DIY LEDs - The write-up

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I've been tagging along for days getting up to speed with LED. This is the right place. My thanks to all that have helped enlighten me. Especially Soundwave for getting the build up and starting the project.
LED is in my feature now. : p
 
I've been tagging along for days getting up to speed with LED. This is the right place. My thanks to all that have helped enlighten me. Especially Soundwave for getting the build up and starting the project.
LED is in my feature now. : p
 
<a href=showthread.php?s=&postid=15344566#post15344566 target=_blank>Originally posted</a> by AndyReef
I know everyone says that the Meanwell eln 60-48D can handle 13 of the Cree XREs, and I know this is a rudimentary question, but how does one go about calculating the number of LEDs that can safely be driven by one meanwell?

For ANY driver, you need to know two things to figure out how many LEDs the driver can handle:

1) The forward voltage of the LED(s) you are using. This is published in the datasheets for the various LEDs. It increases as current increases, so when you look it up, you need to know the current you will be running. Assuming you are using Cree XR-E LEDs at 1000mA, the forward voltage is 3.7.

2) The maximum number of volts the driver can produce. This is also usually in the datasheets, but you need to be sure you are interpreting the specs correctly.

Once you have this info, you just multiply the LED forward voltage by the number of LEDs you want, then check to make sure it's under the max for the driver. Or, to find the max number of LEDs for a driver, divide it's max voltage by your LED's forward voltage. For example, the ELN 60-48 is a 60 watt driver that has a max output voltage of 48v. If you are driving XR-E's at 1000mA, that's 3.7V each. If you divide 48v by 3.7, you get 12.97, so running 12 of these LEDs on these drivers really should be the max.

Some other drivers can be powered from DC, over a wide range of supply voltages (for instance, the buckpucks many are using.) Typically, rather than specifying a max output voltage, these types of driver specify a head required by the driver - for the buckpucks, the supply must be 2 volts more than the output voltage.

<a href=showthread.php?s=&postid=15344778#post15344778 target=_blank>Originally posted</a> by JTL
I would really like to build one for my new DT but I don't think I fully understand the amps that it would draw. The tank will be 44x24x24 so I don't even know how many LEDs I would need, but is a lot. As an example let's use 50 as a starting point. I am currently running (4) T5 54 watt on two ballasts that draw 1.15 amps each. I could double that and only use 4.6 amps and have 432 watts. LED's are going to be better watt for watt but how much better and at how many amps? I am concerned about amps because they are a limited resource and I don't have any easy way to add another circuit.

I find it easier to think in terms of watts than amps, but you can roughly convert given a voltage.

Taking your example of 50 LEDs, assuming we're taking Creed XR-E (the standard choice in this thread) driven at 1000mA (the max, and pretty much the default choice), then each LED is seeing 1000mA of current at 3.7 volts. That's 3.7 watts each. For 50 such LEDs, you'll have 185 watts. If we assume the driver(s) being used are 80% efficient (reasonable, but probably on the worst-case end of the spectrum) then the whole rig will be consuming about 230 watts.

On a wall outlet, that's about 2 amps.

Trying to compare LEDs to other types of lighting watt for watt is tricky because there really isn't a track record yet, but it "seems" as if LED are in the range of half the wattage for an equivalent result compared to T5HO or MH. So if you are running your tank on 432 watts of T5, you could probably get similar results from 200 - 300 watts of LED, assuming a really good design.

Besides the high efficiency of LED (in pure terms of output per watt), the output is also in a much more desireable format - in a pretty narrow viewing angle, which means ALL of the light is going more or less "straight down" into our tanks. Especially with optics, which are less lossy than a reflector. Compare that to a T5 or MH lamp, which gives off light in ALL directions. Even with the best reflector design, there's still going to be more losses than with an LED.

<a href=showthread.php?s=&postid=15345623#post15345623 target=_blank>Originally posted</a> by aeternus12
is it ok to use in reef aquarium 6500 k power led or should i use led 10 000 k or even 15 000 ?

The vast majority of folks in this thread are using Cree XR-E or Luxeon Rebels in the "cool white" color, mixed about 50/50% with blue or royal blues. The "cool white" LEDs are rated in the range of 6500k, and the blues and royal blues peak right around what we normally see in actinic reef lighting. So this combo is pretty close to other forms of reef lighting.

I would not try to think of it in terms of kelvin color, since LEDs produce a spectrum that's much different than other types of reef lighting, so trying to compare based on a single (subjective) number might be misleading.
 
I really need to brush up on my circuit design. With a 60 watt driver like the meanwell, how is the driving current determined?
 
Need to get the colors dialed in, it's a tad blue but the build is pretty much complete! Just need some way to hang it now:)

IMG_1524.jpg
 
<a href=showthread.php?s=&postid=15347279#post15347279 target=_blank>Originally posted</a> by kcress
That looks pretty nice!
You're not going to bother with water are you?

Nah, thinking I might just leave it like it is it's so pretty. Why would I want it full of ugly algae??!!:lol:
 
I have a basketball sized birdsnest skeleton you can paint pink and pretend. Get some of those fish on acrylic sticks at hobby lobby and call it a day.
 
OK I was really into this thread a few months ago, then I had to put it on hold. Now I'm back and I've got money to throw down. I just have a small handful of questions that I'd be grateful if anyone wants to take a stab at:

1. My plan for my 20 gallon reef is 12x white Cree XR-E's and 12x royal blue Cree XR-E's. Does anyone feel like I should cut this in half based on my tank size, and thus only spend half as much money?

1 part b. I was going to get the whites from dealextreme.com at like ~$5 ea, but the blues from LED supply at ~$7.50 ea. Anyone aware of a more reasonable price/option for the blues?

2. If I hypothetically had the 4 strings of 6 Crees running full blast at 1 amp, would this 4.2 amp supply be good enough, or should I step it up to the 6.5 amp?
http://www.mpja.com/prodinfo.asp?number=16853+PS
I don't want to frivolously convert electricity if I can avoid it.

3. Is anyone out there (flashlight enthusiast maybe?) aware of any lenses such as those advertised on dealextreme.com that would allow me to focus my LED lights into NARROW (~10 degrees (yes I understand the trigonometry, I just have a fun idea)) with no artifacts/rings/light spill etc?

Thanks much!
 
widmer; Power supplies really climb the heat curve in the last 20%. This is where the cooling needs to be good, mounting position needs to not be violated, and where the life will be somewhat reduced.

I'd never drive a supply more than about 80% if I could manage that. If the supply is going to be mounted in a cool area or have air mechanically moved thru it, then go for it. Otherwise be conservative.
 
Ive ordered a pile of LEDs to set up led system on my 20" cube, but apparently finding somewhere in Aus that has buckpucks, power supplies or meanwell drivers for a reasonable price is impossible. Subsequently, Im at a standstill haha. I really should have thought this through. You guys have got it easy :D
 
<a href=showthread.php?s=&postid=15347074#post15347074 target=_blank>Originally posted</a> by AndyReef
I really need to brush up on my circuit design. With a 60 watt driver like the meanwell, how is the driving current determined?

The sort of LED drivers we are all using are constant current AC - DC or DC - DC switching regulators. They have circuitry inside them that basically monitors the current on the output side of the driver, and then makes tiny adjustments to the voltage to keep the current at some predetermined setpoint.

So, if you take a driver like the 60-48 mean well, for example, it can be set for 0 - 1.3A current. Let's assume you are running it at 1A (1000mA) since that is a typical max for the LEDs people are using. When you plug that driver in, it creates a voltage across it's output (i.e. your string of LEDs) and then basically lets that voltage grow (almost instantly) until current hits 1A. Then, a solid state switch inside the device turns on and off rapidly to keep the current at that point, by limiting the voltage. The switching frequency is usually in the ~100kHz range, and there are components inside the driver to smooth the switching action, such that the LEDs see only a small ripple in the current, and it's faster than our eyes can detect.

So, the driver will vary the voltage on the output until it's set current is reached. The voltage it needs to reach in order to hit that point is the sum of the forward voltages of all the (series) LEDs it is driving. So, if you have 3 LEDs at 3V each, that 60w driver will hold the voltage at 9V, and the current will be 1A. Thus, you will only be getting 9 watts out of your 60W driver. Or, you could put 16 of those same LEDs on that driver, and you'd be getting 48V at 1A out of it, which is 48W.

If you haven't caught on yet, LEDs and LED drivers are typically far more flexible than other lighting we use in the reef keeping world. If you have an M58 HID ballast (better known in this hobby as a 250W MH ballast), you can pretty much ONLY put matching, 250W bulbs of a certain type on it. In contrast, if you use this "60 watt" mean well driver, you can power a huge range of different LED configurations, as long as the max voltage isn't above 48, and the max current isn't above 1.3A.

<a href=showthread.php?s=&postid=15348790#post15348790 target=_blank>Originally posted</a> by widmer

1. My plan for my 20 gallon reef is 12x white Cree XR-E's and 12x royal blue Cree XR-E's. Does anyone feel like I should cut this in half based on my tank size, and thus only spend half as much money?

Most folks in this thread (and threads on certain nano reef keeping forums) are in the range of 10 - 20 square inches of surface area per high-power LED. This is an arbitrary "rule of thumb" I've made up completely out of thin air, but IMHO serves as a good gut check against successful systems. On a shallow tank like yours you can probably stay at the low end of the spectrum. So let's say 20 inches each. If I remember correctly, a 20 is what, 30 * 12 inches? That would put you at 18 total LEDs. Again, this is a very rough guideline.

1 part b. I was going to get the whites from dealextreme.com at like ~$5 ea, but the blues from LED supply at ~$7.50 ea. Anyone aware of a more reasonable price/option for the blues?

I bought my blues from ledsupply because I only needed a few and was getting other stuff there. Others are reporting good prices from etgtech.com but you have to call and ask for a certain person - the contact info is somewhere in this thread.

2. If I hypothetically had the 4 strings of 6 Crees running full blast at 1 amp, would this 4.2 amp supply be good enough, or should I step it up to the 6.5 amp?
http://www.mpja.com/prodinfo.asp?number=16853+PS
I don't want to frivolously convert electricity if I can avoid it.

+1 to kcress's comment. Go with the bigger supply. It will only "convert" the current you need, the ratings published are maximums.


3. Is anyone out there (flashlight enthusiast maybe?) aware of any lenses such as those advertised on dealextreme.com that would allow me to focus my LED lights into NARROW (~10 degrees (yes I understand the trigonometry, I just have a fun idea)) with no artifacts/rings/light spill etc?

Thanks much!

Cree and Carlco both make 8 degree optics for the XR-E, and ledsupply carries both. I've never used them (the only optics I have are for rebels) so I can't comment about light spill, but I'm guessing it would be easy to shield the optic to block any spill, if you wanted a concentrated "beam of light" look. You've probably found them already, but there are a bunch of really good lighting forums out there with LED sections - candlepowerforums.com comes to mind.

<a href=showthread.php?s=&postid=15349421#post15349421 target=_blank>Originally posted</a> by DannyHennig
Ive ordered a pile of LEDs to set up led system on my 20" cube, but apparently finding somewhere in Aus that has buckpucks, power supplies or meanwell drivers for a reasonable price is impossible. Subsequently, Im at a standstill haha. I really should have thought this through. You guys have got it easy :D

We should all be so lucky to be attempting this in Australia! Cutter Electronics is an ozzie company that has an AWESOME selection of drivers and LED-related products:

http://www.cutter.com.au/

Check them out! A lot of their stuff is aimed at flashlights, but would be really easy to adopt. I don't think they carry mean wells, but they do carry buckpucks, and a ton of other drivers.
 
I have checked out cutters, and I see they have the buckpucks, but I havent found a suitable power supply on there. Im still figuring all this out, but if you want to point me in the right direction Id be forever grateful! I saw the $15USD 6.5A power supplies earlier in this thread, which would be perfect, but the store didnt seem to offer international shipping. If only Id know about all this when I was over in the states earlier this year!

It still seems like meanwells are much cheaper and easier, but its a matter of finding them!
 
Thanks andy, that is also the only place in Aus that I have found that lists them. The issue is, they are out of stock and state a 6-12 week wait. Given that it will work out much much cheaper (meanwells = $100 aus, psu + buckpuck = $200+), I may just order them and wait it out. At least Ill have my leds and optics to play with.
 
I ordered some a few weeks ago for some place here in the US, they are estimating that they will ship in september. Guess that will give me some time to work on other stuff.
 
AndyReef, could you post where did you order it and what was the price, please?

I'm looking to buy 4 ELN-60-48d and interested in some options.

Thanks,
 
Well, just ordered 3 meanwells. I only need two, but if Im waiting 3 months, I figure I may as well get 3. LEDs ordered, meanwells ordered, will order lenses tonight, then we are golden :)
 
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