COHERER

The coherer (or coherer) is a radiofrequency signal detector, consisting of a glass tube inside which extremely fine metal filings are inserted between two electrodes (the metal caps that close the glass tube). Under normal conditions the electrical resistance of the filings is very high, therefore no current flows in the coherer. The resistance drops abruptly when the coherer is affected by a radio frequency signal; the flowing current therefore reveals the presence of the signal.

INSIGHTS