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Thread: Driver mod?

  1. #1
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    Driver mod?

    I was checking out this driver at DE and notice a few comments on bypassing the bridge rectifier.
    I am a newb but where on this driver is the bridge rectifier? Seems like a heck of a deal.
    Sometimes your the windshield, other times just the bug. That's life. (c:
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  2. #2
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    I think it has 4 diodes making a bridge rectifier. These will be the 4 rectangular blocks all next two each other next to the input pins on one of the pictures.

  3. #3
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    Thanks that makes more sense. They talked about it like it was singular and I did a google image search and couldnt find an image that looked like just one thing on the board.

    So to bypass this I would just have to remove them, correct?
    Sometimes your the windshield, other times just the bug. That's life. (c:
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    You would need to bridge two sets of connections if you remove the diodes, if that's what you mean?

  5. #5
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    I just got one of the 13557 today. It is tiny. I was thinking about adding a resistor in parallel with the sense resistor to up the current a bit, but it looks to small for me to work on, and I don't know where to find those small rectangular resistors locally.

    Here's a pic from dx.


  6. #6
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    I have one of those very boards. I have removed the bridge diodes. After removing them I just attached my power input wires to two of the uncovered pads. Well not just any pads but the ones that have continuity with either side of the inductor. I also added a tiny output capacitor. I got a very small thru-hole ceramic cap and simply soldered one end to the led + and one to the led-. Seems like a decent little circuit. If i had a camera that didnt totally suck at macros I would put up a photo. I guess If you need more info i can edit the photo from DX just posted here.

  7. #7
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    That would be awesome. I am sure this would help more than just me.

    Thanks bikerjay!
    Sometimes your the windshield, other times just the bug. That's life. (c:
    Mountain Biking Apparel

  8. #8
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    Here are some photos, my cell phone did a lot better than I thought.

    edit
    Darn need to re-size. Here they are finally
    Attached Images Attached Images   
    Last edited by bikerjay; 12-02-2010 at 07:11 AM.

  9. #9
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    If SMD soldering gives you heartaches, you can bypass the bridge rectifier without removing the diodes. Just connect your DC power source directly to the legs of the electrolytic capacitor (or the connected pads underneath). Be sure to observe the correct polarity or the capacitor will go BOOM.

    Working with SMD resistors can be a pain. One method which works for me is to use a wide chisel tip iron, and heat the entire length of the resistor. The instant the solder liquefies, I pick it off with a fine point tweezer.

  10. #10
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    Hope the photos help. You can see where i attached the power leads after removing the diodes. You can also see the output cap. Its a ceramic cap, so non polar and i think its some where around 1-5 pico farad.

    I have tested the circuit and it does work well. Delivered the right amount of voltage to a cree xr-e. Eventually when I wire it all up for good I will take some measurements with my multimeter.

  11. #11
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    Heck yeah. Thanks bikerjay!
    Sometimes your the windshield, other times just the bug. That's life. (c:
    Mountain Biking Apparel

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