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Thread: High power LEDs

  1. #1
    Robert Hall's Avatar
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    High power LEDs

    Any one know of a good source for large high output LEDs?

    I would like to make some safe lights for the darkroom.

    TIA
    Robert Hall
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    Technology is not a panacea. It alone will not move your art forward. Only through developing your own aesthetic - free from the tools that create it - can you find new dimension to your work.

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    I've thought about giving these (the red one) a shot, if my current bulbs ever get around to dying.

    http://www.superbrightleds.com/specs/E27-W24.htm

    No idea how narrow the bandwidth really is. Some of the papers I'm trying require red, but for other people maybe the amber ones would work too?

    If you give them a shot, let us know how it goes, please.

  3. #3
    Jeremy's Avatar
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    I use these in my darkroom and haven't had any problems with Forte or Ilford paper fogging (10 minute test). They are very bright and one bar of lights was enough for me. Robert, I stll have another bar I can send you if you'd like to give it a shot (and see how bright they are).

    I soldered mine (with some heatshrink tubing on the outside) to a variable output power supply from Radio Shack and run them at 9v just to be on the safe side (12v just seems SO bright!).

    edit: I have some from the same place Lee Gebhardt bought his from. If you search Apug there is a post or two about this.
    Let's see what I've got in the magic trash can for Mateo!

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    Any electronics shop should have leds suitable for your use. Ignore the 15mcd variants but anything between 500mcd and perhaps 2000mcd will be useable. I don't recommend the luxeon style leds as they'll be too bright. As previously mentioned the ones used for show replacement in cars work well but you'll have to reduce the voltage to lower the current and hence light output unless you have a big darkroom. Maybe buy a few different single ones to try - they're at most only a dollar or thereabouts each and in a darkened room they're bright enough.

    Roger.

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    Bob F.'s Avatar
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    I use the Luxeon LED. You'll only need the one - as Roger says, they are *bright*. A simple power MOSFET, 3 resistors and a potentiometer cct will provide a continuous dimmer control, or just use one current limiting resistor and make a shade to adjust the brightness. I made mine so I can plug in external LED heads, but that's probably overkill (and after 6 months, I still haven't gotten around to actually making a remote head - I just plug the LED soldered onto a DC power plug into the remote socket)...

    http://www.apug.org/forums/attachmen...achmentid=3508

    Cheers, Bob.

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    I bought a couple of the red LED bulbs for sale on the APUG classifieds just to check them out. I have not officially tsted them yet for fogging but no apparent problems. They are very bright and only cost about $15 each.
    Jerold Harter MD

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    Pragmatist's Avatar
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    Slightly different use

    Has anyone used these led's to replace the bulb in a conventional condenser head? I am thinking that this might be practical. Any thoughts?
    Patrick

    something witty and profound needs to be inserted here...

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    I have not tried. I've heard the shape of the bulb may be critical to getting even illumination, and the shape of the LED bulb would surely be different from what the enlarger was designed for. Also, incandesent bulbs have a continuous light spectrum, so small dips and bumps in the spectral curves of multigrade papers or multigrade filters won't matter too much. On the other hand LEDs only have a few narrow lines in their color spectrum; if these spots happen to land on a "bad spot" of the spectrum of the filter or paper, it could be hard to get the contrast you want.

  9. #9
    resummerfield's Avatar
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    A LED light shouce for VC papers is a proven concept. See this APUG link. A dimming control would be required for these screw-based LEDs.
    —Eric

  10. #10
    RJS
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    I think Paul Butzi mentioned an LED safelight on his web site. I tried to find the maker and couldn't. Maybe you'll have better luck. It sounded terrific!

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