Talk:Coherer

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Serious Errors[edit]

This sentence is is completely wrong. "More important for the future, the coherer could not detect AM (radio) transmissions".

It is true that the coherer was originally used to simply ring a bell in the presence of RF Energy. However experimenters soon learnt that the basic Coherer could also be used as a Detector when placed in series with headphones.

Marconi's notes on his original Transatlantic transmission showed that his simple un-tuned receiver consisted of a long-wire held aloft by a kite, with a Marconi Coherer in series with a earpiece.

With this he could hear the AM Spark transmissions from England. (incredibly the same paragraph even mentions this!)

And it's important to note that the first Coherer (along with other Detectors) was developed by David Edward Hughes. see https://en.wikipedia.org/wiki/David_Edward_Hughes.

This was long before Branly and Lodge.

Gutta Percha (talk) 13:16, 27 August 2019 (UTC)[reply]

Distinguishing Dot from Dash[edit]

Today's version of this does not explain how the decoherer works to enable the coherer to distinguish a dot from a dash. (Note the coherer latches up at the beginning of both.) John (talk) 16:44, 26 February 2010 (UTC)[reply]

That's a good question. The references in the article don't seem to explain that detail. Slaby shows a recording apparently made on a Morse paper tape recorder that clearly shows different length "dot" and "dash" marks. Perhaps the coherer turned on and off continuously during each code symbol. That is, after the coherer detected the presence of the radio wave and was immediately tapped back to the nonconductive state by the decoherer, if the radio wave was still present the coherer would immediately turn on again, and be tapped again, in a rapid cycle, resulting in a continuous "buzzing" or "trembling" by the tapper during each dot or dash. This signal was perhaps registered by the Morse recorder as a continuous mark on the paper the length of the dot or dash. --Chetvorno^TALK 20:17, 28 February 2010 (UTC)[reply]

You are right, it was that continuous "trembling" action of the coherer & decoherer that made the distinction. That is not explained well though, and I wish I had time to do it. Maybe someone could start it off?? John (talk) 22:16, 28 February 2010 (UTC)[reply]

Do you have a source for this? --Chetvorno^TALK

I found some: G. Marconi, 'Wireless Telegraphy' in March 2, 1899 Proceedings of the I.R.E., p.277 gives Marconi's own description of the trembling action. Also 1, p.345, 2, p.686, 3, p.28 --Chetvorno^TALK 09:48, 1 March 2010 (UTC)[reply]

More serious errors[edit]

"The metal balls will cling together, or cohere..." What? How does that make any sense? How do metal balls or filings CLING together under the presence of Electromagnetic Fields or even short bursts? I think this needs more elaboration, perhaps a major edit/revision. BuildersHutGames (talk) 01:35, 31 October 2023 (UTC)[reply]