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Build a radio wave detector with balls of aluminum foil

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Re: Build a radio wave detector with balls of aluminum foil

#11

That voltage from the crystal creates an electric field, which exerts a force on free charges in the air. (There's always some free charges floating around, like electrons and ions.) These charges accelerate and collide with air molecules, kicking loose more free electrons that also accelerate and collide, and so on, in an exponential chain reaction. We call this an electron avalanche. And guess what happens? Acceler…

This coherer also must be bumped between received sigs.

Re: Build a radio wave detector with balls of aluminum foil

#12
post #8

That voltage from the crystal creates an electric field, which exerts a force on free charges in the air. (There's always some free charges floating around, like electrons and ions.) These charges accelerate and collide with air molecules, kicking loose more free electrons that also accelerate and collide, and so on, in an exponential chain reaction. We call this an electron avalanche. And guess what happens? Acceler…

That is how air becomes conductive.

Electromagnetic waves can exist in vacuum. No (conductive) air is required.

Re: Build a radio wave detector with balls of aluminum foil

#13

That voltage from the crystal creates an electric field, which exerts a force on free charges in the air. (There's always some free charges floating around, like electrons and ions.) These charges accelerate and collide with air molecules, kicking loose more free electrons that also accelerate and collide, and so on, in an exponential chain reaction. We call this an electron avalanche. And guess what happens? Acceler…

I suppose what he is saying is that the crystal creates an electric current in some conductor. That conductor then has an electric field around it. If you had some charged particle nearby there could be a force exerted on it. That author then says "charges accelerate and collide with air molecules". Strictly speaking this is true.

But this description sounds more like a particle accelerator and less like anything to do with radio waves. All of this stuff is irrelevant. As you've pointed out, you could just as easily put the crystal in a vacuum and get RF emissions from it.

Re: Build a radio wave detector with balls of aluminum foil

#15
Jagadish Bose's Mercury coherer , which had the additional property of being self restoring, was "adopted" by Marconi for his radio receiver. Jagadish Bose had no interest in commercialising or patenting his design. It's history is somewhat of a sore point. Most Bengali's believe J.C. Bose was ripped off and not given due credit.

"Sir J C Bose's Diode Detector Received Marconi's First Transatlantic Wireless Signal of December 1901 (The “Italian Navy Coherer” Scandal Revisited)" https://www.tandfonline.com/doi/abs/10.1080/02564602.1998.11...

Non paywalled link https://www.cse.iitm.ac.in/~murthy/sirjcbose.pdf

https://en.wikipedia.org/wiki/Jagadish_Chandra_Bose

Anyhow, rather than grains and gravels of metal that had to be physically separated by tapping, the oil-film-over-mercury would reset on its own due to surface tension when the EM stimulation ceased. This allowed for higher "Baud".

Re: Build a radio wave detector with balls of aluminum foil

#18
post #6

Mehdi from electroboom did video on this, the range is few meters. If I remember correctly the spark breaks oxide layers and makes contact.

Mehdi is such a wonderful educator! I wish I’d had him as a professor for whatever topic he’d be interested in teaching.

Re: Build a radio wave detector with balls of aluminum foil

#19

That voltage from the crystal creates an electric field, which exerts a force on free charges in the air. (There's always some free charges floating around, like electrons and ions.) These charges accelerate and collide with air molecules, kicking loose more free electrons that also accelerate and collide, and so on, in an exponential chain reaction. We call this an electron avalanche. And guess what happens? Acceler…

Yeah, this write-up seems to be confusing a townsend avalanche (what it describes) with far field electromagnetic wave propagation (an entirely different thing).

Re: Build a radio wave detector with balls of aluminum foil

#20

Wait, so you're telling me that my hat instead of stopping mind control attempts is actually AN ANTENNA?

Truth was bound to get leaked at some point. CIA had a good run.

MIT researchers discovered the truth years ago: tin foil hats may actually increase exposure to RF in some bands.

https://web.archive.org/web/20100708230258/http://people.csa...

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