DCV measurement with analog AC voltmeter

Discussion in 'General Electronics Chat' started by abuhafss, Jan 26, 2015.

  1. abuhafss

    Thread Starter Active Member

    Aug 17, 2010
    147
    2
    Hi

    Just wondering if it is somehow possible to measure DC voltage on a cheap panel AC voltmeter?
    I just need a rough measurement to indicate the presence of 200VDC at the output of an DC-DC inverter. I thought of using an NE-2 type neon bulb but, that would light up even at 75V. Any other idea would be welcome.
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,440
    3,361
    Analog meters are generally DC meters. If you know the full scale range of the AC meter, build a voltage divider using two resistors to reduce the DC voltage to suit the range of the AC meter. Calibrate against another DC meter or known voltage source.
     
  3. abuhafss

    Thread Starter Active Member

    Aug 17, 2010
    147
    2
    The meter what I am considering is a mini sized AC panel meter with maximum scale 300VAC. I don't think a voltage divider would be needed because, 200V falls within 300V range. So, the conclusion is a cheap AC panel voltmeter can be used as DC voltmeter without any modification.......Right?
     
  4. WBahn

    Moderator

    Mar 31, 2012
    17,743
    4,795
    No. I think MrChips has in mind a basic analog voltmeter intended to be used as a test instrument, not a specialized panel meter that is intended to be used for one specific type of measurement. Unless you can tear into the meter and remove the filter, I don't see an obvious way to do it.

    If you are in a position to consider which meter you will use, why not just get a suitable DCV panel meter?
     
  5. abuhafss

    Thread Starter Active Member

    Aug 17, 2010
    147
    2
    DC panel voltmeters are comparatively quite expensive.

    I am thinking to use this type

    Panel Meter.jpg
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,009
    3,233
    If the meter has a series capacitor to block DC then it won't measure DC, but just try it and see if it works.
     
  7. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    That looks like it might be a moving iron type meter, not a moving coil type, considering the non linear scale.
    In which case it would be OK on DC.
     
  8. Reloadron

    Active Member

    Jan 15, 2015
    963
    232
    If you read this All About Circuits paper it will explain what many of the posters are relating to as to meter types. The trick becomes knowing what you have as in which type of meter movement.

    Ron
     
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