Decreasing the range of ammeter?

Discussion in 'General Electronics Chat' started by onlyvinod56, Jan 3, 2016.

  1. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    Hello,

    I have an analog ammeter 3A full scale.
    I want to convert it to 100mA full scale.
    I know how to extend the range but how to decrease it? WP_20160103_003.jpg WP_20160103_002.jpg
     
  2. dannyf

    Well-Known Member

    Sep 13, 2015
    1,825
    364
    That black coil-like wire between the two terminals is of low resistance and extends the (current) range of the meter.

    Getting rid of it or replacing it with the right value resistance will get you the desired range.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    Get rid of the internal shunt. Determine the sensistivity of the intrinsic meter movement (likely ~50mV or 1mA full-scale). Then calculate new shunt based on the meter sensitivity.
     
  4. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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  5. wayneh

    Expert

    Sep 9, 2010
    12,145
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    I think I'd use 300mA full scale if you plan to keep the same back plate. You'll remember it now but the next guy won't, and that next guy is probably you in a few years.
     
  6. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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