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Switching Frequency Problem

  1. Nov 23, 2015 #1
    1. The problem statement, all variables and given/known data
    Problem and Diagram stated below
    System 2 Input Impedance: 1k ohms
    System 1 Output Impedance: 100 ohms
    High interpreted as Voltage greater than 2V
    Low Interpreted as Voltage less than 0.5V

    switchingfreq.png

    2. Relevant equations
    Capacitor Charging eqn:
    V=Vo(1-e^-t/RC)

    Capacitor Discharging eqn:
    V=Voe^-t/RC

    f=1/T

    3. The attempt at a solution
    Posted Below

    Scan0009.jpg

    Scan0010.jpg



    Hey guys. This was a problem given to us on one of our assignments and that was my suggested solution...was wondering if what I did was correct.

    Thanks in advance :D
     

    Attached Files:

    Last edited: Nov 23, 2015
  2. jcsd
  3. Nov 24, 2015 #2

    BvU

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    Long story ! Some comments:

    First thing that comes to mind for me is the ##\tau## : you sure it's from the 100 Ω only and not the 110 Ω ? (test: let Rin = 1M Ω !)

    Second: no need for the ##\approx.## sign. Everything is given 'exactly'. Idem for increasing the 2 * 11/10 to 2.3 and decreasing the 0.5 * 11/10

    --
     
  4. Nov 24, 2015 #3

    gneill

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    Staff: Mentor

    As BvU points out, you need to take a closer look at how you determine ##\tau##. Suggestion: find the Thevenin equivalent that the capacitor sees. Note that this will include the load-side resistors too!
     
  5. Nov 24, 2015 #4

    BvU

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    Good thing gn is on the lookout ! I had forgotten those load side guys. Rustiness....
     
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