Question about light dispersion from an LED

Hi,
I'm new to LED lighting but have an interesting application.

I wanted to put some undercabinet lighting in my gunsafe and bought some halogens but they were dangerously hot since IA also store ammunition in my safe.

Decided to go with LEDs since they could be battery powered and would not be hot.

The problem is the shelves are fairly close together and each LED projects a small spot light on the shelf. I would like to be able to diffuse or disperse the light broader. Any suggestions?

Ultimately, I'll use 8 pairs of LEDs in wired in poarallel powered by 6 D-cells. These lights will only come on when the door is opened via a door switch. So I'm not to worried about efficiency. Using the LED calculator I should get about 150 hours of use with this set up.

Any other ideas or concerns with my concept?

Thanks,
Pigseye

Well you have a couple choices here. It sounds like you are using traditional 5 mm LEDs. You probably have the 5mm 20 degree LEDs, which as you noticed, don't produce a very wide beam. If you make your way over to http://www.whiteleds.com you can find wider angle 5mm'ers. In the case that you think 5mm LEDs simply won't cut it, in terms of light output, consider using a 1w Luxeon. Coupled with a converter outputting a low amount of current, the batteries could last for a very long time.

It sounds, however, like you've got multiple shelves, which would make the Luxeon idea much more expensive.

you could take some steel wool and rough up the surface of the LED.
Super fine sand paper would work too. This will give a frosted effect, and spread the light out.

i think dan's solution would be the most cost-effective /ubbthreads/images/graemlins/thumbsup.gif

Rather than scar up the surface of the lens (which is, after all, trying to focus to a small spot), I'd suggest filing or sanding the nose off the lens.

I've cut a bunch of 15 and 20 degree 5 mm parts this way, just file the nose down flat removing the half round part. No need to get a super finish (don't worry about polishing it), just get it smooth and flat. The typical result is a very wide, artifact free, illumination.

Try a couple, I think you'll like the results.

Doug Owen

Luxeons could well be the way forward here. Their uncollimated beam angle is a mighty 140° - ideal for close range applications. Don't forget to mount them on a nice, chunky heatsink (like a Hotlips) to prevent any chance of overheating, though. You could soften / spread the light further with some diffuse glass or some frosted theatrical filters ("gel").

Doug, you're right! Cut off the lens using a grinder and it took only a few seconds.

Did a comparison with ground off lens and ground off lens polished and like you said, didn't notice much difference in light intensity.

Great suggestions!

When my gunsafe lighting is done I'll post a picture.

Thanks,
Pigseye

[ QUOTE ]
pigseye said:
Doug, you're right! Cut off the lens using a grinder and it took only a few seconds.

Did a comparison with ground off lens and ground off lens polished and like you said, didn't notice much difference in light intensity.

Great suggestions!

When my gunsafe lighting is done I'll post a picture.

Thanks,
Pigseye

[/ QUOTE ]

Hey, no charge.....

Glad you tried it, I gotta agree it sounds like it shouldn't work... but does. FWIW, I've made a few arrays of 12 such LEDs (four parallel strings of three in series) run off 12 Volts with a current regulator. Very impressive light for a watt, even using (four for a dollar) Hong Kong LEDs.

Please do keep us informed on your project.

Doug Owen

Oooohhhhh.....

I know of a green LED or two that BEG to have the lense ground flat on. They are artifact CITY!

Teeheehee!!!!!

Cool. Let us know how it works out?

Doug Owen

Update:

My Gunsafe lighting project will have 2 HongKong White LEDs in series with a 47ohm resistor in each enclosure. A total of 8 enclosures will be wired in parallel to 6 D-cells providing 9V.

The boxes are from Radioshack and are either the small black plastic project boxes (2"x1"x1/2") or their small enclosed batttery holders. They didn't have enough stock of either so I'm mixing and matching.

I'm also using the cheap black plastic LED holders and 24 gauge speaker wire.

I've compelted 6 enclosures so far and have installed them on the Top and second shelf (3 each) using sticky back velcro. They provide plenty of ilght but are not bright. My goal is enough light so I can see where stuff is in the safe versus display type lighting.

As you know, there is virtually no heat generated for this application which is important since I also store ammunition in my safe. I know that some people say to not store ammo in your gun safe but for now it's the best place to keep it away from the kids.

The enclosures themselves look pretty good, but you won't see them once their installed unless you look for them. I wish I would have taken more care in aligning the LED holes but they are functional.

There are also 3 lower narrow shelves but I'll only light the top two of this set with 1 light enclosure each.

I've temporarily mounted a switch using velcro that turns on the lights when the safe is opened. It works great so far but I need to find a more permanent and reliable way of attaching it to the safe.

It's going great so far, thanks for the help!

I'll post some pictures later this week to show the boxes and installation. It's incredibly simple but a picture really tells the story.

Thanks,
Pigseye

I did a somewhat botched job on a green.

It is better... but not as smooth as I thought it might be.

I'll try to do a nicer job on the other one, which is somewhat brighter on 3N than the first one.