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Thread: FlexMod P3 Analog/TTL Laser Diode Driver

  1. #161
    Join Date
    Feb 2007
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    Fort Mill, SC USA
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    Quote Originally Posted by kingjamez View Post
    David: What type and value capacitor is now included to help compensate for long lead lengths?
    -Jim
    They are 270 uF. It would be nice to have some guidelines for when they should be used. I keep my flexmods close to my diodes, but is 4-6 inches of leads enough to start using them? I don't know. Maybe an engineer can chime in here.

    David
    Last edited by dkumpula; 03-06-2014 at 15:37. Reason: For correctness
    "Help, help, I'm being repressed!"

  2. #162
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    Jan 2006
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    Hold it guys...

    That capacitor is supposed to go on the POWER INPUT side of the flexmod. It does not go across the diode!

    It's designed to smooth out any voltage drop if your power supply can't keep up with the load.

    Andrew explained it at the NWLEM. He was thinking about the funny spikes I observed on my flexmods when running them at high currents. He theorized that part of the problem may have been a momentary dip in the supply voltage. That would explain the spikes, both positive and negative. I just got a new oscilloscope, so I hope to replicate my tests this weekend to see if the capacitor helps.

    But just to reiterate: that cap does not go across the output of the Flexmod! It's designed to be installed on the power input side only. And it has nothing to do with the lead lengths from the flexmod to the diode at all.

    Adam

  3. #163
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    Feb 2007
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    OK, great, thanks for that correction, Adam! We need to get that info incorporated into the Flexmod instructions for the non-engineers like myself.

    -David

    Quote Originally Posted by buffo View Post
    Hold it guys...

    That capacitor is supposed to go on the POWER INPUT side of the flexmod. It does not go across the diode!

    It's designed to smooth out any voltage drop if your power supply can't keep up with the load.

    Andrew explained it at the NWLEM. He was thinking about the funny spikes I observed on my flexmods when running them at high currents. He theorized that part of the problem may have been a momentary dip in the supply voltage. That would explain the spikes, both positive and negative. I just got a new oscilloscope, so I hope to replicate my tests this weekend to see if the capacitor helps.

    But just to reiterate: that cap does not go across the output of the Flexmod! It's designed to be installed on the power input side only. And it has nothing to do with the lead lengths from the flexmod to the diode at all.

    Adam
    "Help, help, I'm being repressed!"

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