This was very interesting:

BLUE LED.......
Edited 2026-07-04 16:02 by Grogster

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Smoke makes things work. When the smoke gets out, it stops!

Didn't watch the YT Vid, did see part of a documentary years ago about the blue LED.
This reminded me of a more recent Doco, Blue dye and pigment was a difficult colour to make in the ancient world, it was also an interesting process, now we just take it for granted like the blue LED, where would we be without it.