Some how my feeble mind managed to remember this device but I couldn’t remember how to spell it or what exactly it did, I kind of thought it was spelled ( Coffer ) , lol

I think it was in the early 1970’s when I first read of it.

After reviewing many pages on antique and old time electrical devices I finally found it.

The illusive Coherer.

So it appears the device provides a high resistance until a signal is received then the metal shavings “cohere” and electricity can flow in the low resistance.

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

http://people.seas.harvard.edu/~jones/cscie129/nu_lectures/lecture6/coherers/coherer.html


I also found this interesting.

“this may be one of the first rectifying (diode) detectors, because Branly reported it could produce a DC current without a battery.”

https://commons.wikimedia.org/wiki/File:Trepied_01.jpg

Just wanted to share also if anyone has any long lost electrical devices they want to present please fell free to add them to this thread so others can read about them.

PeakPositive

I like the electric rock:
:giggle:

Yes Cycle out-of-place artifact (OOPArt) are always fun.

Antikythera mechanism

Baghdad Battery

London Hammer

Are a few I also like.