The Cats Whisker is the tiny wire that connects to the detector in a crystal radio. While originally a figurative description of a mechanical part, the term grew to encompass the entire detector assembly and also in some English speaking communities to describe the set itself. A wire is a single, usually cylindrical, elongated strand of drawn metal. ... A detector is a device that detects or measures some phenomenon or stimulus, and produces some signal in response. ... The crystal radio receiver (also known as a crystal set) was first built circa 1900 by Greenleaf Whittier Pickard, who used crystalline minerals to detect radio signals. ...

As a detector it is simply a point-contact semiconductor diode, albeit a relatively primitive and unstable one based on the discovery of the semiconductor or "point rectifier effect" by Karl Ferdinand Braun, a German physicist and radio pioneer, in 1874 at the University of Warzburg. Based on this work G.W. Perkard developed the Perikon detector, which was renamed by the public to 'cat's whisker'. A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ... ... Ferdinand Braun Karl Ferdinand Braun (June 6, 1850 - April 20, 1918) was a German physicist, born in Fulda. ... Greenleaf Whittier Pickard - Wikipedia, the free encyclopedia /**/ @import /skins-1. ...

The crystal normally employed is galena, the common sulphide ore of lead, used without treatment directly as it is mined. A rough pebble of this material about the size of a pea, was mounted in a brass cup usually potted with tin or silver-tin solder. One surface was left exposed to receive the contact. Other minerals could also be used among them were cadmium sulfide, iron disulfide (Pyrite), zincate, bornite, and carborundum. It has been suggested that crystallization processes be merged into this article or section. ... Galena is a lead ore. ... In chemistry, a sulfide (sulphide in British and Canadian English) is a combination of sulfur with an oxidation number of -2, with another chemical element or a radical thereof. ... Iron ore (Banded iron formation) Manganese ore Lead ore Gold ore An ore is a volume of rock containing components or minerals in a mode of occurrence which renders it valuable for mining. ... This article is about the chemical element. ... Cadmium sulfide (UK English sulphide), the mineral greenockite, is an hexagonal, yellowish crystal with specific gravity of 4. ... The mineral pyrite, or iron pyrite, is iron disulfide, FeS2. ... The mineral pyrite, or iron pyrite, is iron disulfide, FeS2. ... Bornite (Copper Iron Sulfide) Tarnish of Bornite Bornite is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the cubic system. ... Silicon carbide (SiC) or moissanite is a ceramic compound of silicon and carbon. ...

The contact, (the cat's whisker itself) is merely a springy piece of thin phosphor bronze wire, mounted in a suitable holder so that the entire exposed surface of the crystal can be probed from many directions to try and find the most sensitive working junction. This requires some skill and a great deal of patience even then a good contact can easily be lost by the slightest vibration. Phosphor bronze is an alloy of copper with 3. ...

When these devices were in common use more advanced proprietary versions of 'permanent' detector were available. These consisted of various combinations of pairs of different crystals in fairly heavily spring-loaded contact. Their general commercial use was superseded by the development of vacuum tube detectors, although the expense of of the latter meant that full replacement would take several decades. In electronics, a vacuum tube (U.S. and Canadian English) or (thermionic) valve (outside North America) is a device generally used to amplify, or otherwise modify, a signal by controlling the movement of electrons in an evacuated space. ...

External links

• Tom Kipgen hand made catwisker detectors
• The Crystal Experimenters Handbook PDF devoted to point contact diode detectors.