A Vacuum Diode for Make: Magazine

28 points by luu 4 days ago

TIL the shiny metal coating on top of vacuum tubes is not an X-ray shield, but a reactive coating to scavenge any remaining molecules out of the vacuum.

Cyan488 - an hour ago

You'll find a similar thing in vacuum fluorescent displays as well [0].
[0]: https://ibb.co/XZHWLD3x