For most of us, vacuum tubes haven’t appeared in any of our schematics or BOMs in — well, ever. Once mass-manufacturing made reliable transistors cheap enough for hobbyists, vacuum tubes ...

[Aleksander Zawada] makes vacuum tubes in his home ... on the short list of hackers who can pull off extreme industrial manufacturing at home. Kudos.

The telephone company had problems with vacuum tubes, too, and hoped to find something ... but knowledge about how they worked was scant, and manufacturing semiconductors was difficult.