Homemade coil for a pulse metal detector. Need help from a metal detector to find a cable! Stranded wire for metal detector coil

Making a good reel

Typically, metal detector coils are wound “in bulk” on some kind of mandrel - a pan, a jar, etc. suitable diameter. Then they wrap it with electrical tape, shielding foil and again with electrical tape. Such coils do not have the necessary structural rigidity and stability, are very sensitive to the slightest deformation and greatly change the frequency even with simple squeezing with your fingers! A metal detector with such a coil will have to be adjusted every now and then, and the control knob will constantly leave your fingers with big sore calluses :). It is often recommended to “fill such a coil with epoxy,” but where should you fill it, epoxy, if the coil is frameless?.. I can suggest a simple and easy way manufacturing a high-quality reel that is sealed and resistant to all kinds of external influences, has sufficient structural rigidity and, moreover, provides easy attachment to a rod-stick without any brackets.

For the frame, coils can be made using a plastic box (cable channel) of a suitable cross-section. For example, for 80 - 100 turns of wire with a cross-section of 0.3...0.5 mm, a box with a cross-section of 15 X 10 or less is quite suitable, depending on the cross-section of your specific wire for winding. A single-core wire is suitable as a winding wire. copper wire for low current electrical circuits, sold in coils, such as CQR, KSPV, etc. This is bare copper wire with PVC insulation. The cable may contain 2 or more single-core wires with a cross-section of 0.3 ... 0.5 mm in insulation different colors. We remove the outer sheath of the cable and get several the necessary wires. This wire is convenient because it eliminates the possibility short circuit turns in case of poor-quality insulation (as in the case of wires with varnish insulation of PEL or PEV brands, where minor damage is not visible to the eye). To determine how long the wire should be to wind the coil, you need to multiply the circumference of the coil by the number of its turns and leave a small margin for the terminals. If there is no wire required length, you can make a winding of several pieces of wire, the ends of which are well soldered to each other and carefully insulated with electrical tape or using heat-shrink tubing.

Remove the cover from the cable channel and cut the side walls sharp knife after 1…2 cm:

After this, the cable channel can easily go around a cylindrical surface of the required diameter (jar, pan, etc.), corresponding to the diameter of the metal detector coil. The ends of the cable channel are glued together and a cylindrical frame with sides is obtained. It’s easy to wind on such a frame required quantity turns of wire and coat them, for example, with varnish, epoxy, or fill everything with sealant.

From above, the frame with the wire is closed with a cable channel cover. If the sides of this lid are not high (this depends on the size and type of box), then you don’t have to make side cuts on it, because it bends quite well anyway. The output ends of the coil are brought out next to each other.

This results in a sealed coil with good structural rigidity. All sharp edges, protrusions and irregularities in the cable channel should be smoothed using sandpaper or wrapped with a layer of electrical tape.

After checking the coil for operability (this can be done by connecting the coil, even without a screen, to your metal detector for the presence of generation), filling it with glue or sealant and machining unevenness, a screen should be made. To do this, take foil from electrolytic capacitors or food foil from the store, which is cut into strips 1.5 ... 2 cm wide. The foil is wound tightly around the reel, without gaps, overlapping. Between the ends of the foil in the place of the coil terminals you need to leave gap 1 ... 1.5 cm , otherwise a short-circuited turn will form and the coil will not work. The ends of the foil should be secured with glue. Then the top of the foil is wrapped along the entire length with any tinned wire (without insulation) in a spiral, in increments of about 1 cm. The wire must be tinned, otherwise incompatible metal contact (aluminum-copper) may occur. One of the ends of this wire will be common wire coils (GND).

Then the entire coil is wrapped with two or three layers of electrical tape to protect the foil screen from mechanical damage.

Tuning the coil to the desired frequency involves selecting capacitors, which together with the coil form an oscillatory circuit:

The actual inductance of the coil, as a rule, does not correspond to its calculated value, so the desired circuit frequency can be achieved by selecting appropriate capacitors. To facilitate the selection of these capacitors, it is convenient to make a so-called “capacitor store”. To do this, you can take a suitable switch, for example, the P2K type with 5 ... 10 buttons (or several such switches with fewer buttons), with dependent or independent latching (all the same, the main thing is that it is possible to turn on several buttons at the same time). The more buttons there are on your switch, the correspondingly large quantity containers can be included in the “store”. The diagram is simple and is shown below. The entire installation is hinged, the capacitors are soldered directly to the button terminals.

Here is an example for selecting capacitors series oscillating circuit (two capacitors + coil) with capacities of about 5600 pF. By switching buttons, you can use different capacities indicated on the corresponding button. In addition, by turning on several buttons at the same time, you can get the total capacities. For example, if you press buttons 3 and 4 simultaneously, we get a total capacitance of 5610 pF (5100 + 510), and when you press 3 and 5 – 5950 pF (5100 + 850). This way you can create required set containers for precise selection the desired circuit tuning frequency. You need to select capacitor capacities in the “capacitance store” based on the values ​​​​given in your metal detector circuit. In the example given here, the capacitances of the capacitors according to the diagram are indicated as 5600pF. Therefore, the first thing included in the “store” is, of course, these containers. Well, then take capacitances with lower ratings (4700, 4300, 3900 pF for example), and very small ones (100, 300, 470, 1000 pF) for a more accurate selection. Thus, by simply switching buttons and their combinations, you can obtain a very wide range of capacitances and tune the coil to the required frequency. Well, then all that remains is to select capacitors with a capacitance equal to what you got as a result at the “capacitance store”. Capacitors with such a capacity should be placed in working diagram. It should be borne in mind that when selecting containers, the “magazine” itself must be connected to a metal detector exactly the wire/cable that will be used in the future, and the wires connecting the “magazine” to the coil must be made as short as possible! Because all wires also have their own capacity.

Discuss the article METAL DETECTORS: ABOUT COILS

Who is the owner? There must be a person responsible for electrical equipment who has all the documentation and is the one who gives permission to carry out excavation work in the cable security zone. \

(POT RM 016-2001)

4.14.1. Excavation work on the territory of organizations, settlements, as well as in security zones underground communications (electrical cables, communication cables, gas pipelines, etc.) can only be started with written permission from the management (respectively) of the organization, local government authority and owner of these communications. Towards resolution

4.14.2. If you find cables, pipelines not marked on the plans, underground structures, as well as ammunition excavation should be stopped until the identity of the discovered structures is determined and permission is obtained from the relevant organizations to continue the work.

4.14.3. It is not allowed to carry out excavation work with machines at a distance of less than 1 m, and a wedge - hammer and similar mechanisms - less than 5 m from the cable route, if this work is not related to cable excavation.

The use of earth-moving machines, jackhammers, crowbars and picks to loosen the soil above the cable is allowed to a depth at which a layer of soil remains at least 30 cm below the cable. The remaining layer of soil must be removed manually with shovels.

Before the excavation begins cable line a control opening of the line must be carried out under the supervision of the personnel of the organization that owns the cable line.

4.14.4. IN winter time You can start digging the soil with shovels only after it has warmed up. In this case, the heat source must be no closer to the cables than 15 cm.

4.14.5. The work site for digging ditches, trenches or pits must be fenced taking into account the requirements current SNiP. There should be warning signs and inscriptions on the fence, and warning lighting at night.

4.14.6. When digging trenches in weak or wet soil, when there is a threat of collapse, their walls must be securely reinforced.

In loose soils, work can be carried out without fastening the walls, but with the construction of slopes corresponding to the angle natural slope soil.

Soil removed from a pit or trench should be placed at a distance of at least 0.5 m from the edge of the excavation. The development and consolidation of soil in excavations with a depth of more than 2 m must be carried out according to the PPR.

4.14.7. In the soil natural humidity Without groundwater and in the absence of nearby underground structures, digging pits and trenches with vertical walls without fastening is permitted to a depth of no more than: 1 m - in bulk sandy and coarse soils; 1.25 m - in sandy loam; 1.5 m - in loams and clays.

In dense cohesive soils, trenches with vertical walls can be dug using rotary and trench excavators without installing fasteners to a depth of no more than 3 m. In these cases, lowering workers into the trenches is not allowed. In areas of the trench where workers are required, fastenings must be installed or slopes made.

The development of frozen soil (except for loose soil) is allowed without fastening to the freezing depth.

4.14.8. Under conditions different from the conditions given in clause 4.14.7 of these Rules, pits and trenches should be developed with slopes without fastenings or with vertical walls fixed to the full height.

4.14.9. The fastening of pits and trenches up to 3 m deep, as a rule, must be inventive and carried out according to standard designs.

4.14.10. Moving, installation and work construction machines and vehicles, placement of winches, equipment, materials, etc. near excavations (pits, trenches, ditches) with unreinforced slopes, it is permitted only outside the soil collapse prism at a distance established by the PPR, or at a horizontal distance from the base of the excavation slope to the nearest supporting parts of the above machines, equipment, winches, materials, etc. . not less than indicated in the table. 4.3.

this is for general knowledge...

Towards resolution a plan (diagram) indicating the location and depth of communications must be attached. The location of underground communications must be marked with appropriate signs or inscriptions both on the plan (diagram) and at the work site. There is not a single mark on the surface of the earth!!! this already says something, there are two pillars; one goes down into the ground; the cable on the other rises out of the ground! and that’s it. And the plan is how it’s supposedly laid out!.

Before I describe the technique itself, I want to draw attention to two points:

1. The device may begin to malfunction if moisture gets into this socket (dig in the rain, in fog, accidentally lowered the metal detector into a puddle, and so on).
2. On different metal detectors, this socket may be located in different areas, so I will describe the very essence of the technique, and you will figure out how to adapt some points to your metal detector on the spot.

I began to protect this nest exactly from the moment when it was in early spring, when the snow had almost melted, but in some areas it still lay in a decent layer, I carefully placed my metal detector next to the dug hole, and take the device and fall, and the block right into the puddle. I didn’t get it too wet, fortunately there was a cover on the “brains,” but after this incident phantom signals began to appear quite often. I didn’t immediately determine the reason, so I had to tinker. And the reason is that moisture got directly onto the threads of the socket, and then onto the contacts.

And I also had a case when it started raining during a dig, and naturally, being on the field, everything got wet. I always carry a bag in my pocket, which is put on the block, but in this case, something went wrong. After the rain, about an hour and a half later, constant signals began to sound at everything, even with the metal detector raised. The batteries are charged normally, the coil is intact, the unit itself does not seem to have gotten very wet, but moisture has probably seeped into the socket. Maybe I didn't tighten the nut all the way, I don't know. But in order not to think about this topic anymore, I decided to come up with a way to increase the protection of this particular element of my detector.

A simple way to protect the socket on a metal detector

An ordinary bicycle inner tube, instant glue, and electrical tape came to my aid. First, I cut a rectangle out of the camera, which I glued to the side of my metal detector. I glued it in such a way that the piece of rubber at the bottom completely covered the entire bottom part and slightly extended beyond the block. Then, from the same chamber, I cut out a cylinder, 7 centimeters long. I put this cylinder on the cable from the reel (in the area that goes into the plug) so that a piece of the chamber extends two or three centimeters beyond the cable. The rubber cylinder itself was taped to the cable with electrical tape. That's all.

It turns out that if it snows or rains, if the metal detector accidentally falls into the water, the chance that the area where the cable connects to the unit will be wet is sharply reduced. Coming from below rubber protection, and the piece of the chamber that protrudes beyond the cable, when connecting the coil to the device, fits tightly to the body of the unit. Naturally, this method does not replace the use of a cover for the unit, and, of course, I still carry a plastic bag in my pocket. But with this modification I can walk much more calmly, although I myself looks a little strange from the outside. But it’s better to let it be strange than to completely fail at the current exchange rate.

This is such a simple method, a minimum of time, available to absolutely everyone.

It happens that a cop starts out great, but at one point there are too many false signals. After inspecting the coil, you notice damage to the cable. This is what causes your metal detector to start making noise and giving false signals. Let's figure out why the cable breaks.

The cause of damage to the coil cable or even its fracture can be a simple careless attitude towards the metal detector, or more precisely, towards the cable. It happens that the cable gets caught on branches and stones, or is damaged during transportation. But most often, the owner of the MD incorrectly winds and secures the coil cable, that is, overtightens it.

Here is an example when the cable is pulled tight.

At first glance it does not seem so, but we must remember that the coil moves and during the search it is brought to different positions, and the cable stretches. Let's also add here bad habit bend the coil to the rod while transporting the metal detector. At the same time, the load on the wire also increases. As a result, the cable breaks.

To prevent this from happening, many manufacturers offer limiters - small rings that help secure the cable as needed. It's a good thing, but it doesn't protect 100%.

To avoid cable damage, you just need to follow a few rules when winding the cable.

1. Having connected the cable to the reel, you need to make a loop for free movement. Bend the reel to the rod and secure the cable. Use the clamps that come with the kit, or you can use electrical tape, adhesive tape or tape. In the photo there is an adhesive plaster. Attach tightly.

2. Wrap the cable tightly around the rod to prevent it from dangling. Winding should be done from the front side, not from the back. In the photo - on the left is correct, on the right - not recommended. This way you will be able to maintain the integrity of the cable for a long time.

There is one life hack - after purchase, immediately wrap the lower part of the cable (near the reel) with several layers of electrical tape, so to speak, for prevention.

Such “machines” include XP Deus. Metal detectors are also good in this regard. Minelab series Go-Find, Explorer and CTX3030. For these devices, the cable is “hidden” inside the rod and cannot suffer from mechanical damage.