Have you ever wondered how far the electromagnetic fields from power lines can be picked up? In this experiment I brought a large coil of wire with me far up in the mountains, and attached it to my audio amplifier, and much to my surprise, I still had a pretty strong 60 cycle AC hum at a great distance from the power lines.
The other reason I wanted to get away from the 60 Cycle AM hum, was that I wanted to see how far a giant inductive coil would be able to hear small electromagnetic signals powering the speaker in my small digital tape player.
For anyone interested in knowing the coil size. I used two coils in this experiment. Each coil was wound on a spool that had 34 inch circumference, and each coil weighed about 6 pounds. The wire appears to be 30 gauge. You can use copper enamel magnet wire, or whatever you happen to have, but it seems that the larger the diameter of the spool it's wound on, the more sensitive it appears to be, and the more turns you have, the more sensitive it appears to be. Have fun.
For those who may be interested, I made a longer version on this experiment in the landscape mode you may find more interesting at this link.    • Giant induction coil picking up Audio...