UV Sterilizer with GTL3 bulbs

Discussion in 'The Projects Forum' started by sderrick, Jul 22, 2012.

  1. sderrick

    Thread Starter New Member

    Jul 22, 2012
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    I'm getting ready to order parts to build a UV water sterilizer using the GTL3 UV bulb.

    http://www.lightbulbsurplus.com/index.php?main_page=product_info&products_id=327

    It looks like an incandescent but I'm not sure, I know it has mercury in it aka mercury vapor? I'm wondering if it needs a higher starting voltage? I was going to use a DC-DC linear regulator like this one, I have ample 24-30 vdc supply from a solar setup.

    http://www.acopian.com/store/dcdc-narrow-t.aspx?min=18&max=36

    There will be about 20 GTL3's in parallel to generate 60 watts of UV.

    Can I just hook um up in parallel and throw the switch?

    thanks,

    Scott
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    Welcome to AAC!

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  3. #12

    Expert

    Nov 30, 2010
    16,284
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    That looks like a 3W, 10.5V, incandescent bulb. .286 amps each. The presence of filaments suggests that it just needs 10.5 volts. Total = 5.71 amps except that incandescent lamps have a cold start surge current that is rather high and might put a high tech supply into self-protect mode.

    It looks like you are skimping with a 5 amp supply module, and at $185 each, this is why people like us make our own power supplies!

    Your response?
     
  4. sderrick

    Thread Starter New Member

    Jul 22, 2012
    5
    1
    I know it "looks" like an incandescent bulb, but I think its a Low-Pressure Mercury-Arc lamp,
    which is my concern.

    Do I have to do anything special with starting voltages or can I treat it like any other incandescent bulb and just hook up the power and it will self regulate?

    I found this conversation http://forum.allaboutcircuits.com/showthread.php?t=68736 but its inconclusive.

    From the above conversation it looks like I need to limit the current through the bulb by using a series resistor and a cap to help it start?

    And thanks for the heads up on the power supply, I can easily get the next larger model.

    Scott
     
  5. #12

    Expert

    Nov 30, 2010
    16,284
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    Last edited: Jul 23, 2012
  6. sderrick

    Thread Starter New Member

    Jul 22, 2012
    5
    1
    No that's not right. Those ballast's are for much larger wattage and AC voltage. This is a 10.5 dc 0.3 watt light bulb.

    There seems to be much confusion on the light bulb sites about ballasts and these bulbs. Some say no ballast required others say they are required but don't know which one? Of course most light bulb sites don;t know squat about what they are selling, they just sell stuff.

    Scott
     
  7. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    I do not know the lamps, but I could imagine that the filament is heating the mercury to have the UV portion of light.

    Bertus
     
  8. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    No joke or hoax product. Regular product.

    The filaments are not the high temperature type. Looks similar to CFL filaments (or 4W tube).

    You won't get UV if you just power the filament. This is what I guess.
     
  9. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,804
    833
    The description of the GTL3 states:
     
  10. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    Takao: Again I ask, where does the arc current travel considering there are only 2 contacts on the lamp?

    Answer: It doesn't.

    as djsfantasi just pointed out, these are INCANDESCENT lamps.

    The ballasts I pointed out are sold on the same site, to power UV bulbs, but they are for T5 tubes. After searching diligently, that site does not sell a "ballast" or "fixture" for those bulbs. I can only come to the conclusion that they are 10.5 volt incandescent bulbs and they need 10.5 volts AC RMS or DC.
     
  11. sderrick

    Thread Starter New Member

    Jul 22, 2012
    5
    1
    I think they are as published, Low Power Mercury-Arc lamp bulbs.

    However as somebody previously mentioned they use the filament to provide the heat/arc. Once the filament heats up enough the mercury is lit off and voila, UV light in the 253 nm range!

    The key is to use a current limiting supply or run the bulb in series with a resistor. I'm going for the supply, have ordered one and a few bulbs.

    I'll report back my results.
     
    #12 likes this.
  12. takao21203

    Distinguished Member

    Apr 28, 2012
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    We should apply reason here for this device.

    The filament to me clearly does not look like high temp. incandescent.

    Maybe a special fixture is used, with an external foil pad that works through the glass? And so, maybe needs a special ballast.

    Not so special to me, a small CCFL inverter etc. might work well.

    I also don't get why you put efforts into it. 4W etc. regular UV tubes are cheap.
     
  13. takao21203

    Distinguished Member

    Apr 28, 2012
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    Most gas discharge devices I am aware of use inductive ballast.

    How can the gas discharge happen? 10V between the two heated filaments? That looks a little low to me.

    I rather guess a special fixture is used for these, using for instance a foil pad.

    When I connect one wire from CCFL inverter to a CFL tube, and touch the glass with my hand, the CFL lights up.
     
  14. sderrick

    Thread Starter New Member

    Jul 22, 2012
    5
    1
    All guesses. It's nice to wonder how something works, but in the end, facts are whats needed.

    I can only assume nobody who's read this thread really knows how a DC Low Power Mercury-Arc lamp works. Everybody is basing there "guesses" on how high voltage AC fluorescent and arc lamps lamps work.

    It like having only ever seen an incandescent and trying to describe an LED light.

    Scott
     
  15. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
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    I know how 4 Watt UV tubes work. Including I have used them myself, with different kinds of inverter circuits.

    However this small bulb is not very common. It is not very likely that many replies can exist of a person who is using these bulbs, has used them, or knows them at all.

    Why not use a regular UV tube? These bulbs seem to be speciality product.

    I have at least looked up the manufacturer website.

    If I have professional requirement to use the bulbs, I would contact them.
     
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