Convert a work light to XM-Ls.

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wiljen
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Convert a work light to XM-Ls.

I have a worklight like this one  http://www.northerntool.com/shop/tools/product_200309783_200309783?cm_it...

with a burned out bulb.  I was thinking of stringing a series of Xm-L emitters in it instead of a new 500w halogen.   I have a spare 18V power brick from an old laptop to use and a Pentium 2 Heatsink to mount the emitters on for heat control.   I need help on the driver.  What driver would you put between an 18v DC supply and 3 or 4 XM-l T6 bins?

 

 

Hep me please.

Match
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LED-Tech.de has one that will drive up to 8 XM-L's at 2.8 amps.

Another company called pcb-components.de also has one that'll drive up to 6 of 'em also at 2.8a.

Seems like the Germans get all the cool toys Smile . I've been thinking about picking up one of the first ones to try out on a new build. 

Wait...scratch that.  The above drivers are DC buck drivers....I just noticed you need one for mains.  In that case, I've used this magtech driver from ledsupply.com with great success.  It has adjustable voltage and current via onboard trim pots.  I recently made up a 7 XM-L floodlight driven by one of these off of 120v...and yes, it's a lot of light.  Heads up, this driver isn't the most budget-ty....

MunkyNutz
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You have lots of options depending what you want to do with the light (modes or fixed output), how much of a DIY'er you are (can you solder SMD components) and of course how much you want to spend....

the most elegant solution in my opinion is to use a driver board from TASKLED.COM - the H6CC is capable of driving all 4 XM-L's at full output with variable dimming via a variable pot $32 + shipping  - George also has the H6Flex which has 3 separate "modes" along with stepped intensity levels changed thru a momentary switch - $40 + shipping   --- high quality drivers, excellent components and lots of features -- but fairly high $$$

from DX - DEALEXTREME.com you can find several cheap drivers - but all with require replacement of SMD resistors, capacitors and/or schottky diodes to push the XM-L's to 3A and take the 18-19V input of your power supply.  SKU examples 20330, 36220 could work.  Maybe the best option is a new XM-L driver SKU 57779 which only has high-low-strobe - but each on can handle (2) emitters with the voltage you are suggesting.  See the discussion threads at the bottom of thre item page for lots of testing/mod info from DX'ers. SKU 57779 is $5.00 each including shipping but plan on a long wait - 6-8 weeks depending where you are in the world.  On a side note DX also has AC drivers - but none with output to drive an XM-L to it fullest - could be modded though.

If you want to look more also check out Kaidomain.com, and lck-led.com... there may be others but none come to mind right now.

On a side note... make sure that the PS you are using will be able to supply the amp draw of the emitters... and be aware most cheap laptop supplies are overrated... so you might need to do some testing.

Hope this help to point you in the right direction...

wiljen
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Ok, I'm now messed up worse.    Let me spell out my assumptions, and see if someone can set me straight.

1.)  The XM-L T6 or U2 emitter needs 2.8A current to be at its best.    More than that cooks it, less than that and it is under driven.

2.) The LED themselves have no ability to limit the current draw and will draw all available current and cook themselves if that current is above the 2.8A mark. (give or take a bit I know they dont immediately die at 2.9A most of the time).

3.) My power supply for this project is rated at 19V at 4.9A output.

4.) If I wire in series, the current draw stays at 2.8, if i were to wire the LEDs in parallel though, then it would be 2.8 X the number of LEDs as the final draw for the circuit.

5.)  Could I not wire 2 Xm-L u2 stars in Parallel directly to the DC supply at 19V @ 4.9A and have 2.45A pulled to each LED?

Do I even need a driver in this case ?

6.) what about using 4 in a series / parallel arrangement   2 series of 2 in parallel?   This should drop the voltage delivered by 1/2 and the current delivered to each by half so effectively I should have 9.5V at 2.45A delivered to each emitter  Correct?

Confusius
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wiljen wrote:

3.) My power supply for this project is rated at 19V at 4.9A output.

5.)  Could I not wire 2 Xm-L u2 stars in Parallel directly to the DC supply at 19V @ 4.9A and have 2.45A pulled to each LED?

Do I even need a driver in this case ?

6.) what about using 4 in a series / parallel arrangement   2 series of 2 in parallel?   This should drop the voltage delivered by 1/2 and the current delivered to each by half so effectively I should have 9.5V at 2.45A delivered to each emitter  Correct?

 

to 3)

Quick calculation: your power supply  should give you an output of 4.9*19 = 93,1 W. Each fully driven XM-L is about 10 W, so even with a low driver efficiency of 80 % you should have enough power for 4 XM-L

to 5) and 6)

You could wire them in parallel, but I would't recommend that. High power LEDs sag in their forward voltage under load, and if your emitters aren't exactly matched , they won't 'share' the current evenly. So the one with the lower forward voltage takes more current, which leads to a further sag in the forward voltage, and in the end one LED takes so much current that it burns out, which leaves all the current for the second one that dies shortly after. Better use a driver.

Also I don't know if they can handle 19 V...

I plan to do the same thing with a work light some time, and have found a 'el cheapo' constant current driver on ebay: http://tiny.cc/pwuyu

If the link doesn't work, just do a search for LM2596 on ebay or google, that's the chip these constant current drivers are built around. States up to 4 A output current (use DMM and screwdriver to adjust both output current and voltage), and up to 30 V input voltage. You should be able to find one for 10-15 bucks shipped.

What I would do: use 4 XM-L LEDS in series, with above mentioned driver.

 

What do you pln to use as a heatsink? 30-40 W generate a lot of heat that has to go somewhere...

 

Confusius Say

Take out the fortune before you eat the cookie.

wiljen
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I have several old P2 heat sinks that are giant aluminum blocks with fins.  I'm going to cut the back out of the reflector and mount one of those fins out back to carry the heat off.   Might even try using one with the fans on it.

okwchin
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5.)  Could I not wire 2 Xm-L u2 stars in Parallel directly to the DC supply at 19V @ 4.9A and have 2.45A pulled to each LED?

 

Your powersupply is Rated for 19V 4.9A. It doesnt mean it will limit itself to 4.9A. Thats what a LED driver does, it is meant to limit the current delivered to the LED.

 

Think of power supplies this way - From the point of view of the LED, the power supply looks like it can provide unlimited amps. If you connect something that can draw more current, it will likely try to deliver it, but is not guaranteed to work safely if you ask for more than 4.9A from it. In reality, what usually happens is the voltage drops, or it trips out if safety features are implemented.

The relevance of this to LEDs is that LEDs by nature try to draw as many amps as possible (i.e. LOTS) if the voltage is high enough. 19V is enough to cause the LED to want to draw amps in the magnitude of hundreds of amps, so the LEDs will try, and will likely die in a bright flash.

Its 1am, and my explaining is bad atm, But ive written some stuff about the nature of LEDs and how they use power in relation to drivers in other threads... Sleepy time for me now.

"like everyone else - I’m looking for my next “last” flashlight" -  ohnonothimagain