# Are There Any Strips/Sheets That Diffuse LED's and LED Strips



## CrufflerSteve (Dec 11, 2014)

I have hobbies. A couple are rock collecting and woodwork. Another one is messing around with LED's and tiny computers which is why I'm a member here.

My house really needs new counter tops in the kitchen. I'd seen back lit Onyx slabs and they look cool. It seemed like here is a project that combines all these hobbies. I could under light Onyx tiles with LED's. Onyx isn't that expensive so this could be an affordable project. I was thinking about either using LED arrays I make or strips. The problem with strips is that if there are too many there isn't enough area for the cement to grab. LED arrays would have little holes with the wiring coming up from underneath. I made a test board with holes and did some grooves for strips. The Onyx arrived last night and it is too translucent. It goes beyond hot and needs diffusion. Superbrights are neat since they put out so much light but I need less.






The white strips are super bright cool white lights. The middle strip is a less bright warm white. What I really need is some way to diffuse the light. It would have to be on top of the under layer with LED's and below the Onyx tiles. Has anybody used something like that? I was wondering if I should look at some of those plastic panels for fluorescent light or some sort of privacy acrylic. Any affordable suggestions?

I'd be using an acrylic or epoxy glue for all this so it should work. The old cements are opaque.

An alternate which I'm not so fond of is arrays of lower power warm white LED's. The problem is that I would need a LOT of them. The strip lights are 8mm wide (about 5/16" in the US). It lights a bit less than 32mm wide (1 1/4"). That would be a lot of LED's per square foot and I have a bit over 100 sq feet.

I experimented making an array last night. In two hours I got all the wiring and cut down PC board for attaching 3 arrays of 3 10mm LED's to a plug. I just have to solder it to get it working. That is a lot of work to do several 1000. Strips are so much more loveable since I just have to route a groove, cut to size and solder a couple of wires but I need to diffuse them.

Steve


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## FRITZHID (Dec 11, 2014)

I use the defusing sheets from old flat screen t.v.s and laptop screens. Keep in mind, in order to defuse properly, there needs to be some distance between the LEDs and sheet, as well as sheet and countertop.


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## CrufflerSteve (Dec 11, 2014)

I'm planning on using a 1 1/4" thick under layer. If I can make this work with strip lights it wouldn't be so hard. I can route grooves on the bottom for the strip. Let's say I mount the strips on 1/4" ply I could cut the groove a bit more than 1/4" to leave room for the strip so it doesn't get mashed.when I attach it. The individual LED's are a couple of inches apart. I could drill a conical hole from the top down to it. At the base it wouldn't be much wider than the LED and widening towards the top. Maybe painting the sides of this hole with a reflective paint would help. Perhaps a reflective liner would be even better but it sounds like work since there will be lots of holes. This would give about 1 inch in distance between the diffusing layer and LED's. That's as good as it can get. I was originally planning to groove the top but I guess I've gone upside down.

The old sheets sounds nice but it would be a lot of work to get 100 square feet of the same thickness.

I've seen some interesting diffuser films but they probably wouldn't work here. They get the effect by etching the surface. Once glue is applied on both sides it would be transparent plastic. I need the diffusion to happen inside the diffusion sheet. The more diffusion the better since it would require fewer LED strips or whatever. (I really, really hope 1000 handmade LED arrays are NOT in my future.) If it diffuses well but removes a lot of light I could always go to brighter LED's. LED tech is on my side. They're always getting cheaper, brighter and using less current. The longer I experiment the 

Steve


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## Ken_McE (Dec 19, 2014)

Are you looking for the entire tile to glow evenly?

These guys: 

http://www.ledinside.com/news/2014/1...hin_led_lights

make a thin sheet led that you could run under the entire slab, but they may not be ready for hobbyists yet.


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## Illum (Dec 19, 2014)

1/8" plexiglas, following acetone treatment might work as a diffuser


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## Anders Hoveland (Dec 19, 2014)

One can make frosted glass with a solution of ammonium fluoride. It's not something you would want to get on your skin though, so use long rubber gloves and safety goggles.


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## CrufflerSteve (Dec 28, 2014)

I've totally given up on diffusion and am going with edge lighting. There are two competing brands of edge lit plastic sheets. One is LuciteLux Light Guide. The other is Acrylite LED (Endlighten). I would have preferred to find a source for the LuciteLux since that seems to be what people were using but there is an online site that sells the other stuff in cut sizes. They'll even polish the edges if you don't know how to use a torch.

It really is an amazing product in terms of the evenness of the light. It seems to be a mix of fiber-optic to guide the light through the sheet and diffusing particles. Applying LED's to any other type of plastic would result in a diminishing brightness over distance. These products come rated by the width of the area you need to illuminate from 12" to 78". You pay more for the higher grades. You use a reflective backing and silver edge tape for the non-LED edges. The edges are supposed to be polished. Here's my first attempt to lay it out. 






I'm happy with it so far. The big section has the wrong type of LED strip. The LED's are too big and over 1 3/8" apart. Ideally, there are many small LED's very close to each other to diminish hot spots. If I end up with noticeable hot spots I'll use a small band of opaque calcite at the edges.

Does anybody know about working with these plastics or a forum to ask? There are lots of warnings that I should anneal the plastic to avoid crazing. That means to roast the plastic sheets in an oven to avoid creating lots of small cracks in the plastic when it is bonded. I don't want to have build an oven to roast this but crazing in the light guide sheet would ruin it. I'm building a couple of small pieces to see if this happens. I don't care much about the reflective sheet. I'm bonding that to the under layer with a strong plastic glue. Then the light guide plastic and the Calcite will be glued with transparent epoxy. Then 1/4" of tempered plate glass sits on top. It's going to be a LOT of work but will be cool when and if I get it done. I have hopes of having a small piece done in a weeks.

Steve


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## RoGuE_StreaK (Dec 29, 2014)

If it works out, that's gonna be a nicely unique benchtop! Hook it up to motion sensors so when you walk into the kitchen for a midnight snack it glows to life!


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