convert dc meter to measure ac

Discussion in 'General Electronics Chat' started by lokeycmos, Jan 29, 2010.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    i have an analog dc amp meter that i want to use to measure ac current. im at a loss of ideas. can anyone give me some advice as how to go about this? i figured i could use diodes, but that would rectify the rest of the circuit as well. TY :)
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Convert AC to DC: Opamp+diode+resistors. google "precision rectifier".

    Sense current flowing in conductor: google "Current Transformer"
     
  3. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    sounds like to much work than its worth for my project. i was hoping something much simpler. Ty for your reply. ;)
     
  4. flat5

    Active Member

    Nov 13, 2008
    403
    17
    How sensitive is your meter?
    What is the expected current range?
    What accuracy do you need?
    I'm thinking put a very low value resistor in series and measure the voltage drop across it with a diode in series with one of the meter leads.
     
  5. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    accuracy isnt a big issue. it is a 50mA movement in 5 mA increments. i made a shunt to make it 1 -10amps in 1 amp increments. the reason i want to do this is to measure the current output on my 7 amp variac. that way i will know when it is close to its limit.
     
  6. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    Put a bridge rectifier in the circuit. AC lines of go in series with load, + and - leads of bridge to shunt., meter across shunt. It is that easy.
     
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