I have a set of industrial equipment at work that we record the operation of for troubleshooting if anything goes wrong, and we use MR11 bulb fixtures (small 12v bi-pin halogen) to illuminate the key areas for the video camera.
These lights normally burn out every 2-3 months, leaving the camera unable to record usable images. With the economy on the slowdown, the technicians' time is stretched pretty thin, and it often takes a few days to get around to replacing the bulbs, so I thought I'd try LED replacements.
After a bit of searching, I found these guys, who offer 4 white MR11 LEDs, and ordered 3 different versions for testing:
http://www.superbrightleds.com/cgi-...=MR16&keywords=&cart_id=9145257.23499&next=50
I got the following:
MR11-WHP1 (single LED in an aluminum heatsink)
MR11-WHP6 (6 square LED dies on a board, 77 lumens)
MR11-W12 (12 traditional LEDs on a board)
I didn't order this one, as it's a narrow beam, which may have been my undoing - MR11-WLX1 single LED in a heat-sinked assembly
Only one was spec'ed for lumens, but I was doing a proof-of-concept, so actual output wasn't critical at this point. Once they came in, all 3 were bright enough for my use, so I put the single LED and the 12 LED versions in a couple of fixtures that needed replacements. There wasn't a hugely obvious difference between the outputs of the 3 versions, though the 12 LED was definitely a bit dimmer.
The 1 and 6 LED versions were reasonably white - much cooler than the halogen they replaced, but not dramatically blue-tinged. The 12 LED version was much bluer. Color rendition isn't critical for me, so no big deal.
The fixtures are goosenecks with a screw-on plastic enclosure around the bulb to protect it and keep it in place (the bulbs are held in by spring clamps on the base), a frosted glass lens, and vent slots between the lens and the plastic enclosure. The fixture hangs free in the air, in a temp controlled environment that's in the 70 deg F range, but there's no cooling air flow directed at the lamps.
Anyway, long story short - they lasted less than a month. I walked by recently, noticed the monitor display was dimmer than it should be, and checked them out - both were much dimmer and much more purple, which is a classic sign of an overheated LED.
The single LED bulb, which I had hopes for due to the heatsink, had cracked the glass envelope on one side. I believe the main problem is that they're all in traditional glass envelopes (except for the face, of course), which prevents the heat from radiating away effeciently on the sides.
I went ahead and mounted up the last one - the 6 LED version - and will see how long it lasts, but I don't have high hopes.
They may last longer if the can were metal instead of plastic, or if I drilled vent holes in it, or if I used one without the glass envelope, like the narrow spot version, but I don't have a lot of resources to throw at the problem.
Just a bit of real-world experience with mid-range LED technology.
These lights normally burn out every 2-3 months, leaving the camera unable to record usable images. With the economy on the slowdown, the technicians' time is stretched pretty thin, and it often takes a few days to get around to replacing the bulbs, so I thought I'd try LED replacements.
After a bit of searching, I found these guys, who offer 4 white MR11 LEDs, and ordered 3 different versions for testing:
http://www.superbrightleds.com/cgi-...=MR16&keywords=&cart_id=9145257.23499&next=50
I got the following:
MR11-WHP1 (single LED in an aluminum heatsink)
MR11-WHP6 (6 square LED dies on a board, 77 lumens)
MR11-W12 (12 traditional LEDs on a board)
I didn't order this one, as it's a narrow beam, which may have been my undoing - MR11-WLX1 single LED in a heat-sinked assembly
Only one was spec'ed for lumens, but I was doing a proof-of-concept, so actual output wasn't critical at this point. Once they came in, all 3 were bright enough for my use, so I put the single LED and the 12 LED versions in a couple of fixtures that needed replacements. There wasn't a hugely obvious difference between the outputs of the 3 versions, though the 12 LED was definitely a bit dimmer.
The 1 and 6 LED versions were reasonably white - much cooler than the halogen they replaced, but not dramatically blue-tinged. The 12 LED version was much bluer. Color rendition isn't critical for me, so no big deal.
The fixtures are goosenecks with a screw-on plastic enclosure around the bulb to protect it and keep it in place (the bulbs are held in by spring clamps on the base), a frosted glass lens, and vent slots between the lens and the plastic enclosure. The fixture hangs free in the air, in a temp controlled environment that's in the 70 deg F range, but there's no cooling air flow directed at the lamps.
Anyway, long story short - they lasted less than a month. I walked by recently, noticed the monitor display was dimmer than it should be, and checked them out - both were much dimmer and much more purple, which is a classic sign of an overheated LED.
The single LED bulb, which I had hopes for due to the heatsink, had cracked the glass envelope on one side. I believe the main problem is that they're all in traditional glass envelopes (except for the face, of course), which prevents the heat from radiating away effeciently on the sides.
I went ahead and mounted up the last one - the 6 LED version - and will see how long it lasts, but I don't have high hopes.
They may last longer if the can were metal instead of plastic, or if I drilled vent holes in it, or if I used one without the glass envelope, like the narrow spot version, but I don't have a lot of resources to throw at the problem.
Just a bit of real-world experience with mid-range LED technology.
