27 Jul
2007
27 Jul
'07
12:27 p.m.
On Fri, 27 Jul 2007 13:04:22 -0500, John Foust wrote:
At 07:50 AM 7/27/2007, William Donzelli wrote:
>The idea behind the getter is to clean up and gas that might be
>trapped in the metal elements during pumpdown. A getter is really not
>to clean up gases that sneak in thru the glass metal seals - the
>getters just are not that effective, and as any plumber will tell you,
>leaks only get bigger.
Hmm, that reminds me of a lingering question in my
mind.
As a kid, I remember harvesting tubes from dead TVs behind
the repair shop. Breaking the tube, there was often a ring
at the top, U-shaped in cross-section. I seem to remember
that they were filled with a powder that reacted with
water, fizzing. Am I mixing up this smell-memory with playing
with calcium carbide? What were common getter chemicals?
- John
Very early tubes used magnesium, Scientific American had a great project using a Model T
ignition coil to
turn one into an X-Ray source which refered to them as being old way back then. Long
before the artical
was printed had switched to gallium as it did not radiate.
A quick google found it here :
http://www.noah.org/science/x-ray/stong/
Have fun :)