Thank you! I will take another read through the datasheets. I thought I had checked that aspect, but I've been through so many datasheets for so many different drivers recently....

The STCSx looked most promising because of the lack of external components, but I guess there's always a price...

Those were one of the first driver IC's that I was looking at too. They work well if you have the ability to adjust your input voltage, but lack the flexibility of a true switched inductor buck driver.

Re: STCSx Driver Chips



Ah, found the problem. From the datasheet:
===========================
The power dissipation in the device can be calculated as follow:
PD = (VDRAIN - VFB) x ILED + (VCC x ICC)
===========================

Vfb is always .1V so we'll ignore it for our purposes here. Also Vcc X Icc is never much because Icc is small. So the meat of the equation is:

PD = Vdrain X ILED

In the case of running three LEDs off of a 24V supply, one would have:
Vdrain = 24V - 3(~3.5) = 24 - 10.5 = 13.5V

And at ILED = .7A, 1A and 1.5A this would result in a power dissipation :
Pd = 13.5V X .7A = 9.45W
Pd = 13.5V X 1A = 13.5W
Pd = 13.5V X 1.5A = 20.25W

Ouch. Basically, any voltage from one's supply that isn't used by LEDs' Vforward is multiplied by the current and burned as power in the STCSx. That's UNCOOL! Literally!

Back to the National Semiconductor offerings....

Yup. Now you see the problem Pretty much anything over 1v of difference is going to create too much heat. It's a shame, as it's a nice cheap little IC.

Evil,

Here are some pics of my fixture that I'm working on. It's about 80% finished. Then it's time for the drivers and LED's! Any thoughts? I have 8 fans on this unit. 4 120mm on top and 4 80mm blowing across the heatsinks. There is also a temp. controller for these fans. I should be ordering the LED's in about 2-3 weeks. Sorry abouth the poor quality pics!

Let me know your thoughts!

argyle

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made sure it fit my tank!

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side profile
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all heatsinks have a thin layer of thermal paste and are fastened from the other side.

What kind of acrylic or plastic shield should I use? I know some plastics create static. is there a certain grade or some way that I could tell? There is a hardware store in my town that has 1000's of cut-offs....I want to make sure that I buy the correct kind. Do you have another recommendation?

argyle

Based on nothing more than my 20 years of building and troubleshooting PCs and other tech hardware you could dump the 4 80mm fans. As long as you have some decent vents along the sides and those 120mm are all exhausting away from the fixture you're going to get some very decent air movement with just the 120's. I say this with some degree of confidence because the splash guard is going to form a channel with the vents on the side of the system and force the air across the fixture. Also the 80mm fans tend to be much louder because they spin faster and more even less air than a good 120mm unit. If you can get variable speed controllers for your 120's you might be surprised at how slow you can run them and still keep the fixture cool.

So.. update.. and another question to Evilc66 or whoever can answer,

I have built my array, consisting of 6 Cree XR-E Q5 white on one 1000ma buckpuck, and 6 Cree XR-E RB on another 1000ma buckpuck. Both are run from a 4.0A 24VDC power supply. It is mounted on a 12x5.375" heatsink from heatsinkUSA with the base plate thinned by 50%.

I hooked everything up the other day and ran it for 30-45min just to check the heat output, which went to 125F (no fans yet). Since it is in a AIO hood on a Nanowave 9 I think I will be adding two fans (80x15mm SilenX 24CFM). I think I will mount the fans inside the hood and have them blow air in, onto the heatsink from above (making holes in the top of the hood similar to another mod I saw on here, just more central over the heatsink).
http://www.nano-reef.com/forums/index.php?...nowave&st=0


My question is, I want to add a thermostat failsafe. I have been looking at this one.
http://search.digikey.com/scripts/DkSearch...amp;x=0&y=0
It is rated for 120F.

Is this a good set point for the failsafe? Can I let it run hotter and get a higher temp thermostat, or should I get a thermostat that shuts off somewhere lower? Like 100F?

What temperature can you safely run the LEDs at? The datasheet says RB can run up to 90C junction temperature, and the whites up to 135C junction temp. Ambient air temps are lower, but what is the acceptable temperature range to shoot for on the heatsink?

I don't want to to get a failsafe that constantly shuts off to low, or one that will let me burn up the LEDs. I just want a decent failsafe in case one or both of the fans burn out.

Landon

Where would you guys recommend if I wanted to get 6 R5 Cree XPG's with 40 degree (or wider?) optics?

And what brand optics would you recommend?

And lastly, how high up would you recommend suspending an array, 4"X12", with 12 equally spaced LEDs (6 XRE royals and 6 XPG R5) if they all had 40 degree optics---- over a 14"X14" area? For growing SPS frags.

I'll use wider optics if I can find them for the XPG, btw.

Thanks!

Agreed. While it will work, it is overkill and only adds noise. Looks good though argyle.

For driver and LEDs, I would have started with that and planned out the entire build around it. I may have suggested something already for you, but I can't remember, and I don't feel like digging through multiple pages If I haven't suggested something, give me the tank dimensions and I'll get you rolling.


125F with no fans is pretty good. Won't stay there once you put it in a hood, but you know that already. For a cutoff, 120F seems a little low. I'd shoot for somewhere closer to 200F. Don't worry. Royal blues have the same die temperature threshold as the whites. The 90C temperature you are seeing is when the ambient air temperature is at 85C, which is much higher than you would see in a house.


Wouldn't bother with optics. The tank is shallow and the XP-Gs are silly bright. We should be getting XP series LEDs in any day now.

Which LED light would you suggest for a small refugium? I had this one... ...but it's only 3k, so I got rid of it.

Evil
I would like your suggestion on supplementing/adding on to my tank. Right now I have a 24" 250w 14k (will be switching to xm10k)sunpod and a 24" t-5 nova sitting on the canopy in front of the mh. I want to replace the t-5s with LEDs. It was suggested to me to use 12 6500k cree xp g r5s (no mention of lens) and 12 royal blue cree xp e (no mention of lens). I am looking to put 6 of each on the front of the 250mh and 6 of each on the back of the 250mh. In a prefect world I would like to fit each set of 12 leds on 2" x 20" strip (fit in the top of the canopy). The mh sits 7" off the water and the tank is 21" deep and has two 120mm fans in the canopy. Hopefully I have given all the info needed and appreciate your time and efforts!

Regards

I guess I should have specified... for the test I installed it in the Nanowave hood, with shield in place, and on the tank. I was going for the "real world" application of my unit. The 125F was after about 45min of running at full power. I turned it off, pulled the lid off, removed the light shield, and tested the temperature of the heatsink with a digital thermometer. It was to hot to touch for more than a second or two by hand. If my shutoff threshold for the temperature on the heatsink can be 200F, what you suggest means I might not even need fans in the hood, although I plan to install them.

The closest I found to a 200F chassis mount thermostat from that manufacturer is this one.
http://search.digikey.com/scripts/DkSearch...ame=723-1224-ND
It is rated for 175F and 5A of current. There is another rated for 190F also. But these models all say 120VAC/5A. Is it ok to run them on a DC circuit (24VDC)? Do you think this would work?

Evil,

[quote name='evilc66' date='Apr 26 2010, 09:30 AM' post='2813071']
Agreed. While it will work, it is overkill and only adds noise. Looks good though argyle.

For driver and LEDs, I would have started with that and planned out the entire build around it. I may have suggested something already for you, but I can't remember, and I don't feel like digging through multiple pages If I haven't suggested something, give me the tank dimensions and I'll get you rolling.


My tank dims are 36.5 x 16 x 20h. The sheet that the LED's will be mounted on is 36L x 14W. Not sure which type of optics to go with. I think you told me 80's but I can remember. As for LED's should I just go with the XP-G R5 Cool White or the Cool White Cree Q5 XR-E LEDs?

The fans are actually really quiet....but that's only because the pumps that are running in the other room are louder that them...but even then it's not that loud. I'll just leave them there for now....but thanks for bringing that up

I think I will be ordering the LED's late next week. Can't wait!!!

argyle

should I used thermal paste or conductive pads for mounting the LED's?

Most any 3W 6500K lamp should be a good start. They are easy to find on ebay.


Could be a good option. With a mix of white and blue like that, it will be like adding a ~14K bulb to the mix. If you keep each color on seperate drivers, you can adjust the supplimental color that ends up in the tank. Considering that it is supplimental, then lenses shouldn't be needed.


125F in the hood is very good. You always want to cut off the AC side of any LED setup when you have a thermal cutoff. You never EVER want to disconnect the LEDs from the driver. The 190F cutoff will work just fine.


My normal recommendation for that tank is 12x3. 80 degree optics can be used if you want a little more light, but you could probably get away without them. Stick with XR-Es for now. XP-Gs are nice, but come at a premium right now.


Up to you. Thermal paste requires you to drill and tap for mounting the LEDs. Pads are simple.

Thanks for the reply! I have one more question. Can I put 12 leds in a 2"X20" space on the heatsink. I can make the heatsink longer but the leds would be centered on the heatsink in a 2"X20" area. If this wont work what would be the minium spacing?

Regards

Finally after asking you(evil)so many times about LEDs I bought 4 XP-G's and 5 XR-E RB's.
What kind of coverage can I get with these?
At this point it's build led light, feel confident in the technology then build a bigger light

Evil,

Thanks for all the help! I know I ask alot of questions....I just want to thank you! Hopefully these will be the last few that I ask!

What if I did go with the XP-Gs?...I know the price is a bit more, but are they really worth it and will this change anything with the meanwell "d" drivers or anything else I should know about? Where should I buy the thermal pads from and what kind(not sure what they are called). I'm asking this now, and while doing so I need to check your thread on your build....I do remember something being mentioned.

I've moved my plans up and I will be ordering LED's, Drivers, thermal pads, and the rest of the stuff I need sometime in the next 2 days. I'm just double checking....this is alot of "cheese" to spend and I don't want to mess up

argyle

Thanks for the warning about disconnecting the LEDs from the driver. Didn't really think about that until you mentioned it.

So if my heatsink only gets up to about 130F, can I go ahead and start using it until these fans come in?
What would you call the safe operating temperature range for an LED array on a tank? I really want to go ahead and start putting some SPS frags into my little tank.

You could, but it will depend on the type of heatsink. 12 LEDs on a 20" heatsink will force you to tighten the spacing to about 1.5" on center. More LEDs equals more thermal load.


Depends on your arrangement and spacing.


Going with XP-Gs doesn't change a lot about the array. The increase in brightness would remove the need for optics, but the problem right now is that if you need optics at some time to bump output up a little, there are no options. All optics right now start at 40 degrees and go tighter, which will put PAR levels through the roof. If you can get them for a good price, there is nothing wrong with them at all.

Thermal pads can be bought from Nanotuners.


I like to keep my heatsink temps under 150F for safety (measured right next to the star). Make sure you are measuring properly too. If you are using an infrared thermometer, aluminum can skew the reading by reflecting the light. Use a small strip of electrical tape where you want to measure.

Evil and everyone else.

ETG now sells XP-G optics that go up to 60 degree's. I will have mine today and will post pictures tonight.

-Dave

We already have them on order

Clive,

mmmm.....60's....... gonna be using those soon then. I'm putting together a second array for a frag tank and I want the LED's up higher to keep salt spray off of them.

Hi Evil, How are you?

After read this massive thread i am trying to spread your knowledge for my friends here in Brazil, and now we have a study group in our forum based in this thread !!!. A brazilian friend wants to ask you a few questions and I will try to translate.

His reef has 92x28x28 inches...it´s pretty big!

The typical led configuration (X-re´s, drivers, heatsinks) is very expensive for this tank size...

Is there any possible led solution (with good results) for this reef ???
This lamps are possible to use???? http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...e=STRK:MEWAX:IT
Are PAR38 better suited for this situation?????

Thanks again Evil!!!! Sorry for my bad english!!!!

Hails from Brazil

P.S:If you wanted to see our thread in our forum here is the link:http://www.reefcorner.org/forum/grupo_de_estudo_para_projetos_leds_diy-111283
of course all the discussion are in portuguese...

D.

I'm good

Those LEDs could be used, but setting up an array with them will be an experiment for sure. You will certainly use fewer LEDs overall, but I'm not sure how much money you will really be saving long term at close to $100 for a pair. If you try them (start with a small array to start, two or four LEDs), make sure they are very well secured to the heatsink. These cheap Chinese LEDs have big problems with thermals, so good contact pressure to the heatsink will be key. Keep in mind also that the whites may not be the same color from batch to batch.

PAR38's could be an option too. They could offer a little more flexibility and a little simpler installation solution than building a setup. Just keep in mind the limitations (coverage area, PAR dropoff, etc...) if you look into these more. I have a link in my signature that explains in more detail about these lamps.

I'll see if Google Translate does a decent job and I'll go and check out the thread.

Evil...
I now know not to disconnect the LEDs from the driver using a thermostat, but can you cut the DC power between the Powersupply and the driver instead of the AC line heading to the power supply?
(I am using DC buckpucks).
Landon

Evil and others,

I ordered my Led's, drivers, optics, and power cords today. I think you recommended 36 for my 46 bow, but I decided on 48. I still might order another 12....not sure yet. If I do I may use then on my current build and narrow my spacing, or just keep them for another project.
Anyways, I've received my reefkeeper lite, with the ALC on the way. When I connect the meanwell drivers to the ALC, do I wire them all together?....when I set my ramp times I want all lights on at the same time.

I still need to make a splash guard. Can I use plexiglass from Lowes or do I need a non-static acrylic?

Does anybody have any experience with the reefkeeper lite with the ALC module wired with the meanwell drivers? If so could I see some pics or diagrams? I have read the Digital Aquatics website on how to use these things and it seems pretty simple....well kind of .

Other than those things I think I'm pretty set for supplies. Should I get 18 or 16 ga wire? Or do I need larger than that? I know I need the braided.
I'm guessing I should be done building this unit sometime next weekend.....as long as everything goes smoothly!

argyle

Hi Evil,

I have some question. I have 6,5g netto nano reef 10" high. What is your opinion: How many pieces LED need for the optimal light this size tank? Can I use 1-2 pieces UV led for the best colors ? Under the UV LED, green, and red color is greater? I wish use CREE XR-E, and Royal blue leds. Do you know better leds now, or it's types okay? And what would be the minium spacing between the leds?

Thank you
Gabor (from Hungary:))

Evil,

something you said few posts above when answering a question: "Up to you. Thermal paste requires you to drill and tap for mounting the LEDs. Pads are simple."

Could you confirm that you meant by the above statement that I don't need to drill/tap/screw the XREs to the heatsink if I use the pads? Just use them as double-sided tape for the stars?

That'd be awesome!

thx,

spacey

That's exactly what he means, and exactly what I use. As easy as keeping a sticker book when you were a kid .

Thanks redfish,

I actually couldn't wait and called nanotuners and Chris told me the same thing. I wondered what those pads were for/any better/worse than the paste but never suspected that I can get away w/out having to drill! That totally made my day. Totally worth the $0.49 / piece they sell them for IMO.

spacey

Evil,

I have a 29 Gal biocube. I want to do an open top design and have already designed a bracket system to hold two of your lights. What would you recommend for LPS and softs?? If I want to do SPS eventually, what would I need to do it?? Any help you can offer is much appreciated. I have a lot of experience with MH and PC's as far as DIY goes but ZERO experience with DIY LED's.

(Sorry, to elaborate a little, I was thinking of doing two of your PAR38's )

Evil,

I found these drawings on another forum. Are these correct? They kind of show how to wire the Reefkeeper ALC to the Meanwells and to the LED's. Are these good diagrams to follow? I know my LED arrangement will be different though.

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I received my LED's and drivers on Saturday. Soldered, wired, cut, drilled assembled all the parts together. Finished yesterday with all the testing. Set the current, and turned on.....and....THIS IS THE COOLEST THING EVER!!!! I will be posting pics sometime soon. I'm still working on my ReefKeeper Lite and lighting module...firmware updates or something!

argyle

Hi Evil How are you???

The lost in PAR readings at driven leds at 0.7A against 0.95A is huge??? There is some benefits to run at 0.7A other than temperature?
I am asking you because I found some led drivers here in Brazil that can drive 30, 18 or 12 leds at 0.7A and they are cheaper than import meanwells, so I am thinking to use more leds...narrow optics and run this leds at 0,7A. What do you think about this???

Remembering:

reef 40 x 16 x20 inches (sps and lps)

1) 3 meanwells 39 leds (3x13) 2.5 beteween leds 3 between coluns optics 80 ($$)
2) 4 meanwells 52 leds (4x13) 2.5 beteween leds 3 between coluns optics 80 ($$$)
3) 2 drireon drivers 60 leds (4x15) 1.5 beteween leds 2 between coluns optics 60 ($)

What is the better option????

Thanks again Evil!!!!

Sorry for my bad english

Hails from Brazil!!!!!!!!!!!!!!!!!

D.

I'm back Spent some time in England for some family stuff. Almost didn't make it back on time due to this stupid volcano.


You could, but most cutoff switches are AC rated anyway.


The ramp time controls both ALC channels. You can't set them seperately. Connect all white drivers to one channel, and all blue drivers to the other.

Plexi from Lowes is fine. You don't need anything special for a splash guard.

For wire, you should only need 24-18awg wire for connections to the LEDs.


I'm going to need more dimensions to make a good recommendation.

Those are good.


Make sure you get the latest beta firmware for the ALC from the DA forum.


There is a difference in PAR, but the difference isn't huge. With optics, the change is less dramatic. As for your options, #3 looks good, but bump your spacing up just a little. Go to 2" between LEDs.

Hi Evil, my tank parameters:

8 Gallon
sizes: 30 width, 35 depth, and 30 cm high water level. I wish keep zoanthus, ricordea, blasto, acan, some softies, tridacna maxima blue, sexy shrimp, some dwarf gobies.

How much and which led need, for the optimal, and great lighting? I wish beautiful greens, and reds, and blues colors. I need UV led?

Thanks
Gabor

England, huh? Do you have that sexy British accent? lol...

Now I have an actual question.


I'm thinking... for the moment... of running two different tanks with actinic royals on the same driver.

I have 5 royal blues that I'd like to put over a tank that currently has T5's.

If I have 8 LED's on one array, 5 on the other, can I space the two arrays about 5-6 feet apart using 18AWG wire (still with the LED's in series)?

Not sure if this is correct. I have an ALC unit and it appears to have the ability to put in 2 separate ramp times. I currently use the same ramp time on each channel so I haven't tested it out but I do have separate intensity levels on each channel and that works fine.

Been trying to see where the lamp qty vs pwr supply computes.

How many 3w LEDs would work with a12W 24V 700ma driver. http://www.sunparkelectronics.com/product_...products_id=252

where is everyone ordering their cree xr-e lights from? ive read a couple of the diy's and they all give me etg tech.com and i cant find a way to buy them on there and people said they were paying 6 bucks an led from there but all i can find it 7.50 an led from ledsuply.com

if someone could clarify for me itd be great thanks guys!

You'll have to call ETG. There is no way to buy online though. Try also Nanotuners for $6.29 a piece plus you can get drivers and thermal pads in the same place

^ thats what im talking about, thank you!!

Evil, Could you tell me the wattage/output of my lights? I'm trying to determine what it equates to in t5/mh/pc terms...



panorama 23.5
5x blue stunners
2x uv stunners

Only for you Actually, lost the accent a long time ago. Came over here when I was 13, so you fit in quickly, much to my wife's irritation


You could do it, provided the voltage drop along that wire is really low. You may want to go up to 16awg to minimize that as much as possible.


It may have been updated in the beta firmware. The original firmware only had a single ramp time for both channels.


No offense, but seriously? I think we have covered this a few hundred times. Divide the max output voltage of the driver (24v), by the average voltage drop of the LED at the given current (3.5v for Cree's at 700mA), and round down. It even tells you on the product page that you can run 3-6 LEDs.

The "3W" designation of LEDs is misleading. It doesn't tell you much. The actual wattage of the LED will be determined by the drive current (set by the driver), and the voltage drop. Watts=Volts*Amps.




The wattage of the setup isn't what will tell you what it will be equivalent to. The Panorama strips are 13W each, and the Stunners are 6W each. Again, that doesn't tell you everything. It's all about LED efficiency. I have tested these setups with a PAR meter. You are about equivalent to a 150W MH, but with a little better performance at the bottom of the tank. PAR dropoff with LEDs is far more linear than with MH/T5.

Evil I can't thank you enough for starting this thread and your valuable input. I would like to suggest if you'd consider posting a sticky on electrical work for beginners as related to LEDs, power supplies, wiring etc. I know I would appreciate that. Just a thought.

how far apart do 3w LED need to be from each other? has anybody used the violet colored LEDS?