Evening Republican, Volume 59, Number 84, Rensselaer, Jasper County, 30 April 1917 — KNOW LITTLE OF CRYSTAL DETECTOR [ARTICLE]

KNOW LITTLE OF CRYSTAL DETECTOR

MOST AMATEUR ELECTRICIANS ARE IGNORANT OF SENSITIVENESS Single Crystal Gives Bettor Results - .. Than Combination. Xa spite of tixe fact that crystal detectors play so important a part in experimentation of electrical amateurs, their use is not understood as well as It should be. There are various combinations in use. It will be found, in general, that the more sensitive a crystal is, the more readily will it lose its adjustment or "knock out" from loud Signals or static. The average amateur will get more satisfaction from using a single crystal than from a combination. For example, although a perlkon has many desin He characteristics, there is apt to be trouble from particles of one of the crystal rubbing off and adhering to the surface of the other. This is constantly occurring. Chalcopyrite and sinoite, arsonic and silicon, and antimony «nd silicon are all used in combination, and are remarkably sensitive. An occasional wash with carbon disulphide helps to remove grease and dirt from the surfaces, and often restores them to sent .-enesa. Carborundum is proof against all manner of knockouts, but is unfortunately not very sensitive. A stiff wire or needle makes the beet contact with this substance, and should be pressed down into it with considerable force. A battery must be used with this tectorSilicon is more sensitive than carborundum, and is correspondingly more easily knocked out by static. A light contact is required, and the efficiency Is often improved by applying an exceedingly small potential Galena is probably the most sensitive of the crystal detectors, but is har I to keep in adjustment. It is especially sensitive to static. The wire used should be as fine as possible. Certain violin and mandolin strings are wound with very fine silver wire; this wrapping is more suitable for use with galena. A minute fraction may be cut off the end of the wire from time to time, thus always insuring a clean point. Cerusite requires about the same treatment as galena. Iron pyrite works best with a firm contact and is almost as sensitive as silicon. —Popular Science Monthly.