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Question with my circuit in multisim dealing with op-amp

  1. Aug 21, 2011 #1
    I am drawing a circuit but not getting right result. I am to assemble the circuit below using +-10V supplies with all those specifications I have put in. I leave Node A open and adjust R4 to make Vc=0V. When I measure Vc originally it is about 10VDC(on the DVM). If I use a 100M resistor it only makes it about 3V. What is wrong with my circuit(the second link)?

    http://i812.photobucket.com/albums/zz41/uofmx12/E21ckt.jpg [Broken]

    My circuit:
    http://i812.photobucket.com/albums/zz41/uofmx12/E21ckt_2-1.jpg [Broken]
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Aug 21, 2011 #2
    V2 is upside down. You are supposed to have one end of the potentiometer be at +10 V, but you connected the + end of the +10 V supply supply to ground.

    Also, you have not connected anything to what I presume are the power supply pins for the amplifier symbol.
  4. Aug 21, 2011 #3
    Ok, so I changed the V2 supply. And I am getting about 88mV DC without the +-10 supply to the op amp and about 75mV DC with them connected. But for some reason when I change R4 resistor the the Vc voltage does not change from either 75mV or 88mV no matter what I change the resistor to. So I imagine something is still wrong.
  5. Aug 21, 2011 #4
    I figured it out
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