Milliamp question

Discussion in 'General Electronics Chat' started by electricdan, Feb 8, 2011.

  1. electricdan

    Thread Starter New Member

    Feb 8, 2011
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    I have a question as for measuring Milliamps, i have the Greenlee DM-20 and am needing to dial something in to ~750mA. Is the multimeter capable? I cant figure out exactly which setting i need it on. I have everything in series to measure A but cant figure out the correct setting on the multimeter.
    Here is a link to said multimeter.
    http://www.greenlee.com/product/DM-20.html
     
  2. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    Looks like the meter's maximum current measurement capability is 200 milliamps.
     
  3. electricdan

    Thread Starter New Member

    Feb 8, 2011
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    Thats what i was coming to the conclusion of, dang, will have to get a real multimeter and not some cheapo, lol
     
  4. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    Use the 200mv range with a current sensing resistor placed in series with your loop. A 100 ohm resistor will have 200mv across it with 2 amps of current through it. 750 ma will then display as 75mv. Use ohms law for any other combination.

    The accuracy of the reading will be dependent on the accuracy of the resistor you chose. Most common resistors are 5%. 1% resistors are still pretty cheap.

    The 100 ohm resistor in the above scenario will dissipate 400mw. Be sure to pick a resistor rated at 1 watt or more.
     
  5. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I think you mean a 0.1 Ω resistor. Otherwise, good advice.

    John
     
  6. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
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    Ah, good catch. I can't believe I did that. I guess that's why pencil and paper were invented!
     
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