nothackingnothacking@infosec.exchange
Jun 6, 2026, 9:56 PMHomemade glow lamp: it's borosilicate glass melted with a oxy-propane torch. The outer diameter is 11mm.
The vacuum from my rotary vane pump isn't perfect, and there's a lot of residual air left over (that's what's glowing), but it should still be good enough for a triode or small CRT.
... although I haven't figured out a good way to do glass-to-metal seals yet. This one has copper plated steel wire (CTE=~10 um/[m*K]) passing through borosilicate glass (CTE=~3 um/[m*K]), which aren't close enough to stop thermal expansion from breaking the bond: The tube only worked for a few hours.
Might have to buy some tungsten wire (CTE=~4 um/[m*K]) or figure out a graded seal: soda lime glass bonds to the wire quite well, but it's is very annoying to work with.
The vacuum from my rotary vane pump isn't perfect, and there's a lot of residual air left over (that's what's glowing), but it should still be good enough for a triode or small CRT.
... although I haven't figured out a good way to do glass-to-metal seals yet. This one has copper plated steel wire (CTE=~10 um/[m*K]) passing through borosilicate glass (CTE=~3 um/[m*K]), which aren't close enough to stop thermal expansion from breaking the bond: The tube only worked for a few hours.
Might have to buy some tungsten wire (CTE=~4 um/[m*K]) or figure out a graded seal: soda lime glass bonds to the wire quite well, but it's is very annoying to work with.
