DIY non-contact high voltage detector

With this simple three-transistor detector, you can easily determine whether a cable or installation contains life-threatening voltage. For example, you turned off the electricity in the apartment. And to make sure that all the wiring is de-energized, it is enough to bring a homemade detector to it and make sure that there is no threat to life. In general, this is definitely a necessary thing in the household, and not only in the household.

Life-threatening voltage detector, manufacturing

The device is made with three transistors, without a board for surface mounting.

Please note that the circuit uses transistors of different structures. There are no special requirements for them; almost any will do.
Used as signaling elements Light-emitting diode and buzzer. The role of the antenna is played by a piece of wire 5 cm long.

The detector is powered by two little finger elements.

The body is a transparent plastic tube.

After assembly, if all elements of the circuit are in working order, the detector starts working immediately and does not need adjustment.

Checking the detector

We bring it to a socket with alternating voltage 220V.

Light-emitting diode lights up clearly and the buzzer emits a characteristic signal.
Next we test at a voltage of 380 V.

The result is the same. Everything works without failures.
Next is an ASU with a voltage of 6.6 kV.

Touching something like this is dangerous, so the detector reacts from a distance.
High-voltage poles with a voltage of 13 kV.

Electric locomotive power lines 25 kV.

The higher (and therefore more dangerous) the voltage, the sooner the detector is triggered when approaching an object, notifying you of a serious danger.