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  1. #21

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    Well, like I said, I've got the bits on my desk to make a LED VC head.

    I'm pretty sure that you'd be able to do it with stock parts and a microcontroller. Instead of white LEDs (which are not as efficent as the advertisers would like to think) you should just use blue and green LEDs.

    Depending on sensitivity, you should be able to use the three-color-in-one-pacakge LEDs, which reduce the uneven-color-distribution problems and lets you have a "safelight" mode or lets you use it as a color head too.

    There's a lot you could do with it, mind you. Imagine programming in a split-tone pattern with x seconds at grade 0, y seconds at grade 2, 10 seconds of safelight so you can grab your dodging tools, and then z seconds at grade 4 in a box that, as far as the parts are concerned, costs under $50.

  2. #22
    Curt's Avatar
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    I'm pretty sure that you'd be able to do it with stock parts and a microcontroller. Instead of white LEDs (which are not as efficient as the advertisers would like to think) you should just use blue and green LEDs.

    Hi wirehead, can you give me a lead on where to buy LEDs? I think I will put together a light source for my small 6x6 enlarger to experiment with. I need to have my Beseler 45 in operation or I would use it.

    Many thanks to all the folks here. If anyone else is going to experiment or make one would you please post the info here?

    Curt

  3. #23

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    Curt, I dabbled around and I'm reasonably sure a 5x7 could be made from the LEDtronics modules. I made up a outline and I'm including a side view of my existing 4x5 head you might be able to use. I'm posting it here for everyone, however please keep in mind it's experimental. The last thing I want to do is cause anyone here grief.

    The design is based off my 4x5 -- all I've done is add four more modules to the end of the head for a total of ten 6" strips. Ten modules creates a total of 120 LEDs (cripes!). Printing times would probably be something like two seconds. Something in-line to dim the bulbs (a rheostat?) would be useful. Also, with that many bulbs some kind of ventilation would probably be a good idea; perhaps nothing more than some open slits in the sides of the box with light baffles for passive cooling.

    Superbrightleds.com (posted earlier by Lee) has some neat alternatives to LEDtronics. Also, a completely custom made light, like wirehead's suggestion, might be more practical for a 5x7.
    Last edited by konakoa; 05-22-2010 at 06:57 PM. Click to view previous post history.

  4. #24
    Curt's Avatar
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    Danny,
    Thanks, I have been brushing up on my basic electronics and looking at some LEDs. This is the kind of project that I would enjoy putting together and the strips are a good way to get going right away.

    Curt

    Thanks so much for the diagram and picture.

  5. #25
    Steve Smith's Avatar
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    Thanks for posting these details. I have been thinking about making a 5x4" enlarger and an LED light source seems to be the best way to do it. I may also do some experiments with alternate green and blue LEDs.

    Steve.

  6. #26
    Bob F.'s Avatar
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    You might want to read this (http://www.apug.org/forums/forum41/11082-led-enlarger-head.html) thread and check out Huw's site (http://www.huws.org.uk/). Do a search on "LED ENLARGER HEAD" on the archives here for more.

    Cheers, Bob.
    Last edited by Bob F.; 12-08-2006 at 05:40 AM. Click to view previous post history.

  7. #27

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    I use superbrightleds myself.

    As far as the circutry for custom stuff goes, you need to have resistors to control the voltages. Search for "LED Resistor calculator" and that let you figure out what resistor you need.

  8. #28
    Curt's Avatar
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    Thanks Bob for the info.

    Curt

  9. #29
    Nicholas Lindan's Avatar
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    Quote Originally Posted by jstraw View Post
    Then the relay is connected to the timer?
    Yes: the relay coil is wired to the timer where the enlarger would plug in. The contacts for the relay are wired in series with the LED's so current only flows to the LEDs when the relay is energized. The power supply for the LED's is always on/plugged in.

    Be sure to use a relay with a 120V/60Hz coil [or 220/50 if in Europe, etc.].
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  10. #30

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    I had a thought on Curt's edge burning idea. All that needs is some means of brightening the corners of the light source. The LEDs have light intensity to spare, so I could see some thin nearly transparent material, like tracing paper or a lightly fogged sheet of film, cut into a oval and placed inside the box on top of the diffuser. That would darken the center, but leave the corners bright. Some fiddling of the size of the oval would be needed, but I think that would do it.

    Heck, a filter tray could be made that would slide in and out of the head itself. Mount the oval on a clear sheet of plexiglass, and slide it in and out of the head (above the diffuser) as needed.

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