DIY LEDs - The write-up

[F35-Joint Strike Fighter]

OK, I just found out this LED DIY link and want to build one for myself just for experience before I decide if I want to spend couple hundred of dollards or not. Here is my plan:

4 of CREE XR-E Royal Blue 3W LED with White Lens,
2 of CREE XR-E Q5 Cool White 3W LED with White Lens

Each LED costs $7.79 each from Rapid LED.


Those LED will be mounted on heavy duty heatsink 13"L X 4"W X 3/4"H from my company. It will be driven by fixed 5VDC with variable Amps from 1 to 40 amps industrial power supply from my company as well. Technically, I just wire it in paralle, so the voltage will drop 5VDC each LED and current will depend on LED driven. Do you guys think it is possible project?

Any inputs will be appreciated, and btw, which vendor will have the best deal on those LEDs nowadays?

Thanks!
F35

 

[TheFishMan65]

cyrusthevirus,

I recently ordered from them. They were back ordered and I posted a question on the order threw their site to see when to expect them. No answer, But in the same way I increased the order and got and answer the next day. Read through their help system. If it was cancelled, did you get your money back - just reorder?

Fighter
I don't think it is going to work unless you can vary the voltage. Say you want to run each LED at .5 amps that is 3 total. Well if it is driven at five volts it may be possible to overdrive 1 LED and put all 3 amps threw it. I don't kno enough about the internal structure of the LEDs, but I would not risk it. If you add a series resistor to each LED then it would be OK.

 

[widmer]

Joint Strike Fighter -

It's not commonly recommended that you run the LEDs in parallel. You're best off driving the 6 LEDs in series, but you're going to have to have a 24 volt power supply. This is because as you add things in series, the voltage is additive (in contrast to the amperage, which is not additive when things are in series. Thus 6 leds X a little under 4 volts apiece = 24 volts.

If you were to run the LEDs in parallel, 5 volts would be OK to drive them, but then you would still need to regulate the current going into each one, and it is recommended at this point that each one has a fuse to protect it in case of excess current.

 

[Harry Hood]

im having some trouble picking apart this whole thread...

could someone please post some links to places to get the supplies needed? or consolidate some information for me on what each piece does... my summer project is to build an LED array for a 14 gallon biocube.

im not sure wether to use 3 or 5 watt LEDs, how many, or what parts i would need(drivers? wth is a buckpuck? what lenses? etc)

or if this info is already put together somewhere can someone send me that way?

thanks

 

[Harry Hood]

oh wait, i traced it back to the beginning... found some helpful stuff

i still have a few questions though...

what wattage LED should i use?(im keeping mostly LPS and zoanthids)
how many?

 

[ReefEnabler]

Wiring my 40mm fans in series seems to have worked fine; however, when I just attempted the same thing with two 120mm icecap variable speed fans, it didnt go so well.

These fans have a temp probe to control speed.

I cut the + and - wired of both fans. Connected the positive of one to the negative of the other, and then the remaining wires to the 24v power supply.

The result is that one fan spins at its max speed, one fan spins so slow that when I turned it on, it wouldnt start until I pushed it with my finger, indicating it's not getting startup voltage.

Could the temp probe be messing with wiring them in series?

 

[The Grim Reefer]

So tell me, are these the right white LED's? Prices seems too good to be true.

http://www.dealextreme.com/details.dx/sku.2394

 

[widmer]

Grim: They're the exact same whites that I've got. They're a couple bucks cheaper each because you wait a month for them to show up after you order them

Also, more and more people are going with the XP-G's now, because they're much more efficient (read: more light and less heat at the same time) than the XR-E's. So IMO, you could just as well buy the eight-dollars-and-change XP-G's from LEDSupply.com if you didn't want to get the for less from some place like cutter.com.au. After all, for however many XR-E's you want to buy, you could use 1/3 less XP-G's for the same amount of light.

 

[The Grim Reefer]

Wiring my 40mm fans in series seems to have worked fine; however, when I just attempted the same thing with two 120mm icecap variable speed fans, it didnt go so well.

These fans have a temp probe to control speed.

I cut the + and - wired of both fans. Connected the positive of one to the negative of the other, and then the remaining wires to the 24v power supply.

The result is that one fan spins at its max speed, one fan spins so slow that when I turned it on, it wouldnt start until I pushed it with my finger, indicating it's not getting startup voltage.

Could the temp probe be messing with wiring them in series?

I assume the first fan is hogging all the voltage the power supply can push through.

 

[The Grim Reefer]

Grim: They're the exact same whites that I've got. They're a couple bucks cheaper each because you wait a month for them to show up after you order them

Also, more and more people are going with the XP-G's now, because they're much more efficient (read: more light and less heat at the same time) than the XR-E's. So IMO, you could just as well buy the eight-dollars-and-change XP-G's from LEDSupply.com if you didn't want to get the for less from some place like cutter.com.au. After all, for however many XR-E's you want to buy, you could use 1/3 less XP-G's for the same amount of light.

Dunno, their 10 plus price is 4.36. I just dunno if I trust that company. I'm always preaching to the disciples of the holy alter of TeeFIvery that you get what you pay for. What are they doing that they can sell them so cheap?

Thanks.

 

[widmer]

They come from Hong Kong. Cheap labor, different economy etc etc. I could never get digornio frozen pizzas for less than $6 in the Minneapolis area, but here in Ann Arbor I just picked a couple up for $4.47 each.

Also, a few years ago when my Powerbook's AC adapter quit, I bought a knockoff replacement on ebay which came out of Hong Kong as well. The postage stamps on the package added up to more USD than I paid for the adapter+shipping, so there may be factors at play which can't be explained...

 

[n0rk]

For those hanging on XP-Gs, I hear from a pretty reliable source that RapidLED will be changing their kits from XR-E to XP kits sometime within the next month, as well as having them in general stock. Don't hold me to it, but it seems credible.

Definitely worth the wait in my experience, the difference I've noticed between XR-Es and XP-Gs is astounding

 

[Eel-byte]

Just received my hqi hood to take apart for my led experiment. Time to measure and order the heat sink.

 

[hllywd]

Dunno, their 10 plus price is 4.36. I just dunno if I trust that company. I'm always preaching to the disciples of the holy alter of TeeFIvery that you get what you pay for. What are they doing that they can sell them so cheap?

Thanks.

USPS tracking says mine came through New Jersey a couple days ago so they should be here any time... I'll report back. Assuming they arrive in good shape, I intend to order more. I placed my order on 1/29, so yep, a little slow, but then I ordered them after I ordered some royal blues at about a buck more on a group buy which I don't have yet either... Apparently Chinese New Year had some effect on the shipping and inquiry times too.

Tim

 

[hllywd]

For those hanging on XP-Gs, I hear from a pretty reliable source that RapidLED will be changing their kits from XR-E to XP kits sometime within the next month, as well as having them in general stock. Don't hold me to it, but it seems credible.

Definitely worth the wait in my experience, the difference I've noticed between XR-Es and XP-Gs is astounding

I guess it depends who you listen to... I've had a couple people tell me I'm going to fry everything in my 120 with 96 XP-Es split 50/50 if I use optics. Others say you need to change the split with XP-Gs in favor of the royal blues due to their lower intensity, the brighter XP-Gs wash everything out.

A lot of what I've read says the astounding difference is a downfall of the XP-Gs at the current time. Also to me the lack of a variety of optics could be an issue. Anyway, I'm committed to XP-Es for my first project, maybe I'll try the Gs on a subsequent project once they become more common....

Tim

 

[The Grim Reefer]

USPS tracking says mine came through New Jersey a couple days ago so they should be here any time... I'll report back. Assuming they arrive in good shape, I intend to order more. I placed my order on 1/29, so yep, a little slow, but then I ordered them after I ordered some royal blues at about a buck more on a group buy which I don't have yet either... Apparently Chinese New Year had some effect on the shipping and inquiry times too.

Tim

Cool. I'm doing a 120 too and think I am going to try it with 84 with no optics. Don't plan on clams or a bunch of SPS so we'll see what happens.

 

[n0rk]

I guess it depends who you listen to... I've had a couple people tell me I'm going to fry everything in my 120 with 96 XP-Es split 50/50 if I use optics. Others say you need to change the split with XP-Gs in favor of the royal blues due to their lower intensity, the brighter XP-Gs wash everything out.

A lot of what I've read says the astounding difference is a downfall of the XP-Gs at the current time. Also to me the lack of a variety of optics could be an issue. Anyway, I'm committed to XP-Es for my first project, maybe I'll try the Gs on a subsequent project once they become more common....

Tim

To be honest, I've noticed that the XP-E Royals wash out much more than the XR-Es do in terms of colour, right now I run mine at about 40% of the power of the whites simply because everything is far too blue because they're just so massively bright. Right now, as a general assessment I'd say the XP-Gs are on par with XR-E Q5/R2 in terms of faithful colour reproduction and washout, visually the brightness increase isn't all that huge between the two. For my next build I'm actually contemplating a 1:2 mix of Royals and Cool Whites, the colour seems much more balanced because of the higher colour temperature of the XP-Gs. Overall PAR increase is negligible, just run them at a lower current than you would otherwise. It's all dollars coming back at the end of the day, just you've got a higher ceiling to play under...


Soon enough we'll see much more about them coming out from the "godfathers" of LEDs, problem being right now not many people have solid data about them compared to the XR-Es. Regardless, I'm happy with the decision I made to go with them

 

[Skeptic_07]

So tell me, are these the right white LED's? Prices seems too good to be true.

http://www.dealextreme.com/details.dx/sku.2394

those are great and very very bright. shipping from that company is very slow and unreliable though.

these are brighter though

 

[der_wille_zur_macht]

To be honest, I've noticed that the XP-E Royals wash out much more than the XR-Es do in terms of colour, right now I run mine at about 40% of the power of the whites simply because everything is far too blue because they're just so massively bright. Right now, as a general assessment I'd say the XP-Gs are on par with XR-E Q5/R2 in terms of faithful colour reproduction and washout, visually the brightness increase isn't all that huge between the two. For my next build I'm actually contemplating a 1:2 mix of Royals and Cool Whites, the colour seems much more balanced because of the higher colour temperature of the XP-Gs. Overall PAR increase is negligible, just run them at a lower current than you would otherwise. It's all dollars coming back at the end of the day, just you've got a higher ceiling to play under...

FWIW many of the differences you're observing are probably attributable to the differences in viewing angle between the LEDs you're comparing. XP-Gs without optics don't really look any brighter than XR-Es because the XP-G has a wider viewing angle - it IS in fact making more light, but it's spreading it out a bit more, so the "average intensity" that your eye picks up on appears about the same.

these are brighter though

And also curiously unofficial! R2 isn't even listed on the XR-E binning and labeling guide.

 

[Skeptic_07]

And also curiously unofficial! R2 isn't even listed on the XR-E binning and labeling guide.

that IS very curious... I bought some of them a few weeks back and they're lighting my fuge right now. They are very bright for sure, and irritating to have lit in the room w/ you, but who knows if deal extreme didn't just say that they're R2 and they're actually just selling Q5's? I hope that isn't the case but I wouldn't put it past them.