Recent content by WhiteRabbit

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    Do White and Colored LED's output UV?

    The sparkfun sensor looked like it might false positive for UV on blue light, so I ordered the adafruit analog sensor above (GUVA-S12SD) instead. The GUVA-S12SD will false negative if there's UV just below 400nm, but it's sensitive only to UV and shouldn't false positive. BTW, none of the...
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    weather protection needed for smd LED's?

    Aside from keeping the solderpoints from shorting out due to water, do they technically require any further protection? i.e. does it cause any harmful problems if, say, a 5050 is run while it's wet? Am wondering what the minimum required protection is, if any. I've seen descriptions which...
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    New type of LED star!

    Rice crackers. Isn't stuff like this supposed to be posted in the underground?
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    Delay in power to LED from adapter

    I have a hypothesis that LED drivers whose buck converters operate at a higher frequency are more likely to have a shorter turn-on time. For those here who are experienced at designing power supplies, does that sound correct?
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    Very briefly, what is the effect of LED package sizing? i.e. 3mm vs. 5mm vs. 8mm?

    OK, I think I get it now. According to http://www.theledlight.com/LuxeonLEDs.html, "Low dome" produces a narrower beam, and "high dome" a wider beam. Makes sense. So, low dome is the opposite of what I want. What threw me off is that regular 5mm LED's seem to throw a narrow beam, and so I...
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    Very briefly, what is the effect of LED package sizing? i.e. 3mm vs. 5mm vs. 8mm?

    In a different thread, I notice JohnR66 is recommending a CREE XP-E as the preferred substitute for a "straw hat" LED because it's "low dome": http://www.candlepowerforums.com/vb/showthread.php?242832-Straw-hat-High-power-LED&p=3095722&viewfull=1#post3095722
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    Very briefly, what is the effect of LED package sizing? i.e. 3mm vs. 5mm vs. 8mm?

    I notice that neither digikey nor mouser have anything listed as "straw hat" or "strawhat". Is it a BS category? I'll assume it is. Therefore, strike "straw hat" from the query above, unless you know something that digikey and mouser don't.
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    Do White and Colored LED's output UV?

    In case anyone's compacent, it appears that at least some white LED's are driven by UV. The following excerpt is from the Philips website (link to source provided below): UV LED with RGB Phosphor: White LED can also be made by coating a UV emitting LED with three different phosphors capable of...
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    Do White and Colored LED's output UV?

    I purchased some 5050 LED's from Amazon just recently. http://www.amazon.com/gp/product/B00F6RC4JC/?tag=cpf0b6-20 described as white, though IMHO that label doesn't really fit. To my eyes, they appear more like "light purple" than white, and the photo even seems to demonstrate that: I...
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    Very briefly, what is the effect of LED package sizing? i.e. 3mm vs. 5mm vs. 8mm?

    In particular, I'm wondering what the effect is with respect to straw hat LED's. e.g. In general, what are the optical differences (if any)? Are bigger packages needed to handle higher power? Or is it just a meaningless marketing thing ("My LED is bigger than yours.")? My hunch is that an...
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    Would PWM make an LED appear brighter than a lesser constant current equivalent?

    Closing the loop regarding the XT-E. I received a sample and tested it. I was able to drive it at approximately 60ma and 2.7v and still be within the same power budget. It produces a very nice warm light, and also a nice light distribution. Subjectively, it does seem less bright than the...
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    Delay in power to LED from adapter

    This morning I spent several hours looking, and I can't find anything with a datasheet that shows less than 500ms turn-on time. Most datasheets don't even characterize it. I'm throwing in the towel. I hope someone else has better luck....
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    Delay in power to LED from adapter

    Is that relevant for LED's? Or, if so, are there other ways to achieve the benefits without suffering the delay? I was hoping that there was a CREE-like "blink of an eye" type driver (cf DIWdiver above) that could be purchased to power our respective LED bulbs. In looking at just a very few...
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    Delay in power to LED from adapter

    I barely started looking, and I've already found (an equivalent?) MeanWell whose turn-on time is 500ms: http://www.ledsupply.com/content/pdf/led-driver-meanwell-lpc-35-700_documentation.pdf That already would be a lot less annoying. Can anyone here do better and maybe find one that's faster...
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    Would PWM make an LED appear brighter than a lesser constant current equivalent?

    Thanks! Am wondering if heat from the soldering iron is much of risk for damaging the LED?
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