Multichip LED's vs. array of LED's question

[S2minute]

"Quote:
Originally Posted by jedimasterben View Post
In addition, buying the XM series to run at 700mA or less is just dumb IMHO. They offer less than 20% more flux than the XT-E for ~200% the cost.
Sort of agree with that - XTEs work out a much cheaper initial purchase, but they cost more watts per lumen and they also put out more heat per lumen so you need bigger heat sinks and pay more in energy. Maybe more of an issue here in the UK (since we have sh!t selection of cheap heat sink suppliers and possibly (?) pay more for electricity) but it's still worth being aware of.

Tim "

I Run XML Cold white and Warm Whites @ 1400MA via paired CAT drivers.

 

[perkint]

You really won't find any XM-L or XM-L2 that are decently binned unless they are special ordered from Cree, which none of the 'typical' sources do.

Fasttech and cutter both (usually) give good info and have decent bin XML2s, but not warm/high CRI

A vero 5 would actually be awesome but I dunno how they could make them much smaller, check out the size of the Vero 10!

I just wish they could get the voltage down just a liiiiitttle bit - with 26v even at 300mA you can only run a single one per LDD driver unless you run them in parallel, which is what I'm doing with mine. I normally don't recommend parallel due to danger to the LEDs with too much current or with thermal runaway, but keeping the current low enough so the LEDs can tolerate 100% and keeping them on the same heatsink will help to alleviate issues with that.

Yeah, it's not the physical size, more the power. I suppose I could try parallel, as you suggest. Not something I'd normally consider, but like you say, not so much of a risk if 100% current is still within limits. Wonder how low you can drive them?

What power supply are you using? I thought you said you were going with 48v?

Yeah, sorry. I am getting a 48V for the build for the DT, but I have built a little test light which I'm playing with to try and decide on LEDs/colour ratios (and can be used for QT tank afterwards ). Only running that on 12 or 24V depending on what's on the test, with the intention of buying the most appropriate supply when I've made my mind up (which will probably be 48V due to max string length of 12 x 3.5V (ish) LEDs).

Had a look earlier. No surprise, but no UK sources of the vero No surprise as there's no UK source of any decent LEDs, just about!

Tim

 

[jedimasterben]

Yeah, it's not the physical size, more the power. I suppose I could try parallel, as you suggest. Not something I'd normally consider, but like you say, not so much of a risk if 100% current is still within limits. Wonder how low you can drive them?

I've ran the Vero 10 as low as ~1.5mA and they still struck.

Check these out: http://www.digikey.com/product-detail/en/BXRE-40E0800-B-03/976-1188-ND/4485006

Those are the Bridgelux V8 series. Lower output per chip, and even tinier (less tham 12mm wide). These definitely don't have any optics, though.

Yeah, sorry. I am getting a 48V for the build for the DT, but I have built a little test light which I'm playing with to try and decide on LEDs/colour ratios (and can be used for QT tank afterwards ). Only running that on 12 or 24V depending on what's on the test, with the intention of buying the most appropriate supply when I've made my mind up (which will probably be 48V due to max string length of 12 x 3.5V (ish) LEDs).

Had a look earlier. No surprise, but no UK sources of the vero No surprise as there's no UK source of any decent LEDs, just about!

Tim

Oh poo, you're not in teh US. Can you get any from Farnell?

 

[perkint]

I've ran the Vero 10 as low as ~1.5mA and they still struck.

Check these out: http://www.digikey.com/product-detail/en/BXRE-40E0800-B-03/976-1188-ND/4485006

Those are the Bridgelux V8 series. Lower output per chip, and even tinier (less tham 12mm wide). These definitely don't have any optics, though.


Oh poo, you're not in teh US. Can you get any from Farnell?

12mm? That starts to be fun to solder! If you're as ham fisted as me, anyway

Will have to have a look at the bridgelux stuff. Farnell didn't come up on a quick google earlier, but yeah. They do do them

Starting from USD15 each and all US stock, so an extra USD26 PnP as well

Tim

 

[jedimasterben]

12mm? That starts to be fun to solder! If you're as ham fisted as me, anyway

Will have to have a look at the bridgelux stuff. Farnell didn't come up on a quick google earlier, but yeah. They do do them

Starting from USD15 each and all US stock, so an extra USD26 PnP as well

Tim

Yup, 12mm means you gotta be GOOD at soldering

Farnell is part of the element14 store that serves the UK and part of Europe. http://uk.farnell.com/

And actually, looks like you can get the whole family!

BXRA 950 B
Vero 10
V8


More expensive than this side of the pond, but Bridgelux is an American company so they've gotta import them in over there.

 

[perkint]

Yeah, I was looking at the UK shop - I just quoted the prices in USD. The PnP hurts on quite a few things as they offer US stock where they don't have it in the UK, but the price is strong!!

But, Digi-Key also have a UK site, and do the vero 10 for 7USD and 20USD for PnP. Still strong, but better definitely going to get a few to play with

May as well order another PSU whilst I'm at it

Tim

 

[fakir]

@aiq25: Hi, that's true the colour of the high power LED change with change in current because as the current through the LED increases it increase the temperature across the junction which will lead to change in wavelength and hence the colour of the LED will change. But I think the power difference between 5W and 2W is less so it doesn't matter.