DIY LEDs - The write-up

[customcolor]

using a mean well non dimming driver...do you HAVE to run 12 leds or can you run 6 with no additional resisters ?

 

[der_wille_zur_macht]

using a mean well non dimming driver...do you HAVE to run 12 leds or can you run 6 with no additional resisters ?

We need to know the model. The "popular" meanwells are both dimmable.

 

[noobtothereef]

Just a few questions for the electronic experts, instead of running these led drivers, couldnt one just use resistors? The drivers are just for regulating the voltage and amperage to each bulb correct? Sure it would be a little more work but for a larger led setup thats going to use say 20 drivers , it would signifigantly reduce the cost

 

[der_wille_zur_macht]

See this thread:

http://www.reefcentral.com/forums/showthread.php?t=1751598

Basically, you need to end up with constant current through the LEDs, however you want to achieve that. Off-the-shelf drivers add a degree of controllability you can't get with a static solution, and allow for a slightly more plug-and-play experience. Passively burning off the extra power (resistors) can be cheaper, though. IMHO the best of both worlds is DIY'ing constant current drivers, because then you get the controllability AND cheap price.

 

[Neogenocide]

I've actually got a driver related question now that I'm looking at the specs closer. This is pertaining to the Mean Well LPC-35-700W constant current driver.

Specs:

# 700mA Constant current
# 9-48V
# 120-240V AC input
# Epoxy encapsulated case
# Short circuit / Over voltage / Over current protection
# 100% full burn-in test
# 50,000 hour MTBF
# 18 month warranty
# Mean Well LPC-35 Full Specification


My question is this, how come on the web site that is selling this they are saying it's only good for 12 LED's, however it will support up to 48v? Am I missing something here or is it possible to run 48v/3.2v= 15 led's on this unit. I'm not really wanting to max it out, but after drawing up my layout last night, I need to be able to run 13 otherwise I'll have to modify my design. Am I missing something here?

Thanks for taking a look,

Scott

 

[sammy113]

I'm pretty sure you will be able to run 13 from a Meanwell. I've seen a few people to do it. I also saw one guy running more than 20 LEDs per driver (don't ask me how the hell, saw him at the other nano forum) probably at very low mA or even lower voltage... I don't know but you should be safe with just 13 per driver. I believe there is also some voltage draw from the driver itself so you can't max out the voltage with LEDs

 

[noobtothereef]

if ive read correctly, the drivers and etc you will have a voltage drop and will not push the entire 48 volts, running 15 leds on it you will not get the max output from the leds as they will not get there full 3.3 volts, i think i sa some running 13 of them on that driver i could be wrong and yes im a "noob" so wait till one of the experts chime in here.

 

[der_wille_zur_macht]

It really depends on a few of factors, and it's hard to generalize, though 12 is the "standard" because it generally works in the most situations - it's a very safe number for the 48v ELN and LPC drivers.

If you want to run more, you'd need to do some careful planning and/or measuring. First, you're going to need to pay CAREFUL attention to datasheets. We make all sorts of general statements about LED Vf, but it varies CONSIDERABLY from LED to LED, and even for a specific LED, it'll vary depending on the drive current. A Cree XR-E at 350mA might be 3.2v, but at 700mA it'll be more like 3.5v. Meanwhile, a Luxeon Rebel or a Cree XP-G will generally be lower - making them better choices if you want to run more LEDs: an XP-G only drops 3.2v at 700mA. The difference of .3 volts means a string of 12 XP-G will drop 3.6v less, which is more than one LED worth.

Plus, there's consideration for voltage drop on wiring and bad solder joints, etc. - though those are (hopefully!) very minor compared to one LED's Vf.

Also, most of the meanwell drivers are rated at 48v, but have an internal trimpot that adjusts the max voltage, so in theory you could turn them up a bit if you were near the limit.

 

[der_wille_zur_macht]

if ive read correctly, the drivers and etc you will have a voltage drop and will not push the entire 48 volts

The meanwells are rated at 48v so in theory you can take that to the bank. Maybe you're thinking of buckpucks, which incur a drop themselves, meaning the string's voltage must be that much less (2v for DC buckpucks) than the input voltage. On the meanwells, the driver's voltage drop is taken into consideration for the 48v rating.

 

[extra]

i have some LED-holders by BJB here. Just thought to bring this up here as i think nobody has mentioned them. They are basically solder-less led & optics holders that are very modular and can be screwed. They have push wire terminals, so no soldering necessary. Unfortunately i did not find online shops that have them in low quantities. I think i can't post links yet (link: http://www.bjb.com/), just google for "BJB LED". I like them a lot because optics can be switched easily (just 'clip on').

Yes, depending on just how many LEDs, how close, and the drive levels.

i guess i just need to experiment and build one module in advance for testing. just, what criteria to judge? e.g. i think measuring air temperature in the channel alone would not be that meaningful, as it doesn't tell anything about led junction temp. i'm aware this could be calculated, but this seems way over my head at the moment. i'm also thinking about this issue for controlling fan speeds. what's the relevant temperature to measure? surface of the channel right above the led? drill a small hole into the channel and measure the star surface temp?

The metaphor is NOT a metaphor. It is reality. You just, cannot see that color light with only your eyes.

almost literaly, a light bulb moment :idea:

I will be doing my lights on 0.080" aluminum. 40mil is probably a bit thin.

ok, that's why i thought about going way thicker... 160mil (4mm). i also hope to reduce resonance sounds from the fan if the channel is stiffer.

 

[ReefEnabler]

I'm about to go clean up the LED setup I did awhile ago.

Does anybody know of a male and female DC jack that can accept larger wires up to 12 or 16gauge??

I got some from Radio shack way back when... but they only worked on smaller wires, so the female, bulkhead style DC jack connected to my buckpucks.... but then I had to use some crappy automobile quick-connects to connect the LED array to the male DC jack...

 

[ReefEnabler]

Found this site which has a bunch of panel mount audio connections:
http://www.action-electronics.com/audioconnectors.htm

I'm thinking something like this should work well for a bit larger wire but it doesn't specify

I considered using the Deans connectors but I want to stick with panel mount style, as I already have way too many wires.

I'm also tossing my cheap laptop power supplies and replacing with the 6.5a MPJA supply that soundwave used. Oh and replacing the Luxeon LEDs with Cree XR-Es and MC-Es.... so basically a complete revamp

 

[kcress]

extra; Since most people don't have super small thermocouples and meters, you can just go by the temperature of the metal near the LEDs. If you can leave you finger on it indefinitely you'll be ok. If you can only touch it briefly then you might be ok but you might not.

 

[customcolor]

We need to know the model. The "popular" meanwells are both dimmable.

Mean Well LPC-35-700W drivers is the drivers im getting from rapid led...im getting the 24 q5 kit...should be here by monday

 

[der_wille_zur_macht]

Mean Well LPC-35-700W drivers is the drivers im getting from rapid led...im getting the 24 q5 kit...should be here by monday

The LPC-35-700 is spec'd by Meanwell as good for 9 - 48v output. That equates to roughly 3 - 12 LEDs.

 

[vnguyen]

Hi all,
For the tank with 36Lx18Dx21H (Oceanic 58G), how many of the LEDs I need and what size of optical lense? I'm about to order but want to make sure with you guys first.
Thanks!

 

[der_wille_zur_macht]

How intense do you want the light to be? How high will the LEDs be above the water?

If it were me, I'd probably aim for 40 - 50 LEDs, ~12" off the water, with 60 degree optics.

 

[chriscobb]

A dumb question....are people still using the XRE Q5's or have people switched to the XPG's.....Is there any advantage to going with the XPG's?

 

[vnguyen]

Thanks!
I don't know how high I'm gonna hang the light. How deep can I keep my SPS if I'm gonna go with 48 LEDs, 60 degree optics?

 

[customcolor]

The LPC-35-700 is spec'd by Meanwell as good for 9 - 48v output. That equates to roughly 3 - 12 LEDs.

great cuz i wanted to run 18 of them with 2 drivers of corse