customcolor
New member
and i have them 2' away from my frags!
DIY LEDs - The write-up
- Thread starter JohnL
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widmer
Drug Enthusiast
Nork: It would be easier to validate/offer opinion if you would remind us what size tank you have 
And if you do want to put that fixture up on the ceiling be sure to visit my thread - http://www.reefcentral.com/forums/showthread.php?t=1784873
And if you do want to put that fixture up on the ceiling be sure to visit my thread - http://www.reefcentral.com/forums/showthread.php?t=1784873
customcolor
New member
hey widmer.....
n0rk
More is better-er!
Nork: It would be easier to validate/offer opinion if you would remind us what size tank you have
Touché :lmao: It's a 36x24x13 (at least I'm sure it's a 13" deep, though it could be very well be 12"), and I'm not really needing to light the full surface area. Ideally probably about half an inch within the borders of the tank to give it a sort of edgeless appearance, similar to what you describe in your thread I'd guess. I'm not concerned about intensity or penetration as I know there'd be more than sufficient... moreso coverage capability.
The number I'd had originally planned was for surface coverage as it was to be mounted at surface level... not so much for intensity.
customcolor
New member
remember ....soundwave has 24 leds over each side of his 72 with no optics
widmer
Drug Enthusiast
I don't see any reason to ever put more than 24 of the XR-E's over a 29 gallon tank. Less if they're XP-E's/XP-G's.
Remember I have 18 XR-E's over my 15 rimless which is 12" l by 24" w by 12" h, six feet away from the sand bed and I measure 300 PAR in the water column, with some degree of spill outside of the tank's footprint as well. I have been keeping the lights dimmed down a bit due to the fact that I keep them on for 16 or so hours per day...
perikaruppan
Member
need help on LED placements on a 54" X 24" X 24" tank.
I have designed 5 rows, of (3 row) 15 LEDS and (2 rows) 20 LEDS alternating with a spacing of 3.6" between rows. 85 in all, will delete 1 LED somwhere to get 84 (Drive using a 12 LED Driver)
The 15 LED row have a spacing of 3" and 20 LED row has a spacing of 2.3".
I have shown the approximate LR Arrangement in the tank in grey. the tank is indicated in black, and the hood is indicated in cyan. The hood is 48" X 18". 3" spaced out from the tank periphery.
Thinking of 60 Degree optics.
Will this setup be ok for medium to high lighting requirements?
I have designed 5 rows, of (3 row) 15 LEDS and (2 rows) 20 LEDS alternating with a spacing of 3.6" between rows. 85 in all, will delete 1 LED somwhere to get 84 (Drive using a 12 LED Driver)
The 15 LED row have a spacing of 3" and 20 LED row has a spacing of 2.3".
I have shown the approximate LR Arrangement in the tank in grey. the tank is indicated in black, and the hood is indicated in cyan. The hood is 48" X 18". 3" spaced out from the tank periphery.
Thinking of 60 Degree optics.
Will this setup be ok for medium to high lighting requirements?
kcress
New member
In my readings on this topic I never noticed the following application guide in the Mean Well docs. Anyone considered going mixed parallel and serial?
Alrighty now... This is pretty clever. I'd do it.
If you string a bunch of un-matched Vf LEDs in multiple strings you run a big chance of one string "hogging the current", (which is the actual technical term for it). Hogging never turns out well... :hmm4:
The resistors are there to prevent hogging. Any minor increase in current thru a string/resistor results a larger drop across the resistor partially counteracting the difference.
If a LED shorts the current that is going to divert thru it is going to be contributed thru a bunch of other LEDs and resistors and hence none are going to immediately be over-driven.
Now lets clip out the first LED in a row - it blew open.
Now the 2.5A is going to be distributed around 7 strings.
2.5A / 7 = 357mA.
All the first column of LEDs are going to see 375mA. The rest of the matrix is going to see the same as before!
Now that's the first LED in the string - the worst case. Any other one result in a smaller current increase in its mates.
Now an LED fries shorted...
The entire column will go dark and all the current will run thru the shorted LED - for a short time - before the
wire bonds vaporize, then you're back to one open LED - see above.
This is how all LED street lights are built.
der_wille_zur_macht
Team RC
Your optics are obviously making a HUGE difference.
I've put 24 LEDs over a tank around the size of a 29, without optics, and at 700 - 800mA it seemed adequate but not overwhelming. If I wanted high-light SPS top to bottom, I'd probably want more. FWIW back when I was planning on actually running a nano longterm, it was going to be a ~18g cube and I was going to use 24 LEDs with wide optics and 500mA drive current, mounted about a foot up.Of course there's a lot of variability with optics, drive current, livestock choice, mounting height, etc etc etc. And as you add in optics at a reasonable mounting height, you're kind of locking yourself in to a very high intensity anyways, because you'll need tight spacing to avoid spotlighting.
der_wille_zur_macht
Team RC
Thank you for explaining it in plain English.
It raises a question though. Seems like it would only be effective for many parallel rows - if you tried to do this on an ELN60-48 with two rows of LEDs, the math isn't so friendly.
der_wille_zur_macht
Team RC
That's the way it strikes me - you'd want it so if one column of LEDs lost an LED, the current through the remaining LEDs wouldn't spike to dangerous levels.
Of course, as you go down in voltage and up in current, you trade off more rows for less columns, but since these are all essentially "60 watt" drivers, if you're maxing the voltage and current, the total number of LEDs should remain the same.
Of course, as you go down in voltage and up in current, you trade off more rows for less columns, but since these are all essentially "60 watt" drivers, if you're maxing the voltage and current, the total number of LEDs should remain the same.
TheFishMan65
New member
kcress,
Hogging is important I like bacon
Not sure I agree with the resistor logic. The resistor may help balance the first column, but after that they don't affect anything. The second column has 2.5 amps (current example) that get splits to make the all have the same Vf.
Why do you think if any other one goes (in another column) the rest (in that column) will not have the same 2.5/7 = .357 ma (Ok they will very some)going through it. Each column has to have 2.5 amps if only 7 LED work they will split at around .357 ma
Hogging is important I like bacon
Not sure I agree with the resistor logic. The resistor may help balance the first column, but after that they don't affect anything. The second column has 2.5 amps (current example) that get splits to make the all have the same Vf.
Why do you think if any other one goes (in another column) the rest (in that column) will not have the same 2.5/7 = .357 ma (Ok they will very some)going through it. Each column has to have 2.5 amps if only 7 LED work they will split at around .357 ma
TheFishMan65
New member
Here the same matrix layout (no power supply or resistors) that may be clearer to some people to understand. I tried to show more clearly how the 2.5 amps is supplying each column.
[EDIT]
and not as many rows
[EDIT]
and not as many rows
HeneryH
Henery Hawk
CDIweb.com just quoted me 2-3 weeks for the ELN-60-24-D and 6-7 weeks for the ELN-60-48-D both at $26.71 (10-15 qt pricing). Auth cc on order but billed on ship.
Julie (julie.williammee at cdiweb dot com) has been great to work with so feel free to mention to her that this is part of the Reef Central hobby group.
I'm really not sure which way I want to go here. I'm leaning towards the 24V Matrix (yes, I hated that term orignially but originally failed to notice the bus-bar wiring between strings).
Julie (julie.williammee at cdiweb dot com) has been great to work with so feel free to mention to her that this is part of the Reef Central hobby group.
I'm really not sure which way I want to go here. I'm leaning towards the 24V Matrix (yes, I hated that term orignially but originally failed to notice the bus-bar wiring between strings).
Reef_Matrix29
Water Lover
Did he dim them lower than 700mA of current on each string of white and blue LEDs that you know of?
TheFishMan65
New member
HeneryH,
I kind of thought people kept missing that which is why I redrew it.
wesley,
I don't think he ever said what he is running at. i have been trying to follow that since I want to run in the 350-500 range and have been trying to see if anyone is dimming that low. So I have been watching for final currents. But I may have missed it. Santoki (did I spell that right) does mention in her post, I know because I asked her.
I kind of thought people kept missing that which is why I redrew it.
wesley,
I don't think he ever said what he is running at. i have been trying to follow that since I want to run in the 350-500 range and have been trying to see if anyone is dimming that low. So I have been watching for final currents. But I may have missed it. Santoki (did I spell that right) does mention in her post, I know because I asked her.
Reef_Matrix29
Water Lover
I was under the assumption that it was running at 700 on both strands....that makes more sense to me now. Okay, I need to turn mines down a tad until my PAR meter is delivered on Friday and I can double check for sure. I have my 24x2 rig running at 700mA on both strands with about 12" from non-optic LEDs to water surface and I'm getting a little burning of my brain coral on the sand bed of my 75!! So maybe 500mA will be better...
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