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Homework Help: Why do I get different answers with different methods - Thevenin

  1. Dec 18, 2017 #1
    1. The problem statement, all variables and given/known data
    Determine the Thevenin equivalent of the following circuit:
    https://imgur.com/a/74UjA (Top image)

    upload_2017-12-18_9-53-13.png

    2. Relevant equations
    -

    3. The attempt at a solution
    The last 3 images in the Imgur album are all different approaches.

    I can't figure out what the right one is, and why the other ones are wrong. I spent hours searching on google, and I feel like I understand Thevenin/Norton well -now I am not so sure..-, but to no avail.

    Extra information:
    - Ub = Usource
    - "zal door Rv gaan" means "will pas through Rv"

    EDIT: I think my second attempt is correct. Uth = 5V. The 1st and 3rd method are presumambly wrong. I sort of have an idea of why, but I am still not 100% convinced.
     
    Last edited by a moderator: Dec 18, 2017
  2. jcsd
  3. Dec 18, 2017 #2

    CWatters

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    Science Advisor
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    Can you write down the steps you are taking eg...

    1) Remove load resistors (none to remove in this case)
    2) Replace current sources with..

    etc
     
  4. Dec 18, 2017 #3

    gneill

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    Staff: Mentor

    Hi Yealtas,

    Please upload your images and embed them in your posts as local attachments. You can use the UPLOAD button at the bottom right of the edit window.

    We find that off-site stored images and documents have a tendency to "evaporate" over time, rendering their threads here nearly worthless to members who come across them in the future.

    Thanks.
     
    Last edited: Dec 18, 2017
  5. Dec 18, 2017 #4

    CWatters

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    Yes and Rth = 5500 Ohms.

    Re: First image/attempt: You appear to be shorting the output to calculate I5 when you should be calculating the open circuit voltage (so I5 = 0).
     
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