Hidden wiring detector on K561la7 has poor sensitivity. Sound detector of hidden wiring. Universal Wiring Detector

Good afternoon, dear electronics lovers!
I decided to add and correct something in my apartment network. The time has come for chiseling and drilling the walls, but during this procedure I am always worried about the question: will we encounter wiring in the wall, especially near the electric meter?
This means you need a hidden wiring detector!

Detector circuit that “didn’t take off”

The following scheme was chosen on the Internet:

I decided to add a little creativity and insert the device into an empty bottle of roll-on antiperspirant.

Due to the simplicity of the circuit, I decided not to make a printed circuit board, but mounted everything on the back and belly of the microcircuit. To power the circuit, I decided to use a Li-Ion battery from an old netbook battery and.

The process of assembling and compacting all the contents into the case began.

I decided to make the antenna not from copper wire (as recommended), but from a piece of television coaxial cable. I liked that it was tough but flexible.
Unfortunately, the operation of this scheme did not suit me at all. I experimented with antennas of different lengths and from different materials. I didn't get any results. The wiring was stubbornly missing from the walls.

Modified hidden wiring detector circuit

Then I decided to try adding a field-effect transistor to the input of the device, like the factory device “Dyatel E-121”. After this I was very pleased with the result. The device turned out to be sensitive and quite accurate for a homemade product. Plus, powered by a battery that charges from any smartphone charger with micro-USB.

The device sees approximately 30 - 50 mm in the wall. Much depends on the intensity of the current in the conductor, the material of the walls, etc. In addition, electricians say that you need to get used to any such device.
I am writing an article because such a device is a very convenient, useful and easy-to-assemble design that will be useful to any home craftsman.

A few words about the details

The scheme is simple.
C1 = 0.1 uF (100 nF), ceramic or film. C2 = 150 pF, ceramics. C3 = 4700 pF (4.7 nF), ceramic or film.
C4 = 50...1000 uF x 16V.
All resistors with a power of 0.125 W and above.

Chip K561LA7(4 logical elements “2I-NOT”) can be replaced with imported 4011.

There is a special high-resistance resistor R1 in the circuit. I set it to 100 MOhm. There was no such rating on the radio market, so I had to make a small “bayanka” from resistors. I don’t recommend setting the denomination lower - the sensitivity will decrease.

Any piezoceramic emitter such as ZP-3, ZP-1, etc. can be used as a sound emitter.
For transistor KP103 the most likely replacement of KP303 when the connection changes (it has an n-type channel).
KP103 (p-channel) = 2N3329, J174, J175, J176, J177, MMBF5460.
KP303 (n-channel) = 2N3823, J210, J211, J212, MMBF4392.
How they will work in this scheme - we need to experiment and check.

Total

Here's what happened in the end:

The wife, having heard enough of the device “chirping” during testing, suggested calling the device “Cicada-1”. There were no objections. I just added the letter “M” at the end - it’s a modified circuit!

Quite often, residents of apartment buildings need to attach a picture, hanger, shelf or some other piece of furniture to the wall of their apartment. To do this, you need to mark a point on the wall and drill a small hole with a hammer drill. However, there is always the possibility of getting caught in the wiring hidden in the wall under the wallpaper - in this case, a small renovation of the interior may result in the inevitable call to the electricians. To prevent this from happening, you can assemble a simple hidden wiring detector that will show exactly where the wires are and where they are not.

Scheme

The sensitive element of the circuit is a field-effect transistor KP103, to the gate of which an antenna is connected. You can use a transistor in any package and with any letter index. The device reacts to wires under voltage of 220 V 50 Hz, regardless of whether current flows through them or not. The circuit also uses the K561LA7 microcircuit, which consists of 4 2I-NOT logic elements. It can be replaced with an imported analogue, the CD4011 microcircuit. The LED on the circuit lights up when the antenna is in close proximity to a live wire. As an antenna, you can use a piece of ordinary thin wire, 5-10 cm long. The longer its length, the greater the sensitivity of the device. The circuit consumes approximately 10-15 mA and is powered by a voltage of 9 volts. A regular Krona battery is suitable for power supply. If necessary, any piezoceramic emitter, for example, ZP-3, can be connected to pin 10 of the microcircuit, then a sound will be heard when a wire is detected.

Detector assembly

The circuit is assembled on a miniature printed circuit board measuring 40 x 30 mm, which can be made using the LUT method. The printed circuit board is completely ready for printing; there is no need to mirror it. After etching, it is advisable to tin the tracks; this will simplify the soldering of parts, and the copper will not oxidize.

After manufacturing the printed circuit board, you can solder the parts. You should be careful when handling the microcircuit - it is sensitive to static and can be easily damaged. Therefore, we solder the socket for the microcircuit onto the board and place the microcircuit in it only after the assembly is completed. You also need to be careful when soldering the transistor - if it is in a plastic case, then only two legs are soldered onto the board - drain and source, and the antenna is soldered directly to the gate. If the case is metal, all three legs are soldered onto the board along with the antenna. It is important not to mix up the pinout, otherwise the device will not work. For convenience, the power wires can be immediately soldered to the connector for Krona, as I did. After completing soldering, be sure to wash off any remaining flux from the board, otherwise sensitivity may be affected. It is also advisable to check the correct installation and adjacent tracks for short circuits.

Detector tests

After assembly is completed, testing can begin. We take the crown and connect it to the board, placing an ammeter in the gap of one of the wires. The circuit consumption should be 10-15 mA. If the current is normal, you can bring the detector antenna to any network wire and watch how the LED lights up and the piezo emitter beeps, if installed. The wire detection range is approximately 3-5 cm, depending on the length of the antenna. In this case, you should not touch the antenna, as this will significantly reduce the sensitivity. The device does not require any setup and starts working immediately after power is applied. In addition to network wires, it also responds to twisted pair cable. Happy assembly.

The video clearly shows how such a detector works. With its help, you can accurately determine where the wires from the switch run.

This article will look at the circuit of a fairly simple hidden wiring detector. Making it yourself is not difficult, since all the parts are available and the circuit is not complicated; there is also a file with a printed circuit board. This detector will help you determine the location of electrical wiring that is hidden in the wall, thereby eliminating the possibility of damage to it during certain work.

Detector circuit:

The sensitive element of the circuit is a field-effect transistor, to the gate of which an antenna is connected. You can use a transistor in any package and with any letter index. The device reacts to wires under voltage of 220 V 50 Hz, regardless of whether current flows through them or not.

The circuit also uses a microcircuit, which consists of 4 2I-NOT logic elements. It can be replaced with an imported analogue, a microcircuit. The LED on the circuit lights up when the antenna is in close proximity to a live wire.

As an antenna, you can use a piece of ordinary thin wire, 5-10 cm long. The longer its length, the greater the sensitivity of the device. The circuit consumes approximately 10-15 mA and is powered by a voltage of 9 volts. A regular Krona battery is suitable for power supply. If necessary, any piezoceramic emitter, for example, ZP-3, can be connected to pin 10 of the microcircuit, then a sound will be heard when a wire is detected.

Detector assembly

Once the printed circuit board is ready, you can begin to solder the parts. You should be careful when handling the microcircuit - it is sensitive to static electricity and can be easily damaged. Therefore, we solder the socket for the microcircuit onto the board and place the microcircuit in it only after the assembly is completed.

You also need to be careful when soldering the transistor - if it is in a plastic case, then only two legs are soldered onto the board - drain and source, and the antenna is soldered directly to the gate. If the case is metal, all three legs are soldered onto the board along with the antenna.

It is important not to mix up the pinout, otherwise the device will not work. For convenience, the power wires can be immediately soldered to the connector for Krona, as I did. After completing soldering, be sure to wash off any remaining flux from the board, otherwise sensitivity may be affected. It is also advisable to check the correct installation and adjacent tracks for short circuits.

Detector tests

The wire detection range is approximately 3-5 cm, depending on the length of the antenna. In this case, you should not touch the antenna, as this will significantly reduce the sensitivity. The device does not require any setup and starts working immediately after power is applied. In addition to network wires, it also responds to twisted pair cable. Happy assembly.

If you have to carry out installation work that could lead to damage to hidden wiring, then you need to find a place where the wires do not pass under the plaster. And if you are not a professional electrician, then it is not necessary to buy a special device for one time. You can make a hidden wiring indicator with your own hands from what you find at home.

You can come up with many options for designing a hidden wiring detector. The circuits of some devices are simple and understandable for a schoolchild, while the circuits of others are accessible to an experienced electrical engineer.

They differ in the number and types of elements: look at what you have on hand, and based on this, choose a scheme.

Important! Keep in mind that some homemade products, if assembled incorrectly, may give a signal for no reason or not give it at all at the right time: it is unsafe to use such devices.

Circuit with sound indicator

This non-contact indicator of hidden wiring is based on a microcircuit K561LA7. To protect it from high voltage created by static electricity, you will need a 1 MΩ resistor (in the diagram R 1). The device is powered from the crown (9V). Copper wire or any metal rod with a length of 5 to 15 cm is suitable as an antenna. The golden mean is 10 cm. It is important that the wire does not bend under its own weight.

If you bring the assembled device to a live wire, you will hear a sound resembling a crackling sound. This is possible thanks to the presence of a piezo emitter (in the diagram ZP-3), increasing the volume. With this detector you can search not only for hidden wiring, but also for a burnt-out light bulb in a garland. You can find out about its location by the fact that the crackling stops near it.

Circuit with sound and light indicator

This device can be powered by batteries with voltages from 3 to 12 V. A resistor is used to limit the current R1, the resistance of which should not fall below 50 MOhm. But for the LED (indicated AL307) such a resistor is not provided: it is not needed, because the microcircuit used ( K561LA7) will do everything herself.

When the finder approaches a live wire, not only will a noise be heard, but the LED will also light up. Double indication is more reliable.

Two-element indicator

You only need a chip and an LED. Suitable for assembly DD1 And HL1 respectively. The whole purpose of the work is to connect the pins of the microcircuit so that there are three inverters in the chain. This do-it-yourself hidden wiring finder amplifies the currents that the field induces on the device alternating current in wires hidden by a wall. As a result, when approaching the wiring, the LED light comes on, and when removed or the circuit is broken, it goes out.

2 options:

Connect pins: 3rd – with 8th and 13th, 2nd – with 10th, 4th – with 7th and 9th, 1st – with 5th, 11th – from the 14th;
Connect pins: 3rd – with 8th, 10th and 13th, 1st – with 5th and 12th, 2nd – with 11th and 14th, 4th – with the 7th and 9th.

Microcontroller detector

This diagram shows a hidden wiring finder on a microcontroller PIC12F629. Its action is based on sensitivity to the magnetic field created by a current with a conductor hidden in the wall. Depending on which indication method you prefer (light or sound), you can include a piezo emitter or an LED light bulb in the circuit. Therefore, you will know that a magnetic field has been detected in hidden wiring by a lit light bulb or a characteristic crackling sound.

This device has an undeniable advantage: it responds only to a frequency of 50 Hz - this is the frequency of alternating current. Erroneous signal activation is excluded: a magnetic field from a source with a frequency lower or higher than the specified one will not activate the device.

Hidden wiring alarm without batteries

The DIY hidden wiring detector, the diagram of which is presented above, uses the network itself as a power source. This became possible thanks to the use of a capacitor with a large capacity (in the diagram C1). You can charge it by connecting the device to the network. A charged capacitor produces a voltage of 6-10 V. Moreover, only the brightness of the LED depends on its value; the sensitivity of the device does not decrease from this.

Industrial circuits of professional detectors and their analogues for homemade products

Make Woodpecker at home? Can. But it is complex in an assembly that includes many elements. And the quality of the analog’s work will depend on your attentiveness when reading the diagram and the accuracy of execution. Below are 2 diagrams: the first is industrial, the second is for a homemade “Woodpecker” (click on them to enlarge).

You can play and YADITE 8848, the design options of which are also shown on two electrical diagrams (also enlarged by clicking).

Testing homemade hidden wiring alarms

Before using homemade products, it is necessary to test hidden wiring detectors. It will show if the device is working properly. Testing order:

Find an area where 100% hidden wiring runs (sockets and switches);
Test your homemade alarm by running it along the wall around the outlet;
If the signal is received only at the place where the cable passes, you can use the device;
If the signal appears and disappears in different directions from the outlet, then the device does not work.

Attention! Before searching for hidden wiring, give it maximum load. To do this, include as many electrical appliances as possible. This will help strengthen the electric and magnetic fields that the testers respond to.

To make sure you don’t hit a cable hidden by a wall with a hammer drill or a nail, you need to become familiar with the wiring diagram in your apartment. But often it gets lost, and finding the wires becomes difficult. However, with the help of a homemade electrical wiring detector, you will accurately determine the place where you can hang a shelf or picture. You don’t need to rush to the store for this: you will find all the elements at home in old electronics.

5 diagrams for manual assembly of a wiring finder. Top 8 most popular devices with prices, advantages and disadvantages. Top 4 detectors on AliExpress.

TEST:

Is it necessary to ground the soldering iron when assembling a finder with a field-effect transistor:

When assembling a break finder, in what position should KP 103 be installed:

A. in horizontal;

b. in vertical.

What resistance is needed for the wire when assembling a finder using a radio:

What resistance is needed for the speaker when assembling a device based on a field-effect transistor:

A. 3000-5000 Ohm;

b. 1600-2200 Ohm.

What resistor will be needed when assembling a finder using Arduino?

Answers:

There are situations when you need to find wires, running deep into the wall. A special device that you can make yourself will help you find them. Using simple diagram, anyone can put this together device.

4 steps to build a highly sensitive device yourself

To assemble a simple wire finder device you need:

Prepare materials: a metal rod, a wire for winding around a transformer (with a resistance of 500 ohms), a cable from a microphone with a connector, a radio into which you can insert a microphone.
Wind the wire around a metal rod.
Solder the ends of the wires to the cable and make insulation.
Insert the cable connector into the radio.

After detector ready, you will need to turn on the radio at the highest volume and move the coil along the wall. A changing sound will indicate the presence of wires.

1st diagram for assembling the detector

Look at the picture, which shows the assembly of a wiring finder using a field-effect transistor.

Rice. 1 Assembly based on a field-effect transistor

The device works on the principle of finding an electric field. To assemble a simple wiring finder using a field-effect transistor, you need:

Soldering iron, rosin, solder.
Knife, wire cutters, tweezers.
Field effect transistor (KP 303, KP 103, Kt 315).
A speaker with an impedance of 1600 to 2200 ohms.
Battery (15-9 V).
Switch.
Wires.
Plastic container for mounting parts.

The speaker will emit noise, which will increase when brought to electrical wires.

2nd scheme: with adjustable sensitivity

Look at the picture showing an assembly option for a wiring detector whose sensitivity can be adjusted.

Explanation of circuit symbols:

T-KP 103;
HL – AL107BL;
R1 – 2.0 kOhm;
R2 – 2.0 kOhm;
R3 – 1.0 Mohm;
C1 – 5.0 µF;
C2 – 20.0 µF;
SP – speaker whose resistance is from 30 to 60 Ohms;
L – 20-50 turns of wire with a diameter of 0.3 – 0.5 mm.

3rd circuit break finder

Look at the picture to help you assemble the cliff finder. wiring.

This device will allow you to detect not only the wire, but also record its break. Pay attention to some of its characteristics:

The device is compact;
antenna size – 5-10 cm;
The VT1 sensor is very sensitive. When its shutter is close to the wiring, the LED will light up.

Important! When assembling, KP 103 is installed in a horizontal position. The gate is bent to place it above the transistor.

4th circuit: using Arduino

Look at the picture showing the build of the finder using two transistors.

Arduino– a trade name for hardware and software for assembling lightweight automation systems. Software component: software shell for creating programs, hardware – assembled printed circuit boards. It is intended for non-professional users.

To assemble the device you need: controller (board) Arduino, resistor 3.3 MΩ, LED, wire.

Connect the LED between ground and 11 PWM pin of the controller.
Place a resistor between ground and the fifth analog input.
Connect the wire to the same contact.
Connect Arduino to PC.
Upload the sketch:

int inPin = 5;
int val = 0;
int pin11 = 11;

void setup()
{
Serial.begin(9600);
}

void loop()
{
val = analogRead(inPin);
if(val >= 1)
{
val = constrain(val, 1, 100);
val = map(val, 1, 100, 1, 255);
analogWrite(pin11, val);
}
else
{
analogWrite(pin11, 0);
}
Serial.println(val);
}

Sketch- This special program, created for Arduino. To fill the sketch you need:

Open the program.
Copy and paste the sketch.
Click the fill button.

Then it will happen compilation(converting program code into binary code that the controller will execute). Then, if there are no errors, sketch will be flooded. When you bring the device to the outlet, the LED will light up.

Below is a visual example of filling:

Rice. 5 Example of sketch filling.

Important! It is necessary to power the controller from the battery, since the computer is a source of electromagnetic field. This picture will allow you to assemble a finder using a microcircuit K561La7. For assembly you will need: microcircuit, LED (AL 307, AL 336), battery 3-15 V.

The main point: at the input, the antenna supplies signal. The presence of voltage will be indicated by a lit LED. Logical elements (AND-NOT) are entered in sequential mode, since the outputs of the K561La7 inverse(if there is a signal at the input, then it is absent at the output).

Top 8 devices. Review rating. Which to choose. The best searcher according to the editors

The market offers a wide range of different detectors wire detection. Based on consumer reviews, you can make a rating of devices offered on the market and choose the best one.

ADA Wall Scanner 50

Identifies ferrous and non-ferrous metals, wiring and communication lines.

Search depth: wires (mm) - 50, metal - 50. Weight: 12 Dimensions: 225x130x30(mm).

Reviews: good, unprofessional, identifies wires, but there are mistakes, low price.

Dyi Duwi

The device calculates metal and wiring.

Detection depth: metal – 24 mm, wires – 30 mm. Nutrition: Krona batteries.

Reviews: good equipment, low price, but there are errors in the search.

Rst tc 15

The device detects metal and cable with electric shock Search depth: metal – 38 mm, copper – 19 mm, cable – 50 mm. Runs on Krona batteries. There is an auto shutdown mode and a discharge indicator. Dimensions: 115x70x50 (mm).

Reviews: good device, reasonable price, accurate wiring definition.

Bosch GMS 120

Device detects metal: ferrous and non-ferrous, electrical wiring. Calculation depth (mm): wood – 38, metals – 120, wiring – 50. Powered by Krona batteries. Dimensions (mm): 120x80x50. Reviews: good device, high price.

DSL 8220

Detects closed wiring, communication lines, antenna wires. Has light and sound warning. Weight 200 g. Dimensions: 195x50x20 (mm). Depth search up to 20 mm. Runs on Krona batteries.