2;
14. electrical tape;
15.varnish;
16.threads.
2. 2 capacitors 1nF
3. 2 capacitors 10 nF
4. 2 resistors 100 KOHM
Assembling the metal detector Butterfly
It is necessary to connect all components with a thin insulated wire or solder them on a printed circuit board. To the wall of the case, you need to bring the wires for the speaker. Next, in the body of the Butterfly metal detector, glue the battery connector and fix it with glue.
For the switch, you need to cut holes on the box. You can fix it with glue or silicone. The speaker must be glued to the case from the inside. In order to have good audibility, holes must be made in the case. After that, you need to connect the Butterfly metal detector circuit and body parts to each other. The body on the rod can be sealed in any way.
The rod is connected to the dielectric base for windings using glue, liquid nails or plastic fasteners.
On the next stage you need to assemble the sensor. This element consists of coils and fasteners. Both coil windings must be identical and mirror each other.
Assembly of the first coil
You need a round object with a diameter of 12 centimeters. It is necessary to wind 70 turns using the prepared wire. It must be wound very slowly and carefully so that no damage to the insulating surface of the wire occurs. We leave the two ends of the winding on the sides. It is necessary to fix the winding with threads at a distance of 3-5 centimeters from each other. Saturate the resulting design with varnish. After drying, it is necessary to provide insulation to the winding with electrical tape. Then wrap in foil. The wire around the circumference must be soldered to the foil and brought out. After these manipulations, we again use electrical tape to insulate the winding. The winding should have leads as short as possible.
Both ends of the coil must be soldered to the prepared cable, and the foil wire must be soldered to the cable shield. We isolate well and place the cable in the box where the board is located. The shielded output must be connected to the minus of the board. Next, you should fix the cable along the entire rod, with the exception of the base. This is how the Butterfly metal detector circuit with one coil turned out. We assemble the second coil in the same way.
Setting up the metal detector
At the last stage, the coils are fixed. It is necessary to remove all metal objects and jewelry from the metal detector's coverage area - it is very sensitive.
It is necessary to insert a battery and find the optimal distance between the coils. You need to start with 10 centimeters. If the device does not respond, then this may indicate a malfunction of the Butterfly metal detector circuit or the correct synchronization of the frequency generators. If you bring metal to the sensor, and it starts to make any sounds, then the circuit is working. If there is no reaction, then it is necessary to check the correct connection of the components.
When obtaining the desired result, it is necessary to fix the coils with glue in the correct position.
Do-it-yourself Butterfly metal detector will turn out without difficulty if you follow the detailed instructions.
According to the principle of operation, metal detectors are divided into many types. Consider one of the simplest metal detectors - Butterfly, operating on the principle of disrupting the synchronization of frequency generators. It got its name from the presence of two separate coils resembling butterfly wings (Fig. 1).
Its work is carried out by a microcircuit on operational amplifiers, two of which receive coil signals, and the third calculates the difference, which is output to a piezoelectric speaker. Despite its simplicity, this metal detector, with good settings, shows itself well in the search for ferrous and non-ferrous metals, especially large ones. Described below detailed instructions for the manufacture of this metal detector.
Selection of parts and material
Thanks to the TL074 chip, which performs the entire process of the metal detector, we do not need many details. Let's describe each of them and the necessary material:
- Chip MC1 TL074CN. The numbering of contacts is made from the key on the housing counterclockwise, when viewed from above (Fig. 2).
- Variable capacitor C1 100 pF with a dielectric cap - to eliminate capacitance distortion during adjustment. When buying, try to get heat-resistant types.
- As switch SA1, you can use any toggle switch or microswitch.
- Battery krone G1. You can also use a more powerful power source, such as 8 AA batteries, which will give a total of 12 V. But this will significantly increase the size of the circuit.
- Battery contact connector (Fig. 3). We find in unnecessary equipment, powered by a crown or 8 AA batteries.
- Piezoelectric speaker PZT1 (Fig. 4). You can get it in cheap testers, children's toys and other devices with a tweeter.
- Box for the scheme. Any dielectric box will do, up to a cardboard one.
- Dielectric base for coils and rod attachment. Choose the length in the region of 35-40 cm, and select the width based on the method of fastening the rod. A plastic or plywood sheet will do.
- The bar can be made from a light wooden stick or a PVC pipe. An important point is the manufacture of a dielectric material. Fastening should also be done - without metal components, such as glue or plastic fasteners.
- About 60 meters of PEL wire with a diameter of 0.3 - 0.35 mm. We will wind the coils with them.
- Any foil for winding shielding.
- Well-shielded cable with at least two cores (fig. 5).
- Electrical insulating varnish, threads and electrical tape.
Assembling a metal detector
The scheme of the metal detector is shown in Figure 6.
When assembling on a printed circuit board, the circuit board diagram and the program for its processing and printing can be downloaded from the link. When printing, put a tick on the mirror image. The printed circuit board is also shown in Figure 7.
When assembling by surface mounting, you can glue the microcircuit with the case to the box. Next, we connect the parts according to the diagram with a thin insulated wire. For the switch, speaker and variable capacitor, we bring out the wires to fix the parts on the box. Solder the connector for the battery to the circuit. We fix the scheme with glue.
On the box we make holes for a variable capacitor and a switch. We fix them with glue or silicone. We glue the speaker from the inside to the case and make holes for good audibility. We make the connection of body parts with the circuit. We fix the body on the bar in any convenient way. You can use metal fasteners.
We make a connection of the rod with a dielectric base for windings. You can use liquid nails or plastic fasteners.
The next step is to assemble the sensor - a part of a metal detector that includes inductors and a mount for them. If you follow the article, then you can easily assemble a sensor with your own hands that does not differ in quality from complex sensors homemade metal detectors. Both windings must be completely identical and have a mirror image. Let us describe the assembly of the first coil. Then, by analogy with the first, assemble and connect the second.
We find a round object with a diameter of about 12 cm. We wind 70 turns with a prepared wire. We wind carefully - without bends, fractures and damage to the wire insulation. Leave the two ends of the winding aside. We fix the winding at a distance of 3-5 cm with threads. We impregnate the winding with varnish. After drying, we isolate the winding with electrical tape and wrap it with foil. The foil must never close at the end of the circle! We solder the wire around the circumference to the foil and bring it out (Fig. 8), after which we again isolate the winding with electrical tape. We make the winding conclusions of the minimum length.
We take the prepared cable. We solder both ends of the coil with the cable cores, and solder the wire from the foil with the cable screen. We reliably isolate and insert the cable into the box with the board, after which we make connections according to the diagram. The shielded output must be connected to the minus of the board. We fix the cable along the entire length of the rod except for the base. This will eliminate interference and failures in setting up the metal detector. After we figured out with one coil, we make the second one in the same way.
The coils will be fixed when setting up the metal detector.
Device adjustment
The last step in the assembly is to fix the coils. The Butterfly metal detector is very sensitive, so we remove all metal objects within the range. Do not forget about jewelry on the body - watches, earrings and more. We insert the battery and turn on the metal detector. We start with the location of the coils on the base. The optimal distance between them is 10 cm. If the metal detector is silent, this indicates a malfunction of the circuit or successful synchronization of the frequency generators. We bring a metal object to the sensor. The appearance of distortion or clicks in the dynamics indicates a working circuit. If the metal detector does not react in any way to metal objects, then we check the correctness of the connection of the parts and the serviceability of the battery.
Our task is to fix the windings in a position in which the speaker is silent or produces single rare clicks. After achieving this result, we fix the coils with glue in this position. We fix the sensor cables to the base of the rod to ensure their immobility. You can cut the edges of the base along the contour of the coils.
The last step is to add a device to adjust the timing in the field. We fix plastic tubes on top of both coils and insert iron rods into them. Rods and tubes are selected in such a way as to exclude unauthorized movement of iron. After installing them, we again achieve the ideal setting by moving the rod in one of the tubes (Fig. 9).
While working with a metal detector, you can experiment with a variable capacitor C1 to select the optimal detection distances and the quality of operation. If synchronization fails, we use the movement of ferrite rods to adjust.
It is built on the principle of failure of synchronization of two coils. It is because of such an interesting design, outwardly resembling a butterfly, that the device got its name. Homemade is easy to assemble, and all components are easy to get.
And now about the most important thing, to what depth this miracle of technology is able to see. According to the author, a five-kopeck coin of the time of the USSR is found at a depth of up to 15 cm, which is a pretty good indicator. The device sees a metal lid from a jar at a depth of 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 is enough for 20-30 hours of operation. The current consumption is 15 mA, the device weighs only 500 grams. The device can be adjusted to 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 (VS182, VS546...);
- two capacitors 1000 pf (1 nf or 102);
- two capacitors 10000 pf (10 nf or 103);
- stereo headphones;
- two resistances per 100 kOhm;
- one 3.7V mobile battery;
- 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 body.
Metal detector manufacturing process:
Step one. Device diagram
The circuit is not too rigid, so it is not necessary to accurately observe the number of turns, the rating of parts and the power source. The most important condition is the identity of the right and left sides. Interference during work is compensated, and the soil does not affect the quality of work. If the circuit is assembled symmetrically, it works immediately. The signals from the generators are fed to the X and Y plates.
The picture shows that the frequencies are the same.
When disruptions occur in the headphones, clicks begin to appear.
Now the generators are out of sync.
Step two. Board Assembly
To connect the parts, any glue that does not conduct current is used. The battery must always be charged and have a good capacity, otherwise the setting will constantly go astray. For these purposes, you can use one or two batteries from the mobile.
Capacitors should be used mica, not sensitive to temperature changes. If there is no textolite, the board can even be made of cardboard.
Step three. We wind the coil
The first turn of the coil is soldered to the minus from the battery. Next, you need to wind the coil, for example, on a pan, after ten turns you need to make a loop. Here the wire must 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 10,000 pF and 1000 pF. In this exact way, you need to assemble 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 fit tightly into one another. Coils and circuits for protection against moisture are covered with oil varnish. Coils are glued at a distance of 10 cm.
Step five. Setting up a metal detector
When the metal detector is turned on, a squeak should appear in the headphones. If it so happens that the circuits are not assembled the same, some adjustment will be required. There are two ways to set up 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 is very quiet or stops altogether. On top of each coil, you need to glue tubes with ferrite, then you can adjust the metal detector with a ferrite rod to complete silence.
For beginners simple circuit metal detector on two coils, is based on the principle of disruption of synchronization of these same generators. There are many different metal detector circuits on the Internet, but it is quite difficult for a novice radio amateur to properly configure and adjust the assembled circuit without an oscilloscope. We propose to assemble a simple metal detector with your own hands with simple settings.
Metal detector characteristics
- a coin the size of 5 kopecks of the USSR detects up to 15 cm;
- metal lid from a jar - up to 30 cm;
- metal manhole - up to 60 cm.
- can work in water.
- One battery charge is enough for 20 - 30 hours of operation.
- current consumption - 15 mA.
- Weight 500 grams.
It adapts to the appropriate ground and even with good sealing of the coils it can work in water. By a certain sound in the headphones, you can determine the type of metal.
The circuit is not critical to the power supply, the number of turns and the ratings of the parts.
There is only one condition - the left and right parts of the circuit must be the same!
Interference is compensated, the ground does not affect. Sensitivity does not depend on the scheme, but on the very physics of measurements. We accumulate phase shift.
Symmetrically assembled circuit works immediately. But it's interesting to see.
When powered by 4 V on the coils, about 40 V can be applied directly to the tube.
Signals from generators are fed to plates X and Y
Frequencies match 
Here are the breakdowns.
There were clicks in the headphones.
The generators are out of sync.
We assemble the parts on any non-conductive glue.
If the battery is dead and runs out, then the setting will float away. The phone battery fits well.
For the construction, we use a metal-plastic water pipe. The rod can be detachable, pipes with a diameter of 26 and 20 fit tightly into one another. Capacitors with good temperature stability, mica - this is important.
Cover the coils and circuit with oil varnish. Between the coils 10 cm. We put the coils at a distance of 10 cm and glue it - no need to move
The scheme of the metal detector "Butterfly" with one speaker
Source: majstin.narod.ru
Parts list:
- Transistor - KT315 (VS182, VS546, VS547, etc.) - 2pcs;
- Capacitor - 1000 pf (1 nf or 102) - 2 pcs;
- Capacitor - 10000 pf (10 nf or 103) - 2 pcs;
- Resistance - 100 kOhm - 2pcs;
- Ordinary stereo headphones - 1 pc;
- Power supply (from cell phone) - 3.7 V - 1 pc;
- Wire in lacquer insulation PEV, PEL, PETV, etc. with a diameter of 0.4-0.7 mm.
If you do not have all the necessary parts and board,
You can order them from us
all necessary printed circuit board parts.
How to wind coils?
Detailed explanation of coil manufacturing:0 - oh turn- this is the beginning of the coil (soldered to the track lower according to the scheme (battery minus). Then you wind the coil (for example, on a pan), as 10 turns made, twist the loop, strip the insulation and solder it to the middle outlet according to the scheme, i.e. to the emitter of the transistor ( it will be a withdrawal). Then roll some more 20 turns, cut off and solder the end of the wire to the connection of two capacitors 1000 pF and 10000 pF ( this is the end of the coil). The second coil is done in the same way.
Setting up the metal detector
When it squeaks, it's good! But still, it is not always possible (for various reasons) to make the same generators, therefore it is necessary to adjust one of them to the frequency of the second.
Coarse tuning with the last turn of the coils
We take a piece of aluminum or a larger tin can. We bring to the coils in turn. Above one, the squeak is even higher, above the other it falls silent. On the coil where it stops, we bend the last turn inward (or move the coils, reduce or increase the distance between them), achieve the quietest squeak or until the signal stops. Ferrite tubes must be glued on top of each coil. You can then adjust the ferrite rod to complete silence.
Ferrite core tuning
To do this, take a tube and a ferrite rod, fasten next to one of the coils. Move the ferrite rod in the tube until you synchronize the generators. Ferrite rod with a coil from an old radio (maybe a tube one). Wind up all the wires, leave the frame with the ferrite core.
Video instruction for setting up a metal detector
Can be adjusted with aluminum strips glued to the coil inside or outside. For tuning, we put a strip of aluminum or just canning lids on both coils and move them, achieving the lowest buzz tone.
If clicks are clearly heard in the headphones, this means that the sensitivity of the device is at its maximum.
Another option for frequency tuning is to install a variable capacitor parallel to the 1000 pF capacitor, for example, from an old radio.
Mounting a metal detector
In the absence of a board made of foil textolite or getinax, boards can be made of cardboard.
Photo of manufacturing options for the printed circuit board of this metal detector
Photo of a metal detector by Vladimir Nosikov
Photo of a metal detector by Dmitry Kosnov
