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  1. #21
    Photo Engineer's Avatar
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    Regarding electrical circuits in the darkroom, I have all of mine on GFIs so that if I touch anything wet, and the grounding is not proper, the electricity dies, not me.

    PE

  2. #22

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    Regarding LEDs, I've got a couple of these LED bulbs, one in red and one in white. My intention was to use the red one as a safelight and the white one as a small white light for short periods of use on the dry side of my darkroom. I discovered, though, that both bulbs continue glowing for a minute or two after being switched off. The amount of light output is quite low -- it's not perceptible in normal B&W safelight conditions; I only noticed it the first time I did color enlarging after installing the LED bulb. I don't know if this is a quirk of this particular bulb or if it's true of other LED bulbs.

    The red LED makes a great safelight, though. The afterglow isn't much of a problem for that situation, of course. The light is quite bright and doesn't fog my paper (I've run safelight tests).

    Oh, and PE's suggestion of using GFIs is quite sensible. I've got those in my darkroom, too.

  3. #23
    Lee L's Avatar
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    Quote Originally Posted by Tom Kershaw View Post
    Lee L,

    Would it be possible for you to describe how to construct an LED safelight array?

    Tom.
    I didn't have to really construct anything, just jumper wired together some stock parts.

    For AC powered bulbs I use these http://superbrightleds.com/specs/E27-W24.htm in both red and amber for safelight and white for intermittent light when printing. Check the spectral graph link at the bottom of the page to see if output is suitable for your materials.

    For DC powered arrays I use http://superbrightleds.com/specs/LB1.htm, but they have more choices here http://superbrightleds.com/light_bars.htm that will work. I power the DC light bars, which are designed for a 12V power supply, with these http://www.partsexpress.com/pe/showd...number=120-536 , which I got on sale for about $8 each. This lets me adjust the output to safe and comfortable levels. The supply provides 3V, 4.5V, 6V, 7.5V, 9V, or 12V DC, and 6V or higher provides usable output. I bounce them off the ceiling from the top shelves above my processing bench and behind my enlarger. Just two amber 3-LED sections from a light bar are plenty bounced off the ceiling above my processing bench, and throttled down to 7.5VDC.

    Note that inexpensive jumper wires in different lengths are available for the light bars, and can be routed to physically spread out the LED bars. The light bars I chose can also be snapped into four pieces with 3 LEDs each, then linked with jumper wires.

    I put the Edison based LED array bulbs in cheap aluminum reflector clamp lamps so that I can direct them or fire them off the ceiling. They aren't effectively dimmable because of the internal circuitry to drop the 120VAC supply to the lower DC voltages the LEDs need.

    These http://superbrightleds.com/specs/e27-w8.htm also work well, and are about $4 each in red or amber. Hard price to beat.

    Like Ron and others, I have my whole darkroom on GFI circuits.

    Lee
    Last edited by Lee L; 11-04-2007 at 12:06 PM. Click to view previous post history.

  4. #24
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    Quote Originally Posted by srs5694 View Post
    Regarding LEDs, I've got a couple of these LED bulbs, one in red and one in white. My intention was to use the red one as a safelight and the white one as a small white light for short periods of use on the dry side of my darkroom. I discovered, though, that both bulbs continue glowing for a minute or two after being switched off.
    I was thinking of using the amber ones for safelights, but your comment on 'afterglow' makes me pause as they'll be plugged into an RH Designs Analyser Pro, and the Analyser automatically turns off the safelights when in metering mode to get an accurate reading from the negative.

    Anybody use LED safelights with their Analyser Pro?

    Edit: Just found this in the FAQ's section of the RH Designs website;

    All exposure meters will be affected by safe lighting, even those which claim immunity, so for best results the safelight must be switched off during measurements. The Analyser can do this automatically for you if you wire a conventional tungsten or LED safelight to it.
    So LED safelights are OK after all

    Murray
    Last edited by MurrayMinchin; 11-04-2007 at 03:09 PM. Click to view previous post history.
    _________________________________________
    Note to self: Turn your negatives into positives.

  5. #25
    Lee L's Avatar
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    Quote Originally Posted by MurrayMinchin View Post
    I was thinking of using the amber ones for safelights, but your comment on 'afterglow' makes me pause as they'll be plugged into an RH Designs Analyser Pro, and the Analyser automatically turns off the safelights when in metering mode to get an accurate reading from the negative.

    Anybody use LED safelights with their Analyser Pro?

    Murray
    Unless things have changed lately, the white LEDs are actually blue LEDs exciting phosphors that emit the fuller spectrum. It might be these phosphors that continue to glow. If you're using red or amber for safelight, I'd be very surprised to see any afterglow unless there's a capacitor bleeding off somewhere...

    I just checked white, amber, and red versions of the lamps you're asking about, and saw no afterglow from any of them in the darkroom with all lights off. They were only on for a short time, and I wasn't fully dark adapted, but I don't think you'd see any problems with readings from the Analyser Pro after turning them off, especially if they weren't directed right at the baseboard.

    Lee

  6. #26
    MurrayMinchin's Avatar
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    Thanks Lee, I appreciate that, and thanks for the excited phosphor warning!

    Murray
    _________________________________________
    Note to self: Turn your negatives into positives.

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