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Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Grenadier wrote ...
It's mainly proof of concept, I wanted to make a lightbulb.
Need a pump first though...
A pump from an air conditioner should work. They pull a pretty strong vacuum. I have pulled a vacuum on glass jars and use high voltage or RF to excite it.
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
Those rotary compressors from window AC units do make quite good vacuum pumps. Surplus City used to have them new surplus for under $10 so I had a few I was using. Unfortunately they will seize up if you let them sit around too long, as all mine eventually did. Unfortunately they jacked up the prices on those.
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
Careful, most of them are charged with R22 which is illegal to vent to the atmosphere. It's an HCFC, not near as damaging as the old CFC R12, but still not something you want to vent. The good news is the stuff has value so you can often get it pumped out at no cost.
If it says R-134 go ahead and vent it. Technically it's illegal as it's classified as a greenhouse gas, but it's only illegal to vent it if it's used as a refrigerant, the same stuff is often used as an aerosol propellant, doesn't really make much sense.
Registered Member #514
Joined: Sun Feb 11 2007, 12:27AM
Location: Somewhere in Pirkanmaa, Finland
Posts: 295
Wouldn't be too worried about the refrigerant type. These things leak all the time and it's not like the 'ECO-police' is going to come knocking at your door if you 'accidentally' pierce one. And even for the really environmentally conscious types, R22 has an ODP of what, 0.002, or in other words none. That 1kg that is the usual charge for small air conditioners won't do any harm. The rules are really in place for professional service people, not for your average Joe.
As for the compressors themselves, they pull a decent enough vacuum for some pretty plasma and so probably for a lightbulb too. Apart from that they aren't really that exciting.
Remember to cap off the suction and discharge lines while the compressor is not in use, as the oil tends to soak up moisture. Also keep run times short as the compressor relies on suction gas cooling (that is cool gas from the evaporator), and will heat up quickly pumping air. They are usually pretty robust little buggers, but I wouldn't leave one running for any long lenght of time.
Registered Member #3429
Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288
Nah wrote ...
Adam, have you concidered making a cathode ray tube?
NAH - Thanks for that website link! The author describes many unusual electronic projects such as, how to make a magnetic amplifier, and a "flame triode" that uses an alcohol flame to amplify a signal! Here is a link to his home page: It's a "must read" for any electronics hobbyist who wants to learn about and how to make some very unusual and interesting projects!
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
That was actually one of the first sites I visited on the internet, I remember reading it sometime back in 2007. Fancy stuff there, but that said I still need to find a vacuum pump.
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MacGyver Vacuum feedthrough
