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Thread: Weird SOB/resistor problem

  1. #1

    Default Weird SOB/resistor problem

    I pulled apart a light tonight to piggyback another resistor onto the SOB1000 board in it. I don't have the thread at hand, but I definitely remember reading that soldering a resistor on top of an existing one on the SOB board was the easiest way to up the current a tad.

    The board has two .10 resistors in place already. I remove the positive wire to the SOB and solder the leads from my MM in there to check current. I was getting .62 amps with the stock board. Seems low, but maybe my meter doesn't read right. No problem, it's just something to compare with. So .62 amps is my baseline.

    Then I solder a .12 resistor that I bought from the Shoppe onto one of the existing .10's (R2 position). The solder job is good, no problems. Took my time and had on my magnifying glasses. I fire it back up and it checks .27 amps. It is also noticably dimmer. I desolder the .12 off and re-check the current and it goes right back to .62.

    What am I doing wrong?



    Edit: I figured out why my initial reading was low. I was checking with a fully charged AW C cell (4.15 volts). I added a second cell, doubling the voltage, and the current went up to .96 amps. I then hooked it up to the 3 CR123 battereis that it runs on (12+ volts), and it was also .96 amps. Ok, good. My MM reads close, and the SOB1000 is basically 1 amp. I didn't realize that the SOB wouldn't provide full current to the Seoul P4 from a fully charged AAW C cell.


    That still doesn't explain the reason why the piggybacked resistor lowered the current though.
    Last edited by Greg G; 04-16-2008 at 10:39 PM.

  2. #2

    Default Re: Weird SOB/resistor problem

    Your description seems to defy laws of physics. That's baffling on what's going on.

    Wayne

  3. #3

    Default Re: Weird SOB/resistor problem

    Well this seems to be an input voltage related issue? I put a .12 ohm resistor on top of the .1 on R1. With two AW C cells it puts out 1.36 amps to the emitter.

    If I hook it up to one battery it goes down to .31 amps. I don't understand it, but the light has three lithium ion rechargeables so the board is going in and it'll feed 1.36 amps to the Seoul P4.

    I don't know what's going on. I figured the board would provide the same current to the emitter with one or two 4.15 volt batteries.
    Last edited by Greg G; 04-19-2008 at 12:58 PM.

  4. #4

    Default Re: Weird SOB/resistor problem

    Quote Originally Posted by Greg G View Post
    Well this seems to be an input voltage related issue? I put a .12 ohm resistor on top of the .1 on R1. With two AW C cells it puts out 1.36 amps to the emitter.

    If I hook it up to one battery it goes down to .31 amps. I don't understand it, but the light has two lithium ion rechargeables so the board is going in and it'll feed 1.36 amps to the Seoul P4.

    I don't know what's going on. I figured the board would provide the same current to the emitter with one or two 4.15 volt batteries.
    Basically a single battery is approaching the Vf of the LED and the SOB and going into DD mode.

    Wayne

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