Hello.
Watch the video 15 seconds to understand how the application works.
You can find/trace the wire in the wall.
You can determine the presence of an alternating current (50 Hz, not voltage!) In the unpaired, single wire for urban or industrial network. The scheme is shown at the top.
Current will be well-defined under a load of> 0.6 kilo watts.
Using mentioned above wiring circuit, wire layout can be determined in the wall.
No matter, is the wire zero or phase - the main thing that the current should to flow through one..
The current may be less, but it is better if> 3A.
If one of cords has rupture in wall you always have one of them to pass through/energize it the current.
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It is enough to see the 14 second video.
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You can also scan metal objects only if you use them as a ground for alternating current (50 Hz).
In double wiring , both wire current flow against each other. So standing wave can not be identified.
ATTENTION!
1. Be careful when handling electricity.
2. Not all phones have a magnetic sensor with sufficient frequency measurements.
I've used Samsung S4.
Thank you.