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Strange Gas Tube

Discussion in 'Electronic Components' started by c a l a n d e, Mar 21, 2005.

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  1. Once again I ask this group to help identify an interesting component.
    In this case it's a thick walled glass tube with a pair of electrodes on
    either end. It's length is about 9+3/8 inch (24 cm) and has a 0.310 inch
    (8 mm) diameter. Pictures are at:

    I've shown it to a few electrical engineers and the general consensus is
    that it's some form of high current surge suppresser. I'm almost
    convinced but I can't imagine why it would be serialized. If it is a gas
    discharge tube why is it polarized?

    If you have a good idea of what this tube is please post it here.
  2. jim dorey

    jim dorey Guest

    the bulbs at niagra falls blind-a-million-people-all-at-once look a lot
    like that. tried passing 25kvac through it?
  3. Guest

    that it's some form of high current surge suppresser

    Seems more likely that it's some super-duper voltage regulator tube.
    (Like the much smaller but approximately the same voltage OA2).

    The serialization with a voltage listed to a tenth of a volt makes me
    suspect this, at least.

  4. Don Bruder

    Don Bruder Guest

    PURE guesswork on my part - I'm ready to be wrong on all counts. Or
    pleasantly surprised to be proven correct...

    Looks to me like it might have something to do with high
    frequency/voltage work - perhaps having some connection to things like
    tesla coils and "violet wands".

    What gives you the idea that it's polarized? Or am I missing some tidbit
    of information that I ought to be stumbling over?

    Serialized is easy: inventory control.
    The box picture shows me at least two, possibly three, layers of tags on
    it, and it looks as though the same hand wrote the serial/voltage
    numbers on both, at least on the parts that show through. Could easily
    be Joe D. Clerk tagging inventory on a couple of occasions.

    Presumably, the voltage entry would be the tested-to voltage? At 149.1
    volts, does it arc to soak up overvoltages? Seems a bit long to arc that
    low, though. Which leads me to think it might be some sort of
    strobe-like unit - the reflector/backplate would be the "trigger" line,
    and it needs to get to 148.9 to trigger the discharge? Or perhaps "volts
    148.9" is understood by the staff who stocked this item as "148.9KV",
    and it's actually a (nominal) 150KV surge suppressor? 150KV arcing a gap
    that size makes a lot more sense than 150 volts.

    Maybe something for pumping a laser? No telling what's inside it to make
    what kind of color that could be used to pump, ferinstance, a crystal
    laser of some sort. Careful which way you point it if/when you power it
    up! And a lead-lined jock might not be a bad idea if you plan to breed
    in the future. :) No telling what this thing might put out!

    Looking back at the box...
    Am I crazy, or does it not look like it fits this item??? or is this an
    end-shot? Toss a penny or a ruler or something into the shot for some
    scale. Ditto the tube shots - #1 is good, but needs something for scale.
    #2 is OK, but desperately needs something for scale. And #3... Uh... I
    don't know what to make of it. It doesn't look like the "fittings" seen
    in either #1 or #2. Where'd the little conical "nipple" on the end of
    the electrode go? Is that even the same tube???

    Yoiks! Cancel that... I just this instant see what's going on... You
    flipped the tube end-for-end between #2 and #3. No wonder I didn't
    notice it to be polarized. Ouch, dude, that one made my brain hurt.
    Don't establish an orientation then switch up on the poor innocent
    viewer that way!

    Now that I've done some photoshop-like tinkering, and have the three
    shots laid out oriented to each other (I put the result up at
    <> if anybody's interested), I see
    that it's definitely polarized. Interesting... DC, then. And rated for
    148.9 volts...

    It's gotta be a lamp of some kind. Depending on what, if any, gas is
    inside, and at what pressure, output could be anything from "raw
    arc-flash" to "99 and 44/100ths percent pure UV" that'll cook your eyes
    to about the same texture and functionality as hard-boiled eggs, to
    "lookit the pretty sunset colors". I imagine it's probably pretty bright
    - Of course, for discharge lamps, that tends to be true no matter what
    color the output is. Goggle up before trying to power it up, I'd say...
  5. Looks like a gas-discharge tube, possibly a flash tube, although the voltage would suggest it's for
    continuous discharge - maybe as a light source for lab equipment. Seems a pretty low voltage for
    what looks like a fairly long tube though.
    Try zapping it with a piezo lighter or output of a CCFL inverter to see if you get any discharge.
  6. Guest

    maybe as a light source for lab equipment

    The form-factor of the tube is very similar to small discharge tube
    lamps for lab use. But... such a lab source would certainly be marked
    by which gas is inside and the users would not care what the voltage
    was to the nearest tenth of a volt.

    HV lab supplies long have used gas discharge regulator tubes (OA2 and
    higher-spec variants) as references. IIRC ambient light matters at the
    fraction of a volt level...

  7. Guest

    The electrodes are two different shapes. I'd say that this looks like
    an arc lamp of some kind. Maybe it's for calibrating spectroscopes,
    which would explain the accurate voltage. It's saying run this tube at
    this voltage, and the output spectrum wil be blah blah blah.

    Or it could be a thermometer of a painful kind.
  8. dlharmon

    dlharmon Guest

    I was going to guess Xenon flash tube, but the voltage seems too low.
    I would expect a few KV in that case. Very possibly a laser pump
    source. You might check alt.lasers Whatever it is, it will most
    likely take lots of KV to start.

    Darrell Harmon

  9. Thanks for the photo rework. By the way, there's a red dye on the very
    end of the flat electrode (left side).
  10. I posted as sugested in alt.lasers and someone pointed this out.
  11. Graham W

    Graham W Guest

    I think you'll find that it is a reflection of the red mat it rests on.
  12. Don Bruder

    Don Bruder Guest

    That's an interesting detail - I thought the red on the end of that
    'trode was reflection from the red cloth you used as a backdrop. I can't
    help but wonder what, if anything, that's about...

    Question: Is there an opening in the end of that red-tipped 'trode? Even
    just a tiny pinhole you can see daylight through? On second thought,
    never mind. Irrelevant question, and even if not irrelevant, the answer
    is in the pohotos, even if only indirectly. I was on the mental track
    that this thing MIGHT be a self-contained gas laser, but if that's the
    case, it's a serious oddball, since I see no sign of mirroring on the
    "nipple" or "bullet" electrode end. There'd need to be at least a
    half-mirror there if the thing was intended to be a standalone laser, so
    that's out.

    Which puts me right back to the idea that it's the "pumping" tube from
    an externally pumped laser - It flashes, the light from the flash
    excites the contents of the pumped tube, lather, rinse, repeat at high
    frequency, and suddenly, there's enough energy in the pumped tube for
    the beam to break out through the half-mirror/aperture and show you the
    results of your efforts...

    The "What the heck"? part is the wavelength involved - IF it is indeed a
    flash lamp, like it seems to be.
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