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How To: Modifying ACV-meter into a DCV-meter?

Discussion in 'High Voltage' started by Iron Will, Jun 18, 2012.

  1. Iron Will

    Iron Will New Member

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    Hi guys,
    I have a 450V AC Voltmeter that I want to convert into a DC Voltmeter.
    Can someone please explain to me how?

    Additional Info: I have opened it and there are resistors and diodes put in symmetry and a capacitor in the center.

    thanks in advance,

    Will
     
  2. Pommie

    Pommie Well-Known Member Most Helpful Member

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    My guess would be that it will work without any changes. Try it and report back.

    Mike.
     
  3. Iron Will

    Iron Will New Member

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    I did, with no luck :/
     
  4. dave

    Dave New Member

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  5. Pommie

    Pommie Well-Known Member Most Helpful Member

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    I'm guessing that feeding it 450V DC gives a reading around 320V. This is due to it reading the peak AC voltage. The only way to get it to work properly is to remove all the components and replace them with one series resister. The resistor value should be the existing resistor value times 0.707. This is again a guess but if it does read 320 instead of 450 then probably correct. More info on the components, how they are connected and the meter would be useful.

    Edit, you want a resistor at least as physically big as the existing one. Preferably bigger (Wattage wise).

    Mike.
     
    Last edited: Jun 18, 2012
  6. Pommie

    Pommie Well-Known Member Most Helpful Member

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    If there is only one diode then my previous post is wrong. Can you post a schematic?

    Does it matter which way round you connect the DC?

    Mike.
     
    Last edited: Jun 18, 2012
  7. Iron Will

    Iron Will New Member

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  8. kinarfi

    kinarfi Well-Known Member

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    show us the face of the meter, what dc voltage are you going measure? The same meter can be used for 10 v or 1000 v, depends on the series resistance to get the correct current. Do you know what the Full Scale voltage or current is? usually shown on the face of the meter.
     

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