about voltmeter

Discussion in 'General Electronics Chat' started by Anikets, Aug 27, 2014.

  1. Anikets

    Thread Starter New Member

    Aug 6, 2014
    11
    0
    why there is series resistance in voltmeter?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,515
    2,369
    Because basically a moving coil meter is a current operated device, the series resistor tailors the scale in order for it to indicate voltage according to the value of the resistor.
    Max.
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    A very high series resistance is desired, since ideally you don't want the meter to draw any current and thereby distort the voltages you are reading. The more current it draws from your circuit under test, the less accurate your meter reading will be.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,515
    2,369
    A moving coil volt meter is usually indicated in Ohms/Volt, this figure is ideally as high as possible depending on the FSD current of the meter, this is the desired value mentioned in wanyeh post.
    Max.
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
    395
    Better analog VOMs are rated at 20kΩ/V or better, like my Heathkit MM-1, cheaper ones down to 2kΩ/V.
    Digital meters generally are fixed input restance, Harbor Freight freebees @ 1MΩ, better ones 10MΩ & up.
     
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