First time DIY Journal - Double Regina XPG & B2flex- Mtbr.com
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  1. #1
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    First time DIY Journal - Double Regina XPG & B2flex

    Hi MTBR! Back in October I had been reading around the intertubes, doing research on Magicshine lights. After stumbling upon the Lights DIY forum here on MTBR, I was infected by the ludicrous idea to build my own light.

    A little background on myself. I'm 23 and halfway through a Mech. Eng. degree. While I feel I have a good understanding of how simple electrical circuits work, this is my first time ever using a soldering iron.

    Anyways, after a week or so of intense researching, and another 3 weeks of waiting for parts (grr deal-extreme), everything finally arrived yesterday. I spent a few hours last night, and a few more hours this morning putting it all together. Here's a small overview of what I did. Any and all comments/criticism/questions welcome!

    Part list:

    Cree XP-G LED
    Regina Reflector
    Backlit Momentary Switch
    Hammond Aluminum Box
    5.4mm Extension Cable(100cm) (Magicshine spare cable)
    Y-Cable(for light head and battery power connections) (Magicshine y-cable)
    Li-Ion 18650 Battery Charger
    TrustFire Protected 18650 2400mAh x6
    Compact 6x 18650 Battery Holder (LuminousDIY)
    b2flex LED Driver (TaskLED)


    Photo Journal:

    The parts are finally all here! Some suppliers (Digi-key) arrived within 2 days. Others (DealExtreme) took ~3 weeks.



    Literally my first solder connection....ever. I tell myself I just like learning new things, but maybe I'm foolish? :P



    Battery pack all wired up. Later I wrapped the 2 power wires in electrical tape to tidy things up, and sealed all of the wire connections in epoxy. When I use it, there will be a velcro strap holding the battery cells in place. The entire assembly fits perfectly into a small (point and shoot) cloth camera bag.



    LEDs and B2flex driver mounted onto a piece of aluminum angle (3/4"x1/2") I think next time I'll try to figure out a cleaner method than epoxying the led boards onto the bracket.



    Regina reflectors epoxied in place over the LED boards.



    All wired up! This shot shows the power wires and switch coming through the back plate. That's the bottom of the driver showing all the leads soldered in place. For perspective, the driver board is 1" diameter.



    This shot shows the top of the same board with all the connections made. The random wire connected from the lower part of the driver board to the aluminum angle bracket is to heat sink the driver to the case.





    It's alive! (and still naked. I thought I'd test it out before epoxying the bracket into the case)



    And here are some completed shots. I'll try and take a picture of the beam at night sometime in the next few days.









    Anyways, I had fun and learned a lot....I'll be trying it out on the trails asap.

    Theoretical lumen numbers:
    Cree XP-G R5 = 139 Lumens (when driven @ 350 mA current)
    I have 2 LEDs, and my driver has a max. of 1500 mA current. Based on the Cree datasheets, 1500mA results in ~340% of the standard lumen output.

    139*2*3.4=945.2 lumens (theoretical)

  2. #2
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    Great first build there.
    A suggestion on the soldering would be not to have such a close-up picture.
    My soldering looks much better the further you are from it. Seriously though looks like you did fine with the iron.

    You are going to be really happy with your beam pattern I would guess.
    So what are you going to put on your bars to compliment the helmet light?

  3. #3
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    Nice build!

    Can you provide a link to the switch?

    I am doing the waiting game now for some parts but it is like an early Christmas when the boxes start arriving. lol
    Sometimes your the windshield, other times just the bug. That's life. (c:
    Mountain Biking Apparel

  4. #4
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    wow, neat and speedy build. I've just finished something very similar and it's an awesome light. Personally, I thought the 1A setting was more than bright enough, but that might be due to the slow speeds at this time of year (snow + rocks = ouch).

    One tip on heatsinking the driver - instead of using a wire, you could in future flip the driver over and epoxy a small square of alu to the gold patch, then epoxy that to your LED plate. As for attaching the stars, if you get 20mm stars it's fairly easy to tap a couple of holes for each star and then use 4-40 screws (or M2/ M3 allens in the UK) to hold them down.

    The switch I used was this one . Works beautifully.

  5. #5
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    Very nice,

    Welcome to the DIY club.

    What thickness is the L-bracket? A little thicker one would help with thermal transfer.

  6. #6
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    Looks like 2mm.

    I think I would have tried some practice joints on some scrap first :-), but looks like you did ok.

    How did you modify the Regina? - it wouldn't have fitted over those joints stock.

  7. #7
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    jGell, nice build but I'm going to be a little bit critical if I may. (Please look on it as me trying to save you the cost of a new driver and nothing else, I've blown more than one in my time)

    The pic that shows the close up of the driver shows that there are wires that extend throught the board and you bent them back up over the side of the board. Trim these back as much as possible to try and avoid unnecessary shorts should things move around at all, which they will do on a mountain bike.

    You can use nail clippers to do this if you have nothing else small enough but make sure the trimmed bits are cleaned off the board.

    Nice work and welcome

  8. #8
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    Emu is correct on those pesky wires. If you can't trim just cover/pot all the soldered wire ends with a thin layer of 5 minute epoxy.

  9. #9
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    Thanks for the input and comments guys! I didn't want to ask 100 questions beforehand, as it would have just been pointless until I actually went and tried to build the thing. That's why I've posted this now that it's done, to try and get some input on my techniques.

    odtexas: I'll just be running this for now. We'll see how that goes, but I'll probably add a bar light to it sometime next year. Maybe a 2x 3up XPG, or possibly something using that new Cree LED (the name escaped me at the moment)

    Streamline.by.design: It's the same switch mattthemuppet linked below you. It has an LED incorporated into it to use with the Status lead on the b2flex driver.

    mattthemuppet: Thanks for the tip on heatsinking. I wasn't sure how to proceed with doing that, but decided to just use a wire and go for it.

    il2mb: It's 1/16" thick angle, at 1/2"x3/4". How would a thicker angle aid in heat transfer?

    MrLee: That was definitely a challenge, and something I'd change next time. I ordered the 10mm circular boards with holes in them, thinking the holes were for mounting the reginas. After the shot of the LEDs above, I re-soldered the connections and flattened them to get the reflector as close as possible. As it is there's maybe a .5mm gap between the regina and the board.

    emu26: That is something I had noticed. The back side is where I soldered, so it's fairly good there. I'll likely open it up and try to trim anything that's still loose. I guess that brings up a fairly good question. I used 20 gauge stranded wire for the project, as anything less than that isn't rated for the 1.5A I'll occasionally be driving the LEDs at. The driver board etc. obviously wasn't built for wire this thick. What is typical in that situation? I just pushed the 20 ga. wire through and wrapped any loose strands up.

    Anyways, thanks for the comments guys. Keep them coming!

  10. #10
    A waste of time it is is
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    jGell, I use this stuff for everything from the driver to the LEDs, switches etc.

    My power cable is usually something bigger and what I do is actually trim any strands that won't fit through the board off where I have stripped the insulation to, if that makes sense. I will also trim off anything that protrudes through the boards by than about a mil or two. As I said, I've killed some drivers and only a fool doesn't try and learn from his mistakes.

    Hope it helps

  11. #11
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    A heckuvalot better than my first build, or my first BFlex light.

  12. #12
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    Nice work, this makes me want to build instead of buy. Is that going to be around 4+ hours on high for run-time then? 2400*6 / (1500*2) = 4.8? (minus some for losses).

  13. #13
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    Quote Originally Posted by black_box
    Nice work, this makes me want to build instead of buy. Is that going to be around 4+ hours on high for run-time then? 2400*6 / (1500*2) = 4.8? (minus some for losses).
    power used by the LEDs will be 3.36Vx2x1.5 = 10W + 10% efficiency loss = 11W.
    a 3s2p 4800mAh battery will be 11.1Vx4.8 = 53Wh
    runtime should be ~ 53/11 = 4.8h

    so, exactly what you worked out

  14. #14
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    oh and it's really not that hard to make a light like this, plus you get the satisfaction of having a light as bright as some really pricey factory lights (like the $500 L&M Seca 700 my friend has)!

  15. #15
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    Quote Originally Posted by mattthemuppet
    power used by the LEDs will be 3.36Vx2x1.5 = 10W + 10% efficiency loss = 11W.
    a 3s2p 4800mAh battery will be 11.1Vx4.8 = 53Wh
    runtime should be ~ 53/11 = 4.8h

    so, exactly what you worked out
    I think 53Wh is high, that assumes that the battery voltage stays constant at 3.7V and that the batteries provide a full 2400 mAh If the LEDs each receive 1.5A, i'd tack the 10% on there and drop the batteries to 2200? 2200*6 mAh / 3300mA = 4 hours even.

  16. #16
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    Quote Originally Posted by mattthemuppet
    oh and it's really not that hard to make a light like this, plus you get the satisfaction of having a light as bright as some really pricey factory lights (like the $500 L&M Seca 700 my friend has)!
    you said you have a similar light? How does it stack up against the ms lights?

  17. #17
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    Nice job jGell.
    Very similar to what I have planned to build in the near future.
    Got any beamshots, or saddle time yet?
    How did you mount it up?
    Look, whatever happens, don't fight the mountain.

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