My new DIY LED red safelight

Discussion in 'Darkroom Equipment' started by michael_r, Aug 24, 2011.

  1. michael_r

    michael_r Subscriber

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    Hi everyone,

    I thought I'd post this in case anyone out there is interested in this very simple, quick safelight project.

    I've always been happy with my dad's old traingular Kodak safelight. I change the OC filters periodically and although it doesn't give alot of light, I've simply grown up this way so I'm used to the fairly low light level, and I get very long safe times with VC paper.

    Recently I wanted to start doing some masking experiments with Ortho film, so I needed a red safelight. Well, the Kodak filters are quite expensive, and I couldn't even find a red #1 or #2 (dark red) in the right size, so I thought about LEDs.

    A fellow APUG member, handle KonaKoa, suggested a simple LED project. I was nervous about it at first since I know virtually nothing about LEDs and how to wire them, drive them etc. But with KonaKoa's help it turned out to be super easy - basically plug-and-play - and very cheap too. All I had to do was buy a pre-fab LED strip, 12V power supply and PWM dimmer from superbrightleds.com.

    For those who are more adept at soldering and are willing to spend a bit more time on it, superbrightleds actually sells red component LEDs that peak at 660nm. This would be a better wavelength for longer safe times with Ortho films (and virtually any paper). Since I wanted a more simple project, I bought the pre-made strip, which uses LEDs that peak at 626nm. While not the ideal red, I figured if the light level was low enough it could work as a starting point. The small strips come with 30 LEDs. This is extremely bright, which is why the dimmer is a must. It dims my pulse width modulation, so that there is no change in the color. Even so, I cut the strip down to 12 LEDs (cutting points are indicated every three LEDs on the strip) and it is still quite bright. I could have probably done with just one segment (3 LEDs) but whatever.

    Using some scrap wood, I put a "rail" on each side of the strip. This way I can put the safelight pretty much anywhere (like on a shelf or even on the floor) and have it shine upward to reflect off the ceiling, without the paper or film being within the viewing angle of the LEDs themselves, which are intense point sources of light. The result is a soft, diffuse red lighting without hot spots, and I can just turn the dimmer up or down depending on where I position the light, and how much light I want.

    I also have a sheet of Rubylith which I can simply place over the LED strip for longer safe times. I tested this up to 20 minutes with pre-exposed paper and found no fogging. I didn't bother testing longer but it would be an interesting experiment.

    For even longer safe times I could also put a Kodak #2 filter over the LED strip. A #2 filter over red LEDs makes pretty much the safest safelight I can think of for any purpose, whether it be printing or working with lith film for masks etc.

    I've attached a few pictures of this simple DIY device for anyone interested in trying it, and if anyone is interested I can provide the detailed product numbers of the strip, dimmer and power supply. Assembly took about 10 minutes.

    Thanks again to KonaKoa for this idea.

    Michael
     

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  2. Anscojohn

    Anscojohn Subscriber

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    What do you figure it cost, all together?
     
  3. wildbill

    wildbill Member

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  4. michael_r

    michael_r Subscriber

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    About $35 total for the LEDs, power supply and dimmer.

    By the way nice to see Anscojohn is still around (slightly) :smile:
     
  5. Newt_on_Swings

    Newt_on_Swings Member

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    Next project... encase led lights into a light saber housing. Mount multiple red and orange lightsabers in darkroom. win
     
  6. smieglitz

    smieglitz Subscriber

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    I've used LED strips connected to a small AA battery pack also.

    For another inexpensive red safelight search Sylvania 29970 - 13W CFL Twist Red for a bright cfl bulb solution that screws into a standard socket. I think I paid about $8 for them at Lowes.

    They are surprisingly bright for such low wattage. I use them in my wetplate darkroom but assume they would be fine for other ortho materials.

    [​IMG]
     
  7. ath

    ath Member

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    Or just buy a complete red LED bulb fitting a standard lamp socket. Works great for me since years. Before that I bought a bunch of high efficient red LEDs to build my own but other things were more important.
     
  8. Lee L

    Lee L Member

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