LED Sign - How to?

Hi!

Hoping y'all can point me in the right direction and shed some light on this (ba-dump-ba - double pun! )

I'm building a sandwich board for the sidewalk in front of our shop; here's a quick sketch to give you an idea of the layout.



I have 2 pieces of 3/4" plywood with 12" holes cut out. In these holes will be pieces of 3/8" translucent red plexiglass and I want to light these up using LEDs powered from a 24V SLA battery pack. I had originally planned to countersink 8 bare red LEDs around inside of the plywood but am worried that the light will be too direct (ie. 8 spots of light) and not give the even glow I'm looking for.

Any suggestions? Any particular LEDs I should be looking for? Maybe those LED strips would work?

Thanks a ton, and I'll be sure to post a snapshot when it's done.

Christian

Not sure what you're building, but if you sand either the front or the back of the plexiglass rod then it will "glow" evenly.

Side Lit?

I'm wondering if you could drill mounting holes along one edge of the plexy and shine in lots of 3mm red LEDs from the side? This would avoid hot spots.

Re: Side Lit?

Ken_McE said:

I'm wondering if you could drill mounting holes along one edge of the plexy and shine in lots of 3mm red LEDs from the side? This would avoid hot spots.

Click to expand...

Then you could hook up a chaser controller.

Luxeon Star side-emitters were invented for this!

you can drill a blind hole in the thickness of the material transparent - from the rear - and poke the led into the hole.

It feeds light into the material, and the light comes out where ever you have sanded the back of the material.

But, you have to grade you sanding, else the effect is brighter near the led.

There are plenty of other ways to do it.

And it can be tricky to get a really even effect.

Steve

Thanks for the suggestions!

I was seriously deluded in thinking that 8 x 5mm Red LEDs were going to give even close to an adequate amount of light More like 80 LEDs.

I like the Luxeon idea, but the graduated sanding sounds a bit tricky. The 3mm around the perimeter is also cool, but sounds like a lot more work than I want to embark on

Am I missing something? Maybe I need to play around with some Luxeons to see what they'll do... At least battery power shouldn't be too big an issue with 24V, 9Ah

Thanks again!

Christian

Well, the method that we've been skipping over is to mount a one or three watt red LED a foot or two back from each panel and light it from behind. You would experiment with the distance to let the beam spread out to match the size of the plexi piece.

If you want to try cavity lighting (it's what they do with modern led exit signs)you would build a shiny chamber behind each panel and put a bunch of little leds in there, let the collective light wash out mostly evenly.