This simple circuit is able to detect signal from your cellphone antenna and converts it to electricity to power an LED
( the best thing about this is that its completely passive and doesn't require batteries )
this circuit requires:
RF diode ( search ebay for: RF diode or microwave diode)
Peace of wire
I have Noticed that it only detects phones working on (EDGE), ocasionally works on 3G
I have a low knowledge about RF but I think it has to de with the shape and/or length of antennas.
So if you can contribute to make it work better please do so.
( this is based on a video i saw a long time ago on you tube )
the video had no instructions.
here is the link
(RF energy, LED, tesla, passive, electricity)
Step 1: LED+RF diode
First Solder the led parallel to the Rf diode