Perhaps the simplest radio one can build is the crystal radio. Using a diode as a detector, the design generally uses less than 10 components and no battery, getting its power to run from the radio ...

[George Trimble] likes to build crystal radios. The original crystal radio builders used high impedance headphones. In modern builds, you are as likely to include a powered amplifier to drive a ...

Homemade crystal radio in wooden case, back is open, appears to be a spark gap on the front panel, loose coupled tuning inductance inside. Allied shipping tag #102.

overall: 7 in x 5 in x 4 1/2 in; 17.78 cm x 12.7 cm x 11.43 cm ...