In May 2000, as school was winding down, a class of eighteen fourth graders were winding up, literally! They wound their own electrical coils to build their own radios. I perceived the students to be totally enthusiastic about the prospects of such a fascinating homebrew project.
These radios have very few parts and consume no power. That's right: No batteries, no plugins, no solar power, no fuel cells, no wind power, no generators, ad infinitum. Crystal radios steal their power directly from the air waves using an antenna to grab the power out of the air. They are not loud, but they work.
The design we used is an adaptation of a 1932 design called the Mystery Radio, so called because it is a mystery that it works. The mystery is that one end of the antenna coil is not connected to anything (!), seemingly in violation of electrical rules, and the radio still works great. It is important to realize that the performance of this radio was considered state of the art in 1932. Enjoy the images.
The wire was tied to a chain link
The resulting coils were wound beautifully.
The coils have two windings. This student
The Elmer's Glue is resting on the baseboard
The Dr. Pepper can finds service
See what I mean about
The Dr. Pepper can is surrounded
When you slide the paper and
To see a more advanced crystal radio I built for a contest, CLICK HERE .
If you want to do more with crystal radios, here is one really good link: CLICK HERE.
E m a i l (click here, then click on link by the picture on following page)
Counter added May 1, 2001