The simplest hidden wiring detector in a hurry. Hidden wiring detectors Magnetic field search unit

By doing construction work Often there is a need to check the wall for the presence of wiring in it. To conduct a search, you will need a detector that reacts to metal. You can purchase this device in a factory version or make a finder hidden wiring with your own hands. This article will discuss the nuances of the internal structure of detectors, as well as methods for their manufacture.

Factory detector circuits

There are several types of factory-made detectors:

1. Electrostatic. The advantages of such a device are the simplicity of the internal structure and the ability to find metal objects at a considerable distance. The disadvantage of the detector is that it can only search in a dry environment. Otherwise there will be false positives. In addition, only those wires that are energized can be detected.
2. Electromagnetic. Advantages include simple circuit design and highly accurate wiring detection. There is only one drawback, but a significant one: in addition to voltage, you need a fairly powerful load - at least 1 kilowatt.
3. Metal detector. This device is a standard metal detector. The main advantage is that there is no need for tension. Disadvantages: detects any metal (not just wiring), and is also structurally complex.

The simplest circuits of homemade devices

There are several schemes of such devices.

With sound indication

You can make a simple hidden wiring detector with your own hands using resistor R1. This resistor protects the circuit from induced voltage. Moreover, even if you install it, this most likely will not affect the operation of the device.

Hidden wiring detector circuit with sound indication

A copper conductor with a length of 5 to 15 centimeters is used as an antenna. When wiring is detected, a specific crackling sound is produced. The piezo element is connected according to the bridge circuit principle, which allows you to control the volume level.

Sound indication combined with light

This circuit is also simple - you only need one chip.

Hidden wiring finder circuit on a microcircuit

Features of the circuit: the value of resistor R1 must be equal to or greater than 50 MOhm. The LED is used without resistance limitation, since the microcircuit performs this task independently.

On a field-effect transistor (first circuit)

Transistors of this group are extremely responsive to an electric field. This feature used in the diagram below.

Field-effect transistor wiring finder circuit

From the picture you can understand that the device is very simple; you can make it yourself, without using any special devices. The supply voltage indicator is from 3 to 5 V. The current required is so small that the detector can operate for 5-6 hours without shutting down. The antenna coil is fixed with a 0.3-0.5 mm wire to the core, which, in turn, has a diameter of 3 mm. The number of turns depends on the wire itself: 20 turns for a 0.3 mm wire and 50 turns for a 0.5 mm wire. The antenna can function both with and without a frame.

On a field-effect transistor (second circuit)

Another option for making a hidden wiring detector with your own hands using a field-effect transistor is to use the KP103 microcircuit. This field grass is characterized by high sensitivity. If its gate is in close proximity to the wiring, the resistance is reduced, which leads to the opening of other transistors. After this, the LED begins to glow.

Note! Polevik KP103 can be used with any letter, just like the AL307 light diode. The fact is that bipolar transistors with such conductivity have low power, and the transmission coefficient must be significant. Therefore, instead of KT203, it is recommended to choose KT361.

The device is small in size - assembly can be carried out even in a marker housing. The antenna extends through the hole in the marker. The antenna length is from 5 to 10 centimeters. However, if the wiring is not too deep in the wall (no deeper than 10 centimeters), you can get by with the length of the leg field effect transistor.

Hidden wiring detector circuit using transistor KP103

The KP103 transistor is installed horizontally, and the gate must be bent so that it is located directly above the transistor body.

Metal detector

Schematic diagram of a metal detector

The metal detector circuit looks like this:

• frequency generator (100 kHz) - VT1;
• detector - VT2;
• indication - VT3, VT4.

Generator coils are wound on a ferrite core. The rod diameter is 8 millimeters. The number of turns on the first coil is 120, on the second - 45. The wire is selected as PEVTL 0.35.

The metal detector should be adjusted away from metal products. The adjustment is made using trimming resistors R3 and R5 in such a way that the generation practically disappears (uneven glow of the diode and low brightness). Next, the R3 tincture occurs in order to extinguish the emitter.

The next step is to adjust the sensitivity. This is done using a piece of metal (you can use a coin) and a pair of resistors. Moreover, it is recommended to repeat the sensitivity adjustment periodically. To optimize the process and make it more convenient, regulators can be built into the body of the metal detector.

The configured device turns on when the antenna is close to metal - the light diode begins to blink.

Wiring alarm without batteries

This detector uses the network directly as a power source. This circuit is possible through the use of a high-capacity capacitor (indicated in the diagram as C1). The capacitor is charged from the network. In a charged state, the capacitor transmits a voltage of 6-10 V. In this case, only the brightness of the light diode depends on the voltage, but this indicator does not affect the sensitivity of the device.

Schematic diagram of a hidden wiring finder without batteries

Wiring detector on microcontroller

The diagram above shows a hidden wiring detector built on a PIC12F629 microcontroller. The operation of the device is based on responsiveness to magnetic field. This field is formed by current flowing through a conductor located in the wall.

In the scheme you can use LED lamp or piezo emitter. When a magnetic field is detected, a lamp lights up or a piezo emitter begins to crackle, depending on the preferred type of indication.

The advantage of the device is its ability to respond only to a frequency of 50 Hz, which is the frequency alternating current. Thus, false alarms of the finder are excluded, since the device will not respond to other frequencies.

Two-element indicator

Schematic diagram of a two-element detector

In this case, you need a microcircuit and a light diode. You can choose DD1 as the microcircuit, and it is recommended to take HL1 for the LED. The task is to connect the leads in such a way as to create three inverters in a circuit. As a result, the device will amplify the currents that flow to the device from the alternating current field in the wiring located in the wall. When wires are detected, the diode lamp begins to glow. When moving away from the wall or breaking the chain, the lamp goes out.

There are two options for implementing the circuit:

1. Connection of terminals: third to eighth, second to tenth, fourth to seventh and ninth, first to fifth, eleventh to fourteenth.
2. Connection of terminals: third with eighth, tenth with thirteenth, first with fifth and twelfth, second with eleventh and fourteenth, fourth with seventh and ninth.

Industrial circuits of professional detectors

You can assemble the device at home professional level. However, such equipment has enough complex circuit, and it will take a lot of effort to make it. Below are two diagrams to choose from: the first relates to an industrial device, the second to homemade device"Woodpecker".

Scheme of an industrial signaling device for hidden wiring
Scheme of a homemade wiring detector “Woodpecker”

You can also make a device like YADITE 8848. Below are two options for such a device.

Schematic diagram of the detector on TC4069UBP
Wiring locator diagram for 74HC14AP

Checking homemade wiring finders

Before using a homemade device, it is recommended to test its performance. Checking will show correct assembly.

The test is performed as follows:

1. We find an area where there is definitely hidden wiring. For example, it is guaranteed that there are wires in the wall leading to switches and sockets.
2. We check the selected area. To do this, we bring the device to the wall and observe the indication.
3. If the signal is received only at the point where the cable passes, the device is working properly and can be used.
4. If the signal appears and disappears in different directions, it means the device is faulty.

Advice! Before starting the test, the wiring must receive maximum load. To provide such a load, we connect as many electrical appliances as possible to the network. As a result, the magnetic and electric fields to which the devices respond are enhanced.

So, it is not necessary to purchase a wiring detector in a store. This device can be made at home if you follow the above diagrams.

To all site friends Radio circuits Hello! In this article I want to talk about a very simple and useful device, which, for some reason, is almost not mentioned on the Internet. This circuit contains only three parts, and the name of this device is very simple. So, what does this circuit consist of:

1. DD1 - Chip K176LA7 / K561LA7 / K176LE5 / K561LE5(Underline whatever applicable). As you understand, the device uses one of the above - they have the same pinout;
2. R1 - At least 1 megaohm - to avoid death of the microcircuit from static electricity;
3. Q1 - Any piezo emitter (with a built-in generator is undesirable);
4. B1 - Krona battery or similar;
5. WA1 - Antenna - at least 5 cm (in the photo 10 cm, bent).

Circuit operation

The microcircuit elements are used here as amplifiers. Element DD1.1 amplifies the electromagnetic field “caught” by antenna WA1 (interference from the network), then the amplified signal goes to element DD1.2 and quartz Q1, which are connected via a bridge circuit to increase the sound volume (or rather, unpleasant crackling). Below is a photo of this device (sorry for the quality):

From the “tin” side:

And now, a super compact view (glued together in a moment):

Notes

1. The device does not shine with intelligence and intelligence.
2. This device is suitable for empirical detection of hidden wiring (+ 20 cm).
3. The sound is quiet, but audible and caustic. Can't be confused with anything!

I won’t attach a printed circuit board; I think the circuit is not complicated. I also wanted to make a recording of the detector’s operation, but the camera is UG... Yours sincerely - Antracen.

During the renovation process, you have to remove partitions, break down walls, or move sockets and switches. It's not an easy job. Electrical cables are laid inside the walls under the plaster, and if done incorrectly, an accident can occur. Even the usual installation of bookshelves is dangerous without first locating the cable locations. Having wiring diagrams, you cannot be sure that they correspond to reality, because the previous owner could independently change the wiring without noting this in the diagram.

That is why it is necessary to determine the location of the cables. There are now quite a few detection devices on the market. hidden electrical wiring, but the price sometimes bites. Sometimes it's better to take advantage ready-made diagrams seekers of hidden wiring, and do everything with your own hands, having received the device you need in your household.

The simplest indicator

The first option is the simplest indicator of hidden wires. Necessary materials to make it yourself:

We wind the wire onto the magnetic circuit, solder the ends to the cable, insulate it, insert the connector into the microphone input and the hidden wiring finder is made with your own hands in about half an hour. Turn on the maximum volume and move the coil along the search surface. Based on the change in sound, we find the location of the hidden cable.

Single transistor detector

The following scheme was developed by V. Ognev from Perm. The finder uses a feature of a field-effect transistor; it is very sensitive to the slightest interference. When aiming at its gate, the channel resistance changes. This causes a large change in the current flowing through the phone, resulting in a change in sound. The phone must be high-resistance with a resistance of 1600-2200 Ohms, the battery must have a voltage of 1.5 - 4.5 volts, the polarity of its connection does not matter.

When searching for hidden wiring, the device is moved along the wall and the location of the wire is determined by the sound power. Instead of a telephone, you can use an ohmmeter with a built-in power source, then a battery is not needed.

Detector with three transistors

The device for detecting wiring is made on the basis of three transistors, two bipolar KP315B and one field-effect KP103D. A multivibrator is assembled on KP315B, and on KP103D electronic key. The schematic diagram of the hidden wire detector was developed by A. Borisov.

The principle of operation is the same as in the second option, only instead of a telephone a multivibrator with light indication is used. When the detector is turned on and there is no pickup on the antenna probe, the LED does not light up. When radiation appears in the area of ​​the probe, the field-effect transistor closes, thereby triggering the multivibrator and the LED begins to flicker, indicating the presence of electrical wiring.

Parts used in accordance with the diagram, push-button switch – KM-1, power source – any battery or accumulator with a voltage of 6-9 volts.

You can use a plastic soap dish or a school pencil case as the finder body. The blinking frequency of the LED can be adjusted by changing the characteristics of the multivibrator, changing the values ​​of resistances R3, R5 or capacitors C1, C2.

Electrical wiring detector on two digital chips

The hidden wiring finder circuit developed by G. Zhidovkin is very simple.

Composition: 2 digital microcircuits, piezoceramic emitter ZP-3 and 9 V battery. The role of the antenna is played by the segment copper wire 10-15 cm long and 1-2 mm in diameter.

Induced oscillations from the electromagnetic field of the wiring lead to a change in the output signal of the K561LA7, which is supplied to the input of the K561TL1 with Schmitt triggers. As a result, a characteristic cracking sound is heard, signaling the presence of a cable.

Device based on K561TL1

Unlike the previous version, the wiring finder based on K561TL1, in addition to an audible alarm, has a light indication.

The essence of the work is as follows. When the antenna is brought close to a live wire, an electromotive force with a frequency of 50 Hz is induced in it. This signal goes to the operational amplifier, then to the LED and the input of the K561TL1 microcircuit with a piezoceramic emitter at the output. This causes the audio frequency generator to start and the LED to flicker.

The finder is economical, the maximum current with the indicator on is 6-7 mA.

The antenna is made of one-sided foil fiberglass laminate measuring 55x12 mm. Initial sensitivity is established variable resistor R2. If installed correctly, the device, developed by S. Stakhov (Kazan), does not require adjustment.

Universal Wiring Detector

You can make a universal hidden wiring indicator with your own hands, provided that you have some skills in drawing up radio circuits.

Finder contains two independent block: hidden live wiring finder and metal detector. This allows you to detect electrical wiring when it is laid in steel sleeves or when there is no voltage in the network. Additionally, the detector searches for and finds old de-energized wiring, fittings, nails and other metal objects.

The detector is based on two operational amplifiers KR140UD1208. The hidden wiring detector unit is practically the same as the previous device, only without an audible warning.

The metal detector unit works as follows.

A high-frequency generator is assembled on the KT315 transistor, which is put into excitation mode using variable resistance R6. The output signal of the generator is rectified by the KD522 diode and transfers the collected signal to operational amplifier The KR140UD1208OU comparator is in a state where the audio signal generator assembled on the K561LE5 digital chip is in standby mode and the LED goes out.

By rotating the variable resistance R6, the operating mode of the KT315 transistor is changed so that it is at the generation threshold. Status control is carried out using indicator light and a sound signal generator. They should switch off. To detect hidden wiring, you need to bring the device to the wall, when the antenna (inductors L1, L2) comes close to the metal, the magnetic field changes, generation is disrupted, the comparator starts up, and the LED lights up. The piezo emitter begins to emit sound with a frequency of 1 KHz.

Small metal detector

The detector is designed to search for hidden wiring, fittings and other metal objects.

The main difference from previous models is that you do not need to wind the inductors yourself. Instead, a relay coil is used. The work of the finder is based on the task of isolating the difference frequency of two generators, when, when approaching a metal object, one search generator (LC) changes its oscillation frequency.

The metal detector includes LC and RC generators, a buffer stage, a mixer, a comparator and an output stage.

The frequencies of the RC and LC generators are selected to be approximately the same, then, after passing through the mixer, the output will already have three frequencies. The third is equal to the difference between the frequencies of the RC and LC circuits.

The low-pass filter subtracts the difference frequency and sends the signal to the comparator, where a square wave of the same frequency is formed.

From the output element, the meander goes through capacitance C5 to the telephone, whose resistance should be approximately 0.1 KOhm. Since the capacitance and active resistance of the telephone form a differentiating RC circuit, an impulse will be formed during the rise and fall of the meander. As a result, a person will hear clicks with a frequency twice the difference.

Detection of hidden wiring will be detected by a change in sound frequency. The coil is taken from the RES 9 relay, and the moving elements are removed.
Since the relay contains 2 coils with different cores, the common terminals of the windings must be connected to capacitance C1, and the core and variable resistance housing must be connected to a common bus.

Double-sided foil getinax or fiberglass is used as a printed circuit board. The finder parts should be placed on one side; the other side does not need to be etched, it must be connected to the common bus of the device.

A battery and an inductor from a relay are attached to the second side.

The board is installed in any non-metallic case where the phone connector is attached. Setting up a metal detector begins with adjusting the frequency of the LC generator by selecting capacitance C1. The frequency should be in the range of 60-90 kHz.

Then we change the capacitance of capacitor C2 until sound appears in the phone. When adjusting the resistance in different directions, the sound should change.

Depending on the setting, the frequency will change and the detector will make a sound as if searching for a radio station. The closer the metal, the louder the sound. The tonality depends on the type of metal.

Non-standard methods

Finally, it’s worth describing a couple unusual devices to search for hidden wiring, which can be done even by people who do not have knowledge of electronics. If the house has a regular compass, then this is a ready-made wiring indicator. Before use, the wiring should be thoroughly loaded, and look for the location of the wire by the deviation of the compass needle.

The second method is more effective; the force of a magnet is also used. A permanent magnet, preferably neodymium, is attached to a piece of thread and slowly drawn along the wall. Where the cable or fittings pass, the magnet will deflect. This happens due to the generation of magnetic current by electric current. This is how basic knowledge of the physics of magnetic phenomena helps.

If the wires in the house are hidden in the thickness of the wall, then sometimes you have to look for their location. Let's look at how this can be done. A self-assembled device can be an assistant in this matter. You don’t even need to be a professional in the field of electronics or a radio amateur - the simplest circuit for a hidden wiring detector allows any home craftsman to make it.

In our article we will try to avoid complex scientific and technical terms. We will try to write it in a way that everyone can understand. We will not only provide schematic diagrams of hidden wiring finders, along with the names and brands of parts for assembly, but also show how the pinouts of the elements are located.

Although repairing damaged wiring is not very difficult, it is still advisable to avoid it. Therefore, it is necessary to determine the wiring diagram in the following cases.

1. When remodeling a house and moving partitions, moving door and window openings.
2. If we are going to do renovation work, associated with the installation of various elements in the thickness of the wall or ceiling. Even when hanging a picture on the wall, you can accidentally touch a wire.
3. If we are going to install heating devices. Although they may not be mounted on the wall, pipes and radiators are not allowed to be adjacent to electrical wires; they must be located at a distance of at least half a meter to prevent damage to the insulation from overheating.
4. When repairing and upgrading the wiring itself (for example, installing additional lamps or sockets).

Of course, you can simply turn off the power to the house and connect the damaged wires, but this is inconvenient and dangerous for many reasons.

• Do modern renovation Without a power tool it is impossible; if we turn off the power supply, we will not be able to use it.
• When installing fasteners in the wall, we do not know how far away they are from the wires. It is possible that, without noticing, we did not break the wire, but damaged its insulation. Then the self-tapping screw and the metal shelf it secures will be energized.
• There is a possibility that we will damage the ground wire. This is not noticeable, but the devices he was going to and the people using them will be without protection.

Why do you need a wire detector?

Of course, you can find the location of the wires in other ways:

1. According to drawings- they are not always there and no one is insured that there were no deviations from the project.
2. According to the location of electrical appliances, distribution boxes, sockets, switches and lamps. They are connected by straight vertical or horizontal lines. As in the previous case, this may not be the case due to the “fantasies” of unqualified electricians.
3. Carefully opening the wall trim (especially those with sheet materials) - a labor-intensive and costly method. But if you are going to make repairs, then after removing the wallpaper you can often see traces of sealed grooves or bulges in the plaster, under which wires are hidden.

For all the above reasons, it is clear that you cannot do without an indicator of the location of electrical wiring.

Why make an indicator yourself?

For the reason that it is pleasant to use something made with your own hands. At the same time, you can save money. You can also buy the device; its price ranges from 1000 rubles for Chinese models with little functionality to 10 thousand for professional equipment.

The price of parts for self-assembly is an order of magnitude lower. In addition, almost any device circuit for detecting hidden wiring intended for radio amateurs does not contain rare elements; everything can be extracted from broken household appliances.

How does a hidden wiring finder work?

The search for hidden wiring is based on two principles:

1. any conductor under current emits electromagnetic radiation;
2. metal, even non-magnetic (aluminum and copper) affects the external magnetic field.

To search, either a conductor under current is determined by its radiation, or a magnetic field is induced and its change is determined (like metal detectors). Devices can work on one of the principles or combine two, since each of them has its own pros and cons.

Advantages and disadvantages of searching by electromagnetic radiation

The advantages include:

1. the device does not respond to pipes and fittings in the wall;
2. you can find the location of the conductor break;
3. the scheme is simpler.

On the downside:

1. the wires must be live.
2. After the break the wire is not visible.

Sensitivity increases if current flows through the wires (load is connected). If there is no load, then the wire is detected anyway, since alternating current passes through a kind of capacitor (capacitance) between the device and the wiring. Therefore, you can also look for the location of other cables (television, digital) by connecting an alternating current generator to them. This is the method used by signalmen.

Advice. After a break, the wire can be found by connecting the generator on the load side.

Pros and cons of working on the principle of a metal detector

There is only one plus - you can search for unconnected wires and pipes.

More cons:

1. more complex scheme;
2. less sensitivity;
3. It is difficult to find wires in a reinforced concrete wall.

Now let’s look at the hidden wiring detector circuits and their implementation:

Advice. Sometimes, instead of a finder, you can use a simple phase indicator. Its neon light lights up even without contact with the phase wire, when approached.

The simplest scheme

This is the simplest scheme, so we’ll talk about it first, and explain all the little things in more detail (let those who understand not laugh). Anyone can collect it if they want.

1. field effect transistor type KP 103 or KP 303 (designated VT);
2. power supply 1.5-5 V (one or more batteries);
3. electromagnetic telephone (designated SP);
4. wires;
5. any switch or toggle switch;
6. an ohmmeter (designated Ω) or an avometer (tester), although you can do without it.

The only tools you need are a soldering iron and wire cutters. For soldering, naturally, you must have solder, flux or rosin. Now let's talk more about the unclear details.

Field-effect transistor

The most important detail, in the diagram it is indicated like this:

We look at the right side of the figure, the left is not important to us, its conclusions are indicated by letters:

• “Z” - shutter (the direction of the arrow indicates type p or n; we also do not take this into account now;
• “I” is the source;
• "C" - stock.

If no voltage is applied to the gate of the transistor, then there is a large resistance between the source and drain, and almost no current flows. Having applied voltage, we open the gate and reduce the resistance (like opening a tap on a pipe), the current begins to flow. Moreover, field-effect transistors are very sensitive; the hidden wiring detector circuit is based on this feature.

This is what this part looks like in the photo.

Transistor KP 303 has the same appearance, but differs in marking. After the numbers there is also a letter designation, we do not take it into account. A second version is available in a plastic case in the form of a prism and three flat terminals at the bottom.

How the pins are located on the body should be clear from the figure below. On it, a transistor in a metal case is depicted with the terminals down; you need to navigate by the key.

Attention. Field-effect transistors can burn out from electrostatic interference. Therefore, when working, it is advisable to ground the soldering iron and your body (using a metal bracelet and wire).

This is not a telephone device, but only a part of it (the device got its name from here), it looks like this:

They come with a body made entirely of plastic. Suitable for old rotary phones. It is located in the tube in the part that is adjacent to the ear (from which we hear the interlocutor). In order to remove the phone, you need to unscrew the decorative cover and disconnect the wires at the terminals.

The marking is not important to us except the resistance, it should be in the range of 1600 - 2200 Ohms (can be designated Ω).

The phone works on the following principle - there is an electromagnet inside, which, when current flows through it, attracts a metal membrane. Vibrations of the membrane create the sound we hear.

This is a measuring device for determining resistance.

It looks like this:

If it’s difficult to find, then we’ll do without it, the scheme will work just like that. If necessary, you can draw conclusions for connection and use a “tester” (avometer or multimeter - the same thing) during the search in resistance measurement mode. Almost everyone has this device.

Advice. A simple field-effect transistor with clamped terminals (drain and source) in the crocodiles on the avometer probes can serve as an “ersatz finder” for hidden wiring. The Avometer naturally works in resistance measurement mode.

Assembling the circuit

We assemble all the parts using a canopy using wires according to the diagram. We solder a piece of single-core wire 5-10 centimeters long onto the transistor gate. It will act as an antenna.

After assembly, you can pack everything into any suitable case, such as a plastic soap dish.

Looking for wiring

We bring the device turned on to the wall and begin to move the antenna along it. In the place where the live wire is located, a humming noise grows from the phone (like a working transformer). The closer to the wire, the stronger the sound will be.

You can more accurately find the wiring using the ohmmeter readings; when approached, it shows the least resistance. To work with an ohmmeter, turn off the power to the device.

How the device works

The whole point (as we have already said) is the high sensitivity of the field-effect transistor. The electromagnetic field induced on its gate with the antenna opens the transistor. Current is applied to the phone, and it begins to emit sound signals at a frequency of 50 Hertz (alternating current frequency).

An ohmmeter measures the resistance between source and drain. It becomes smaller as the gate signal increases.

Now let's look at more complex devices, without going too deep into the details.

On the chip

A very common hidden wiring finder circuit is based on the K561LA7 microcircuit.

Attention. The microcircuit may be designated without the letter “K” in front - this means that it is not general purpose, and the special one is of higher quality.

This is a digital chip with the simplest logic, but it works great as an amplifier.

Here you go circuit diagram with microcircuit pinout:

The numbers on the diagram indicate the pin numbers.

In addition to the microcircuit itself, we also need an LED. This can AL307 or its analogues (AL336) with any letter designation and any color, as well as a power source of 3-15 V.

Attention. If we choose a power supply greater than 3-5V, then the current through the LED must be limited by a series-connected resistor of 1-1.5 kOhm.

The principle of operation is simple - a signal from the antenna is supplied to the inputs, as in the previous case, it is amplified. The fact that there is voltage at the input is indicated by the lighting of the LED. Two logic elements (AND-NOT) are connected in series, because the outputs of the microcircuit are inverse, that is, if there is a signal at the input, then there is none at the output and vice versa.

The only disadvantage of this finder is that it does not determine the distance to the wire.

It can also be mounted with a canopy and placed in any convenient building.

Having considered simple circuits detectors of hidden electrical wiring, we will describe the design for experienced radio amateurs.

Combined hidden wiring finder

This device is a “two-in-one” device that can operate both in electromagnetic radiation search mode and as a metal detector.

Here is his diagram:

The selection of modes is carried out by switch S 1, which can supply voltage to one or another unit; we will consider them in turn.

Metal detector unit

It is located in the upper part (currently disabled according to the diagram) and consists of the following nodes:

• Magnetic antenna on a ferrite rod (WA 1);

• A generator assembled on a KT315 transistor (VT 1) and a second magnetic antenna coil (L2);

• Receiver unit on the first coil of the magnetic antenna (L1), capacitor C2 with a detector on the KD522 diode (VD1);

• Amplifier on microcircuit 140UD12 (DA1);

• Indicator in the form of a KIPMO1B LED (others can be used instead, for example AL 307);
• A pulse generator lasting up to a second based on two logical elements of a digital microcircuit of the simplest logic 561LE5 (D1 1; D 1 2);
• An audio frequency generator on the two remaining elements of the microcircuit;
• Piezoceramic emitter ZP-1 (VA 1).

How does a metal detector circuit work?

• The generator is tuned to a frequency close to the receiver's transmission threshold. Trimmer resistors R2 and R6 are used for this.

Advice. To adjust the device during operation, it is even better to select R2 not as an adjuster, but as a variable one, with a knob displayed on the control panel of the device.

• If there is metal nearby, the settings of the generator and receiver circuits change, and the generator signal passes through the receiver's frequency filter.
• Additionally, the operational amplifier - comparator DA 1 has a response threshold compared to the voltage supplied from the divider across resistors R9, R10 to its second input. If this value is exceeded it starts working. The signal is amplified by the operational amplifier to a level sufficient to be perceived by the generator at D1, D2 as a logical unit and start it. The HL 1 LED is also connected to the output of the amplifier, which, when illuminated, indicates that wiring has been detected.
• The signal from the first generator periodically triggers the audio frequency generator on D3, D4. A piezoceramic emitter connected to the generator output emits an intermittent signal.

Magnetic field search block

To start it, you need to set switch S 1 to the second position. This knot is much simpler. It is assembled on a second operational amplifier DA 2.

An antenna is connected to its input, and a second HL 2 LED is installed at the output. If there is interference (signal) at the antenna, the amplifier will raise its level and light up the connected LED.

Device assembly

We won’t give advice here, as the assembly instructions are useless, the techniques are the same as for installing all radio-electronic devices. It is difficult to make it with a canopy; it is better to use a printed circuit board.

Radio amateurs themselves know how to do everything. But there is one caveat - for stable operation you need to separate the magnetic and conventional antennas as far as possible.

Sometimes, if you don’t have a hidden wiring finder or the time (desire) to assemble it, you can try to find it using other devices.

Let me give you a few examples:

• Let's not forget about Oersted's experiment, which discovered the relationship between magnetism and electricity. The scheme for searching for hidden wiring is as follows - we connect the load and, based on the maximum deviation of the arrow, we find the position of the wires. The main thing is that the current is significant, for example, the iron or vacuum cleaner is turned on.

• A radio tuned to the maximum wavelength can respond to the wiring. The method works especially effectively if there are sources of high-frequency interference in the network.

• An electrodynamic microphone connected to an amplifier; the most common electret microphones today do not operate in this way. You can also use the pickup of an electric guitar by first removing the strings from it. It is better to search using a “single-coil” (narrower, in one row) than using a “humbucker”, which has protection from external interference.

• If you still have a cassette, or even better, a reel-to-reel tape recorder or player, then you can remove their head by removing it and extending the wires and look for the wires, using it to turn on the device for playback.

Attention. The magnetic head must be connected with a shielded wire.

• Some people also try to search for wires using applications on their smartphone. But on personal experience I will say that the method does not work. I used the “Metal Detector” program, so she did not see the closely held wire to which a three-kilowatt motor was connected. Although maybe I'm wrong.

I hope that our article not only gave you the answer to what a hidden wiring finder circuit looks like, but also helped you assemble this device yourself. We are also glad if you understand why you need to know the location of the hidden wires. Make home repairs quickly and safely.

During apartment renovations, especially in old houses, an electrical wiring diagram is required. Otherwise, when drilling holes or tapping, you can damage hidden wires that are energized.

Important! Regardless of whether you know where the wiring is located, work in the room should be carried out during a power outage.

A metal and hidden wiring detector is used for searching.

Such a device can be purchased at a power tool store. This is essential equipment for repair teams. However, if you are simply renovating your apartment over a period of several years, the cost of purchasing it is irrational. The design of the device is simple. A craftsman who knows how to hold a soldering iron can make a wiring detector with his own hands. In this case, its value will tend to zero.

How to make a wiring detector yourself?

There are two main concepts:

1. Voltage multiplication principle;
2. A radio receiver on a microcircuit that detects an electromagnetic field.

Both designs are easy to manufacture and are assembled using accessible components. If you are into electronics, you can pick up radio components in your workshop. Even if you buy them on the radio market, the cost is incomparable with a factory sample.

Determinant of hidden wiring on transistors

Components for manufacturing:

1. A multistage voltage multiplier will require ultra-sensitive transistors. BC547 has proven itself well. These are silicon miniature bipolar triodes, with n-p-n structure. They have a fairly high gain with minimal noise;
2. Low power resistors. 1Mohm, 1kOhm and 220Ohm. For the first, second and third cascade, respectively;
3. Indicator LED;
4. Batteries or accumulators;
5. Frame.

Schematic diagram of the device:

The first stage receives a weak signal from the antenna, shown in the diagram with an arrow. It is an electromagnetic field created by electrical wiring.

Tip: To increase the search efficiency, it is recommended to plug in a low-power electrical appliance that creates interference, for example, a room fan.

A small current appears at the emitter, which is repeatedly amplified by the second stage. The almost finished signal is fed to the base of the third transistor (cascade). After amplification, a electricity, sufficient to light up the LED. The device is powered by 6 volts.