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Registered Member #3925
Joined: Fri Jun 03 2011, 10:50AM
Location:
Posts: 121
hey,
i am gonna use a compressor from a fridge, as a vacuum pump, ive not tried it, but it seems it can pull a vacuum of 27 in. Hg. would that be good enough to make a (crappy) crt or vacuum tube?
Registered Member #2941
Joined: Fri Jun 25 2010, 08:08AM
Location:
Posts: 143
Two of those pump in series are some time enough for some type of gas laser (cvl /Carbone dioxide ),it might work for a demonstration CRT,but for a vacuum tube I doubt..
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
There are illustrated instructions for converting a fridge pump into a vacuum pump in Stong CL The Scientific American Book of Projects for the Amateur Scientist New York 1960.
The fridge pump is intended to be used together with a mercury diffusion pump, whose construction is also described in a practical way for the home constructor.
The two pumps pulling in series are used to evacuate a linear accelerator powered by a Van der Graaf Machine, also described with drawings.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
If you Google glow discharge and Grimm glow discharge you will find many fascinating experiments that can be performed at the pressures attainable by your fridge pump, mostly needing only a few hundred to a few thousand volts to get into the business.
Registered Member #2941
Joined: Fri Jun 25 2010, 08:08AM
Location:
Posts: 143
I have to apologies for my previous post, I have seen some one making a triode at atmospheric pressure with in a candle flame, I assume the flame is needed to assure enough atom of the gas are ionized to guaranty some electric conduction and those pump can reach a vacuum where gas is easy to ionize ,so it might be that demonstrating a triode is possible even with fairly low vacuum....
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Grenadier wrote ...
I'm pretty sure that a compressor from an AC unit + a mercury diffusion pump is they way to go if you don't feel like buying a 2 stage vacuum pump.
I don't think anyone nowadays would choose a mercury diffusion pump, Adam, because of the toxicity hazard. Diff pump oils are costly, but will last a long time if you take care of them.
The Javac A/C pump is popular with UK enthusiasts, is relatively inexpensive, and claims a lowest pressure of 25 microns.
But a fridge pump is a very good place to start on modest means, and can produce a pressure low enough to observe all sorts of very interesting phenomena - more so than high vacuum in many respects.
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using a fridge compressor vacuum pump to make a vacuum tube?
