Reasonably accurate ATX power draw

Discussion in 'DIY Server and Workstation Builds' started by WeekendWarrior, Jan 8, 2016.

  1. WeekendWarrior

    WeekendWarrior Active Member

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    I would like to measure the power through an ATX connector within 1-2% accuracy from 1W to 100W. Inexpensive is good but not an absolute requirement.

    Can anyone recommend a way to do this other than constructing my own jig using a shunt resistor?

    For reasons that are somewhat detailed I want to measure the power at the ATX connector rather than the 120V line.

    Thanks in advance for any assistance --
    Dave
     
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  2. Chuckleb

    Chuckleb Moderator

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  3. WeekendWarrior

    WeekendWarrior Active Member

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    Thanks @Chuckleb for this suggestion, but Zalman says that it is not usable below 10W. I hope to measure power at or below 1W unless nothing economical can do that.
     
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  4. John

    John New Member

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    Just measure the voltage and current inline DMM or amp clamp. Calculate for power.
     
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    Jon Massey likes this.
  5. Marsh

    Marsh Moderator

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  6. John

    John New Member

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    Don't even need a Fluke. Requirements are 1-2% F.S. of 100W. Can hit those with free DMM from Harbor Freight :)
     
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  7. Marsh

    Marsh Moderator

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    1% of 1W is 0.01 watt
    0.01 watt / 5 volt is 0.002 Amp or 2 Milliamp

    In this case , a fluke meter is cheap investment.
     
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    T_Minus likes this.
  8. John

    John New Member

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    1-2% Accuracy of Full scale so +/- 1 Watt so you would be in the hundredths of an ohm. Once you're in the milliohms you're going to need to shell out some cash.
     
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  9. WeekendWarrior

    WeekendWarrior Active Member

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    Thanks for everyone's comments - they are helpful.
     
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  10. Deslok

    Deslok Well-Known Member

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    I'll second the DMM from harbor freight although i'm more inclined towards this one i've had it for years and use the probe to spot check case temps(and server room temp) regularly, granted i've got several of the free ones too, mostly so people don't walk off with the nice one.
    14 Function Professional Digital Multimeter with Sound Level and Luminosity
     
    #10
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