DIY LEDs - The write-up

[blasterman789]

Of the folks that have actually built their own lighting how many have already or have thoughts of adding a controller to their lighting

Feh....never had this on my halide gear, so I don't find it required on my LED gear. A cheap $8 digital timer suits me fine. It has two modes; off/on.

For off hours viewing I've considered adding some dim cool-white as 'moonlights' because I've noted this is actually when I spot a lot of problems. After all, the moon is 'white', not 455nm blue. Also remember that cool-white don't have the insane PAR that RB's have, so adjust accordingly.

Another reason is I'm constantly tweaking my LED configuration, and it's easier to do this without being locked into a specifc controller config. I'm going to be testing some 10watt 440nm emitters here soon, and it's just easier that way. For a top down fixed design like many others have it's less restricting to get fancy.

 

[westmoorenerd]

Hmmm Stu, any word on the light spread of the 3-up fixture?

 

[CJO]

I'd like a show of hands please. Of the folks that have actually built their own lighting how many have already or have thoughts of adding a controller to their lighting so that they can have one setting for viewing times and another setting for off viewing times?

I purposefully used the ELN-60-48D drivers so that I can use it with my Apex unit for dimming.

CJ

 

[swannking]

I was wondering what are the dimensions of the cree XP-G/XR-E stars. What is the maximum reasonable number of leds I can fit on a 12"X4" heat sink?

 

[der_wille_zur_macht]

Swan, attached is a PDF of Cree's design doc for the star. Keep in mind that this is Cree's own star, for the XR-E package LED. You will want to verify that the star matches what you end up with, as some vendors use their own stars (instead of Cree's) and the solder pads might be in different locations for other Cree stars. But, generally, when someone says "star" this is the physical footprint you will get.

Regarding max density, IME it'll be more limited by thermal problems than physical packaging. You're going to need a heck of a heatsink AND lots of fans, or water cooling, for a maximum-density build. The most-dense I've gone is 8 emitters on a common PC CPU heatsink with a fan. At moderate drive currents, it was OK. At max currents, it got really hot.

 

[CJO]

Most people order them on 20mm stars. I think that you can also get them on 10mm stars.

You could reasonably fit 12 on a 12"x4" heat sink. It is really based on how much cooling you have.

CJ

 

[der_wille_zur_macht]

Most people order them on 20mm stars. I think that you can also get them on 10mm stars.

I've never seen a 10mm star shape, but have seen square and round 10mm MCPCBs. And also a billion other sizes and shapes.

Cutter has probably the most comprehensive inventory of MCPCBs for people with unusual needs:

http://www.cutter.com.au/products.php?cat=Metal+Core+PCB

People looking for maximum density will probably want to either go to 10mm MCPCBs or multi-LED PCBs (or multi-emitter LEDs, i.e. Cree MC-E).

 

[woowoodengy]

LED color help

LED color help

hey guys i am planning an LED build for my 260gal. although color choice may be better with individual stars i just dont like all the wires criss cross and even if i drill the heatsink to conceal the wires is just not the look i am going for. i would like a nice AI or even maxspect fixture but its just out of my price range. so i decided to go with led strips from here http://www.reefledlights.com/accessories/cree-led-strip-light/ but i cant decide color choice. i have a 84" long tank by 24" wide by 30"tall i figure i can get two 36" X 8.5 heatsinks and use 15 strips on each but what would get me the best color for my tank? here are 3 choices that i have drawn up. i will use dimable Mean Well ELN-60-48D drivers on all LED's. the strips come either 6 royal blues or 6 cool whites or mix 3 blues / 3 whites what should i do???

 

[TheFishMan65]

Sure would be nice if they told you the size (maybe 12 inches), but maybe I missed it. I would avoid mixing Royal Blue and White on the same strip. If you want to simulate sun rise/set this would mess up the common practice of turning on one color and then the other.

 

[der_wille_zur_macht]

Agreed, in general - consider your dimming/control plans and allow that to dictate - otherwise, the typical 50/50 mix is probably a good starting point. Though, of course, best practice will be to just order a bunch and try out different combinations until you get what you like. Working in "chunks" of 6 sure is cumbersome, even on a larger tank.

 

[hairy_frogfish]

That sounds like an OK plan. I'd "bin" your LEDs by voltage to get even strings.

Also, with a 14 cool white : 10 royal blue ratio, you may find it's overly white.

Thanks for the advice, will post with the result of the DIY

 

[swannking]

Question about the dimmable driver. It has been mentioned that the regular 9V DC power supply can be used but the voltage is not regulated and is variable. Let say if I have it checked and running it under certain load, does the voltage fluctuate or remains the same assuming everything else (ie. the load and other variables which I don't know about) is the same. I am thinking of hooking up a small "inline" voltmeter to the dimming 9V power supply so I can monitor the actual voltage while making adjustments under load. So once it is set, it should stay the same right?

 

[TheFishMan65]

If the 9V supply supply is less than 10.5 volts wiht no load then you should be OK. If it is more than that you probably want a different supply, IMHO. If it is 9V with the dimming load you are probably OK, but you riskj damaging the meanwell to find out. People have reported no problem with some higher voltages, but it does not mean that the life time might have been shortened.

 

[wld1783]

hey guys i am planning an LED build for my 260gal. although color choice may be better with individual stars i just dont like all the wires criss cross and even if i drill the heatsink to conceal the wires is just not the look i am going for. i would like a nice AI or even maxspect fixture but its just out of my price range. so i decided to go with led strips from here http://www.reefledlights.com/accessories/cree-led-strip-light/ but i cant decide color choice. i have a 84" long tank by 24" wide by 30"tall i figure i can get two 36" X 8.5 heatsinks and use 15 strips on each but what would get me the best color for my tank? here are 3 choices that i have drawn up. i will use dimable Mean Well ELN-60-48D drivers on all LED's. the strips come either 6 royal blues or 6 cool whites or mix 3 blues / 3 whites what should i do???

I would go with option three as you could really tweak the colour by only dimming the blues. If you go option 1, I would use no optice or 80 degree optics in the center white. I just added a center white XP-G along with some Royal Blues to my 144 LED fixture to replace some of the T5s and found with no optics the 120 degree spread worked well on my tank.

Bill

 

[der_wille_zur_macht]

So once it is set, it should stay the same right?

Yes. I would not bother with an inline meter unless you're curious and like to tinker. Even with an "unregulated" DC power supply, this will be a fairly stable circuit once it's running.

 

[nitjt]

I have had my XP-G and XP-E array going for a couple of months now and I am now starting to get some Blue LED's to go out? I have 7 strings of 13 LEDs powered by Meanwells and on some stings I have 3 or 4 LEDs in a row not lighting up. The first couple will light up then 3-4 out then the last on the sting will be on? I thought if one went out the entire string would go out?

 

[wfournier]

check for shorts, also try checking across the LED, they can fail closed.

 

[der_wille_zur_macht]

My bet is shorts to the heatsink due to weak connections and/or salt spray, corrosion, etc. bridging a conductor to the heatsink. First off, check to see if your heatsink is conducting!

 

[nitjt]

I don't think the heat sink is conducting, I have 5 heat sinks all of which have seperate white and blue strings on them but only the blue are out. When I use a battery to test the Blue LEDs that are out they don't come on I test where I have them connected in series and on the star pads with out solder but no light? I can't expalin why its only the blues?

 

[TheFishMan65]

What current did/are you running your blues at? I assume the are XR-Es. How hot was the heat sink getting? It sound like the shorted out which I think means they got over worked.