DIY DO-IT-YOURSELF HIDDEN WIRING DETECTOR

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An AC voltage detector is a device that detects the presence of alternating current over a short distance without any electrical connections to the line.

This simple device will help you determine the presence of life-threatening voltage in the network and wires, help you find the place of cable laying in a concrete or brick wall.
The scheme is very simple and from a minimum number of parts. The circuit of the device is a composite transistor, consisting of three conventional. The result is a sensitive amplifier (with a DC gain of more than 100,000), the load of which is the LED.
If you have all the components, the assembly will take no more than an hour. This scheme is probably the most common and most effective for beginner hams.

Required Components

Battery type "Krona" - 1 piece.
LED - 1 piece.
Transistor 2N3704 (or domestic CT3102 or CT315) - 3 pieces.
Resistors:
-1MOhm - 1 piece.
-100 kOhm -1 piece.
-330 Ohm - 1 piece.
-220 Ohm - 1 piece.
Switch - 1 piece.

Aluminum or copper continuous thin wire - 5 cm

Detector design

I etched the board and soldered all the elements as it should, but you can also assemble them on the breadboard by soldering the jumpers with a normal wire. The circuit turned out to be very sensitive.

After assembly, the detector is ready for operation and does not need to be configured. If for some reason the device does not respond to anything - check that all elements are turned on correctly and that the transistors are working.
Detector construction and video testing:

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