DIY LEDs - The write-up - (split again)

Hey guys sorry this is a bit off topic but this was the best DIY LED thread i could find. I was wondering if you guys could help me set up a LED light system. I plan on growing some tomatoes and would like to use the same set up you created but with less lights. Here are the materials I plan on using.
1) 4 deep red endostar leds. http://www.ledsupply.com/07007-pdred-c.php
2) 4 Royal blue endostar
http://www.ledsupply.com/07007-pr000-b.php
Ok because i only plan on using 8 lights in total how many buck pucks and what type should i use? Finally my last question is can I use the same power supply or will i need to buy a different kind?
Please get back to me and i thank you for your time.
 
Anyone have experience popping LEDs off a heat sink and re-using? I plan on just gluing mine down with artic alumina only. Since I am experimenting I was not going to bother with drilling and tapping the heat sink until I like the arrangement. Also is there a reason I don't see anyone using nylon screws? Does it just get too hot for them? Seems like a better way to help prevent a short.
 
Okay, I posted a while ago about resurecting a PFO solaris I4 unit using cree XP series LEDs, and have been doing some serious reading about this. Here is my question I have not been able to answer. With the solaris drivers which I believe I read use a 1000mA drive current, if I were to run 2 series/parallel lines off of each, would that reduce the current to 500mA? In other words, could I use the driver leads which currently runs 3 blues at 1000mA to run 2 strings of 3 for a total of 6 blues at 500mA? From what I've read, this would not increase the total forward voltage so would I need a larger power supply to effectively double the number of LEDs? Thank you in advance for any information in support or against this idea.
 
mkart said:
Anyone have experience popping LEDs off a heat sink and re-using? I plan on just gluing mine down with artic alumina only. Since I am experimenting I was not going to bother with drilling and tapping the heat sink until I like the arrangement. Also is there a reason I don't see anyone using nylon screws? Does it just get too hot for them? Seems like a better way to help prevent a short.
Click to expand...

i know forsure if you take artic alumina and mix in some artic silver #5 you will get a very strong bond.. and better heat transfer but the LED will be removable without damage if needed. i used this recipe many times gluing heatsinks to the ram chips on video cards. if you need to remove them it will separate much easier. the artic alumina would rip the whole ram chip off with the heatsink and the mixed version you could still make out the writing on the ram chip after you seperated them.
 
jamesbm1001 said:
Okay, I posted a while ago about resurecting a PFO solaris I4 unit using cree XP series LEDs, and have been doing some serious reading about this. Here is my question I have not been able to answer. With the solaris drivers which I believe I read use a 1000mA drive current, if I were to run 2 series/parallel lines off of each, would that reduce the current to 500mA? In other words, could I use the driver leads which currently runs 3 blues at 1000mA to run 2 strings of 3 for a total of 6 blues at 500mA? From what I've read, this would not increase the total forward voltage so would I need a larger power supply to effectively double the number of LEDs? Thank you in advance for any information in support or against this idea.
Click to expand...

Yes! You can do that. The only issue you might encounter is that the two strings need to be matched in their total forward voltages and having only three in each string will limit your balance swapping choices a little.

I guess I have to ask why you don't want to stick with the original counts?
 
Dukester said:
i know forsure if you take artic alumina and mix in some artic silver #5 you will get a very strong bond.. and better heat transfer but the LED will be removable without damage if needed. i used this recipe many times gluing heatsinks to the ram chips on video cards. if you need to remove them it will separate much easier. the artic alumina would rip the whole ram chip off with the heatsink and the mixed version you could still make out the writing on the ram chip after you seperated them.
Click to expand...

Interesting mixing the 2 for a solid but weaker bond. I still say screw them down. I've fiddled enough with my fixture that it has been well worth simply unscrewing and replacing and moving LEDs. I use a #40 drill bit and #4 sheet metal screws with a #4 nylon washer under the head. Its close enough that they self tap.

Some say a gentle twist with a pair of pliers and you can get the star off the heatsink. Friend of mine bought a whole tank setup with a DIY fixture on it...he will be attempting this method so he can reuse the LEDs on a different fixture....still seems dicey though.
 
For efficiency purposes, lower current=less heat/watts consumed. Also as I understand it, pushing them to their max doesn't benefit the lumen output/watt performance as it is not a linear gain in output.

So just double checking my understanding, halving the drive current will half the watts consumed as well? As for the imbalance of the 2 strings, couldn't a simple resistor on each string solve that? I'm not an electrical engineer or anything so I'm pulling my information from what I've read online, which is not always the most reliable of sources. I have been toying with the idea of expanding a 24 inch 50 led version to a 100 led custom build.
 
jamesbm1001 said:
For efficiency purposes, lower current=less heat/watts consumed. Also as I understand it, pushing them to their max doesn't benefit the lumen output/watt performance as it is not a linear gain in output.

So just double checking my understanding, halving the drive current will half the watts consumed as well? As for the imbalance of the 2 strings, couldn't a simple resistor on each string solve that? I'm not an electrical engineer or anything so I'm pulling my information from what I've read online, which is not always the most reliable of sources. I have been toying with the idea of expanding a 24 inch 50 led version to a 100 led custom build.
Click to expand...

yeah but with todays LEDs they're pretty efficient. While its not a linear gain if you look at an XPG spec sheet you will find the minimum lumen output rating to be rated at 350ma and about 139 lumens which is considered 100% and if you go up to 300% (417 lm) you will find a drive current of 1300ma...so while not linear its a boat load more light for 250ma off of linear.....

But yes, halving the drive current halves the watts consumed but since you want to double up the strings to halve the drive current per LED, you're doubling the LED count thereby keeping total watts consumed the same.....no?

Are you really considering putting 100 LEDs on a 24" footprint?
 
No I'm scrapping the housing all together. My tank is 65*24*15h so it's shallow and doesn't need a whole ton of light, but I need coverage. I've been planning this Tank for awhile now and lighting has been back and forth for me. I'm tossing around the idea of using some extremely narrow optics (10 degree or less) and roof mounting the unit so I can have a nice top down view. Price wise I've also thought of using a cheaper led such as bridgelux, but there goes efficiency. At least now I could do it as they have a 700mA max current limit.:rolleye1:
 
hoping someone can help me with a driver for my 8 gallon biocube.

I recently built a Rapid LED setup with 38 Crees split between two MeanWell 60 48D drivers and am so happy I decided to retro my biocube hood with LED's as well. The tank isn't running yet (will be an office tank). I didn't want or need Crees for this little system so ordered some Bridgelux and they should be in this week (6NW, 6RB, 2violet)
I'll probably only use 4 or max 5 of the NW. I had a spare Meanwell driver I didn't use from the other build but its a constant driver rated 700mA which I now realize for a biocube is way overkill. What do you suggest for a driver or do you think the constant would be OK with some screen or diffuser between the LED's and the water.
 
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CT...I did all my testing and research on a 14g cube 2 years ago and used 12 Crees and it was way overkill and i bleached SPS until I dropped down to 4 whites and 8 RB...the zoas didn't mind too much. I am running a combo of cheapo's 20,000k with Cree RB on a 29g and those are also over kill and run the whites very dimmed. On an 8 gal I would recommend no more than 3 whites and 6 RBs....probably 2 whites would be enough. You could perhaps get away with an ELN 30-48....runs max at 630ma and is dimmable.

ctreefer said:
hoping someone can help me with a driver for my 8 gallon biocube.

I recently built a Rapid LED setup with 38 Crees split between two MeanWell 60 48D drivers and am so happy I decided to retro my biocube hood with LED's as well. The tank isn't running yet (will be an office tank). I didn't want or need Crees for this little system so ordered some Bridgelux and they should be in this week (6NW, 6RB, 2violet)
I'll probably only use 4 or max 5 of the NW. I had a spare Meanwell driver I didn't use from the other build but its a constant driver rated 700mA which I now realize for a biocube is way overkill. What do you suggest for a driver or do you think the constant would be OK with some screen or diffuser between the LED's and the water.
Click to expand...
 
Last edited by a moderator:
So am I correct in thinking that I can balance the draw of 2 parallel strings by using a resistor? If so, how do you know what size resistor would be needed? Again, parallel strings going from 1000mA to 500 mA.
 
brassmonkyballs said:
used 12 Crees and it was way overkill.........................until I dropped down to 4 whites and 8 RB....
Click to expand...

Is this special BMB math?
43cuc6f.gif
 
jamesbm1001 said:
So am I correct in thinking that I can balance the draw of 2 parallel strings by using a resistor? If so, how do you know what size resistor would be needed? Again, parallel strings going from 1000mA to 500 mA.
Click to expand...

You've got it wrong. You use the resistor to help you balance the strings. It's used as a measuring tool so you can "detect and correct" any imbalance.
 
I think i just worded it badly. Running 2 parallel strings of 3 leds each off of a single 1000mA source will provide 2 strings running at 500mA. Now the vF of the strings won't be matched perfectly and would be hard to swap leds to make it match, so one string will draw a higher current than the other in most cases. Using a resistor inline with each string as a limiter then keeps one string from drawing more than the desired current. Please let me know if I'm way off because I honestly don't know. Thank you.
 
you would have to 1st measure the imbalance (to which Mr K recommends using 1 ohm inline fuses), and then calculate the proper resistor (with ample watt capability too) to put in line of the higher voltage string. I'm sure kcress can tell us why its probably not a good idea. So I recommend just trying it without being fancy and see where they land. Less LEDs just gives you less options to swap but its not impossible.
 
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