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Dumb scuba products

Discussion in 'General Scuba Equipment Discussions' started by Moogyboy, Nov 27, 2019.

  1. StefinSB

    StefinSB Manta Ray

    # of Dives: 200 - 499
    Location: Santa Barbara, CA
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    The reason why a dedicated blue light is generally better than a white light is with a blue filter is mainly the available output power in a the desired wavelength. E.g. if you start with blue and white LEDs with an output power of "10", the white LED will only deliver a fraction of that after the blue excitation filter is installed. For both approached you would need of course a yellow filter in front of your eye/camera to block the excitation wavelength (blue in this case).
     
  2. Kharon

    Kharon Solo Diver

    # of Dives: 200 - 499
    Location: Upstate NY
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    Thanks for the explanation. Makes perfect sense.
     
    StefinSB likes this.
  3. Rich Keller

    Rich Keller Solo Diver

    # of Dives: 5,000 - ∞
    Location: Long Island NY
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    Seems like a real bad idea as advertised but I have never seen one in person. Looks like it could be modified to install a reg and comms. Lose the snorkel part and vent air from the top of the mask. Making a poor mans band mask.
     
  4. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
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    I was told by Charlie Mazel, the man behind NightSea, that LEDs are fundamentally UV to begin with, and must have a phosphor on them to allow that white light....that is, the phosphor is excited by the LED light and emits white. So to make a UV (or approximately so) light, you need only to eliminate or change the phosphor...thus it is "brighter". I think I have the facts straight here, and am sure I'll be corrected if they are not!
     
  5. StefinSB

    StefinSB Manta Ray

    # of Dives: 200 - 499
    Location: Santa Barbara, CA
    701
    457
    63
    The blue LED was made possible by creating a high energy gap pn-junction using InGaN. It was not made by “just eliminating” some internal Phosphor layer. In either case, I am not sure what your point is.
     
  6. The Ruttmeister

    The Ruttmeister Angel Fish

    # of Dives: 0 - 24
    Location: Bay Area, CA. USA
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    Errrrr... kinda yes, but also no.

    Colour LED's (red, green, blue etc) are the colour they are due to the material the emitter is made from and they emit moncromatic light (unlike a tungsten light source with a filter, LED's are only producing a pure narrow frequency of light). This is why RGB LED lights make people look weird, they don't actually include any yellow light (if you want good colour rendition and colour mixing you need RGBA, or Red Green Blue and Amber). Non-UV LED's emit zero UV.

    White LED's are basically what you describe, they are actually a blue (not UV!) LED with a yellow phosphor slapped on top. That phosphor absorbs the blue light and re-emits it as enough of a spread across the spectrum that you get a good enough approximation of white light. If you look at the graph of output vs frequency of a white LED you'll see that it has a big spike in blue and a broad hump across yellowish.

    UV LED's are less common, for a whole bunch of reasons. Like the fact that the UV light actually degrades the plastic the diode is housed within, so they have a much shorter service life. Plus UV applications often require very high output, but high intensity UV point-sources (like LED's) are quite hazardous. So diffuse sources are preferred.

    White LED's are less efficient than other types, partly due to the phosphor losses, partly due to the way we perceive and measure light.

    To the original point, yes, 10W of blue LED will always be much brighter than 10W of white LED with a filter. Filtering LED's is generally not done at all, as its very in-efficient and typically produces poor results (due to the output spectrum of white LED's).

    Blue LED light is no substitute for a UV source though. It will produce some interesting effects due to its monochromatic spectrum, but it will not produce fluorescence.
     
    Kharon likes this.
  7. CT-Rich

    CT-Rich Solo Diver

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    So that moisturized air flows threw 40” LP hose. Have you ever run something threw the hose to check for mold?
     
  8. CT-Rich

    CT-Rich Solo Diver

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    My dive old computer had a audible alarms. I had no idea for about 5 years. I never dive with my hearing aids. My buddies never mentioned it.
     
  9. CT-Rich

    CT-Rich Solo Diver

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    What these statistics don’t show are the numbers of divers that dropped weights and survived. When a dive goes sideways and a diver makes it to the surface and drops his weights or tries to make a buoyant ascent, there a no statistical data to work off of. This corpse retrieval device seems more dangerous than any significant benefit.
     
  10. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
    8,298
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