Designing an LED build

[Mr. Microscope]

So, I've been reading up for a while and trying to get a grasp on the proper way to build LEDs. It seems that most people go with the MeanWell drivers, but I don't really understand how the dimming works relaying it in with a separately purchased potentiometer or building a LM317 voltage regulator for the power supply. I've seen a few builds where people are using the LuxDrive BuckPucks with built in pots and it seems a lot simpler. I worked up a basic model of a potential build to go above my next tank (Mr. Aqua 25 gallon 18 inch cube). This shows the basic grasp of the build concept. I understand about +/-. So, I didn't include those in the model. I'm sure that I'm missing a few things in my design. I'd like to have everything hooked up to one power supply (including the fan). I forgot to add the power cord, but I'm pretty sure it just goes from the wall to the power supply. Here are the images:

I'm sure it can't be this simple. Please feel free to rip it apart and give me constructive criticism. I'd appreciate any suggestions and/or corrections. I'll keep reworking the design. I'm in no rush to build it.

Cheers!

[disaster999]

i would use 2 power supplies so you get the dust dawn effect. with one power supply you wil have both blue and white led come on and off at the same time

[Cheetos]

Nice build model! OK 2 things....you cant run 8 LEDs on a buckpuck. 6 is the limit so either cut down on the LEDs or add another puck. Also that 12V power supply wont drive that many LEDs. You will need a 24 volt power supply which also means you need either a 24V fan or two 12V fans wired in series if you want to run them off the same power supply as the LEDs. HTH!

[Mr. Microscope]

i would use 2 power supplies so you get the dust dawn effect. with one power supply you wil have both blue and white led come on and off at the same time

Yes, I like that. 2 power supplies it is. Thanks.

 

Nice build model! OK 2 things....you cant run 8 LEDs on a buckpuck. 6 is the limit so either cut down on the LEDs or add another puck. Also that 12V power supply wont drive that many LEDs. You will need a 24 volt power supply which also means you need either a 24V fan or two 12V fans wired in series if you want to run them off the same power supply as the LEDs. HTH!

Hmm. Some serious reworking is necessary here. Thanks! Can two bucks be connected (one with pot) to one series of LEDs?

[mrg02d]

Yes, I like that. 2 power supplies it is. Thanks.

 

 

Hmm. Some serious reworking is necessary here. Thanks! Can two bucks be connected (one with pot) to one series of LEDs?

 

Nope, one buck per string. Even easier would be to use two dimmable meanwell drivers, one per string. They have a power supply built in.

 

Matt

[JBM]

your going to want to put those buck pucks in a project box away from the tank.

[lecroj]

What type of enclosure are you going to use?

[Mr. Microscope]

your going to want to put those buck pucks in a project box away from the tank.

 

Everything will be neatly tucked away. I just want to get all the guts sorted out first.

 

What type of enclosure are you going to use?

Not sure yet. Suggestions appreciated. I'm more focused on getting everything hooked up properly.

[marinoob]

you can run all 8 on 1 buckpuck but the max power they would get would be 500ma which is half of what white cree's can handle so in your case it wouldnt be good to only run them at half power but check out my build its been running for a little while now. you would probably be better off dropping to 6 led's per string or going with a meanwell. but it is possible to do it with 1 buckpuck for 8 led's it would just be 2 parallel strings of 4 led's running at a max of 500ma with a 1000ma buckpuck.

 

i wish they made a 1400ma buckpuck so we could run at a 700ma but i havent found 1.

[Mr. Microscope]

you can run all 8 on 1 buckpuck but the max power they would get would be 500ma which is half of what white cree's can handle so in your case it wouldnt be good to only run them at half power but check out my build its been running for a little while now. you would probably be better off dropping to 6 led's per string or going with a meanwell. but it is possible to do it with 1 buckpuck for 8 led's it would just be 2 parallel strings of 4 led's running at a max of 500ma with a 1000ma buckpuck.

 

i wish they made a 1400ma buckpuck so we could run at a 700ma but i havent found 1.

 

Hmm.. Good to know. I see more research is required on the drivers. I guess I haven't learned about the specifics of their capabilities such as mA VS. the number and potential of the LEDs. I was just looking for a simple plug and play design with dimming capabilities.

 

Sigh... It's tough to see all these awesome builds and not be able to replicate them. But, I'm determined to learn. I want to, "measure twice, cut once" so to speak. I feel like I've been reading up for months and still don't understand the basics. That's why I came up with the model. If I could get my hands on the right supplies, I feel like I could piece it together (hands-on learning etc.). I wonder if there is an LEDs for Dummies book out there somewhere (though, again, I have a hard time learning from just reading).

 

Thanks marinoob!

[marinoob]

you will need more than a 12v power supply also. if you do the 2 strings of 4 leds in parallel you would need a 16-18v 2amp power supply for just the buckpucks. and do a different power supply for the fan.

 

you need to do your research i first started talking with evil back and forth about 4 months ago probably. best thing you can do is take your time dont rush things and do your research. my led fixture running at 500m "looks" 2x brighter than my t5ho fixture so hopefully it performs that much better. i dont like to be in my room when it is running at 100% :-)

[doctaq]

at 24v you will max out at 6 leds not 8 a buckpuck should only handle 6 leds anyways

 

you power supply is 12v that will not be enough, if you want 12v for fans get two of the same fan and run them in series

[Mr. Microscope]

you will need more than a 12v power supply also. if you do the 2 strings of 4 leds in parallel you would need a 16-18v 2amp power supply for just the buckpucks. and do a different power supply for the fan.

 

you need to do your research i first started talking with evil back and forth about 4 months ago probably. best thing you can do is take your time dont rush things and do your research. my led fixture running at 500m "looks" 2x brighter than my t5ho fixture so hopefully it performs that much better. i dont like to be in my room when it is running at 100% :-)

 

So, if I want to have the whites and blues on two separate power supplies, the fan will need it's own (three power supplies)? This is turning out to require more research than my initial pico setup and becoming a hobby in itself. Thanks for the encouragement.

 

at 24v you will max out at 6 leds not 8 a buckpuck should only handle 6 leds anyways

 

you power supply is 12v that will not be enough, if you want 12v for fans get two of the same fan and run them in series

 

I'm open to an array of power supplies. I want to hammer everything out before making any purchases. So, in general, do most people run a fan on it's own power supply?

[marinoob]

this is from the 700ma buckpuck datasheet

 

 

you could use a 12v 1a power supply with a 1000ma buckpuck to power 6 led's @ 500ma

or

you could use a 24v 1a power supply with a 1000ma buckpuck to power 12 led's @ 500ma

 

those diagrams do not show grid wiring but thats what i did to protect my led's better.

 

running in parallel series is riskier but cheaper. i saved almost $100 on my build by using it. but who knows it could all die in 6 months. or it could last me for years. either way the technology will keep progressing and i will probably want to upgrade again soon....

 

here is what evil has to say about grid wiring. taken from CaptiveReefs.

 

Any time you wire in parallel, you divide the total current by the number of strings. You can wire in as many as you like, but the current seen by each LED drops. You can wire 26 LEDs in two strings of 13, but your max current is ~750mA.

 

I really don't recommend wiring in parallel though. There are many issues with this scheme that can actually damage more LEDs if a single one fails. There are far more cons than pros. The only pro is that you can run more LEDs on a single driver.

 

First problem comes during operation. Voltage differences between LEDs create imballances that can put undue stress on the LEDs. Lets say you do two strings 13. Both strings have to be equal in size, and will see the same total voltage. If the total voltage drop of one string is lower than the other, it will be forced to run at a higher voltage, and as a result, a higher current. The imbalance doesn't create issues short term, but can cause a reduction in life long term. The increased voltage can also cause a spectral shift in the whites.

 

The next issue shows up during failure events. The normal failure mode of an LED is to fail open. If that occurs, it will take out the string it's connected to. When that happens, the total current isn't divided anymore by all the strings. This can create problems depending on how hight the total current is. With the ELN-60-48D, it's not too bad, but the current is still beyond the spec limits of the LED and can shorten the life of the LED. If the current is too high, the LED can be severely damaged quickly.

 

If in the event of the LED shorting (rare, but it happens), the voltage imbalance that I mentioned earlier gets worse in the string that has the dead LED. With the loss of an LED, damage tot he remaining LEDs can happen very quickly.

 

There have been some attempts at reducing the damaging effects from running in parallel, but none of them cover all of the problems at once. There is a simple circuit called a current mirror that can help with imabalances between strings, but won't protect from LED failures. Meanwell documents a method of parallel wiring where all the LEDs are wired in a grid. This will help with the majority of issues, as there is always a current path if an LED fails. The effects of a voltage imbalance are less with this method. The drawbacks to this method is that you need a minimum of three strings, and it's a ton more wiring.

 

I know this was kind of a long answer, but it covers all the issues with parallel wiring.

[doctaq]

you dont need 3 power supplies, just run two fans.

two power supplies, one run the blue leds and fan, the other run the whites

[marinoob]

not trying to battle you doctaq because i love reading his posts. but couldnt he run just 1 powersupply if he is going to run 2 12v fans in series? if he gets a 24v 2.5a or 3a power supply that would be 2a for the 2x1000ma buckpucks and that would leave .5a-1a left over to run the fans. and that would leave him with 1 powersupply for the whole thing??

 

but then it would leave him with 1 plug for power supply so both whites and blues would have to come on at the same time. unless he went with a controller of some type to control the pots on the buckpucks.

 

 

 

So, if I want to have the whites and blues on two separate power supplies, the fan will need it's own (three power supplies)? This is turning out to require more research than my initial pico setup and becoming a hobby in itself. laugh.gif Thanks for the encouragement.

 

ok i see he wants the 2 seperate

[Mr. Microscope]

this is from the 700ma buckpuck datasheet

 

 

you could use a 12v 1a power supply with a 1000ma buckpuck to power 6 led's @ 500ma

or

you could use a 24v 1a power supply with a 1000ma buckpuck to power 12 led's @ 500ma

 

those diagrams do not show grid wiring but thats what i did to protect my led's better.

 

running in parallel series is riskier but cheaper. i saved almost $100 on my build by using it. but who knows it could all die in 6 months. or it could last me for years. either way the technology will keep progressing and i will probably want to upgrade again soon....

 

here is what evil has to say about grid wiring. taken from CaptiveReefs.

 

Seems like an interesting way to go about the wiring. So, by this method could I run one 24V 1A power supply with a 1000mA buckpuck on 6 LED's at 1000mA, or does the parallel series always split the amperage? Thanks for digging up that quote from Evil. Good info there.

[marinoob]

Seems like an interesting way to go about the wiring. So, by this method could I run one 24V 1A power supply with a 1000mA buckpuck on 6 LED's at 1000mA, or does the parallel series always split the amperage? Thanks for digging up that quote from Evil. Good info there.

 

when you run parallel series it always splits the 1000ma between the number of series. if you had 3 paralell series of 6 leds you would be powering all the led's at like 333ma

 

but you can run a 24V 1A power supply with a 1000mA buckpuck on 6 LED's at 1000mA with just 1 series of 6 leds

[Mr. Microscope]

when you run parallel series it always splits the 1000ma between the number of series. if you had 3 paralell series of 6 leds you would be powering all the led's at like 333ma

 

but you can run a 24V 1A power supply with a 1000mA buckpuck on 6 LED's at 1000mA with just 1 series of 6 leds

 

Ah.. My Electricity and Magnetism Physics class is all coming back to me. I see.. Thanks! Why is it that just 6 can be run off of one buckpuck (in 1 series)?

 

Edit: Okay I see the specs of it on ledsupply.com. 18x1W or 6x3W

[Mr. Microscope]

Nope, one buck per string. Even easier would be to use two dimmable meanwell drivers, one per string. They have a power supply built in.

 

Matt

 

Hmm. It's starting to look like this might be the way to go. Thanks Matt.

[marinoob]

the problem with dimmable meanwells is now you will still have to get a changeable(not sure of correct term) 10v powersupply to connect to each meanwell to control the dimming feature. im not sure if you can use 1 10v power supply for 2 meanwells or if you need a seperate power supply for each but i would think 1 powersupply for both meanwells would work. also not sure about running a fan on the same power supply. i dont know much about meanwells i havent researched them yet but i plan on it. doctaq would have to answer that :-)

[evilc66]

To do a Meanwell setup with just one external power supply, you would need a 12v 1A power supply, 2x LM317 circuits for Meanwell dimming, and a fan.

[marinoob]

To do a Meanwell setup with just one external power supply, you would need a 12v 1A power supply, 2x LM317 circuits for Meanwell dimming, and a fan.

 

that sounds like a good bet right there. and you have the ability with the meanwells to expand up to 12/13 led's per meanwell incase you wanted to expand in the future.

[Mr. Microscope]

I'm working on design number 2.

 

So, I'm looking at this product:

http://www.nanotuners.com/product_info.php...products_id=119

 

Linked here as a Variable voltage AC adapter:

http://www.nanotuners.com/product_info.php...products_id=630

 

I'm guessing this is somewhat different from a potentiometer. Does it go inbetween AC power and the MeanWell, or beween the MeanWell and the LED's, or is it like a Pot and it comes out of the side of the MeanWell?

[sandcruiser]

for dusk/dawn you could also just run a totally distinct, smaller LED array-- something like a few 5mm LEDs on a 12v power supply that also runs the fan(s).

 

that way your fans come on before the other LEDs (which is of negligible benefit) and go off after the LEDs (which does help reduce soaked heat going back into the aquarium)

 

also you could go with something "fancy" like cyan or UV 5mm leds that could produce some interesting effects on corals, perhaps, without throwing your color balance out of whack.