DIY LEDs - The write-up

[TheFishMan65]

I don't think you can guarantee a short or open failure. Running a total of 700 across two strings where either can take the 700 ma (or more) is reasonably safe (as you said if it can be cooled). The problem is if you miss it and another goes bad, and another, etc. Then there is a LOT of extra heat.

 

[SWINGRRRR]

Very interesting thread and can see the benefits either way. I think it ultimately comes down to whether your preference is efficiency or total light output. From an efficiency standpoint, it actually sounds like it makes more sense to use twice as many LED's and run them at 350mA rather than push them to 1000mA. However, the overall electrical savings may not justify the cost of the additional LED's.

Hopefully for anyone new person reading this, I agree with you completely. I choose to go with more LEDs, 84 vs 72, and run them at a lower current. When I get the final Arduino shield, Ill probably set them all at 500mA and go from there.

 

[n0rk]

That driver will take the PWM signal from the Arduino no problem, based on the datasheet cutter have for it. It also describes it as available in a pinned or wired form, so it would be virtually interchangeable with a buckpuck.

Though, IMHO, if you're handy at soldering, you should just DIY your drivers. You can probably save money. You mentioned those being cheaper than buckpucks - I'm not seeing that. The price for the dimmable version at 1200mA is coming up as $23.40 USD.

Excellent, that was what I wanted to hear. I saw the spec in the datasheet but wanted to confirm because I'd heard before they needed a boost of some kind. Not all that much cheaper than the Buckpucks, but it does have two distinct advantages for the money... I can put more on a string (and run at 35v if I decide to go that way), and drive the white strings harder. Considered building my own drivers but ultimately decided not to as I've not really got much spare time (woohoo, 75 hour weeks!) and I suck major *** at reading schematics. This way I can just drop 'em in, set, and forget.

Thanks for the confirmation mate, s'all I needed to hear :beer:

 

[n0rk]

Also, for anyone interested in moving from XR-Es for a new build, this might be of interest... just got notification from Cutter...

Cree, Inc. (Nasdaq: CREE), a market leader in LED lighting, announces a breakthrough new lighting-class LED platform, the XLamp® XM LED. This new single chip LED delivers record-breaking efficacy of 160 lumens per watt at 350 mA. The LED also delivers 750 lumens at 2 A, which is equivalent to the light output of a 60 W incandescent light bulb at less than 7 watts.

“This new platform continues Cree’s well-established record of turning R&D innovations into products,” said Chuck Swoboda, Cree chairman and CEO. “We continue to set the pace for LED performance, establishing new benchmarks that make you wonder why anyone would consider last-century’s energy-wasting technology.”

A cool white XM LED driven at 350 mA can produce 160 lumens at 160 lumens per watt. The new platform has a larger footprint than Cree’s XP family and also offers the unique combination of very high efficacy at very high drive currents. At 2 A, an XM LED produces 750 lumens at 110 lumens per watt. The thermal resistance of the XM platform is 2 degrees C per watt— an industry-leading technology breakthrough and a 350 percent improvement over Cree’s flagship XLamp XP-E LED.

Samples of the XLamp XM LEDs are available for order with standard lead times and commercial availability is targeted for Fall 2010.

Now THAT is a spicy meatball.

 

[tahiriqbal]

Hopefully for anyone new person reading this, I agree with you completely. I choose to go with more LEDs, 84 vs 72, and run them at a lower current. When I get the final Arduino shield, Ill probably set them all at 500mA and go from there.

I think it's a catch-22 situation here, do we use more LEDs and keep them at lower voltage or less LEDs but driven at high ampage:hmm6:. My thinking is more toward using less but driving them higher would give you better punch for the deeper tank. I do understand added benefits of driving LEDs @ 350mA will increase the life expectancy and also elimination of heatsink fans etc but then again you would still need a sharp and large enough heatsink to hold lots and lots of LEDs and may add additional costs.

I can assure you that LED technology is moving so fast and it wont be that long before you will see much high efficiency LEDs for aquarium use. I would say, save your investment and go with less LEDs and drive them hard for the next couple of years and by then you will have something else to play with at much cheaper price.

 

[tahiriqbal]

Just noticed....not a very big diffrence between 72 and 84 LEDs.

 

[Troy McClure]

New XM lamps? 160 lumens per watt. Sounds like my planning has to start all over again!


http://www.cree.com/press/press_detail.asp?i=1271079100891

 

[tahiriqbal]

Here we go again....lol...

Press Room

Cree Announces Revolutionary New LED Platform Delivering 160 Lumens per Watt

XLamp® XM LEDs Are Most Efficient Lighting-Class LEDs in the Industry

DURHAM, N.C., April 12, 2010 — Cree, Inc. (Nasdaq: CREE), a market leader in LED lighting, announces a breakthrough new lighting-class LED platform, the XLamp® XM LED. This new single chip LED delivers record-breaking efficacy of 160 lumens per watt at 350 mA. The LED also delivers 750 lumens at 2 A, which is equivalent to the light output of a 60 W incandescent light bulb at less than 7 watts.

“This new platform continues Cree’s well-established record of turning R&D innovations into products,” said Chuck Swoboda, Cree chairman and CEO. “We continue to set the pace for LED performance, establishing new benchmarks that make you wonder why anyone would consider last-century’s energy-wasting technology.”

A cool white XM LED driven at 350 mA can produce 160 lumens at 160 lumens per watt. The new platform has a larger footprint than Cree’s XP family and also offers the unique combination of very high efficacy at very high drive currents. At 2 A, an XM LED produces 750 lumens at 110 lumens per watt. The thermal resistance of the XM platform is 2 degrees C per watt— an industry-leading technology breakthrough and a 350 percent improvement over Cree’s flagship XLamp XP-E LED.

Samples of the XLamp XM LEDs are available for order with standard lead times and commercial availability is targeted for Fall 2010.

 

[Tron87]

Hello guys. I have gotten some work done on my LED fixture. So far only the blues are hooked up.

I am wondering about heat at this point. My LED's are mounted on two pieces of bolted angle aluminum that comes out to 4mm thick. There is Artic Silver between the pieces so heat conduction is very good. I have run the LED's for about 2 hours but haven't had more time to stay home and monitor.
How long does it take for the LED's to heat up to full temperature? After 2 hours am I feeling the full heat or is there more to come?

 

[Jay1982]

To the people who ordered from Cutters: I'm lost as hell on this site, lol. I went to products but all the options here are confusing me (too many words probably). Looking at the XR-E options there I'll show you where I am confused via my awesome MSpaint skills.

 

[Ben's Reef]

Hello guys. I have gotten some work done on my


How long does it take for the LED's to heat up to full temperature? After 2 hours am I feeling the full heat or is there more to come?

From what I've gathered you should have a heat sink behind them to avoid them becoming "too hot to touch". Any hotter and it lowers the lifespan as well as weakens the adhesive (if you use that stuff). After several hours of run time with the lid on I'd imagine they are maxed out heat wise.

But what do I know... I'm just a data gathering hopeful at this point still. Haven't decided to dive in and make the investment yet.

 

[Reefer08]

Has anyone considered adding leds to a T5 reflector? Drill small holes were the led will protrude. The reflector could be mounted to the heatsink also. Good idea?

 

[Dannyrotorpilot]

LOL, yeah that cutter site made me run like a kid from a dentist office! That website is very confusing!:crazy1::eek2::eek1::hmm4::spin2::fun5:

 

[akindbro4u]

LOL, yeah that cutter site made me run like a kid from a dentist office! That website is very confusing!:crazy1::eek2::eek1::hmm4::spin2::fun5:

If you email them they will answer any questions. They have great customer service, I highly recommend them.

 

[n0rk]

Definitely, Cutter are awesome at customer service. I called them up once to ask about a driver and ended up talking for two hours about pretty-much everything LED related. Very friendly people to deal with.

 

[akindbro4u]

Definitely, Cutter are awesome at customer service. I called them up once to ask about a driver and ended up talking for two hours about pretty-much everything LED related. Very friendly people to deal with.

That would be an expensive phone call for me. lol. But I could imagine. I modified the order i placed, and got four responses confirming it.

 

[HeneryH]

Cutter just screwed me a bit, they sat on my order for three weeks with no feedback. Since I shipped airmail they never gave me any indications that my order never shipped. Finally after three weeks I wrote them asking what the normal delivery to the states was and they responded "uh, yes, we'll be mailing it out in the next few days. we had some problems here".

Anyway, I hope that was a one-time problem.

Jay1982, Their web site is confusnig especially when you order a MCPCB with multiple LEDs per PCB. Sorry, can't be more help on that one. It looks like you started your order with the MCPCB then selected the LED. I did the opposite, I started with the LED then selected the MCPCB. That may be a little easier.

 

[der_wille_zur_macht]

Here we go again....lol...

Press Room

Cree Announces Revolutionary New LED Platform Delivering 160 Lumens per Watt

Carp! Slow down, Cree! :lol:

Their stock jumped a bunch recently; I was wondering if that was in anticipation of a new product. Looks like it was. Also a few vendors dropped wholesale-quantity pricing on XP-Gs last week. . .

I am wondering about heat at this point. My LED's are mounted on two pieces of bolted angle aluminum that comes out to 4mm thick. There is Artic Silver between the pieces so heat conduction is very good. I have run the LED's for about 2 hours but haven't had more time to stay home and monitor.
How long does it take for the LED's to heat up to full temperature? After 2 hours am I feeling the full heat or is there more to come?

"Full heat" will likely be within minutes on most configurations. After 2 hours, I'd expect it to be well equalized with respect to the environmental conditions it was exposed to. The only thing I'd be worried about would be if you're not running it in a realistic environment - i.e. if you test it sitting on a table in open air, then bolt it into a narrow, hot canopy.

To the people who ordered from Cutters: I'm lost as hell on this site, lol. I went to products but all the options here are confusing me (too many words probably). Looking at the XR-E options there I'll show you where I am confused via my awesome MSpaint skills.

It IS confusing. You've currently got the right options chosen for a Q5 cool white. It looks like they don't have any royal blues on individual MCPCBs right now.

Has anyone considered adding leds to a T5 reflector? Drill small holes were the led will protrude. The reflector could be mounted to the heatsink also. Good idea?

Bad idea. LEDs and T5 lamps inherently spread light in a very different manner. T5 reflectors are designed for T5 lamps. If you mount an LED in the manner you're describing, only a VERY VERY VERY small percentage of the light will even hit the T5 reflector, which means it won't have the chance to do much for you. Plus, T5 reflectors are expensive when compared to getting a suitable number of cheap optics, which WILL do a lot for you in terms of directing light.

 

[hllywd]

Has anyone considered adding leds to a T5 reflector? Drill small holes were the led will protrude. The reflector could be mounted to the heatsink also. Good idea?

There is no need to use a reflector other than if you want to use optics specifically for the LEDs to reshape their inherent beam. With these LEDs light is emitted only in the direction it is mounted. According to Cree's data sheet, whites emit a cone of light approximately 90° wide, and royal blues approximately 100° wide. T5s emit light 360° around the tube therefore the need to redirect any misdirected light in the appropriate direction with a reflector. With these LEDs all of the light should already be aimed in the right general direction, that's why many people don't even opt for optics!
Tim

Oops too slow of me...

 

[akindbro4u]

It IS confusing. You've currently got the right options chosen for a Q5 cool white. It looks like they don't have any royal blues on individual MCPCBs right now.



.

They had such a demand for the royals they are way behind. They just started making them again on friday. They made and shipped mine as soon as they got them in. If you shoot them an email they can tell you the lead time, but they have a higher demand than anticipated, and are trying to recover. I just bough 60 of them, so that may have put them a few short of there anticipated sales for the month. Also cree is a little slow on delivery of the xpg line, as they are in very high demand. Maybe with the recent announcement that will slow down a bit with people holding off for the new product.