[aimor]

An alternative method: build a LEctenna.

https://www.nrl.navy.mil/STEM/LEctenna-Challenge/

I stumbled across this little project a few weeks back, ordered the parts (just a diode and an led), and it works. Put a bowl of water in the microwave (or dinner), turn it on, then wave the lectenna around the cracks and see where it lights up.

I originally found the lectenna by researching if it was possible to power an LED wirelessly by leeching power from a house 60Hz line. I haven't made any progress on that, so if you have ideas I'd love to hear them.

[fy20]

If you run a low voltage 24V DC power cable for lighting next to a 220V AC line (I'm in Europe, no idea if 120V does the same) it's quite easy to get a situation where there is enough power for LED lights to be lit even when switched off. This is why low voltage wiring (lighting, ethernet, hdmi, etc) should not be ran parallel to AC power cables.

[dhdc]

Oscilloscopes often pick up some small voltage at 60Hz when the probe isn't connected to anything, and that voltage increases when a human touches the probe by acting as an antenna. But this is because of the scope's high input impedance(1-10MΩ); as soon as you try to power something off that, the voltage just collapse to zero.