During repair work, you need to demolish partitions, tear down walls or move electrical outlets with switches. There is electrical wiring under the plaster in the middle of the walls, and making mistakes can lead to accidents. Even the trivial hanging of a kitchen cabinet or bookshelf can carry a risk of electric shock. To avoid this, use a wiring finder that you can assemble yourself.
Content
- The simplest indicator circuit
- Single transistor detector
- Scanner with three semiconductor triodes
- Portable metal detector
The simplest indicator circuit
You can assemble an elementary diagram of a hidden wiring finder with your own hands from radio components that are at hand. To assemble the device, you will need the following materials:
-
core (magnetic circuit); - transformer winding wire with resistance ≈ 500 Ohm;
- microphone cord with a plug;
- a radio receiver with a microphone jack.
The winding wire is wound around the core, the ends are soldered to the microphone cord and insulated. The plug is inserted into the microphone jack. The wall wiring finder is ready in no time. The volume of the receiver is set to the maximum mark and the coil is held in the places of the proposed wiring. The change in sound will indicate the location of the hidden electrical wiring.
Single transistor detector
This detector uses the functionality of a field-effect transistor, which responds to even the slightest interference. When aiming at the shutter of the seeker, the resistance of the channel changes.
This provokes a strong fluctuation in the passing current in the phone with a change in the sound signal. The phone must have a high resistance of 1.6 to 2.2 kOhm and a galvanic cell with a voltage of 1.5 to 4.5 V. When connecting a galvanic cell, the polarity can be ignored.
To find hidden wiring in the wall, the detector scans its surface or partitions, according to the increasing sound signal, the location of the electric wire is determined.
The phone can be replaced with an ohmmeter with a built-in rechargeable battery, then there is no need for a galvanic cell.
Scanner with three semiconductor triodes
The manufacture of this hidden wiring detector circuit is based on three semiconductor triodes: two bipolar and one field. On bipolar transistors, a multivibrator is equipped, and on a field-effect transistor - an electronic key. The fundamental difference from the second option is the use of a multivibrator with a light notification, and not a telephone.
The detector in operating mode in the absence of radiation will not signal with a light indicator. As soon as there is radiation in the area of the measuring rod, the field-effect triode should close and activate the multivibrator. The LED lights up, signaling the presence of an electric wire.
The following elements are used in the scheme:
- small-sized button KM-1;
- battery or galvanic cell from 6 to 9 V;
- measuring rod;
- detector housing.
Any plastic box of a suitable size will be suitable for making the detector housing. The blinking frequency of the diode is regulated by converting the parameters of the multivibrator, adjusting the ratings of the capacitors or resistances.
Portable metal detector
The purpose of the metal detector is to find hidden electrical wiring, metal frames and profiles.
The main difference from previous designs is the use of a relay coil instead of an inductor. The principle of the metal detector is to isolate the difference frequency of the LC and RC generators. When approaching a metal object, the oscillation frequency of the search generator changes.
The design of the metal detector includes:
- high and low frequency generators;
- buffer and output stage;
- mixer;
- comparator.
The frequencies of the generators are chosen to be almost identical. When they pass through the mixer, three frequencies are generated. The third frequency will be equivalent to the difference between the oscillating circuits and the RC frequencies. Difference frequency determined by low pass filter, which sends the signal to a comparator (comparator), where a periodic square wave (square wave) with the same frequency occurs.
The meander hits the phone, the resistance of which should be ≈ 0.1 kOhm through the capacitor C5. Since a differentiating RC circuit is formed from the capacitor and the active resistance of the phone, an impulse appears at the upper and lower points of the meander. As a result, clicks will be heard, the repeatability of which will be twice the difference frequency. Determination of hidden wiring will be carried out by converting the frequency of sound.
Before starting the test, the wiring must be loaded to the maximum. To ensure the required load, connect as many electrical appliances as possible. This will provoke an increase in the electric and magnetic fields to which the detectors receive a response.
