According to Wikipedia, and I quote; “A foxhole radio is a radio built by G.I.s during World War II. The foxhole radio differed from the crystal radio. A razor blade and pencil were used as a diode in a foxhole radio while a piece of crystal is used as a diode in a crystal radio.
The foxhole radio is like a crystal set in that it does not require an external power source. The radio is powered by the radio frequency that it receives. This made the foxhole radio ideal for the prisoner of war (POW). Prisoners of war made these radios to keep up with current events.
Generally, this radio is called so because of the foxholes – small man-made underground shelters used along defensive lines during the war, and so, any radio built during the war can be regarded to be a foxhole radio, but ideally, this radio does NOT use semiconductors and does not have access to a power supply. In 1942 Lieutenant Colonel R. G. Wells was a prisoner of war in Japan. Wells built a foxhole radio because he lacked information about the international situation. The whole POW camp had a genuine craving for news by whatever means according to Wells.” – End quote.
Necessity is the mother of all inventions in those days and since there was a serious lack of “Radio Shack” or electronic stores in POW camps, basic knowledge and a lot of imagination made it possible. Nothing has changed much today and radio waves work as they did 50 or 100 years ago. It’s pretty much energy in the air and these foxhole radios will allow you to catch some of that energy and convert the electromagnetic waves into sound. (Batteries not needed!).
These video clips will show you how to make a foxhole radio receiver out of virtually nothing;
And if you want a more challenging project, here’s how you can make a crystal radio;
Enjoy these fun projects.