Crystal Detector Materials Available Radio Receiver Set Technology Article

OddMix.com - Technical Note - Crystal Radio - TN080402 - Karl Nagy

Bunnel JOVE Crystal Detector [8 Kbyte]
Picture 1. Vintage Crystal Detector

On Picture 1 is a basic crystal detector from the 1920s. This advertisement originally appeared in the The Wireless Age monthly published in 1921. At the beginning of the radio era, construction of crystal detector radios used to be a popular pastime. They were made most often by beginners, because of its inherent simplicity, modest parts requirement and ease of construction. Crystal radio sets perform well almost anywhere if a high-strung long wire antenna is available, or if strong stations are nearby. Short-wave crystal detector sets work great almost everywhere when wave propagation is good to exceptional.

At the beginning of the Radio Age the crystal material for this radio wave detectors were the subjects of intense search. Many thousands of radio amateurs tested numerous materials in different circuits and configurations. It was found that even two uninsulated copper wire inserted into a small fresh potato, functioned well as a passable working detector! So did a double-edged "Gillette" razorblade when touched by a lead removed from a short stub of a number two pencil. The resultant data of (then) known minerals shown below is the summary of that intense search.

This table was published by E.T. Wherry, American Mineralogist, Issue 10, part 2, page 28, 1925.

                               TABLE OF RADIO DETECTOR MATERIALS

                                        GOOD DETECTORS:

                              Pyrite, impure.        Enargite
                              Tennantite             Galena impure.

                                        FAIR DETECTORS:

                            Grahphite         Linneite         Hessite
                            Octahedrite       Glaucodite       Sylvanite
                            Brookite          Rammelsbergite   Calaverite
                            Molybdenite       Chalcocite       Zincite
                            Pyrolusite        Boegerite        Tiemannite
                            Lollingite        Berzelianite     Coloradorite
                            Hematite          Famatinite       Clausthalite
                            Tasnite           Stromeyerite     Chiviatite
                            Chalcopyrite      Aquilarite       Guitermanite
                            Tetrahedrite      Naumannite

The first item in the Good Detectors column - pyrite - is available from OddMix. A pocket of three small crystals is $6 shipping included within the continental United States. Click here to order crystals.

Not only crystal detector set building provides many happy hours, but it is still the best way to learn about radio, antennas, waves propagation, construction techniques and other important matters that can lead to a valuable and excellent hobby. Many current radio amateurs have started out building a crystal detector receiver as the first ever radio set they made.

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