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| slburris:
More neat stuff I picked up from Sure electronics. A 10watt LED on a heatsink plus a 1.5amp constant current supply: http://www.sureelectronics.net/goods.php?id=340 http://www.sureelectronics.net/goods.php?id=1125 The LED I received looks essentially like it does on their website. No markings on it that I could see. I removed the screws and there was heat sink compound between it and the heat sink. No idea who actually makes this LED, could it be from Seoul Semiconductor? Looks like there 4 dice inside. The power supply is actually two converter boards. They are paralleled on a carrier board to provide the 1.5amp constant current. The carrier board places them a little too close together. The converters don't both fit well, so either these boards need to be trimmed more, or the carrier board isn't laid out correctly. Still it's possible to smash them together as shown. I've tested the LED with an external supply -- it is very bright. I accidentally looked at the LED while it was on, and I was seeing afterimages for about 10 minutes. The heat sink didn't seem to get very warm, so that's encouraging. Next up, I need to test the converters. My plan is to build this into a floodlight for some nice LED lanscape lighting. I'll use this as a wall washer type light. Two LEDs should be about 900 lumens -- I think that's sufficient for what I have in mind. Scott |
| slburris:
Time for some testing! I soldered the boards into their carrier, wired up a power supply and connected the output to the 10w LED on a sink. In the first picture, you can see that the supply is providing 1.238amp to the LED, measured with my UniTrend UT70D meter. I put a large washer with a hole over the LED, otherwise it hurts my eyes to be this close. Next, you can see the power supply which is feeding this. 11.98v at 0.956amp. Things are heating up, so let's pull out the IR thermometer. Continued in next post..... Scott |
| slburris:
In the first photo, we're measuring the temperature of the heatsink, 89F. The second and third photos are the temperature at the middle of each of the two buck converter boards. They seem to be be pretty evenly matched. The last photo is the setup with the washer removed. Although the LED looks bright, the iPhone camera doesn't have the dynamic range to fully capture how bright this is compared to its surroundings. All in all, I'm pretty happy with both the LED and the power supply. Next I'll be integrating it into a floodlight case and see how it looks as a landscape light. Scott |
| Zero999:
--- Quote from: shafri on September 19, 2010, 04:17:02 am ---have a question... why this LED need additional power supply board to work on? cant we directly connect to battery? --- End quote --- Because it requires a constant current source and a battery gives constant voltage. You can use a power resistor but the efficiency will be poor and the LED will dim as the battery voltage drops. A SMPs such as the once shown above wastes little power and the LED stays the same brightness until the battery voltage drops too low for it to work properly. |
| slburris:
--- Quote from: shafri on September 19, 2010, 04:13:49 am ---good report, keep it coming! 1A@12V is quite a monster LED! --- End quote --- Note that LED sees about 8 volts at 1.2amps, which is close to 10 watts. The forward voltage of the LED is 8 volts (I think because there are 4 LEDs wired in series). The switcher has a constant current output, instead of the usual constant voltage output, which is what you want for driving LEDs. Scott |
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