1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Am I in right direction?

  1. Oct 26, 2009 #1
    Set R1 = R2 = 500 ohms, then choose any R3 and plot I versus V1 and V2 for V1 and V2 are between 1 and 2 volts until you find a value of R3 that limits the magnitude of the current to .5 to 2mA.

    DP45-1-1.jpg ; DP45-2.jpg


    KCL
    i1, i2 = inv(A)*x
    i = i1 - i2





    I made some large changes and found a few errors with my previous attempt so I deleted that photo and added the new photo of my current work. The equation was derived from using the formula above in reference to matrices. My question is whether or not this is accurate and if so why are my values off? The closest value i can determine is when R3 = 1000 however it doesn't give me i from .5 to 2mA (0.0005 to 0.002). Checking from the extreme values of the source voltage when R3 = 1000:
    Low: v1 = v2 = 1, i = .0008A
    High: v1 = v2 = 2, i = .0016A
     
    Last edited: Oct 27, 2009
  2. jcsd
  3. Oct 26, 2009 #2

    berkeman

    User Avatar

    Staff: Mentor

    Sorry, I'm not understanding your problem statement. V1 and V2 both can vary between 1-2V? What does your notation "V1 = 1:0.01:2" mean?
     
  4. Oct 26, 2009 #3
    sorry it's a matlab notation I'm using. It means V1 = 1 to 2 in increments of 0.01. The incrementation is for me when I'm plotting the function.
     
  5. Oct 26, 2009 #4

    berkeman

    User Avatar

    Staff: Mentor

    Can you post your MATLAB plots?
     
  6. Oct 27, 2009 #5
    I only have MATLAB on my laptop and haven't had a chance to plot the function yet but if you take the extreme values as I have with v1=v2=1 and v1=v2=2 that will tell you the range of the function.
     
    Last edited: Oct 27, 2009
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook