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Change ac volt meter to a dc volt meter

Discussion in 'Electronic Basics' started by [email protected], Jul 3, 2005.

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  1. Guest

    I have few ac volt meter 0 to 30 volt, and i would like to buld
    a car battery charger, can i just use one diode series on the
    conection to convert the ac volt meter? Can any person help. thanks!
     
  2. redbelly

    redbelly Guest

    No.

    You will need to get a DC volt meter.

    Mark
     
  3. You can try to measure AC voltages using a DC meter this way. However, some
    types of AC meters act on DC voltages as well. You can try out using a DV
    voltage source and a series resistor - of let's say 10k - to stay on the
    safe side.

    petrus bitbyter
     
  4. The first you should do is open one of the AC voltmeters, find out what
    components there are inside. Chances are great that you can use part of
    the circuit for DC, with some simple change.
    There may be a capacitor to isolate for DC, and in that case you can
    simply bypass with a short piece of wire to get a DC voltmeter.

    As somebody said, try using the meter for DC, it may work directly.
    Check the calibration of the scale in this case.

    A more complicated alternative is to build a chopper which transforms a
    DC voltage into AC so it can be amplified with AC amplifiers and
    measured by an AC voltmeter.

    A chopper has a measuring input prope which is quickly switched between
    ground and the point to be measured.

    This creates an AC signal with an amplitude equal to the voltage
    difference between ground and the point of measurement.

    The switches can be electronic switches or relays.

    After the chopper stage, and optional AC amplifiers, we put the
    rectifier, but your AC voltmeters probably already contain rectifiers.

    Chopping is a way to measure very small DC voltages. The created AC
    voltage has exactly the same amplitude as the DC voltage. It is then
    easy to amplify the AC voltage. We have decided the frequency ourselves
    and it doesn't change, so we can use tuned amplifiers to amplify the
    signal by a certain number of decibels, or by a certain amplification
    factor.
     
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