Stu July 7, 2011 Share July 7, 2011 For the LED gurus, I have a question regarding spacing of LEDs on my heatsink: I have 2 potential layouts. The heatsink is 10" x 17". One array clusters the LEDs with about 2" spacing both vertically and horizontally. The other has 2" horizontal spacing, with ~2 3/4" - 3" vertical spacing. No optics. I am retrofitting into a Nova Extreme Pro fixture, so it will sit about 4" above the water surface. There are 20 XP-E RB's and 10 XP-G NW's, with 15 each being powered by a Thomas research driver. The tank is 20"L x 18"W x 20"H, although the area with corals is about 17"L x 13"W. Which looks like the better layout? Link to comment Share on other sites More sharing options...
Guest thefishman65 July 7, 2011 Share July 7, 2011 I would like to see what is white and what is blue but I think I would go with the second option. Link to comment Share on other sites More sharing options...
Stu July 7, 2011 Author Share July 7, 2011 I would like to see what is white and what is blue but I think I would go with the second option. Since it's 20RB's and 10NW's, I figured I would do RB-RB-NW. Any suggestions on that front? Since each driver can handle 15 LEDs, I will have 15RBs on one driver, and 5RBs and 10NWs on the other. Link to comment Share on other sites More sharing options...
Guest thefishman65 July 7, 2011 Share July 7, 2011 Sounds ok, but is the start of the next line RB RB NW or RB NW RB or NW RB RB Not sure it matter, but I would probably try and stagger them. Link to comment Share on other sites More sharing options...
Mando77 July 7, 2011 Share July 7, 2011 You should not mix XP-E and XP-G's on the same driver be sure that each LED is with its own driver. Those LED's are completely different and require their own separate tuning. The XP-G's are much more powerful. You might be able to have them work together, but I don't recommend it because that will either burn one of the LED's out (probably the XP-E Link to comment Share on other sites More sharing options...
Guest thefishman65 July 7, 2011 Share July 7, 2011 You can mix LED anyway you want. There are a few basic rules. 1) The maximum current should be set for the LED that has the lowest allowed current. In this case the XP-E at 1 amp. Ideally there should be some safety that will not allow the driver to over this. Some drivers have a pot some people add fuses. Sorry not real familiar with the TR driver, but if you really need help I can read up. 2) Now pick the highest current that you expect to run at (it maybe the same as step 1). Read the data sheet and determine the voltage drop at that current for each LED add them up until you reach about 90% of the voltage of the driver. LEDs have a slight variation from the graph and the 10% leaves room for the driver to supply the extra voltage to reach the desired current. Maybe you can get closer maybe not you won't know till you string the LEDs. The heat sink is 10x17 the tank 18x20. You can go closer to the edge, but right at the edge would leave 1.5 inches to the edge of the tank. IMO a lot of that light will be outside the tank so coming in some is probably better. No back to front you (may) have more of a problem since 4 inches is left unlit at the edges. Probably fine, but I would not go much more than that since you only have 4 inches to spread the light. Link to comment Share on other sites More sharing options...
Chad July 7, 2011 Share July 7, 2011 You should not mix XP-E and XP-G's on the same driver be sure that each LED is with its own driver. Those LED's are completely different and require their own separate tuning. The XP-G's are much more powerful. You might be able to have them work together, but I don't recommend it because that will either burn one of the LED's out (probably the XP-E's) or shorten the lifespan dramatically. As for the layout I would try and spread them out as far apart and use as much space as you can. I like the top pic the best, but you need to add another driver, and when you add another driver you could add a few more lights. I recommend adding more royal blue. The XP-G white is very very bright. Sorry if OT at all, but I am not sure I understand this, I follow the desire to want to individually adjust colors being a driver to put like colors on a power supply, but not the reason why one of the LED types would burn out faster. LED drivers are constant current, and LEDs are a fixed resistance (or voltage drop), as long as you stay within the voltage and current ranges on the LED drivers, why would one type be driven harder? I am sure I am missing something, what is it? Link to comment Share on other sites More sharing options...
Stu July 7, 2011 Author Share July 7, 2011 You can mix LED anyway you want. There are a few basic rules. 1) The maximum current should be set for the LED that has the lowest allowed current. In this case the XP-E at 1 amp. Ideally there should be some safety that will not allow the driver to over this. Some drivers have a pot some people add fuses. Sorry not real familiar with the TR driver, but if you really need help I can read up. 2) Now pick the highest current that you expect to run at (it maybe the same as step 1). Read the data sheet and determine the voltage drop at that current for each LED add them up until you reach about 90% of the voltage of the driver. LEDs have a slight variation from the graph and the 10% leaves room for the driver to supply the extra voltage to reach the desired current. Maybe you can get closer maybe not you won't know till you string the LEDs. The heat sink is 10x17 the tank 18x20. You can go closer to the edge, but right at the edge would leave 1.5 inches to the edge of the tank. IMO a lot of that light will be outside the tank so coming in some is probably better. No back to front you (may) have more of a problem since 4 inches is left unlit at the edges. Probably fine, but I would not go much more than that since you only have 4 inches to spread the light. I appreciate you guys' input. While I've attempted to do as much research as possible throughout the process, some of the science/math of it still escapes me. This is the driver: http://www.nanotuners.com/product_info.php?cPath=81&products_id=751 And here is the data sheet: http://www.thomasresearchproducts.com/2010Datasheets/TRC-040%20Series%2003-24-10.pdf As far as I know, there is not a built-in pot as a safety (I am assuming you are referring to something like the screw on Meanwell drivers?). I was under the impression that the safety is built-in to this driver. As you can see from the pics, both configurations have the stars going all the way to the edge (front and back) of the heatsink, so I think that's the best I'm going to be able to do with front to back spread. An overflow occupies the better part of the back 2 or 3" of my tank, so I think I'll be alright in that respect. I'm more concerned with side to side coverage, as my rockwork (with corals on it) comes close to the sides of the tank. I think the square configuration would work better for blending colors and avoiding banding, but I'm just worried about having dark sides of the tank if I do go with that array. And Chad, no worries about going OT; if it helps me and others understand this stuff better, I'm all for it! Link to comment Share on other sites More sharing options...
Guest thefishman65 July 7, 2011 Share July 7, 2011 Those are fixed current so as long as the voltage is in range you should be fine. However, IMHO you really want dimmable drivers. Link to comment Share on other sites More sharing options...
Stu July 7, 2011 Author Share July 7, 2011 I'm confused. It says on the website "Featuring dimming control and built in reference voltage". I also spoke with the guys at Nanotuners and they said they are dimmable; just need to connect a pot. Link to comment Share on other sites More sharing options...
Chad July 7, 2011 Share July 7, 2011 It actually doesn't look like the data sheet for the driver matches what they are selling. The model number for what they are selling is TRC-040S070DS, and the model number for the datasheet is TRC-040S070PS. Try http://www.thomasresearchproducts.com/LEDDatasheets/TRC-040%20Dimming%20Series%2009-20-09.pdf Link to comment Share on other sites More sharing options...
Stu July 7, 2011 Author Share July 7, 2011 Phew. They just put the wrong link up. Thanks for catching that Chad. I was worried I had the wrong drivers. Link to comment Share on other sites More sharing options...
Chad July 7, 2011 Share July 7, 2011 No problem, I was trying to figure that out too about the time Rob posted, it didn't make sense Another oddity, though, is that nanotuners sells 10k ohm pots alongside the TR drivers... however, the datasheet calls for a 20k ohm pot to be used for the dimmer. Link to comment Share on other sites More sharing options...
Stu July 7, 2011 Author Share July 7, 2011 Well I'm glad you mentioned that; I ordered 2 pots from ledsupply the other day, which the guy said were 5k pots. I'm guessing this is a problem? Link to comment Share on other sites More sharing options...
Chad July 7, 2011 Share July 7, 2011 Pots are cheap, and you can probably find what you need locally at a radioshack - so I would probably go with a 20k as recommended. That being said, I can't tell from the DS what would happen for sure, although it does say that the current range for the dimming circuit is -10mA to 2mA, with a 5k ohm pot, that would draw ~2mA (or the maximum advertised value of the circuit). If I was forced to take a position, I think it would be fine if the 5k ohm pot was properly power rated (0.02W). Link to comment Share on other sites More sharing options...
Stu July 7, 2011 Author Share July 7, 2011 Thanks Chad. I'll take a look and see what Radio Shack's got. Link to comment Share on other sites More sharing options...
Mando77 July 7, 2011 Share July 7, 2011 You shouldn't mix LED's on the same drivers. Why would you want to limit the XP-G's? You might as well get XP-E's? All the vendors I have worked with said to put 1 type of LED on a driver. I don't think they would just say that. If I was going to drop $300 or $500 on a set up I would do it exactly as they say. I wouldn't try to get around it. Link to comment Share on other sites More sharing options...
Stu July 7, 2011 Author Share July 7, 2011 You shouldn't mix LED's on the same drivers. Why would you want to limit the XP-G's? You might as well get XP-E's? All the vendors I have worked with said to put 1 type of LED on a driver. I don't think they would just say that. If I was going to drop $300 or $500 on a set up I would do it exactly as they say. I wouldn't try to get around it. The reason why I don't want 15 XP-E's (what the driver can handle) as opposed to 10 XP-E's and 5 XP-G's is because if I did so, I would have to dim down the XP-E's considerably for a desirable color. I don't want a yellow 10k tank; I want a bluer look, and the majority of research I have done indicates that a 2:1 blue to white ratio looks better (at least when using neutral whites vs. cool whites--I went with neutral whites to better bring out reds and pinks). If I went with a 1:1 ratio, I would have to dim down the white string significantly to get the right color. If I'm not mistaken, this would basically be wasting potential PAR. Take a look at the explanation on post #2964 here: http://www.nano-reef.com/forums/index.php?showtopic=186982&st=2960&start=2960 Link to comment Share on other sites More sharing options...
Guest thefishman65 July 8, 2011 Share July 8, 2011 Sorry I thought I posted after the new spec went up. i agree a 5k or 10k should be fine. Byrnes who did you talk to? Rapid LED (IMHO a reputable dealers) sells a mixed kit: XP-G and XP-E Link to comment Share on other sites More sharing options...
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