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Homework Help: AC ammeter

  1. May 11, 2010 #1
    Hello all!!!!!!

    I must design an ac ammeter which uses successive approximation ADC,has a specified voltage of 0,15V and individual entrance resistors for measuring currents of 200mA,500mA,1A.

    Any suggestions on how to build such a device would be highly appreciated!
  2. jcsd
  3. May 13, 2010 #2


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    Staff: Mentor

    Welcome to the PF. What can you tell us about A/D conversion? What functional blocks do you need to have outside the ADC for signal conditioning? How do you plan to handle the AC aspects of this design problem? What frequency range AC do you need to handle, and how many bits will you use in your ADC?
  4. May 15, 2010 #3
    I have found the AD572 wich basically is a 12-bit successive approximation integrated circuit a/d convertor.
  5. May 15, 2010 #4


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    Science Advisor

    You could have a look at this post which describes an AC ammeter (1st diagram):


    Read the whole thread here:

    The shunt is optional and the current meter shown just works on DC.

    The shunt could be across the meter if you like. This gives a more linear readout for the meter but results in some drop in the supply voltage due to diode drops.

    For an A to D converter, the meter input should be filtered with a large capacitor to get a steady readout.
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