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What is typical internal resistance of analog voltage meter?

  1. Oct 19, 2012 #1
    What is typical internal resistance of a voltage meter on a handheld analog multimeter, and also what is typical resistance on its ammeter?
     
  2. jcsd
  3. Oct 19, 2012 #2

    berkeman

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    Staff: Mentor

    What is the context of the question? Is this for schoolwork?

    You can get both answers by looking at a datasheet for a typical analog meter. You can use Google Images to find some typical ones, and then look at their datasheets at the manufacturer's websites.
     
  4. Oct 19, 2012 #3
    You mean the stone-old models where the current derived from the measured circuit moves a needle?
    For sure you won't find a datasheet on the Internet. I used one in 1989 and it was very old-fashioned then.
    One common value of internal resistance was 20kohm/V, which means that on the 10V scale it had 200kohm, on 100V scale 2MOhm and so on, due to resistors added in series when changing the scale.
    You can also understand "20kohm/V" as "50µA at full needle deviation".
     
  5. Oct 19, 2012 #4

    berkeman

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    Staff: Mentor

    Oh wow, I wasn't thinking of that angle. I was thinking along the lines of transistor-based analog meters like my old Radio Shack one I had back in high school (a million years ago).

    I guess the OP will have to be more specific in his question...
     
  6. Oct 19, 2012 #5
    Ahh the classic Simpson 260 is still in production - you will find the datasheet.

    As for the Resistance - in reality ALL analog Meters are really current meters: For Higher current precision shunt ( parallel ) resistors are added and for voltage and high precision resistance are. So the minimum current to deflect the meter is part of the measurement of the "quality" and then - how high of a grade of resistors used to make the different settings.

    So compare the Simpson 260 DS with a Radio Shack $20 special..... of course the Simpson was designed forever ago - and the RS was probably deigned last year.

    Very long winded way of saying - there is no typical.
     
  7. Oct 20, 2012 #6
    Of course a less old meter would be better...

    EXCEPT that when I created the RFID technology at 13.56MHz in 1989, induced voltages were (still are!) so huge that electronics went crazy, and I had to exhume the already stone-old passive voltmeter to get sensible measurements.

    Maybe Red123 is in a similar situation?

    The kohm/V were written on the instruments at that time; if not, the resistance can be measured with an ohmmeter.
     
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