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Sep8-10, 02:05 PM
PF Gold
Dadface's Avatar
P: 2,022
Take a long piece of wire as an antenna connect one end of the wire to one side of a suitable diode and the other end of the diode to one side of a pair of high impedance headphones or an earpiece.Connect the other side of the headphones to a suitable earth(ground) such as a water tap and listen in,you will have built a basic type of radio called a crystal set.You can improve your radio by the addition of extra components such as a variable capacitor and a coil to make a tuning circuit.No battery is needed and the antenna picks up radio waves the energy coming from the radio transmitters.It is an old technology and the earliest radios were crystal sets.The circuit you are looking at works on a similar principle.You are taking "energy from the air"in the form of radio waves but it is still "crap" as expressed by stewart because the amount of energy is miniscule.