Choose device values given Vin and Vout

Discussion in 'Homework Help' started by applefat, Oct 12, 2007.

  1. applefat

    Thread Starter Member

    Oct 12, 2007
    10
    0
    Hello;

    I've really been pulling my hair on this AC analysis design question, though I assure you I have put in a significant amount of effort before coming here. The attached circuit is VERY simple, so I clearly must be making the same mistake over and over.:confused:

    What I've tried to do mainly is approach it like a reverse thevenin-equivalent problem, but instead of having to find Vo, you already have it. Then you choose a value for one of the resistors and go from there, using impedance, but I absolutely cannot get a reasonable answer (that is, POSITIVE resistances and REAL capacitance!)

    I've tried nodal, thevenin, and mesh (simultaneous equations), but the latter especially went nowhere fast.

    Please, anyone who can point me in a good direction for properly approaching this problem will earn a huge amount of appreciation!!!
     
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  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    Is the voltage out 25 volts, or 2.5?
     
  3. applefat

    Thread Starter Member

    Oct 12, 2007
    10
    0
    2.5, sorry. The part after the @ is the phase btw, if that wasn't completely clear.
     
  4. techroomt

    Senior Member

    May 19, 2004
    198
    1
    are you positive about that phase number of 104 deg? i did not think reactance could cause any more then 90 deg phase shift, and even then it is only ideal.
     
  5. applefat

    Thread Starter Member

    Oct 12, 2007
    10
    0
    Yep, it's what the assignment sheet tells me anyway, and while it could be an error, he isn't really known for them...

    The functions:
    Vi = 12cos(1000t) V
    Vo = 2.5cos(1000t+104) V
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    That's a head-scratcher - I thought RC combos only approached 90 deg phase shift. I'm glad I never had to mess with those school problems.
     
  7. Distort10n

    Active Member

    Dec 25, 2006
    429
    1
    You sure this is not a trick question? You cannot have anymore than 90 degrees of phase lag with a capacitor.
     
  8. applefat

    Thread Starter Member

    Oct 12, 2007
    10
    0
    Hmmm, interesting insight... I will email the instructor, thanks for the clue guys.
     
  9. The Electrician

    AAC Fanatic!

    Oct 9, 2007
    2,281
    326
    If you make R1 a negative resistor it can be done. :)
     
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