Build a Radio Wave Detector with Balls of Aluminum Foil

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

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".

https://archive.ph/ea6TC

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? Accelerating charges create a changing electric field—which, yup, creates a changing magnetic field, etc., and that disturbance radiates outward as an electromagnetic wave.

Huh? It has nothing to do with "free charges in the air." That's... kind of the whole idea behind EM theory.

That said, I've never heard of anyone building a detector out of balls of aluminum foil, so that's pretty cool. I'd classify it as a rectifying detector rather than a coherer, though, because nothing is physically moving. A real coherer had to be physically bumped or tapped between received signals.

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

I don't think a radio wave detector would ever stop detecting these days, unless you put it inside a faraday cage

"Balls of Aluminum Foil" he he he