overview: We created a simple crystal radio inspired by the following website http://www.crystalradio.net/cub_scouts/index.shtm... Materials: piece of wood/cardboard
4 in piece of one inch diameter PVC pipe
large paper clip
30-100 ft of antenna wire
27 feet of copper wire, coated
drill 1 N34A signal diode
47000 Ω carbon resistor
Test results - We attempted to use this radio both inside and outside, outside worked better; it allowed more white noise and almost voices to come through. The voices get louder as you silence the people around you and create a web of wire to nest yourself in. We would suggest having closer to fifty feet of antenna wire to get stations more consistently.
Radio waves alter the electric and magnetic fields around the antenna, moving electrons between it and the ground. The coil (whose length is effectively adjusted by the movement of the paper clip) acts as a capacitor which charges and discharges at a resonant frequency corresponding to the frequency to which the radio is tuned, enhancing the desired signal and discarding the others. The diode converts the signal to an intermittent direct current at the frequency of the radio waves whose average intensity over short periods of time affects the movement of the speakers, thus decoding an amplitude-modulated signal.