DIY LEDs - The write-up

[peterbrescia]

I disconnected all the power to the unit, used the 2 AA batteries one end to the heatsink and the other tested each screw and soddering joint. Only one light lit up, I removed the scrws and tested again and there was no more short. Could it be that the srews are transfering power from the led star to the heatsink? The sodder was no where near the screws.

 

[CJO]

Are you using metal screws? If you are, do you have a nylon washer between the screw and the star?

CJ

 

[der_wille_zur_macht]

As CJO stated, the screws must be insulated - typically people put nylon washers under the head of the screw. Otherwise, the screw may contact something conductive on the LED star (solder, an unused solder pad, an exposed trace, the edge of the LED itself, etc.) and cause a short.

 

[CJO]

The red wire goes to the first + led pad at the other end of your string of LEDS. Your volt meter should be set at amps for this test.
It is ideal if you have a second volt meter so you can read the voltage at the same time, by hooking it to the outputs from the driver. The red lead to the red wire and the black lead to the black wire. Your meter should be set to DC volts using a scale higher then the driver can out put. For a 48 volt driver you want the 50, 100 or 200 volt DC scale depending on your meter.

A couple quick caveats-
-Make sure that you are using a string of LEDs (say 6-12). If you use less, you have a chance of burning them out, even if you have the driver turned all of the way down.
-Most multimeters require you to change the positive lead's socket when you change from measuring voltage to measuring amperage. Make sure that you do this correctly.
-Be sure to turn off your driver before turning off or disconnecting your multimeter.

CJ

 

[peterbrescia]

As CJO stated, the screws must be insulated - typically people put nylon washers under the head of the screw. Otherwise, the screw may contact something conductive on the LED star (solder, an unused solder pad, an exposed trace, the edge of the LED itself, etc.) and cause a short.

I am using metal screws, they came with the kit from "rapid led" I thought they would be ok as is

 

[sammy113]

I was helping out a friend with hes lamp and we used Meanwell ELN 60-48D with a simple 10K pot and 9V wart for dimming. Just confirmed that meanwells sometimes DO come with over 1000mA from factory so you want to turn down SVR2 cause we blew up 3 LEDs before noticing what was the problem. I know it has been discussed and posted a few times. just a friendly reminder for those building new lamps

 

[der_wille_zur_macht]

I am using metal screws, they came with the kit from "rapid led" I thought they would be ok as is

In theory, it's possible to screw down the typical HP LED star with conductive screws and not have a problem, but if you don't KNOW about the danger, it's extremely likely that you WILL have a problem.

If Rapidled is providing screws in their kits, IMHO they should do one of the following:

1) Provide nylon insulating washers
2) Provide extremely clear and obvious instructions indicating how to be SURE the screws don't cause shorts

#1 is clearly the better option, since it's very, very easy to accidentally have a metal screw touch something conductive on the surface of the LED, as you've discovered.

 

[Misos Anthropos]

Go back to page 171 there is a good summary there. It should answer most of your questions.

Thanks. This thread is mammoth. I made it thru all the splits. But when I got to the last one and saw 180 + pages I got discouraged and skipped to the end.

Sez "Use Cool-white or royal blue". Wow....I'm surprised. I wasn't aware you could mix all CCT colors with a RB and a CW.

Lots of options there.

You know, many of the recent commercial fixtures I'm seeing hit the market aren't Cree based, and they are starting to mix other LED colors other than RB and 'Street Light Bin' cool-whites. But, they are making and selling lights commercially while you guys aren't. Is there a connection there?:lol2:

I'll PM Misos with some options to do what he wants - Not what you want.

I'll take any help I can get!!

Two disclaimers:

1) LED color choice, ratios, etc. are a rather personal thing, in the same way that some people like 20kk MH and others don't.

2) LEDs as used for reefs are still relatively new, and people are trying different combinations of different LEDs every day, so even the best "rules of thumb" are more or less in a state of flux.

That said, there are basically two decisions to make:

1) Which model(s)/bin(s)/etc. of LEDs to use?
2) Which colors, and in what ratios to each other?

To answer question #1, most people place overall efficiency as a high priority. Currently, that means that Cree products win out - the XP-G for white, and the XP-E or XR-E for colors.

To answer question #2 - well, that's the point at which personal preference and other factors have a strong influence. MOST people follow the "standard" choices that Soundwave laid out in his build - a mix of cool white and royal blue LEDs.

If you use XP-G for the cool white and XP-E for the royal blues, you'll probably want to be somewhere in a 60:40 ratio of royal blue to cool white. If you "cheap out" and use less-powerful LEDs for either color (XR-E whites, Luxeon Rebels, eBay China Special, etc.) then you may need to adjust the ratio depending on the relative intensities of the LEDs you use compared to XP-G/XP-E.

Some people have begun experimenting with neutral or warm white LEDs. The results aren't really "in" yet so consider this an experimental option - the vast majority of DIY builds have used cool whites though, so to some people that may be the "safest" choice.

Whatever direction you think of going, especially with a large build, I'd suggest ordering a few dozen assorted LEDs and a few drivers, and play with different combos. Then you can order the rest of the LEDs you need based on your own impressions.

Overall efficiency is a major concern. I have a lot of hobbies, and none are cheap. So I try to find the most efficient way possible to do things. I dont wanna "cheap out" so it will take quite a while to get everything together and actually get the tank going.



I figure if I copy a method thats worked, for now, as I gain experience I can begin experimenting.

Misos, I just completed a build for a six foot long tank, and if you go to my homepage and then click on one of the first links named "Taqpol's DIY LED Build" it will take you to a thread where I discussed various construction issues as well as a lot of pictures showing the spread of different optics that we have available to DIYers. I did end up using some CREE Neutral Whites in my white strings, but only because I thought I would like a slightly warmer color. My tank is too new and unstable to really show of coral pics yet, but I will try and get some true color pics of the light in general as soon as I get my SLR back.

So far my favorite DIY LED fixtures color is that produced by Sammy113, I think you can find his thread on here somewhere. Still, all the LEDs we've been working with lately have the PAR to make corals grow so the choice of color is largely personal.

I certainly have questions for you!! I really like the way you built your pendants. being able to aim and array of lights where you need it seems like it would be immensely useful. the main thing I'm curious about is since your tank is so much wider than mine (30 in. compared to 18 in.) would copying your design be overkill? Or would it be fine since the depths are pretty close?(mine is 25 in. deep).

Nice build!

If you ever have an occasion to be in the Denver area feel free to stop in, I can show you what I've built for my 120. Give you a good idea what you'll need to get the results you want over your 180.

Ya know, sir.... I dont get down to Denver much since I quit driving truck, but if have the occasion to go, I will take you up on that offer. There doesnt seem to be a whole lot of reefers up here in Casper!!!

 

[Taqpol]

I certainly have questions for you!! I really like the way you built your pendants. being able to aim and array of lights where you need it seems like it would be immensely useful. the main thing I'm curious about is since your tank is so much wider than mine (30 in. compared to 18 in.) would copying your design be overkill? Or would it be fine since the depths are pretty close?(mine is 25 in. deep).

Nice build!

You could very easily copy my build and use all 60 degree optics and get a crazy high amount of PAR. As my PAR numbers show my light is a bit lacking around the front and back edges of the tank due to the 30" width, but that is not a problem to me because of the way I designed my rockwork I don't plan on having any corals at the extremities. If you wanted to save some more money and still have a totally acceptable amount of PAR you could even drop the entire front row off my heatsink fixtures and use only eighteen LEDs per fixture.

 

[jureivis]

i am going to ask a stupid question why you fixed your LED fixture like 30cm from the top of the tank? Would lowering position of fixture help to get higher PAR readings on the bottom of tank?

Could you indicate an overall price of your fixture? Which looks serious btw

 

[Reef_Matrix29]

No questions are stupid...Yes, lowering your fixture does increase PAR, but so does putting tighter optics on it, though you will have to raise it back up to prevent color bleaching.

 

[TheFishMan65]

I read about a new driver that might want to be considered. They are along the buckpuck idea, meaning separate power supply. But they can handle a higher voltage so maybe 9-10 LEDs each. They are also water proof meaning they can be splashed, but not submerged.
A write up
Link to order page - search for cc35

 

[pheinzig]

As you can see in my post yesterday I plan of integrating my DIY LED project into my ATI T5 fixture.
My 32 Cree LED (20 x Q5 XR-E Cool White, 12 x XR-E Royal Blue) build is now side to side with the 6 x T5. But I want to mix the lights more.

I really think it's a great combination. I will be adding 10 more white LED (Cree XP-G R5), and loosing 2 x T5.
To compensate for the more white LED's I'll probably replace 2 white-blue T5 with actanic.

I did an experiment for 1 week:
Had all my RB off for 7 days(originally I had a 50/50 split XRE white/XRE RB)
Basically the colonies where under a yellowish light(much like a 10k MH).
When only the XRE whites were up and running.

In 7 days I had browned off and almost killed 3 SPS colonies.
Adding my RB back to the blend, and Ive stabilized 2 of them...not sure if the third will make it.

If you've never done an array before, Im just recommending you use caution and go with the tried and true blends that people are doing. Based on my experiment, my next array will be a 60/40 split RB/W(maybe as high as a 75/25).

To me it seems that the corals seem to like the RB better. I cant confirm fully till I let my corals recover a bit, then I will go exclusively RB for 7 days and see how they take it.

 

[staggeringwade]

Is it OK to test Leds with 2-AAA batteries? How about AA batteries? I was thinking about going to Radio Shack and picking up battery holder that house two AAA for testing.
Wade

 

[der_wille_zur_macht]

Yes, that's fine if you just want to verify that an HP LED works. Don't light the LEDs for more than a second or two though, as you'll risk damage to the LEDs (if they're not heatsinked) and/or the batteries.

Another option that seems often overlooked on here is that most multimeters have a diode test function that should verify correct polarity and operation of an LED.

 

[CJO]

I did an experiment for 1 week:
Had all my RB off for 7 days(originally I had a 50/50 split XRE white/XRE RB)
Basically the colonies where under a yellowish light(much like a 10k MH).
When only the XRE whites were up and running.

In 7 days I had browned off and almost killed 3 SPS colonies.
Adding my RB back to the blend, and Ive stabilized 2 of them...not sure if the third will make it.

If you've never done an array before, Im just recommending you use caution and go with the tried and true blends that people are doing. Based on my experiment, my next array will be a 60/40 split RB/W(maybe as high as a 75/25).

To me it seems that the corals seem to like the RB better. I cant confirm fully till I let my corals recover a bit, then I will go exclusively RB for 7 days and see how they take it.

Thanks for doing this experiment. Did you measure the PAR values with and without the RBs? If not, it may be that you just didn't have enough light to support the SPSs without the RBs being on rather than it being the color of the light.

CJ

 

[pheinzig]

Sorry no. I do not have the proper equipment to measure that.
However...maybe I can give you a bit more detail and you can extrapalate a more educated conclusion.

The panel that I dimmed out was a 12+12 panel(aka 50/50 split). So I went from 24 lights total(12w/12b),down to 12 XRE whites. The corals in question were under these 12 LED's at a water depth of approximately 6" (with the panel about 10" off the surface).

The RB aren't nearly as bright as the Whites anyways(lumen wise) so I don't see how it dropped too significantly. Especially at that shallow of a depth.

What do you think? Maybe the par reading was too low? Remember the 12 XRE's were on an 8x10" panel footprint. And the SPS colonies in question where directly under that. They where flourishing under that position with the RB+W, I just checked on them 20 min ago. I still feel one is toast, but the other two seem to be on the road to recovery.

 

[der_wille_zur_macht]

The RB aren't nearly as bright as the Whites anyways(lumen wise) so I don't see how it dropped too significantly. Especially at that shallow of a depth.

We talk a lot about lumens in LED threads, but it's important that we interpret and use that information correctly. IMHO in our hobby, lumens makes sense pretty much in only one instance - when comparing (like spectrum) white LEDs. In other words, if you wanted to compare the output of LED model X and LED model Y at power level A, then lumens is an acceptable parameter to discuss.

However, if you're comparing LEDs of different spectra, especially entirely different colored LEDs, and especially especially when discussing their impact on photosynthesis, then lumens is more or less meaningless, since it's tied to a certain spectral range that's not really linked to the photosynthetically active spectrum for our corals..

If we are trying to compare different colors of LEDs as far as their effect on photosynthesis, then the most readily attainable measurement for us hobbyists is PAR, but even that's not really perfect.

It's not well understood in the hobby how specific spectra (within the range of PAR) affect coral growth/color, so assuming PAR and all else is the same, IMHO, observational results are about all we have.

 

[kcress]

pheinzig; You should note that the human eye is lousy with respect to brightness judgments. So statements like "nearly as bright" are crazy subjective. For a photosynthetic creature it can make a vast difference. I'm afraid your test while interesting has tangled up color with photon flux. So one can't make any kind of statement about either.

You would need to have twice as many whites, essentially to replace the missing blues, to allow a statement about the blue verse white. And as CJO points out best would be a PAR meter that allows you to readjust to the same PAR in white as you had in the mixed scenario.

 

[Doc's_reef09]

okay so i have been throwing around the idea of going led on my 40 breeder. so i thought about doing to 36 led retrofit and putting it on a 30 in heat sink. here is a starting idea for me. only thing i will need outside the retro is fans and a heat sink i believe.

[/IMG]
thoughts and postive comments are appriciated