Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Simple Op Amps questions

  1. Jun 17, 2006 #1
    ok, can someone explain these two circuits?

    should be pretty simple, but i can't seem to do it right... the book im learning from doesn't have the full solution, so i have to guess what's wrong with my calcs, and i don't think it'd be a good idea to learn like this to my exam...

    i'll explain what i did:
    for the second one with the V_ref on both sides:
    the v_out due to V_in and V_ref i'd get [tex]\frac{(V_{in}+V_{ref})R_F}{R_G}[/tex]
    and due to the other V_ref i'd get [tex]\frac{-V_{ref}R_F}{R_G+R_F}\frac{R_F}{R_G}=V_out-\frac{-V_{ref}R_F}{R_G+R_F}[/tex]
    because [tex]\frac{V_{ref}R_F}{R_G+R_F}[/tex] is the voltage of the entrance to the Amp, so the current would be [tex]\frac{-V_Amp}{R_G}[/tex] and so the voltage in V_out would be... oops, now that i explained what i did i found the problem.... i thought the voltage in the Amp is zero, but it isn't for the second time...
    no i add them and it's fine

    i'll write in a bit what i did for the other circuit... i nust run...

    [EDIT]
    you can just ignore this whole silly post... i found my error, just needed to go out with my friends and see a stupid movie to clear my head, i feel like so stupid i got stuck with such a simple circuit for so long...
     

    Attached Files:

    Last edited: Jun 17, 2006
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you help with the solution or looking for help too?
Draft saved Draft deleted



Similar Discussions: Simple Op Amps questions
  1. Op amp question (Replies: 13)

  2. Question about Op-Amp (Replies: 7)

  3. Op Amp Question (Replies: 1)

Loading...