1
\$\begingroup\$

I am a newbie with these type of applications, but I am trying to see if this idea would work out.

Essentially what I am trying to do is build a large panel 2ft x 20ft that will act as one large light strip. I want to have light dissipating material to spread the light evenly over the entire thing. Behind that I want to use a number of LEDs to provide a low-power and low-heat solution.

  1. Right now I am looking at LEDs in the range of 25-50 lumens. Would this work out to provide more even lighting, or would it be better to use LEDs with higher output?

  2. Would I still need a heatsink? Say I use this 26.8lm LED, each individual LED would consume just 0.2 watts. I would be putting this in a grid with roughly 30 LEDs per 2ft x 2ft tile, but I'm not sure how much energy would be wasted as heat.

  3. Is there an idea material for the panel so that the lighting is most evenly distributed?

\$\endgroup\$
1
\$\begingroup\$
  1. It depends. Are the lights for accents or illumination? How densely you mount the LEDs and how many you use will also be a factor. The room size, mounting location, and intended use are all important as well.
  2. Based on the experience I've had with LEDs, probably not. Only if you are using super bright LEDs should you need a heatsink. The datasheet should indicate if one is suggested or not. I know certain LED devices for photography that are made you be bright and left on for extended periods of time will use them. However, the typical LED strips and similar devices sold by many of the electronics and hobbyist retailers do not require a heatsink. The warmest component is likely to be the power supply.
  3. I built a poker table with LEDs in it. My first instinct was to get a frosted glass or acrylic type of material to diffuse the light. I found it was still pretty easy to distinguish the individual LEDs. On a whim, I went to a local sign shop, and they suggested white polycarbonate. That is what I used, and it can be seen at the website I linked. Underneath I used an LED strip. I am still able to tell that the strip is in the middle of each partition, but the diffusion is much better in person than is shown in the picture. That said, a white, acrylic material (Plexiglass) would diffuse the light just as well, but the polycarbonate is stronger and has a better surface finish.

All in all, I would look at LED strips or pre-built strands of LEDs and space them apart evenly to fit the width of your panel. The power you need depends on the specific application, but it's better to get brighter lights than you need and dim them with a microcontroller and/or LED driver if you can afford it. Heat shouldn't be an issue unless the LEDs are tightly clustered and very bright. Check the datasheets. My project had no issue. Look around for a thin, white plastic material to diffuse the light evenly.

Edit: If you do go with the LEDs linked in the question, Cree has an application note on thermal management.

\$\endgroup\$
  • \$\begingroup\$ Your table is actually very close to my desired application, though my design would still require individual LEDs rather than strips, though the design from the strips to a circular pattern should not differ too much. I'll also look at the Arduino controller as I haven't gotten that far for how I'm going to control them all. \$\endgroup\$ – Thebluefish Feb 1 '14 at 16:00
  • \$\begingroup\$ If it helps any, most of the strips I've seen you can cut to size and solder back together. I could cut the ones I used every 2 LEDs. I had to do that with mine to size the strips for each partition. It could be easier than using SMT components depending on your skill set and tools available. The Arduino is probably overkill if you are just dimming a single color without an effects. That was one of the first embedded electronics projects I did, so I wanted a lot of flexibility. Plus, I didn't have much experience with other microcontrollers at the time. \$\endgroup\$ – Justin Trzeciak Feb 1 '14 at 16:06
  • \$\begingroup\$ I was actually looking at multi-color as an option, but originally decided for white for the reduced complexity. I am still going for white for a ceiling-mounted lighting panel. However this answers exactly my questions for some other projects as well. \$\endgroup\$ – Thebluefish Feb 1 '14 at 16:12

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.