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Write Differential Eq ?

  1. Jun 25, 2012 #1
    Hi ,
    Can anyone help me on this problem please?!
    Answer is given but i want to know steps to come to it, i think i tried a lot to solve it but i couldnt come to the given result.
    Thanks to all
     

    Attached Files:

  2. jcsd
  3. Jun 26, 2012 #2

    tiny-tim

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    hi xmenus! welcome to pf! :wink:

    show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
     
  4. Jun 26, 2012 #3
    Here's the link of doc..I think i tried loop method and many other forms but.... here i just showed the analogy i tried but i couldnt come to the result.(First circuit is different one)
    I took an other example just to show or ask if the other circuit can be solved with the same analogy?!

    https://www.dropbox.com/sh/7g4vmpl4uhjbyl4/wwNdGrKm5o
     
    Last edited: Jun 26, 2012
  5. Jun 26, 2012 #4

    tiny-tim

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    it's rather difficult to read :redface:

    anyway, what is D ? :confused:
     
  6. Jun 26, 2012 #5

    psparky

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    That's a tough circuit you posted for finding a differential equation.

    Don't know for sure....but perhaps a node analysis on the upper right hand node? Current in equal current out sorta thing.

    Using SL and 1/(SC) may simplify things as well.
     
  7. Jun 26, 2012 #6
  8. Jun 26, 2012 #7

    tiny-tim

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    ah, D = d/dt !

    ok, you've replaced C and R3 (in series) by an impedance Z1

    (btw, wouldn't Z3 be an easier name to keep track of? :wink:)

    then you've replaced R2 and Z1 (in parallel) by Ze

    but then you've stopped (presumably you're going to replace L and Ze, then replace that and R1?)

    well, that looks fine so far :smile:

    what's the difficulty?​
     
  9. Jun 26, 2012 #8
    The problem is that it's not working like that.I cant come to the result, i dont know!?
     
  10. Jun 26, 2012 #9

    tiny-tim

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    but you stopped, you only got as far as Ze :confused:
     
  11. Jun 26, 2012 #10
    No,actually i worked on it till to the end but the result i got is not like the given one.
    You are right, i didnt post other steps,but on that way it didnt work!
     
  12. Jun 26, 2012 #11

    tiny-tim

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    we can't comment on why it didn't work unless you show us what you did
     
  13. Jun 26, 2012 #12
    Finally,after many attempts, i solved it :D !

    I might post the solution so anyone can find it useful maybe.
    Thank you a lot anyway,and thank for your time!
     
    Last edited: Jun 26, 2012
  14. Jun 26, 2012 #13
    Solution is in .pdf file.

    Regards
     

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