The main element of many hidden wiring detectors is a field effect transistor. All other elements - amplifiers, power, indication or generator ...

Did you know that you can do without any additional radio components at all?

Just take only one transistor and a multimeter, and go in search of what is hidden from our eyes :)

Don't believe? I’ll tell you about this in a smart way now, and at the end of the article I will demonstrate in the video version of the article how it works :

The simplest hidden wiring detector

In my experiments, I used field-effect transistors of the Soviet-style KP103E and 2P301B.

The principle of the technique is very simple:

Switch your device to resistance measurement mode. The measurement limit is 10 kOhm or 20 kOhm.

The resistance between drain and source can change if the transistor is exposed to an electromagnetic field. The shutter is not connected to anything - it will be our antenna. If you solder a wire 3-5 cm long to the gate, the sensitivity of the circuit will increase.

It is enough to bring the transistor to the wire that is connected to the mains voltage - the drain-source resistance will increase by 1.3 - 5 times.

According to this indicator, we can conclude that there is a wire somewhere nearby.

Keep in mind that the field effect transistor is afraid of "static", so put a cambric on the end of the gate.

We will conduct two experiments: with a pointer device and with a digital one.

From this outlet, the wire goes to the left.

So, the transistor is away from the outlet and the wall. Look at the scale. Note the position of the arrow.

Now let's bring it to the outlet.

Wow!!! The arrow went to the left! What values ​​were there - it does not matter. The main thing is that the arrow changes its position depending on the distance to the electrical wiring.

Now let's test the technique with a digital multimeter:

We will drive the transistor along the wall from top to bottom. (The red arrow shows the actual location of the wire.)

As long as the transistor is away from the wire, the junction resistance is 780 ohms.

As the transistor passed through the cable run, the resistance increased to 2000 ohms.

Having passed the place where the cable lay, the resistance returned to its previous value - 780 ohms.

If you are interested in the method, first practice in those places where you know exactly the route of the cable or wire.

Video version of this article: