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  1. #21
    NedL's Avatar
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    In my post above I should have mentioned that it was the *same* print that I made twice before comparing.

    Since then, I too have finished a Kodak-style test with this led light. I used only one, located as I mentioned about 5 feet above my working area in a fixture with a metal reflector, aimed up at the ceiling. I tested Adorama Brand VC paper, with up to 7 minutes before and after threshold exposure. It tested safe. I suppose to be 100% forthright, I should mention that I preflash paper through a green filter, and that's what I did for these tests. Next up will be Arista.edu VC paper, which my old safelight setup caused to fog.

  2. #22
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    For those of you who have purchased this product and still have the original box it came in, what is the maximum AC voltage these LED globes are rated to ? We use 230V in OZ but there is no mention of the rating on the web page. Some of the other LED globes on that site are rated to either 110V or 110/240V but they don't come in red.

  3. #23
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    I also have used LED safe lights (superbrightleds.com) for a few years now and never had issues with fogging. There's quite a bit of data on this in already existing threads but LED bulbs tend to be narrowband which is what one wants. I always use red, never OC or equivalent.
    Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.

    http://www.flickr.com/kediwah

  4. #24
    NedL's Avatar
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    Quote Originally Posted by PeterB View Post
    For those of you who have purchased this product and still have the original box it came in, what is the maximum AC voltage these LED globes are rated to ? We use 230V in OZ but there is no mention of the rating on the web page. Some of the other LED globes on that site are rated to either 110V or 110/240V but they don't come in red.
    The box says "Voltage:110VAC". Sorry

  5. #25

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    I recently purchased one of these http://www.amazon.co.uk/dp/B00C665QY..._am_gb?ie=UTF8, which has 24 LEDs in a single bulb. It is equivalent to about a 40-50w incandescent bulb and is completely safe. I've been using it for lith printing with total times for the paper bring exposed to the light of almost an hour. This includes Forte polywarmtone which can be dodgy even under a dim red safelight for long exposures.

    Having previously worked with one very dim 15w bulb behind thick red plastic it is a joy to use. There is no need for a safe torch from judging the shadows of my lith prints, I can see them come up clearly. The bulb gives a 120 degree angle of coverage which covers the whole of my darkroom nicely.

    There is no way I would ever go back yo incandescent bulbs.

  6. #26
    clayne's Avatar
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    Yeah the pure red LED bulbs are great. The only thing better is the Thomas Duplex sodium vapor but I actually found it too bright for the light level I was already used to working in.
    Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.

    http://www.flickr.com/kediwah

  7. #27

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    Quote Originally Posted by polyglot View Post
    The thing about LEDs is that they are bandgap devices, they (usually) emit light at exactly one wavelength only. No other wavelengths are possible, because the wavelength is defined by the photon energy, which is defined by the difference in chemical energy levels in the semiconductor.

    Some manufacturers will deliberately mix multiple dopants to broaden the spectrum so this is clearly not true of all LEDs, but the basic simplest cheapest red LED you can make is a single-bandgap device. Obviously one must still test to make sure they don't have a deliberately spread-spectrum device or that the paper they're using doesn't somehow have a tiny bit of sensitivity out to the longer wavelengths.
    ............
    That's not my experience. A simple test: view the light reflected from the base of a CD at the angle that gives the "rainbow" effect and see if there are other colours present. I now have safe red LEDs but only by choosing some extreme deep red units. Most red LEDs that I tested showed orange..yellow..even cyan.

    If you have some that are a single wavelength could you let us know the spec because Id' be interested in trying them?

  8. #28
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    Quote Originally Posted by NedL View Post
    The box says "Voltage:110VAC". Sorry
    No probs. I could probably open one up to see which components are rated below 240V (e.g. caps, regulator etc)

    I previously purchased some amber LEDs and one day will plan to screen and test them myself.

  9. #29
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    Quote Originally Posted by PeterB View Post
    No probs. I could probably open one up to see which components are rated below 240V (e.g. caps, regulator etc)
    Please do not. Changing the supply voltage requires significant redesign of the switching regulator, not merely up-rating some of the components. The frequency and/or duty cycle will change and the magnetics will not be appropriate any more. It will either not work or be a significant fire hazard, even with uprated components. The component ratings required are NOT the supply voltage; some (depending on the switcher topology) need to be rated up to 3x higher, e.g. 600V for use on 240VAC supply.

    "Do not meddle in the affairs of wizards for they are subtle and quick to anger". Switching power supplies are well and truly into that territory.

  10. #30
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    Thanks polyglot. Are you certain it contains a SMPS and not a Tx + a linear regulator ?

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