DIY LEDs - The write-up
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der_wille_zur_macht
Team RC
Worthless. The "specifications" listed on those eBay items are clearly 100% incorrect (there's no such thing as a blue LED that performs in the manner they're claiming!) If you go to the manufacturer's website, the real specs are pretty poor.
Plus, those are just bare LEDs, no MCPCB stars included. So figure another 75 cents per LED to buy PCPCBs, then you'll need to reflow solder them on yourself (not for the faint of heart).
Thanks
crvz
Team RC
dwzm, do you have a link handy to this type of DIY? I think I want to try that out next, now that my LED light rack is online.
der_wille_zur_macht
Team RC
Not really. I've described it in general terms in a bunch of threads. I mean to do a very literal step by step but it's one of those things that always gets pushed to the back burner. Basically, my approach would be to get a cheap Arduino clone, an RTC (realtime clock) breakout board, and wire it up. For buckpucks or drivers that can take the PWM signal in the format the Arduino generates, that's all you'd need. For Meanwells, you need something to translate the signal to 10v. There's been a good thread on this - if you search "meanwell" in thread titles in this forum it'll show up. I designed an Arduino shield that does this translation and has now been tested by a few people with both P-type and D-type meanwells, so at the least, you could just copy that design.
Regardless, you should be "out the door" for $30 - $50 or so, with a controller that can fade up to 6 "channels" of LED drivers (several drivers per channel if you need), and would be expandable for other tasks if you wanted them down the road.
Regardless, you should be "out the door" for $30 - $50 or so, with a controller that can fade up to 6 "channels" of LED drivers (several drivers per channel if you need), and would be expandable for other tasks if you wanted them down the road.
Jay1982
New member
Major props to der_wille_zur_macht for answering my ridicuously long post!! Thank you once again!
The more I'm thinking about it, the more I might want dimmable lighting so that I don't shock my corals from the get go. I'll need to read up on fixing up the meanwells since they run more LEDs per unit than the buckpucks.
kcress
New member
LEDs can run much hotter than you would expect for a long time. That said, a simple rule of thumb is: If you can touch the heatsink directly behind a properly mounted star without discomfort you're running your LEDs at a fine long lived temperature. That's around 105F. A painful hot tub is about 106F.
PhilipOSU
New member
I spoke with someone yesterday that had 600 par on there sandbed with the XR-Es. With the additional 30-40% output of the Cree XP-G LEDs over the XR-E cool whites I am a bit concerned over how much I will need to "dial back" the XP-Gs with the dimmer to not crush my tank with light. I understand that that running more than 12 LEDs off of a driver will cut back the number of milliamps that each LED will recieve thus lowering output. However, I was wondering if this will hurt the efficiency of the LEDS. As I am figuring I would probably not have to dim the driver as much this way to keep from pushing too much
Or is the better route using no optics on the XP-Gs and just planning on using less overall LEDs? My current plan is to run 120 LEDs over my 220G tank. 40 XP-G Cool Whites to 80 XR-E Royal Blues.
Or is the better route using no optics on the XP-Gs and just planning on using less overall LEDs? My current plan is to run 120 LEDs over my 220G tank. 40 XP-G Cool Whites to 80 XR-E Royal Blues.
Jay1982
New member
Assuming I were to purchase from heatsinkusa's 5.886 Inch Profile extruded alumium: With my tank dimensions of 58L-24H-23W how big should I strive for each of my 3 heatsink to be? I don't want to do the bare minimum and I don't want to accidently make it too small the first go around. Like I said in my previous post I'll be running two large fans but I don't want to have to rely on them.
http://www.heatsinkusa.com/storename/heatsinkusa/ViewDept-263910.aspx
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TheFishMan65
New member
Phil,
Not sure what you mean by adding more LEDs to a driver. If you add too many in series then there will not be enouh voltage and they will not light. Adding complete string in series will actually procude more light (at least for the XR-E). If I remember XR-E produce about 200 lumen at 1 amp. Place three string in series and each LED will produce almost 100 lumen so a total increase of 50%. The only way to get less light (easily) is to use a dimmable circuit and cut back the current or PWM.
Jay,
Based on reading any of the heat sinks from Heatsink USA should work with a fan if the spacing is 2-3 inches between LEDs.
Not sure what you mean by adding more LEDs to a driver. If you add too many in series then there will not be enouh voltage and they will not light. Adding complete string in series will actually procude more light (at least for the XR-E). If I remember XR-E produce about 200 lumen at 1 amp. Place three string in series and each LED will produce almost 100 lumen so a total increase of 50%. The only way to get less light (easily) is to use a dimmable circuit and cut back the current or PWM.
Jay,
Based on reading any of the heat sinks from Heatsink USA should work with a fan if the spacing is 2-3 inches between LEDs.
der_wille_zur_macht
Team RC
While I agree 100% that cooling is important - beyond keeping the LEDs from insta-death, the cooler they are the longer they'll last. But - melt the solder on the star? It strikes me that the LED itself would vaporize long before that would happen.
Willing to buy a plug & play Arduino board for a Meanwell "P"
Someone Make me one!
Just want fade in, fade out. Simple
If you're serious, shoot me a PM. I can walk you through doing it yourself, no need to hire someone. I did that prototype run of the "ELN dimming shield" mentioned in the other post and I've got lots of extra PCBs (minimum order was 10). Technically there are some flaws in the PCB layout but they're still totally usable, so if people want them I'll give them away for the cost of shipping. Beyond that, you just need to buy an Arduino and a RTC and get your hands on some code (which I can provide, or others - several people have written this stuff.)
der_wille_zur_macht
Team RC
Adding too many LEDs to a driver MAY result in less current, but it's happening because the driver is no longer regulating current - it's just bouncing off it's max voltage. This is NOT A HAPPY PLACE! You don't want to do that on purpose. If you want less light, my first preference would be to keep the same number of LEDs and run them at a lower power level (choose a driver with a lower current, or dim them). Second choice; keep the drive current the same but use fewer LEDs.
I know this is probably a little against the popular approach, but I would not choose optics based on desired intensity - I would choose optics based on height of the fixture above the tank and depth of the tank, then control intensity via drive current and LED count.
In addition to what fishman said above, keep in mind that you want the LEDs to be evenly distributed across the surface of the tank. It's OK if they start several inches in from the edges, but if you use a 5.8" heatsink on a tank that's 23" wide, you'll have more than 8" of tank in front of and behind the heatsink with no coverage. If you're set on the 5.8" heatsink, I'd run two of them in parallel along the length of the tank, if that makes sense.
tahiriqbal
Sialkot
I have been trying to get my touch screen controller to work with Meanwell ELN-68-48P driver and have asked Meanwell for a bit more detail on their driver - the datasheet isn't too clear on the requirements of the PWM input. It should be fairly easy to design a circuit with the communications interface to work with the driver and the microcontroller. All I need to find from Meanwell is the tolerance of the 10V signal (i.e. does it have to be exactly 10V or would 9V or 11V be OK) and what current I need to supply to it. This will affect the rest of the circuit - if I only need to supply a low-current signal where the voltage isn't critical then it is far simpler and cheaper than if I need exactly 10V and / or a modest current. I did notice that the transfer function of the dimming isn't exactly linear - l have to decide if people will put up with that or if I need to be able to calibrate the unit to the Meanwell driver. Does anyone knows if signal has to be 10V or could it be less 9 / 11Volt?
I would also like to know if anyone could put me in the right direction for EMC testing and how does it works in Europe?
Many thanks
I would also like to know if anyone could put me in the right direction for EMC testing and how does it works in Europe?
Many thanks
SWINGRRRR
Premium Member
I dont know about the XR-E RBs, but I used the XP-E RB, and my tank is severly blue. Thats running the whites at 500mA and the RB @750mA. Its real blue to me and I used a 50:50 with 84 LEDs total over a 135. Id liken it to a 20K+.
I would love to follow that build. I use the "P" on my tank with the Arduino. I was very impressed with your other touchscreen controller. The way I understand it is that 10V is 100%, so as you go down, you get less of a percentage of total power. I dont know what the max is, but 10V is the target I wouldnt exceeded. I tried to measure current draw on my DIM circuit, but my DMM wouldnt go that low.
Jay1982
New member
I'm not set on what heatsink to purchase. I was just taking one of them as an example so that I could figure out the dimensions I should use for the heatsink so I can see how much room I have to work with. I'm trying to figure out how much alumimum I need to order or get cut.
I did a rough sketch to see how I would be able to fit 80 LEDs over my aquarium. I did not factor in that I want 2 angled panels with one flat one. I am thinking that I'll just be able to have the pieces cut (before wiring of course, lol) and then play around with the angles and space between the two angled pieces and the center piece will be able to be adjusted depending on how far out I place the panels. By my calcuations if I did 2 inches per, with a 2 inch "frame" around the leds the fixture would equate to 35 inches long and 15 inches wide, which would be more affordable. Question is though is that would there be enough alumium to cool the LEDs? I would probably need higher fins to better the heat disappation.
Anyways, the sketch below is reflective of just a flat piece of alumium. The rectangle is the actual aquarium scaled down on my piece of paper. The blue circles are the LEDs. Note that the nodes aren't completely centered. I marked how off center the leds are (left side there is 6 inches of room, right side 4.5 inches, top 3.8, bottom 7.3. I plan on centering the actual fixture but find that this is a good way to see how I would be able to place the LEDs. Please ignore the lines that connect some of the leds, they mean nothing in terms of the setup as it was a grid I created so that I could get the lights alinged properly.
So it would seem that if I placed my LEDs 3 inches apart (thanks for the info Fishman) I should be able to fit 16 LEDs per row with 5 rows. Now if I have this I could probably put my fixture 20 inches above my water surface with 60 degree optics (am I correct with the optics and distance?)
5 Rows of LED would equate to 15 inches from the first row to the last (north to south). So if the LEDs require 2-3 inches of space between each I would assume that there should be 3 inches of space from the row to the edge of the heatsink? If so I'm basically looking at a heatsink with a the dimesions of 21 inches wide and 52 inches long. Is this correct? Or is there a way of getting it to be smaller? This seems like a pretty expensive option for a heatsink (if its required than I'll do it), but if there is a cheaper way to go around this then I will, maybe by reducing the distance to 2 inches in between LEDS, I could then opt for tighter optics at 40 degrees.
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rcgates
Premium Member
Willing to buy a plug & play Arduino board for a Meanwell "P"
Someone Make me one!
Just want fade in, fade out. Simple
Here is a one with an LCD interface:
http://www.ultimatereef.net/forums/showthread.php?t=363432
der_wille_zur_macht
Team RC
Jay, I think you're in the right ballpark, but don't get too wrapped up in spacing - just get heatsinks that come close to covering most of your tank and space things evenly on them.
Since your tank is so wide front-back you might want to do two of the narrow heatsinks (the 5.whatevers) parallel as I suggested above - that would be cheaper. You could even do 6 of them, such that you end up with 3 "pairs."
In the end there are a million "right" ways to solve this problem, so don't get TOO wrapped up - just come up with something that gives you reasonable coverage and go with it.
Since your tank is so wide front-back you might want to do two of the narrow heatsinks (the 5.whatevers) parallel as I suggested above - that would be cheaper. You could even do 6 of them, such that you end up with 3 "pairs."
In the end there are a million "right" ways to solve this problem, so don't get TOO wrapped up - just come up with something that gives you reasonable coverage and go with it.
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