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Joined 2026-09-21 Message
Incoming links: Wireless Telegraphic Communication by Guglielmo Marconi
Coherer 2026-10-18
A filings coherer changes from high to low electrical resistance following electrical excitation. A local battery supplies the readout electric current; a tap resets the detector. It records events rather than the incident radio wave waveform.
Marconi described nickel and silver filings between silver plugs, with a cell and sensitive telegraph relay controlling a tapper and recorder.[ref]
Wireless Telegraphic Communication by Guglielmo Marconi. 1909 lecture, printed p. 197, Fig. 1 and following paragraph: coherer construction and local readout
Tuned spark wireless apparatus 2026-10-18
Guglielmo Marconi's 1909 lecture describes antennas with earth connections and separate coupled receiving circuits. His 1900 system coupled a closed capacitor–inductor–spark gap loop to a transmitting antenna. Coil spacing adjusted coupling; inductance and capacitance adjusted tuning. All four circuits were tuned together. By 1909 his company's stations mainly used magnetic receivers, rather than coherers.[ref]
Wireless Telegraphic Communication by Guglielmo Marconi. 1909 lecture, Figs. 2–3, 6 and 8 and associated paragraphs; receiver paragraph at Fig. 25
Those are a participant's retrospective descriptions, not a complete account of priority. An earth connection is part of this antenna arrangement; it is not a universal requirement for radio communication. Nor does tuning an isolated LC circuit ensure that its frequency remains unchanged when strongly coupled to another circuit. The coupled resonant circuit model quantifies that distinction.