Crystal Radio Gallery Page 3

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The coils for crystal radio sets are typically wound around a 1 1/2 to 2 1/2 inch (38 - 64 mm) diameter core, using 75 to 150 turns of 24 to 20 gauge wire. These are typical numbers, not critical. What is critical is that the individual loops of wire around the coil are wrapped touching the next one over, but that they do not ever overlap. It is also important that whatever attaches the coil to the base can not touch the coil's wire, especially if it is a metal tack or nail. A coat of shellac or varnish helps to keep the coil together. Let it dry thoroughly before using. If a wiper type switch is used, the varnish will need to be scraped away along its path.

It is a fairly simple process to make a working radio using a modern germanium diode for a detector. However, the reason these are called crystal sets is because the detector was originally a piece of crystal. You can still make your radio the authentic way with a crystal and cat's whisker. Detector stands are still manufactured, one good source being Antique Electronics Supply, 6221 S. Maple, Tempe, AZ 85283-2856 USA (phone 602-820-5411). A crystal detector includes a crystal, a cat's whisker, which is a special thin wire that contacts the crystal, and the stand that holds the components in place. The most common crystal used is a small piece of galena, which is fairly common, and can be found in many rock and hobby shops. BIG safety pinThe cat's whisker is most often composed of phosphor bronze. Once in circuit, the whisker can be moved about on the crystal's surface to find the most "sensitive" spot. The pressure of the whisker on the crystal is also adjustable. There are some other crystals that will work, so there is much room for experimentation with crystal fragments that you may already have.