I'm trying to build a simple AM crystal radio, however, I'm not getting any voltage registered when using it. This is the kind that's only powered by the radio waves. The site I was using to design it makes the circuit clear and how the radio works pretty self-explanatory, but I couldn't read their diagram for making a good antenna. Right now I just have a wad of 22 gauge insulated speaker wire I'm holding up really high so I figured I'd ask stackexchange how to make a good antenna.
How can I build a good antenna for a crystal radio? Here's the site http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_p014.shtml
Best Answer
The simplest antenna for a crystal radio is a long wire (say 10m), and up as high as you can get it. On the roof is best if you can get up there. The wire should be stretched out, not rolled up. Outside is best, to avoid signal loss in any metal in the building's structure. Make sure the antenna is attached with insulators at both ends. To make it simple, take your long wire, attach one end with an insulator. Unwind enough of the wire to reach the other end. Attach it there with an insulator as well, but don't cut the wire. Instead, use the remaining wire to connect it to your radio.
The voltages generated by a crystal are very small indeed, and they are at radio-frequency AC, so they may not show up on a simple voltmeter. You should be able to see the signal with an oscilloscope though.