Looking for some help to build a box with LEDs inside

Hey all,
I've got the ultimate newb question here, I apologize if it's been covered to death.

I don't know any of the correct terminology for this stuff, so I'll just describe it as best I can.

I build small boxes with lights inside, in the past, I had to make a way to open the box so the incandescent bulbs could be changed as needed. Needing to open the box altered the design and all around made things more difficult. A while back I thought, why not use LEDs? They put out much less heat than incandescents, and there is no need to open the box once they're inside (correct?).

So, I need to figure out how to make a LED array(?) to go inside of the boxes. Basically I need 10-30 LEDs per box, in most cases placed in random spots around the inside. The ability to dim the LEDs would definitely be nice too. The boxes would plug into the wall, no battery power here.

I know very little about working with electricity (besides the most simple stuff), though I am no rookie at building things in the workshop, and given good instructions, I can figure out most projects.

With that said, is there a kind soul out there who might help to walk me through this? Or does anyone know of any good resources for the laymen?

Thanks!

Eric

That's OK. We all started from zero so no need to apologize. Try the On Semi's 4011. It can drive 30 5mm LEDs (e.g. Nichia NSPW500CS) at 30mA in series from a 120V AC line with a minimum of componentry. I don't know what your box looks like, but 30 LEDS will put out quite a bit of light (and heat), so experiment first to make sure you don't overcook things.

Hey Frenzee,
Thanks for your response!
I checked out the link, and though I somewhat understand what that thing does, I'm still confused as to what else I need to do with it in order to make it work for my application. lol

Because I am so clueless on this subject, I'm wondering if it might be better (and safer) for me to buy a plug 'n play LED array from somewhere. Does anyone make such a beast? Because of the way I want to arrange the lights, I would need something that would give me the option of how many LEDs I want, as well as the length of wire attached to each.

Or if I do attempt to make this thing myself, does anyone perhaps have any pictures or step by step instructions to help a dude out? :thinking:

I'm not sure it you'll be able to find step-by-step instructions for your exact application, but Instructables has a ton of DIY tutorials. Why don't you give us more details as to your space constrants, ventilation or lack thereof, how much light output you'll need, how spaced apart the LEDs need to be and so forth. Page 4 of the datasheet that I gave the link to above, provides the schematic for puting together the basic circuit, but you still need to buy the parts, construct the circuit board (or bread board) and put it all together. Have you ever done any soldering or made a PC board before? If not, it might be easier to have someone else give you a hand. Or, if it works dimension-wise, you might want to try and out-of-the-box solution using an LED home light bulb like this one.

Thanks for responding again, sorry it's taking me so long to write back, work has been brutal these past few weeks.

The LED lightbulbs are definitely cool, and will be a big help for some of my projects, but with the intended effect of this particular box, I don't think it will work this time.

Here's what I've built: an acrylic box measuring 10x48x4, it will be completely sealed, though I can drill some 1/2" holes in the back for passive cooling. The acrylic is a solid color, so I will need a decent amount of light to be able to see it from the other side. For the sake of this post, let's say I'll do 20 LEDs, spread evenly around the box (hopefully reducing the heat). They need to be clear, with the largest viewable angle as is reasonably possible. Having the ability to dim the LEDs would be a plus, just in case it turns out 20 will put out too much light at full power. They don't need to blink or do anything fancy, just plain ol' LEDs.

I have done a decent amount of soldering over the years, and I think I might have made a PC board at one point, though it's been a long time. If I knew exactly what I was supposed to be soldering to where, I think I could make it through that part.

Given all that, do you think this is something I can pull off?

Instructables is a great site! That'll become quite a time burglar for a DIYhead like me! I'm still sorting through all the LED posts, trying to see if anything might be similar to what I'm trying to accomplish here.

Thanks for your time!

Cheers~
Eric

If you've made PC boards before, I think you can probably do this on your own. Again I refer you to the design on page 4 of the On-Semi's 4011 datasheet. That schematic is a simple as it gets. You can get free samples from On-Semi, but you have to pay for the shipping. The only other components you'll need are a perfboard like this, one resistor, some lead wires, probably a grounded on/off switch would be a good idea, and a prototype box, all of which you can find at RadioShack.

One thing I would add to the above is this: if you plexiglass is tinted, I try to get colored LEDs that match the plexiglass. That way most of the light will not be blocked.

How much light do you really need inside this box? you can probalby get away with a few high power LED's like cree's or Luxeon's.

I guess, what was the original wattage of the incandescent bulb, this way we can estimate how many LED's you might need.

I feel like I'm making some headway here! :twothumbs

I'll look into getting a sample from On-Semi.

Are the high power LEDs interchangeable with the regular ones, or will I have to build the whole thing different? It's hard to say exactly how much light I want this to put out, since in the past I was limited by incandescent size (I used appliance bulbs) and heat output. Ideally I'm looking for the box to have a nice glow, but still leave a room somewhat dim. Sorry, I realize that's kinda vague... lol

Ok, I just got my package from Onsemi, wow those dudes ship fast. I have a couple of quick questions before I run to Radioshack: what type of resistor do I need to get if I'm planning on about 12 LEDs (I think I'll order some of these: http://www.besthongkong.com/product...d=246&osCsid=a24ccb43dfbf56fa5001a58a4264a226 )

Also, what do I need for a power source (I'm assuming I need a transformer, right?)

I imagine I'll have some more questions once I start putting this thing together, but I think I'm good for now. Thanks again, guys!

Anyone?

What's this you are making? Small sealed boxes with LEDs inside? What will you do with them? Do you need to worry about heat? How bright does it have to be? How big are the boxes? You're not planning on putting Schrödinger's cat inside are you?

Schrödinger's cat, eh? Hmmm I am considering that... now. hehe

So yup, small sealed acrylic boxed with LEDs inside, created to be an artistic/interior design item that would serve as a lamp. Therefore it is not out of the question that these may be left on for several hours at a time. So, depending on the amount of heat released by ~10 LEDS, that may be a problem. I can cut some holes in the underside of the boxes to help release heat, but considering what they are, I don't think fans will be an option. As far as brightness, it's kinda hard to say, but I guess something akin to a 25W frosted incandescent might be close.

Sorry for the delayed response there, my notification got turned off or went to the junk folder by accident...

Aww come back guys...

This product may suit your needs, a ready-to-use dimmable LED light bar, just add heatsink:
http://www.luxeonstar.com/category.php?id=442&link_str=442

Thanks for your response!

While that probably would work great for me purpose, it's a bit pricey. With that kind of cost involved, these boxes simply won't be feasible. I'd rather save the money, and figure out how to do it myself... if I can. lol

Cheers~

Yeah that would be a bit pricey. I am a beginner just like you but I did make a headlamp using 3 high power LEDs. I combined two different instructables to do it. If you can solder and understand the very basics of some circuitry you could very easily do this yourself.

If you only want to match the output of a frosted 25w incandescent then I think you could probably accomplish your task with two or three high power LEDs. The following has circuit diagrams for power them http://www.instructables.com/id/Circuits-for-using-High-Power-LED_s/
I used the circuit in step six and added a switch for dimming.

It also explains how to use the LEDs a bit. I would recomend looking at something other than the luxeons that he recommends as they are a little outdated and there are newer ones that are more efficient. The LEDs here http://www.dealextreme.com/details.dx/sku.1445 give off a lot of light for the price and power that they use (95 lumens at 350mA).

An issue that you might run into though is the fact that LEDs don't give off light in every direction. You could get around this by pointing one at each viewable side of your cube. It also might work if you just pointed them out, its hard telling without some testing. If you have any more questions just post them and I will try to answer them. I just learned most of this stuff myself so its pretty fresh.

Thanks for the links! I'll give them a thorough read in the morning and see if they'll let me do what I'd like to accomplish. I'll probably be posting back tomorrow with more questions.

Thanks again.

Do the LEDs have to be evenly scattered throughout the box? Could you possibly achieve the same lighting effect by having a few high powered LEDs (SSC, Cree, K2) clustered on a metal hemisphere (or a similar shape)? It the shaped mount would angle the LEDs for more even light distribution, it would provide some heatsinking and it could be placed at point where the wires enter the box. I'm also thinking that with the LEDs widely spaced in the box the wires might cast shadows on the acrylic.

Not sure if that makes any sense to you, just a sorta thinking out loud.

Yeah, that definitely makes sense. For some of the designs I have in mind, it would work to have all of the LEDs in a central location, for some it might not work as well, but at least for the prototype I'm making it would be perfect.

So the consensus seems to be high powered LEDs, if I go that way, is the LED driver I already bought (mentioned early in the thread) going to be worthless, or can I use it with the high powered variety?

Ok, so I went to Radioshack today, and picked up a pc board, project enclosure, 5 5mm red LEDs, and some resistors. I had no idea what value of resistors I should get, so I ended up with 1/2w 560-Ohm-- will they work for this project? With the exception of a power supply, I think I have everything I need...
Am I on the right track here? Using the fore mentioned items along with the Onsemi LED driver, I should be good to go, right? For the power, can I just steal a transformer from an old cordless phone or something? Or do I need to buy a special one?
Also, are there different types of pc board? The led driver I have is super tiny, and it looks like the holes are too far apart on the pc board for its size.