LED Lights in an Enlarger Head

[Pete Watkins]

I've recently aquired an old De Vere 45a with cold cathode head. It seems O.K. at the moment but has anybody here made up a do it yourself LED lighthead? The "bulb" isn't going to last for ever.
Pete.

[R Mann]

You should take a look at this -

http://www.reefcentral.com/forums/sh....php?t=1826521

[Dave Grenet]

Check out http://huws.org.uk/

I'm working on my own Graflarger LED head at the moment but I have a little way to go and it isn't really a priority...

Do you have any electronics experience?

[jon.oman]

http://www.ledtronics.com/products/P...px?WP=C349K594

http://www.deadbread.com/crumbs/23c.html

Take a look at the above links. This guy made his own from simple plug-in LEDs. No electronics work to do.

[Pete Watkins]

Many thanks for your help. I have a "tame" electrician on hand if I feel that I need one. I'm a total coward with electrics so I'll get him to check everything that I do anyway.
Thanks again,
Pete.

[Jerry Bodine]

[QUOTE=jon.oman;646953
[URL]http://www.deadbread.com/crumbs/23c.html[/URL]QUOTE]

To quote from near the end of this article:

"The light spectrum of the white LEDs could be a problem for some people using variable contrast paper. I use VC paper, and VC paper does work with my enlarger -- however the maximum paper grade I've been able to obtain is about 3 1/2 - 4. The problem is how VC paper is designed. The hard paper grades -- about grade 4 and up -- in variable contrast paper are triggered by ultraviolet light. Tungsten and fluorescent "cold" lights produce small amounts of UV, but white (and blue) LEDs don't."

Can anyone confirm that blue LEDs don't generate UV and that UV is necessary to reach Grade 5?

[Jack Dahlgren]

[QUOTE=Jerry Bodine;647053]

http://www.deadbread.com/crumbs/23c.html[/URL]QUOTE]

To quote from near the end of this article:

"The light spectrum of the white LEDs could be a problem for some people using variable contrast paper. I use VC paper, and VC paper does work with my enlarger -- however the maximum paper grade I've been able to obtain is about 3 1/2 - 4. The problem is how VC paper is designed. The hard paper grades -- about grade 4 and up -- in variable contrast paper are triggered by ultraviolet light. Tungsten and fluorescent "cold" lights produce small amounts of UV, but white (and blue) LEDs don't."

Can anyone confirm that blue LEDs don't generate UV and that UV is necessary to reach Grade 5?

UV LED's are available for less than a buck. If you wanted to build a light source with a couple of different colors you could avoid the whole idea of filters and just dial in different amounts of each spectrum to control contrast. This works for B&W - Color would be a different problem altogether.

[Robert Hall]

[QUOTE=Jerry Bodine;647053]

http://www.deadbread.com/crumbs/23c.html[/URL]QUOTE]

To quote from near the end of this article:


Can anyone confirm that blue LEDs don't generate UV and that UV is necessary to reach Grade 5?

LED's have a vary narrow spectrum. They are like the flutes (musical instrument) of the lighting world.

If VC papers need UV, then that might be a problem. Of course they make UV and IR LED's too.

[3e8]

[QUOTE=Robert Hall;647076]

If VC papers need UV, then that might be a problem. Of course they make UV and IR LED's too.

Based on the last post here, the peak sensitivity for high contrast is 450-460 nm, which corresponds to most "royal blue" LED's, not just "blue" LED's.

Bryan

[Eric Woodbury]

Nothing wrong with cold cathode and it will last a very long time. If it worries you, consider getting a spare tube.