Recent content by Kinnza

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  1. K

    LCR study concludes untinted white is not on the BlackBody locus

    Dr Freyssinier from Lighting Research Center (LCR) of Rensselaer Polytechnic Institute presented at SIL 2012 the last experiment covering tint perception along all CCTs, a long needed study. Although results has been in the past suspected by experts, this is the first time it is empirically...
  2. K

    Brightest production LED’ delivers 17,675 lumens

    It would depend of the final price, of course. With the highest power model being sold below $55 for 83W (1.5A) up to 180W (3A), it really allows to build point-like light sources for cheap, as the power requirements falls between low voltage category, below 60V and 3A. Replacements for 70-100W...
  3. K

    Philips Award Winning LED Bulb Review

    Yesterday I found that Dough Leeper has performed an awesome teardown of the L-Prize winner Phillips lamp. Extremely detailed, great pics and the highest rigor as he always did :thumbsup:. It has been years since the last time he posted on CPF but I'm very glad he continues sharing his...
  4. K

    CRI - marketing ploys

    I was actually answering to that question, but probably I wasn't clear enough. English is second language for me, sometimes I have it difficult to explain nuances. Color rendering and color tone are related, but are not the same thing: -Color tone is the "tint" of the light itself, as seen...
  5. K

    Philips Award Winning LED Bulb Review

    I dont think there is such data yet, not enough time for that. I believe the way Phillips manage it is by running LEDs very soft. At the current and temperature of typical operation, lm manteinance at 30Kh is going to be over 98%. The problem with long term color stability when there are no...
  6. K

    CRI - marketing ploys

    CRI figure is completely unrelated to color temperature/tone/tint. Color tone of cool lights (high K) tend to be somewhat bluish while warm whites tend to be yellowish, and that is valid irrespective of the CRI, as the CRI is calculated against a reference of the same CCT (Correlated Color...
  7. K

    Cree XM-L is a year old now; what next?

    If I remember well, Haitz article stated a trend of doubling performance/cost each 18months, and not a constant increase on performance, as we all know (Haitz included) the physical limits of energy conversion into visible light. For many years, LED manufacturers were focused on increasing the...
  8. K

    Philips Award Winning LED Bulb Review

    Osram took the same path. The reason after it is well explained in the paper I linked above. If you use a narrow peak on the orange-red, you need the green peak is on the short green, or the final solution falls off ANSI accepted white, is less efficient photometrically and have poor CRI. Osram...
  9. K

    Philips Award Winning LED Bulb Review

    No, it is the orange Rebel. 660nm is deep red with very low photometric efficacy (little lumens produced), nobody uses it for human's lighting, as it adds little lm and just improve marginally CRI (if any). Most solutions are using orange-red LEDs, with peak wavelengths below 620nm. Actually...
  10. K

    Philips Award Winning LED Bulb Review

    Fully agreed, actually there is some other brands releasing such bulbs right now, but emitting about 800lm instead of 900lm. In the next two years this level of performance should become very usual at much lower prices. For the moment, at bulbs.com its at $59.99.
  11. K

    Philips Award Winning LED Bulb Review

    About 450nm peak wavelength, no any emission in the UV. As with any powerful blue emitter, never look at it directly from close distance. But it is unconfortable well before the threshold for eye's damage, so actually your instintive reflex are protection enough.
  12. K

    Philips Award Winning LED Bulb Review

    They got such improvement by changing the way of achieving the warm white tone. Instead of using blue LEDs and a remote phosphor which convert a large percentage to long wavelengths (red tones), in this lamp they used blue and red LEDs, with a remote phosphor which only converts to shorter...
  13. K

    P=IV question

    P=IV is valid just for DC current. When working with AC, you need to take into account the Power Factor. In AC, VA (voltamperes) is not the same that power consumed: VA are higher than P because the circuit needs to have more current flowing in it due voltage and intensity (A) are out of phase...
  14. K

    LED Forward Voltage VS Junction temp relationship

    You need to know accurately how the LED varies Vf as temperature raises. Usually, that info is obtained by running the LED at very low current (or short current pulses, usually 25ms) on a hot plate. Once that factor is known accurately, it is easy to know increase of Tj just measuring drop in...
  15. K

    Philips L-Prize LED Bulb 93.4 lumens/watt - 910 lumen output

    Initially, it would be worse because the finned heatsink has way more surface area (3x easily). But thank you for posting the thermal pic, it clarifies it very well and explain why the no finned heatsink may work as well. 30F difference between the upper and lower area of heatsink means...
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