Circuit Analysis (First time post so hope I get this right!)

Discussion in 'Homework Help' started by Zumii, Apr 19, 2007.

  1. Zumii

    Thread Starter New Member

    Apr 19, 2007
    I have a circuit that I need to solve for the current in the load resistor, firstly using norton's or thevenin, and then by using mesh / nodal or superposition.

    The main reason I need help is that I have had a long break from college after a car accident, and can not find my notes on these topics...hehe and a bit embarrassed to ask my course tutor now that this is over a year overdue.

    I have spent some time finding info on the net and have made some progress, but any hints or suggestions would be more than welcome.

    I do not want solutions or anything, but am more interested in a plan of attack or adjustment of my thoughts on how to solve the problem that I am attempting as follows, as I feel I am missing something important or doing something moronic.

    First, a very bad drawing is attached, hopefully all info is clear.

    I am trying to use thevenin's theorem, and removing the capacitor and right hand side voltage source, calculate the inductor and resistor in parallel, then calculate with the capacitor.

    Then reverse this process, eliminating the left voltage source first and proceeding from there, finally combining both results to get the value of I for RLoad. (or am I making this all too complicated?)

    If anyone knows of a location of a roughly similar problem I could look at anywhere that is roughly similar maybe this would be easier, I have not been able to find a similar enough problem to analyze and compare with. :(

    I have found this site the most helpful so far with regards to getting closer to solutions, and any help would be most appreciated.
  2. recca02

    Senior Member

    Apr 2, 2007
    try reading the online tutorials on this site.
    the thevenin's example is quite similar(so may be the others).
    in case ur problem persists, feel free to ask.
  3. Zumii

    Thread Starter New Member

    Apr 19, 2007
    Thanks for the pointer to the tutorials....
    So, to start, finding the current...

    1. Remove load resistor (snip) label A and B
    2. Calculate series LC circuit with voltage of 15 (10 and 5 combine?) giving 15 + j0 V, for j3 and -j2 to find Thevenin Impedance (Zth)...

    Having a bit of confusion with this, but i think i might have it now....

    Xl = 6.283 + j3
    Xc = 0.159 - j2

    Hence Zth = Xl + Xc = 6.442 +j1

    3. Then replace resistor, and add to Zth giving 16.442 + j1

    4. using Ohms Law I= E / Z = 15 + j0 / 16.442 + j1 = 0.912A....+j1??

    :) ??
    Comments appreciated.
  4. recca02

    Senior Member

    Apr 2, 2007
    abt the circuit dia
    have u clearly mentioned all details abt the sources (i m confused voltage source )
    assuming voltage sources.
    i= 15<0/j (can u ppl use casio fx 991 series then u wont need to do all
    convn :) )
    vth=10<0 - 15<0/j*3j
    zth= j3*(-2j)/j

    i think that shud be it (i havent solved networks for quite some time and hence i
    may have done some trifle mistake)

    ok let me explain it (u may get a correct answer since i didnt solve on paper)
    5<0 + 10<0
    ------------- (after removing load)
    now remove sources and short (assuming voltage source)
    the net impedance looking from load will be j3 ll -2j.