Vacuum in a Can

Discussion in 'Electronic Projects' started by alfa88, Mar 20, 2017 at 10:31 PM.

  1. alfa88

    alfa88

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    In anticipation of my receiving an order of a couple H.P. Friedrichs' books I've been contemplating how to achieve a vacuum for some of the projects. There are those CO2 cartridges so I wondered if anyone has come up with a vacuum cartridge. In lieu of that is there a low cost alternative to achieve a light bulb/ thermionic valve worthy vacuum?
     
    alfa88, Mar 20, 2017 at 10:31 PM
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  2. alfa88

    BobK

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    A vacuum pump comes to mind.

    Bob
     
    BobK, Mar 21, 2017 at 12:28 AM
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  3. alfa88

    Audioguru

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    If you connect a vacuum cartridge to something that has normal gas or liquid pressure then the pressure in each would become the average.
     
    Audioguru, Mar 21, 2017 at 1:13 AM
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  4. alfa88

    shrtrnd

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    BobK's advice is the right choice for creating a vacuum in a closed container.
    You said you want this low-cost. Find somebody in your area with a vacuum pump and make a deal with them.
     
    shrtrnd, Mar 21, 2017 at 1:13 PM
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  5. alfa88

    KMoffett

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    KMoffett, Mar 21, 2017 at 1:57 PM
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  6. alfa88

    BobK

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    Did anyone ever think about the term "vacuum cleaner?" Isn't a vacuum perfectly clean already?

    Bob
     
    BobK, Mar 21, 2017 at 4:41 PM
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  7. alfa88

    alfa88

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    I pretty much suspected I'd be hitting the same vacuum issues as the old light bulb guys of yesteryear. Even a 2 stage vacuum pump is purported as insufficient. I was just hoping someone was aware of a solution. 'Vacuum in a can' was just a pipe dream.
     
    alfa88, Mar 21, 2017 at 5:43 PM
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  8. alfa88

    KMoffett

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    You gave no indication on the level of vacuum or flow rate need for your "projects". Maybe roughing and diffusion pumps are what your looking for?

    The devil's in the details! :(

    Ken
     
    KMoffett, Mar 22, 2017 at 1:49 AM
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  9. alfa88

    alfa88

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    I found a site that suggests 10-4 Torr to 10-6 Torr. Also suggesting a 3 stage diffusion type pump. Too rich for my blood. A typical vacuum cleaner is 25 Torr at best. The air con. vacuum pumps I've looked at are using different specs but I'm assuming they're inadequate and a 2 stage diffusion pump is still too pricey. I guess I should shelve this idea.
     
    alfa88, Mar 22, 2017 at 7:32 AM
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  10. alfa88

    alfa88

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    Canned vacuum no. Helium possibly.
     
    alfa88, Mar 24, 2017 at 6:37 AM
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  11. alfa88

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    The problem with vacuum in a can is that all I've ever been able to get is the diluted vacuum. I want a concentrated vacuum so that (say) 100mL of concentrated vacuum can evacuate a couple of cubic metres.

    Hmmm... if that was positive pressure, that would make it 20,000 bar (approx). That's 2 * 10^5 bar.

    Now because I want negative pressure, that would only be 2 * 10-5 bar, right? (hahahaha)
     
    (*steve*), Mar 24, 2017 at 11:37 AM
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  12. alfa88

    alfa88

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    The more I delve into this the more I am impressed how the old timers were able to push the limits back then. ~20 years after the Edison bulb the extreme vacuum was replaced by using an inert gas ,argon or nitrogen. But that's light bulbs.
    As the name implies a vacuum tube is an evacuated glass tube. In the distant future I'll try using helium at atmospheric pressure and see if I can make a home made light bulb and then triode.
    I never took physics so I'm really out of my league.
     
    alfa88, Mar 24, 2017 at 7:08 PM
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  13. alfa88

    duke37

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    I don't think you can make a valve, the electrons will bump into the helium atoms.
     
    duke37, Mar 24, 2017 at 10:54 PM
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  14. alfa88

    BobK

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    And ionize them if there is enough energy.

    Bob
     
    BobK, Mar 24, 2017 at 11:09 PM
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  15. alfa88

    alfa88

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    Well that's no fun.
     
    alfa88, Mar 25, 2017 at 6:09 AM
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  16. alfa88

    duke37

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    That could be a lot of fun:)
     
    duke37, Mar 25, 2017 at 8:50 AM
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