dedicate a section of this web site to the crystal radios.
These small radios can work without any power supply system, donít
needs any batteries or power supply.
The listening is possible
only through headphones, needs a good aerial and, of course, you can
receive only local broadcasters.
radio is composed by a tuning circuit, to pick up the
electromagnetic waves, and a detector which is used to convert the
electrical signal into low-frequency sound audible through
tuning circuit itís composed by a coil and a variable capacitor
or, in the oldest models, by a variometer.
detector is a galena crystal mounted on a base, which could be made
in different shapes, and a filiform pointer connected to a lever.
the pointer lever with the hand, itís possible to find the best
contact with the crystal and obtain a good reception.
crystal detector operation was very precarious, usually during the
reception you need to move the pointer several times to be able to
have an acceptable listening.
the advent of semiconductors, after 1950, a germanium diode was used
instead of the crystal to obtain a better and more stable listening.
a lot of medium-wave broadcasters stations has been closed; the
power of those remaining has been greatly reduced so now itís very
hard to operate with these sets.
In these pages you can see photos of different crystal radios.
Some of these were produced by companies and one of them was
home-made(or perhaps made by small artisan).
crystal radio (
last version )
crystal radio (with crystal)
crystal radio (with diode)
made crystal radio