DC proportional to AC voltage

Discussion in 'General Electronics Chat' started by vks_foe, Mar 8, 2009.

  1. vks_foe

    Thread Starter Active Member

    Jan 11, 2009
    55
    5
    Hi,
    i have to measure an AC voltage of peak 325 volts(230V rms) and get a DC equivalent of smaller magnitude.

    i.e. for AC 230V rms...... DC o/p = 2 volts.
    Also the DC output should vary linearly either with AC peak or AC rms.

    Suggestions please.
     
    RRITESH KAKKAR likes this.
  2. DedeHai

    Active Member

    Jan 22, 2009
    39
    0
    very simple solution:
    use a diode to cut off the negative half-waves, connect it to a capacitor to charge it to the peak voltage and use two resistors as a voltage divider. you may even use a trimmer as one of the resistors to adjust the desired output voltage (if needed)
     
  3. vks_foe

    Thread Starter Active Member

    Jan 11, 2009
    55
    5
    Will the sensitivity be good???
    i want 2 volts DC for 230 V AC.... that has to be fed to an error amplifier.. so the Dc voltage should be fairly stable and flat ... using capacitor can removes ripples but i fear that sensitivity will be poorer.
    Even a 1 volt change in i/p(230 rms) should be detectable...
     
    RRITESH KAKKAR likes this.
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Use a step down transformer to reduce the AC voltage and for safety. Make the output on the order of 6 VAC. Use two op amps to make a precision rectifier and absolute value circuit. Gain in the absolute value stage can be adjusted for your 2 VDC output equivalent to 230 VAC in.
     
    RRITESH KAKKAR likes this.
  5. vks_foe

    Thread Starter Active Member

    Jan 11, 2009
    55
    5
    THANKS for all your replies!!
     
    RRITESH KAKKAR likes this.
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