Digital DC Ammeter circuit

Discussion in 'General Electronics Chat' started by skilkhan, May 25, 2015.

  1. skilkhan

    Thread Starter New Member

    Nov 8, 2011
    I bought a digital DC ammeter and cannot figure out whether the shunt is already attached with this meter or I have to connect it my self? This is its back image, SHUNT 75 mVDC. If I have to connect Shunt myself, can I use simple resistors as shunt because I cannot found proper shunt at the shop form where I bought it?? Thanks in advance.
  2. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
    Re: The markings on the instrument --- FWIW my guess is that the shunt must be such that it drops 75mV at full scale current (IOW think of the un-shunted meter as a 75mV (FS) voltmeter) -- That being the case:

    R(shunt)=.075/I(full scale)
    While the required minimum power handling capability of the shunt is given by:
    P=.00563/R(shunt) -- of course provision of a 'safety margin' is advisable...

    A shunt fashioned of a conductor or 'nichrome wire' trimmed for accurate calibration is a good practical approach... Of course said shunt must be of sufficient caliber ('gauge') so as to minimize Δ Temp. over the desired dynamic range of the instrument.

    Best regards
    Last edited: May 25, 2015
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  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
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