Kevin said:

Well the video does have some turning in it and may well spark a smile
from those here who have messed about a bit with old-timey radio
tubes. I still remember when all the grocery stores had a small
machine in the corner somewhere where customers could test and buy
tubes for their tvs and radios.

http://blog.makezine.com/archive/200...ccum_tube.html

I got a little off topic, even for an off topic post. Interesting
video nevertheless. 6th grade science fair project was a homemade
vacuum tube. Didn't have access to fancy metals, tools, glass, or
vacuum pumps, and parents weren't the least bit interested in
education, so I had trouble with the filaments burning out
prematurely. Had to keep an extra under the table for such
occurrences. Won 3rd place in state against a barrage of projects made
by other parents - questioning the kids revealed they hadn't a clue
what their project was or how it worked. Damned Lockheed jerks.
Envelopes were spice bottles, seals wouldn't maintain a vacuum - what
bit I could muster - but they worked for a while. The scrap heap later
turned out to be my friend.

Remember the Zenith Transoceanic receiver?
Tubes, A & B batteries, stinky leather case.

When a big solar flare or EM pulse knocks this modern stuff offline
permanently, you may find this knowledge useful. And damned the
government to hell for de-allocating the VHF spectrum and NTSC to
cell-phones. National security my ass.


Greg G.