Search results for query: *

  1. W

    Romisen RC-T5 4-Cree - notes on Shark driver upgrade

    I still haven't turned this thing into a bike light, still looking for the time to do it - other things have been taking priority. Mounting will be somewhat problematic. I won't be using the full battery tube, since it will be wired to a water bottle battery, so that decreases the weight a bit...
  2. W

    Romisen RC-T5 4-Cree - notes on Shark driver upgrade

    I just received a second RC-T5 to modify for use as a bike light, and did some Lux and current draw comparisons with my first one that has been modified with the Shark/Remora boards. Keep in mind that there may be differences in the Vf/efficiencies of the LEDs between the two that may account...
  3. W

    Romisen RC-T5 4-Cree - notes on Shark driver upgrade

    I've heard of people mixing thermal paste into two part epoxy to get some kind of thermal epoxy, but I don't know what mixing grease into epoxy would do for its bonding properties, I don't think it would be good. Maybe it would be good enough to use as a potting compound.
  4. W

    Buck driver suggestions

    I'll bet input current will exceed 3 amps, but might stay under the 4 amp input limit even toward the end of Li-ion discharge. Let us know how it turns out. I would just make sure the Shark is thermal epoxy potted, because it will be dissipating a couple of watts of power itself while trying...
  5. W

    Romisen RC-T5 4-Cree - notes on Shark driver upgrade

    Have at it!
  6. W

    Romisen RC-T5 4-Cree - notes on Shark driver upgrade

    Bryan - LEDs are current driven devices. You want to regulate the current to the desired level, let the voltage fall where it may. This is in contrast to incandescent bulbs which are voltage driven. If you don't regulate current, and drive it with a fixed voltage level that at first seems...
  7. W

    Buck driver suggestions

    One other thought - you could probably use the Shark boost driver with three Li-ion cells in series. When Vin exceeds Vout at drive current, then I believe the Shark goes "direct drive" but there will be a voltage drop across the Shark board. That drop is commonly about 0.4 volts. If you really...
  8. W

    Buck driver suggestions

    If you wanted to run them at well less than 1 amp, you could do this easily with your three Liion cells in series and a buck driver. Unfortunately, your three Crees at one amp puts them right in a no man's land for drivers, and as others have said you would be best off with a boost/buck...
  9. W

    Romisen RC-T5 4-Cree - notes on Shark driver upgrade

    The only way to calculate the driver efficiency with certainty is to measure input voltage and current directly, and output voltage and current directly while driving the LEDs. The Vf of the LEDs can be highly variable, so guessing at an average isn't going to yield a good value for driver...
  10. W

    Romisen RC-T5 4-Cree - notes on Shark driver upgrade

    Forrest - Were you able to pry out the original driver board and ring clip without desoldering the board from the ring?
  11. W

    Romisen RC-T5 4-Cree - notes on Shark driver upgrade

    For those interested in doing this, I'm posting some notes on my upgrade. Sorry, no photos. You can see some photos of the innards here: http://www.candlepowerforums.com/vb/showthread.php?t=183756 See posts 103, 106, and 119. I used the Shark/Remora combination from The_Sandwich_Shoppe These...
  12. W

    Upgrading LED, can I use thermal grease instead of epoxy?

    I've used Darell's method many times with good results. If you want to make your own thermal epoxy, get some alumina powder from the Sandwich Shoppe and mix it into your epoxy until it has a peanut butter consistency. I can't imagine adding a grease based compound (thermal grease) to expoxy...
  13. W

    HDS mod opinion

    Powernoodle - You should get just about a doubling of lumen output from the Seoul LED, maybe a lot more, maybe a little less depending on the bin of LED in your existing EDC. As you know, a doubling of output is pretty easy to see in side-by-side comparisons, but might not knock your socks...
  14. W

    Modding the U2 with Seoul

    No. Yes. Yes. No. Re-read the thread for details.
  15. W

    Awesome HDS Mod by Milky...

    I'm using an SSC P4 with the stock reflector in an HDS B42. Without modifying the reflector, throw (max lux reading) stayed the same, though the hotspot was larger and spill was brighter for overall more light output. This was in comparison to the LED that previously lived there, a "joker"...
  16. W

    Fully functional U2 modding with SSC P4 USXOI

    You could make a U2 with a P4 work properly with 6 volt primaries by putting about 4 power diodes in series with the LED, but I'm not sure it would be worthwhile to do so. Those serialed diodes would be dissipating almost as much power as the LED, and runtime would suffer. You would basically...
  17. W

    Fully functional U2 modding with SSC P4 USXOI

    Adding a diode with a Vf of about .7 v to a Luxeon with a Vf of 3.6 v gets you to a Vf of 4.3 volts - thats not going to regulate with 6 volts Vin, it will be direct drive at a level likely to damage the emitter and perhaps the U2 circuit.
  18. W

    Fully functional U2 modding with SSC P4 USXOI

    I don't think anyone has ever argued that the U2 circuit functioned properly when Vin was much above Vf of the LED: it certainly isn't a buck circuit as we usually think of it. I suppose it is a matter of semantics, because it does function with some buck properties when Vin is below the LED Vf...
  19. W

    Fully functional U2 modding with SSC P4 USXOI

    Re: First step of SF U2 modding with SSC P4 USXOI Good work! You could do the same thing by installing an SSC with an unusually high Vf. What is the Vf of the LED that you used in this installation?
  20. W

    Fully functional U2 modding with SSC P4 USXOI

    Re: First step of SF U2 modding with SSC P4 USXOI It would also be interesting to see what the Vf of the LED is at each of those drive currents, and what happens to the drive current of the lower levels when the Vin is in the 4.10 - 4.20 v range.

Latest posts

Back
Top