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Thread: Current drain of a 532nm 10mw laser pointer

  1. #1
    Join Date
    Aug 2007
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    Indianapolis, IN
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    196

    Default Current drain of a 532nm 10mw laser pointer

    I just hooked up an ammeter to a laser pointer and got a value of 196 mA. Does that seem right for a (10mw output) green laser pointer? @ 3.2v.

    While I measured the laser did not operate - so I'm curious if I did something wrong.

  2. #2
    Join Date
    Jan 2008
    Location
    Stockholm, Sweden
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    799

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    How did you hook the meter up? Current needs to be measured in series with the load, while voltage is measured in parallel. If you connected the ammeter in parallel with the load (laser diode), essentially all current flowed through the meter and none through the laser diode.

    However, because laser diode drivers are typically current regulated (i.e. they will vary the voltage to achieve a certain current) your measurement might still be somewhat accurate. If it is a cheap laser pointer it could be voltage regulated though, and then you need to measure the current in series with the load.

  3. #3
    Join Date
    Mar 2008
    Location
    Canton, GA USA
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    384

    Default

    Hi Shobley -
    Are you trying to measure the current through the diode or the current being pulled from the battery? They're probably pretty close, but you'll get a more accurate reading if you measure in the correct place. Either measure in line (in series) with the diode or measure in line (in series) with the battery.
    Tim

  4. #4
    Join Date
    Aug 2007
    Location
    Indianapolis, IN
    Posts
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    Default

    I hooked the meter up between the cathode of the battery and the terminal it connects to inside the casing.

    So this would be in series - correct?

    I'm not sure how you connect in series with the battery or the diode, I thought series was series, however you hook it up.

    Although does this mean on the other side of the driver? If so then I can't get in that far...

  5. #5
    Join Date
    May 2008
    Location
    Wisconsin
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    449

    Default

    It sounds like a feasible number to me whether you measured it correctly or not.

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