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  1. W

    MagLED mod = alkaline sudden death?

    My guess is the GF or someone else used it when you weren't looking. Or they are just bad batteries. One other possibility is that they were nearly dead when you last used it, and kept going because the Vf of the LED is lower when hot. When you turn it off and it cools down, the Vf goes back...
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    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    OK, those are pretty much the current draws I am getting with my upgraded light. Usually it takes a doubling of output to notice an increased amount of light (unless you are doing a side-by-side comparison). Which is why I was so surprised that the output with the new driver seemed so...
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    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    Based on the current draw, mine was in line with what others had reported with the stock circuits. The only other thing would be to measure current draw on your upgraded light. It should be about 1.6 amps at 8 volts, or 12-14 watts at whatever voltage you supply it. The original was about...
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    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    forrest - You definitely rewired the LEDs so they are now all in series? The LEDs are originally wired so that you have only two in series, and the two series pairs are paralleled with each other. If you kept this wiring scheme then each LED would only be getting about half the current it...
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    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    Then you run it on the middle level, which should provide about 1 watt to each LED, about what Maximum was on the original driver.
  6. W

    Any mods for the Surefire U2?

    An X bin LuxV should give you form 130 to 160 lumens out the front of a U2. Those are Surefire lumens, not Chinese lumens. How much of an improvement you get depends on what came in your U2. If your hotspot is greater than 2000 Lux, you probably wouldn't see much improvement with an X bin.
  7. W

    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    OK, the notes on the mod are posted here: http://www.candlepowerforums.com/vb/showthread.php?t=194513
  8. W

    Any mods for the Surefire U2?

    There is no emitter swap that retains the same functionality. The LuxV in the U2 has a Vf of about 6.5 volts, and there isn't anything else that really works. You can wait until an X-bin LuxV shows up (rare bird) or hope Lumileds eventually comes out with a LuxV using their updated (like Rebel)...
  9. W

    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    I think you are looking at about a 100% increase in output with the Shark driver. Its pretty dramatic to my eyes.
  10. W

    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    I'll post a verbal writeup of some aspects of the upgrade in the "Homemade and Modified Lights" forum. I wish I had had the foresight and patience to document it with photographs.......
  11. W

    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    I just used the preassembled Shark/Remora combo from the Sandwich Shoppe. You could save $17 or so assembling them yourself. With the assembly, you have two wires coming out for the LED string, and you just have to supply the Vin (+) and Gnd (-) from your power source. Hmm. I guess this should...
  12. W

    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    I'm not sure what instructions you are referring to?
  13. W

    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    I might do some comparison shots later. As for the heatsink, I think its adequate for limited runs handheld, and continuously on a moving bicycle.. When I screwed the heatsink back into the head, I used Arctic Alumina liberally on the threads. The external head begins to heat up pretty quickly...
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    Romisen RC-T5 4-Cree - upgraded with Shark Driver

    Just finished replacing the driver in this light with the Shark/Remora combo board from The Sandwich Shoppe. It wasn't technically difficult, and it would be a lot easier to do the second time around. The biggest difficulty is with fully disassembling the light. From there it is fairly...
  15. W

    4 Cree Light !!

    Francois - What did you have to do to remove the circuit board assembly from the main heat sink???
  16. W

    4 Cree Light !!

    To address the findings of Jazchau, I'll post my measurements. There may be a lot of variablility in the Vf of the LEDs that are used in these lights, so voltage vs. current draws may vary quite a bit sample to sample. Here is what I got, measuring voltage at the head with a separate DMM. Volt...
  17. W

    4 Cree Light !!

    For relatively short periods hand held at 1 amp, the heat sinking won't be much of an issue. On the bicycle, constant airflow over the light will keep temperatures lower, even with less than optimal transfer from the mounting plate to the head. Some thermal compound on the threads will be of...
  18. W

    4 Cree Light !!

    I like this light, it seems very well made for a mere $50. It isn't as bright as I would have expected from four good Crees, even being driven at a mere 500 mA each, which is what I calculate the stock driver circuit is doing. I've ordered a Shark+Remora board from the Sandwich Shoppe so I can...
  19. W

    4 Cree Light !!

    I just finished some measurements of the head attached to a bench power supply. Voltage was measured at the head, and current from the BK1743 power supply readout. I don't have the exact numbers right next to me, I'm back at work. But, the gist of it is that the light pulls about 7 watts between...
  20. W

    Tiny cr2 flashlight recommendations

    I like CR2 lights too. Mostly because I have about a hundred barely used cells salvaged from medical devices, but the slightly smaller size is also very nice. The Liteflux LF4 is a great little light. Although learning to program it takes a little study and practice, its nice to be able to set...

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