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Amplify AC Signal

Discussion in 'Electronics & Electrics' started by Renza, Mar 19, 2015.

  1. Renza

    Renza Member

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    I need some help from some of you electronics wizards out there!

    I have a 0.333vac RMS signal from a current transformer (0.333v at peak current). I need to amplify this to 3.33v peak to peak with a DC bias of 1.66v.

    Pretty much, I have this:

    [​IMG]

    and I want to amplify it to this:

    [​IMG]

    Is there an easy way to do this with minimal components? Maybe a single opamp?

    Bit out of my depth here so sorry if I say stupid things :upset:
     
    Last edited: Mar 19, 2015
  2. dakiller

    dakiller (Oscillating & Impeding)

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  3. OP
    OP
    Renza

    Renza Member

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    Last edited: Mar 19, 2015
  4. dakiller

    dakiller (Oscillating & Impeding)

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    That is a good paper.

    You want the circuit "Inverting Amplifier (AC Coupled)"
     
  5. OP
    OP
    Renza

    Renza Member

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    Thanks, that's helped heaps!

    I have kinda got the result I wanted:

    [​IMG]

    I have used random values for the resistors and caps. Not really sure what they should be either. Also not sure what I opamp I should select, probably want a quad channel one if possible.

    [​IMG]

    Thanks again, your help has been invaluable!

    edit: Is this Opamp suitable? http://docs-asia.electrocomponents.com/webdocs/1381/0900766b81381145.pdf
     
    Last edited: Mar 20, 2015
  6. dakiller

    dakiller (Oscillating & Impeding)

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    What voltage supply do you have, and what frequency will you be using?

    Because any common opamp isn't going to run at 3.3v and isn't going to be able to swing its output to the rail as they call it (most opamps can only output 1v less than their power supply at max, one that can go all the way are called rail to rail)

    Just looked at that opamp, and I think it will work actually. Goes down to 1.8v and Maximum Output Voltage Swing is to within 25 mV of the rails. The stuff you find at the likes of Jaycar are old and low performance opamps, and you need to be careful that they will work for your application.
     
  7. OP
    OP
    Renza

    Renza Member

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    3.3 v supply and 50hz, nothing high frequency. Yep that's a rail to rail opamp so I think it should do what I want.

    Will be ordering from e14 or RS. dont even bother with jaycar these days unless I need something now!
     
  8. starkers92

    starkers92 Member

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    Are you doing this to measure with an ADC? If you are you could also use a ADC with a negative rail, however I could just be having a stab in the dark here :thumbup:
     

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