Bollinger County Museum of Natural History
the crystal radio

The Amazing Crystal Radio!

by Guy Darrough

In the early 1900's, modern man created the means to transmit signals. Almost immediately inventors and common folk began making devices to receive the signals. Thousands of these "home-brew" radios were constructed from discarded junk, and most amazing is that they work without being connected to a power source!

If a person had the money during the 1920s he could buy a quality store-bought crystal radio like the one above. It was very reliable and only needed an antenna, a ground and earphones to function. The procedure was to tie a Coke bottle to a long wire and throw it up into a tree, then run the wire inside the house and connect to the radio. Then a wire from the radio was attached to a water pipe or a metal rod that was hammered into the soil, to ground the radio. Now attach your headphones, adjust the cat's whisker on the galena crystal, move your slide tuner to the proper setting and you're hearing local and world news!

These primitive receivers brought in radio stations from hundreds of miles away. There are over 20 radios in working condition on display at the museum. Come see our exhibit and learn why they call them crystal radios.

The crystal radio pictured was made from scratch with whatever was available at the time. The radio body is a hollowed out section of 2 x 4 and uses a primitive "switchboard" system for tuning in stations. To be able to hear news or even a voice was comforting and exciting during those early days of radio. A hand-written testimonial on the back side exclaims that his radio receives stations from hundreds of miles away and how everyone should build one. No power required!

crystal radio two

The Foxhole radio during World War II

Crystal radios were even used by soldiers on battlefields during World War II. Melancholy and long periods of boredom could be relieved by listening to music and getting the baseball scores. Regular tube-type radios were nearly impossible to get and they required batteries that were unavailable. Fortunately many of the American G.I.'s had built radios before the war and were able to construct primitive crystal radios from scrounged materials. The wires, hardware, and headset could be salvaged from destroyed vehicles. The coil was made from a toilet paper tube and the components were mounted to a wood base cut from an ammo crate. To make an antenna, they would attach a rock to a long wire, and throw it up onto a tree limb. The ground wire was sometimes attached to a bayonet that was pushed into the soil. But there was a problem, the radio needed a hard-to-get device called a crystal detector to 'detect' the signals being transmitted from the radio stations. Then, some American G.I. came up with an ingenious idea, he found that a razor blade would act as a crystal detector when the point of a safety pin, or a pencil lead, was touching the blades surface. With this small discovery, American G.I.'s were able to build radios and keep in touch with events back home. Only one original 'foxhole radio' is known to have survived the war.

fox hole radio


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