# 5mm LEDs for Strip/Tube Lighting



## Vardarac (May 19, 2008)

Let's say I have a narrow, diffused plastic tube. I plan to string up a TON of 5mm LEDs in this thing, each of them facing from one end of the tube to the other. If I want this tube (viewed mainly from the side) to appear as BRIGHT and UNIFORM as possible, day or night, what do you think is the best compromise I can get between mcd intensity and viewing angle for each LED? Also, can you recommend any particular dealers to buy such LEDs from?

One last thing - Can you tell me if any of the following companies are reputable/disgraceful, particularly with regard to quality/spec accuracy of their 5mm LEDs?

Super Bright LEDs
LEDtronics
DealExtreme
UniqueLEDs

Thanks in advance. Aspiring sabersmiths will thank you one day...


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## Lightingguy321 (May 19, 2008)

can I suggest Vishay as another company to look into, they have some very well made 5MM LEDs in the color area (Red, Green, Pure Green, Blue Green, Orange, Yellow). Their white LEDs may not be the brightest but they have the nicest beam pattern out of any of the 5mm LEDs that I own. Optek is another good company.
Super bright???
LEDtronics-OK
Dealextreme-OK, some not as good as others
Unique????


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## Vardarac (May 20, 2008)

Lightingguy321 said:


> can I suggest Vishay as another company to look into, they have some very well made 5MM LEDs in the color area (Red, Green, Pure Green, Blue Green, Orange, Yellow). Their white LEDs may not be the brightest but they have the nicest beam pattern out of any of the 5mm LEDs that I own. Optek is another good company.
> Super bright???
> LEDtronics-OK
> Dealextreme-OK, some not as good as others
> Unique????



Thanks for your help 

This is one of Unique LEDs' products. The specs seem like BS to me for an RGB LED; too good to be true, you know? I'd just like a second opinion on this.

Also, still wondering what the best cross between viewing angle and intensity is.http://www.unique-leds.com/index.php?target=products&product_id=1853


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## Vardarac (May 30, 2008)

I'm still looking for the best LEDs suited to the purpose of building a UNIFORMLY BRIGHT lightsaber blade, assuming I want to make it an LED array saber and not merely a "flashlightsaber" that uses a single high-power Luxeon or something similar. 5mm size or smaller is required; I need to be able to fit these little buggers into a .25" ID hole. Thanks to you guys, I know some good companies to get my LEDs from, but I still need to know what kind of specs I'm looking for.

The blade's inner workings will be constructed almost identically to the pictures shown in this Chinese tutorial. The original maker recommends LEDs with a viewing angle of 45 degrees, but I think I might be able to find LEDs with wider viewing angles/greater lumen outputs than their 45 degree counterparts. It's all very confusing to me whether I'd get a brighter blade by getting LEDs with greater lumen output, or slightly smaller viewing angle (not too small, of course!) with greater forward intensity. I'd really appreciate help with this, as I've been literally searching for the right LEDs for months.


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## Skywise (May 30, 2008)

Interesting project. 

The level of 'uniform-ness' will mostly be determined by the actual tube and less the LEDs, but I guess I would go with the widest viewing angle you can find (I think its 140 degrees). 

I also noticed that all of the LEDs are in parallel - which can cause some issues. You probably want to use fairly high quality LEDs, otherwise variations in current consumption and internal resistance could screw up the uniform lighting.

In regard to lumen and mcd - you cannot compare the mcd rating for two LEDs with different viewing angles, but you can (somewhat) calculate the lumens based on the mcd and viewing angle, but I don't think brightness will be an issue with 60 LEDs. A bit worried about the power aspects.. you would need 3.6V @ 1.2A, that will eat some serious batteries.


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## Vardarac (May 30, 2008)

Skywise said:


> Interesting project.
> 
> The level of 'uniform-ness' will mostly be determined by the actual tube and less the LEDs, but I guess I would go with the widest viewing angle you can find (I think its 140 degrees).



Ok, thanks. You're probably right about the tube, though- I can coat my clear tube in diffusing film or something similar to get uniformity. That still leaves me with the question of whether I then still NEED to go for the widest viewing angle. If not, I'm back to square one and need to figure out what the best combination of view angle/intensity is for highest brightness.



> I also noticed that all of the LEDs are in parallel - which can cause some issues. You probably want to use fairly high quality LEDs, otherwise variations in current consumption and internal resistance could screw up the uniform lighting.


Yes, I've been warned many times about this. That's why I asked around about quality manufacturers- I understand that Vishay, Optek, and Nichia are all good. I've also tried a few LEDs from this site. While they have nice-looking specs (supposedly "guaranteed"), I've noticed from trying them out that most of their LEDs have a "doughnut-hole" pattern. While this isn't a problem for my purposes, some users on these forums have said that it's something absent from higher-quality LEDs. To add to the problem, I don't have the foggiest clue as to how to actually test these LEDs and see how consistent the specs really are with what I got.



> In regard to lumen and mcd - you cannot compare the mcd rating for two LEDs with different viewing angles, but you can (somewhat) calculate the lumens based on the mcd and viewing angle, but I don't think brightness will be an issue with 60 LEDs.


This is where there's a bit of a snag: the blade I'm making has a thick outer layer of white closed-cell polyethylene foam, which won't let nearly as much light through as just diffusing film and a clear polycarbonate tube would. It still does let a good portion through (as a diffused glow), but I want this thing to be BRIGHT- Therefore I'm aiming for maximum all-around light output, which is why I'm still unsure what the best combination of view angle/intensity is.



> A bit worried about the power aspects.. you would need 3.6V @ 1.2A, that will eat some serious batteries.


I'm covered on that. I have a bunch of 2.5 Ah+ rechargeables I can use in this thing (specs of the batteries are apparently accurate for the manufacturer per testing on a review site). I probably won't have this thing on for more than a half-hour at a time anyway.

Thanks a lot, Skywise.


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## Amonra (May 30, 2008)

you can just sand the tops off the brightest led's you can find to turn them into nice smooth wide angled led's.


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## Skywise (May 30, 2008)

> This is where there's a bit of a snag: the blade I'm making has a thick outer layer of white closed-cell polyethylene foam, which won't let nearly as much light through as just diffusing film and a clear polycarbonate tube would. It still does let a good portion through (as a diffused glow), but I want this thing to be BRIGHT- Therefore I'm aiming for maximum all-around light output, which is why I'm still unsure what the best combination of view angle/intensity is.



Something I just thought about .. I am not sure how widely those are available and what quality you can get, but I have a few LEDs that have a 140degree angle. The seller called them 'straw hat' and they are at least 1/3 shorter (if not even 1/2) then a normal 5mm LED package, so with the current design you would be able to get 30 - 50% more LEDs into the tube (and in turn 30-50% more light and power consumption). Beyond that I would probably still go for the highest viewing angle possible. Otherwise I would be concerned that a good percentage of the light just travels straight up thru the chain of LEDs and produces a bright spot at the very top of the blade. 

Sanding the LEDs works good to turn clear LEDs into diffuse LEDs, but you do loose some brightness. 

PS: Found this link just as FYI on what type of LEDs I am talking about

http://www.hebeiltd.com.cn/?p=leds.4.8mm


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## Vardarac (May 30, 2008)

Thanks guys! Just two more questions and I'll get to work on this thing!

What are the best RGB LEDs you can recommend?
What grade sandpaper should I use to diffuse the LEDs?


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## Skywise (May 31, 2008)

Vardarac said:


> What grade sandpaper should I use to diffuse the LEDs?



I use the finest that I had, 220, but I recently played with a PET bottle at the beach and had an idea ... I was going to try how shaking the LEDs in quartz sand works (or to stir the sand with a LED), may be more uniform in scratching it up and alot easier in large numbers. You could try that and let me know how it works


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## Vardarac (May 31, 2008)

Ooops. Those LEDs you linked me to seem to be sold on a website that doesn't appear to accept orders under $99. Any other sources you could point me to? I've only thus far been able to find another manufacturer of similar LEDs, but they're slightly wider and they're more expensive (probably has to do with being an American firm).


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## Skywise (May 31, 2008)

Vardarac said:


> Ooops. Those LEDs you linked me to seem to be sold on a website that doesn't appear to accept orders under $99. Any other sources you could point me to? I've only thus far been able to find another manufacturer of similar LEDs, but they're slightly wider and they're more expensive (probably has to do with being an American firm).



The link I posted was mostly for informational purposes, not as a seller recommendation or anything. The ones I had were off eBay, which means you're basically buying the cat in the bag, both quality and specs (tho I have to say that quality wise all LEDs I've ever gotten of eBay were good, but I may be lucky). Gotten mine from this guy but he does not appear to be particular cheap (in comparison, usually 100pcs 5mm LEDs from "unknown source" run me around $10 delivered, not sure if/why these 4.8mm are more expensive): http://stores.ebay.com/TopBright-Led-Store

Edit: The key seems to be specifically the 4.8mm form factor. Quite a few sold on eBay: http://search.ebay.com/4-8mm-LED


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## Vardarac (May 31, 2008)

Skywise said:


> The link I posted was mostly for informational purposes, not as a seller recommendation or anything. The ones I had were off eBay, which means you're basically buying the cat in the bag, both quality and specs (tho I have to say that quality wise all LEDs I've ever gotten of eBay were good, but I may be lucky). Gotten mine from this guy but he does not appear to be particular cheap (in comparison, usually 100pcs 5mm LEDs from "unknown source" run me around $10 delivered, not sure if/why these 4.8mm are more expensive): http://stores.ebay.com/TopBright-Led-Store
> 
> Edit: The key seems to be specifically the 4.8mm form factor. Quite a few sold on eBay: http://search.ebay.com/4-8mm-LED



Oh, I didn't notice the distributor the "straw hat" sellers have. They don't have a minimum order. There's a $5 "handling" fee, but it beats having to order $99 in LEDs. The strawhats come at about 20 cents each not including the fee and shipping.

Any RGB LEDs you can recommend?


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## Vardarac (Jun 11, 2008)

I just got some straw hats from the American distributors. They're plenty bright and cast a faint wash over a totally dark room.


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## snarfer (Jun 12, 2008)

Hey what about using some of these?

http://www.dealextreme.com/details.dx/sku.9073
http://www.dealextreme.com/details.dx/sku.13087

they appear to be pretty long and are available in different colors.. Only thing is your light saber might have gaps in it if you were stringing together several lengths...


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## SemiMan (Jun 12, 2008)

Would I be right in assuming there is no way you can use surface mount LEDS? That would give you the best distance from the LED to the tube and allow multiple leds to mix better giving better uniformity.

You can use one of the many mcd/angle to lumen calculators on the web to compare LEDs of similar brightness.

If I was going to do this, I would probably use one of the PLCC4 type SMT LEDs from Avago, Osram, etc. Some can be driven up to 50mA.

Semiman


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## lctorana (Jun 13, 2008)

end up with somthing like this?

http://www.ledshoponline.com/led_lightbar.htm


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## Vardarac (Jul 7, 2008)

Thanks for your help, guys. I'm just now getting down to starting my solder job. First I have to figure out how I'm going to space my 60 LEDs/resistors for the length of 35" I have planned, then how I'm going to bend/trim the components to fit in this space without damaging them. I might even consider making several smaller strings of them and joining those in series rather than parallel so I can pick out a better configuration for my batteries. It's gonna be a bit of a bumpy ride. I'll post pictures of how this thing looks when I'm done; I don't expect it to be very impressive since my outer sheathing will probably be a light grey polyethylene foam (dims and diffuses the light considerably). That's ok, since this is a Mark I for me.


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## Vardarac (Jul 11, 2008)




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## hyperdynelabs (Jul 11, 2008)

Cool, I am glad to see the lux folks finally embracing what we have been pioneering for the last several years. Good luck on your blade, looks good so far!

http://www.hyperdynelabs.com/hyperblade


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## Vardarac (Aug 5, 2008)

Thanks for the compliment. However, I got into the idea building my own saber without being biased for any particular technology. I don't see why you assume that I am a "Lux man" merely because I have a presence on the TCSS forums.

Anyway, back on topic- this is more for Skywise's reference- I didn't have much luck trying to diffuse my LEDs by shaking them in sand.


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## Oznog (Aug 6, 2008)

Even a "quality" mfg does not _guarantee_ Vf will be matched so the initial current will be balanced when paralleling. It's "nice" and high quality mfg often does have closely matched Vf but it's not a really significant criteria.

It won't matter much anyways, because of the negative temp coefficient of Vf. In parallel, even if perfectly matched, the one on the middle will be warmer than the one on the end, dropping its Vf which increases the current on the hot one and decreasing the current on the cold one. This further increases the current and temp of the hot one and can result in a destructive thermal runaway, or at least just a visible inconsistency in light intensity or lowered life because some devices are being run at more than the max rated current.


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## Vardarac (Aug 6, 2008)

Oznog said:


> Even a "quality" mfg does not _guarantee_ Vf will be matched so the initial current will be balanced when paralleling. It's "nice" and high quality mfg often does have closely matched Vf but it's not a really significant criteria.
> 
> It won't matter much anyways, because of the negative temp coefficient of Vf. In parallel, even if perfectly matched, the one on the middle will be warmer than the one on the end, dropping its Vf which increases the current on the hot one and decreasing the current on the cold one. This further increases the current and temp of the hot one and can result in a destructive thermal runaway, or at least just a visible inconsistency in light intensity or lowered life because some devices are being run at more than the max rated current.



Adding additional wires from the power source to dimmer sections of my LED string seemed to alleviate the problem (the string was brightest closest to the power source, so I added two more lines, one in the middle and one at the far end).


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