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  1. M

    Help me calculate LED Junction temp

    Hi I have all the figures but I don't know quite how to put it together to calculate a realistic junction temperature. My stabilised aluminium heatsink (old CPU heatsink) temp: 45deg C (with a big fan pointed roughly at it) LED board 7up cutter XP-G R2 at 1000mA (23W) stuck directly to...
  2. M

    Oil cooled LED

    Hi guys ther does appear to be a small amount of misunderstanding. Take a light case, any case with fins etc......Fill the front end of the case with oil and seal up. That is the end with the optics LED's mounted on MCPCB etc...Seal up any holes to the back of htecase ie that wires pass through...
  3. M

    Oil cooled LED

    Has anyone tried or thought of filling the front end of an LED light with oil to cool the LEDS? Obviously it would have to be sealed well from the back end round cables etc...but if it was possible and any case design is good so that the residual heat is still dissipated to the air then it would...
  4. M

    MC-G on the cards?

    I'm ressurecting this thread to ask the question from another viewpoint: What was the time difference in months between the XR-E being released and the MC-E being released? I'm conviced Cree will make a 'surprise' announcement about a quad die XP-G around march 2010. Marco.
  5. M

    MC-G on the cards?

    Surely there will be an MC-G on the cards shortly after the XP-G? Marco.
  6. M

    Has anyone tested an MC-E to destruction?

    At what point did the bond wires start fusing? What about permnent die damage/colour shift? Marco.
  7. M

    Candles,Lumens, 5mm LEDS and SMT LEDS

    Why are 3-10mm LED's always specced in candels/candela and SMT LED's specced in lumens.? They both have optic domes so I don't understand why an aboulute measure of light output ie Lumens cannot be used for both? I can't even finda formula to covert candles to Lumens. I think candles...
  8. M

    Measurment of Vf vs Tj

    Superb experiment! That was exactly the information I was looking for cheers.
  9. M

    MC-E Vf vs temperature?

    There is obviously a clear linear relationship between luminous flux and tempereature, as per the datasheet But does Vf vary with temperature? There is no mention of this in the datsheet. If I have to measue a batch of MC-E's for Vf at varying currents is temperature an issue? Marco.
  10. M

    SSC Acriche

    I work with Mil equipment and the flashlamps that energise the YAG rods get pumped with 10,000v 10 times a second. I accidently earthed myself with one forfinger on the lamp trigger! Luckily the exit hole was on my thumb. However my body travelled 8ft backwards without me knowing how I actually...
  11. M

    4S MC-E direct drive on 12 NiMH cells

    Hmmmm 12.8v, 3.2v Vf per die, I might just order another Flex driver! It's quite a bit lower than 4 XR-E's.
  12. M

    4S MC-E direct drive on 12 NiMH cells

    Thanks fo the info. Back to the drawing board!.
  13. M

    4S MC-E direct drive on 12 NiMH cells

    Is it a bit too risky? (single MC-E 4 dice wired series) Fully charged voltage 12S-NiMH on the pack will be 16.8v for a few moments after power is applied, which will give 4.2 Vf per LED for a few seconds after the power goes on .Maybe in excess of 1500mA. The voltage will quickly drop to...
  14. M

    Current through individual Dies on MC-E / P7

    If individual dies/emitties have slightly different Vf's then how do each die (in a paralell arrangement) get exactly the same current? Take for example the P7. Rated to 2.8A: The total current available is 2.8A but if each die has a slightly different Vf then they might take: 0.7A, 0.7A...
  15. M

    Cree MC-E (4S) at 1000mA too high?

    Thankyou for the info. I believe it is a round board, not Star with the emitter pre-attatched - I don't know if star vs round will make a difference to the heatsinking. (anyone ever tried filling the front end with oil as cooling before?) Steve, if i'm using a 'pill style' module to swap my...
  16. M

    Cree MC-E (4S) at 1000mA too high?

    Hi All, I have a quick question on the Cree MC-E that I haven't seen addressed: The dies are only rated to 700mA but has anyone tried running them at 1000mA with a good heatsink? I've got a mixture of stuff coming from cutter (including MC-E on 4S board) and was going to try run this off the...

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