Recent content by cpf user

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    Soldering iron tips

    Anyone know where to get extra long soldering iron tips for Weller SP40 irons? 1.5" long chisel tip, to reach into tight places.
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    Lumen maintenance for PC or PMMA lens

    It needs to be waterproof, for underwater marine operation. It has about 1/2" of potting/encapsulation, which also heat-sinks it a bit. Optical clarity is not important since it is monochromatic (red), and the the slightly-amber PU that we have been using lets the red get through.
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    Lumen maintenance for PC or PMMA lens

    All the chinese leds have plastic domes, which have silicone domes under them. One supplier was able to provide glass, but no others. The encapsulant/potting that we are using now is more of a standard clear (slightly amber) polyurethane. Needs to cure very firm, with a slight flex. Any you'd...
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    Lumen maintenance for PC or PMMA lens

    This was my original way, but the particular silicone had a strong candy smell to it, and after a week or two, the LED would fail. So like was said above, it takes a while for the material to attack the dome. The domes in those cases were plastic. Then I found glass; it solved the problem, but...
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    Lumen maintenance for PC or PMMA lens

    No it really needs to be pourable into a container where the LEDs are mounted, so the LEDs can go into salt water. About 1/2" thickness of material over the LED.
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    Lumen maintenance for PC or PMMA lens

    It's the conformal coating that I mean by encapsulant. The polyurethane is put on top of the LED lens.
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    Lumen maintenance for PC or PMMA lens

    Silicone allows impurities in the encapsulant to degrade the LED to failure. Glass lenses prevented this. Anyone know of an LED manufacturing contact who can put glass lenses on?
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    Lumen maintenance for PC or PMMA lens

    The usage is for inside of products that need monochromatic light; there is no exposure to sunlight. Currently we use glass primary lenses, but they were discontinued. The 3w LED stars are encapsulated in polyurethane.
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    Lumen maintenance for PC or PMMA lens

    Anyone have any longevity data or experience with polycarbonate or acrylic primary lenses, especially on 3w power LEDs ? I need to make sure it will keep 90% or more transmission for 16,000 hours. Note that I'm referring to the dome lens, not an added secondary lens.
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    Cheapest way to protect silicone domes

    Aside from glass-dome LEDs (are there any cheap 3w ones?), what is a cheap way to protect the silicone dome of a 3w cree? No lensing is needed; a very wide angle would be best. I've already ordered some chinese convex lenses of 13, 15, 18, 20 and 23mm, and will try siliconing them on, but...
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    encapsulating the Cree LED dome/lens

    They look to be too expensive for production. The Chinese 3w stars we use now are $0.60 each in lots of 1000.
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    Computer power supply good for LEDs ?

    Yes it did say that failure could happen.
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    Experiments in LED encapsulation

    Here is what seems to be new evidence of failure caused when potting contacts a silicone dome: www.cree.com/products/pdf/xlamp_chemical_comp.pdf
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    encapsulating the Cree LED dome/lens

    Old thread, but new info: www.cree.com/products/pdf/xlamp_chemical_comp.pdf Basically, any encapsulant at all, in contact with a silicone dome, alters the chemistry of the dome when light and heat are applied. In worse cases, such as ours, the LED fails. We were having about a 50% failure rate...
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    Computer power supply good for LEDs ?

    I think I found the problem: www.cree.com/products/pdf/xlamp_chemical_comp.pdf‎
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