I have also long been interested in doing neon tubes for fun, as well as lasers and other fun things. I have both diff pumps and a turbo pump which I want to configure into a vacuum workstation built on an old ultracentrifuge chassis. So I was looking at neon sign electrodes as a possible starting point for some of this stuff.
Would placing a cold trap inline before the turbo pump capture any possible mercury or other contamination? I would think that the vapor would be pulled through by the roughing pump anyway. Am I correct in remembering that some diff pumps actually used mercury versus oil? I'm pretty sure the two I have both used oil. One was from ebay, the other from the aforementioned ultracentrifuge. At least one of my 3 Welch rotary vane roughing pumps needs a rebuild (if not all of them). Man, rebuild kits have skyrocketed in price! Haven't tested the other, more modern roughing pump yet. On Sun, Oct 24, 2021 at 11:10 PM joshua dejaen <[email protected]> wrote: > I have an edwards e2m1 that I bought used for $200 which theoretically can > reach .38 microns. > > Its pumping speed however is slow and my rubber stoppers are not helping. > My thermocouple gauge burned out unfortunately so I can't measure my > current vacuum but I would not be > > surprised if I was achieving 5 microns or lower after extended pumping. > > A diffusion pump is not necessary in my opinion for experimenting, but > probably is needed if you want to make a tube that will last for decades. > > Bombarding is an issue I have not solved, I currently just heat the tube > with the torch for a while pumping to remove impurities and call it good. > > This leaves the electrodes unprocessed however and will lead to a shorter > life. > > Simplifier and myself have both also both made functional Triodes using > nothing more than a rotary vane pump, and he was able to achieve below 5 > microns with his generic Chinese > > pump. > > > Here is a link to Simplifier making a helium discharge tube using only a > cheap rotary vane pump https://simplifier.neocities.org/discharge.html > > And his Homepage https://simplifier.neocities.org/index.html > > He has a whole list of vacuum and glass related projects and does them in > the simplest way possible. > > > > > > > On Sunday, October 24, 2021 at 7:03:38 PM UTC-7 gregebert wrote: > >> Did you need to use a diffusion pump to get below 10 microns ? Years ago >> I researched doing neon tubes, but got discouraged by the high-cost of the >> vacuum equipment and the dangers of bombarding. >> >> On Sunday, October 24, 2021 at 11:32:33 AM UTC-7 Chuck wrote: >> >>> I distinctly remember some of Dalibor's first tubes from mnay years ago >>> when he first started experimenting. >>> >>> He made one that looked a lot like this one. Nice Work! >>> >>> Chuck >>> >>> >>> >>> >>> ---- Original Message ---- >>> From: "joshua dejaen" <[email protected]> >>> Sent: 10/24/2021 2:36:14 AM >>> To: "neonixie-l" <[email protected]> >>> Subject: Re: [neonixie-l] Re: Homemade Purple Nixie Tube >>> >>> Thanks for all the comments, sorry I could not reply sooner. >>> >>> I have added mercury to glow tubes in the past but I have not wanted to >>> contaminate my new pump. >>> >>> I could do it on my old pump but it is not able to pump below 1 torr and >>> the tube would be left with impurities. >>> >>> My electrodes consist of copper welded to tungsten with a nickel buffer >>> and then the tungsten welded to nickel wire that forms the digits inside >>> the tube. >>> >>> The tungsten forms the actual seal to the pyrex glass and the copper >>> provides a nice external lead. >>> >>> I heat up the tube with the torch while pumping for about a minute and >>> let it pump under high(ish) vacuum (5-10 microns) for 30 min. >>> >>> I then open the bleed valve and adjust the pressure until the glow looks >>> good and seal it off. >>> >>> I also have made Triodes in the past and those require about 15 min >>> heating with the torch on the pump along with an hour of pumping. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> On Wednesday, October 20, 2021 at 12:49:28 PM UTC-7 [email protected] >>> wrote: >>> >>>> I don't recall for certain if it was NeonJohn or another guy, or even >>>> what group it was in. Could've been the old geigercounterenthusiasts group >>>> on yahoo. This was some time ago, when we were laughing about the insane >>>> overreaction to breakage of CFLs in school classrooms. I've never tried >>>> opening a tube in a controlled fashion myself, but have seen tiny droplets >>>> in broken ones, usually near the ends of the tube. >>>> >>>> Been playing with glass laser tubes a little the last week. Found that >>>> Gammex patient positioners used both red and green HeNe before diodes took >>>> over. Got one that won't lase though the plasma tube is a nice bright >>>> pink. It hisses or buzzes continuously but no beam output. The PS is good >>>> as it lit up a couple of similar size d tubes last night when I tried. I >>>> need to completely remove it and try sighting through the bore. It's >>>> possible it's leaking and coming up in pressure slowly and is now dead. I >>>> was looking at the metal evac/fill tube where it's crimped off and >>>> wondering about the possibilities of re-gassing... I have a couple of >>>> those metal tube ends with some defunct old tubes I got from Laser Sam a >>>> couple years back for experimenting. More interests, less time... >>>> >>>> >>>> On Wed, Oct 20, 2021 at 2:37 PM Mac Doktor <[email protected]> wrote: >>>> >>>>> >>>>> On Oct 20, 2021, at 2:59 PM, Nick Andrews <[email protected]> wrote: >>>>> >>>>> A guy built a device to try and capture the mercury, thinking he could >>>>> recover and build up a small supply. He found that he never could get any >>>>> significant quantity from the tubes. >>>>> >>>>> Did he condense the vapor first? >>>>> >>>>> >>>>> Terry Bowman, KA4HJH >>>>> "The Mac Doctor" >>>>> >>>>> https://www.astarcloseup.com >>>>> >>>>> “...the book said something astonishing, a very big thought. The >>>>> stars, it said, were suns but very far away. The Sun was a star but close >>>>> up.”—Carl Sagan, "The Backbone Of Night", *Cosmos*, 1980 >>>>> >>>>> >>>>> >>>>> >>>> -- >>>> >>>> >>>>> You received this message because you are subscribed to the Google >>>>> Groups "neonixie-l" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected]. >>>> >>>> To view this discussion on the web, visit >>>>> https://groups.google.com/d/msgid/neonixie-l/4D0670A0-1C14-4185-8491-4629E387CD7C%40gmail.com >>>>> <https://groups.google.com/d/msgid/neonixie-l/4D0670A0-1C14-4185-8491-4629E387CD7C%40gmail.com?utm_medium=email&utm_source=footer> >>>>> . >>>> >>>> -- >>> You received this message because you are subscribed to the Google >>> Groups "neonixie-l" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> >>> To view this discussion on the web, visit >>> https://groups.google.com/d/msgid/neonixie-l/17081a57-50be-4398-85ba-fc7572f0e209n%40googlegroups.com >>> <https://groups.google.com/d/msgid/neonixie-l/17081a57-50be-4398-85ba-fc7572f0e209n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/15ae8936-7bdb-40e9-95d3-12833dabb3a5n%40googlegroups.com > <https://groups.google.com/d/msgid/neonixie-l/15ae8936-7bdb-40e9-95d3-12833dabb3a5n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. 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