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Amplifier/Electronic question

  1. May 10, 2010 #1
    1. The problem statement, all variables and given/known data

    "The graph shows the characteristics of four different voltage amplifiers (A-D). The input voltage to these amplifiers is limited to between + & - 600mV.


    If you cannot see it properly it also says "If the input voltage is as shown (see bottom graph), sketch the output voltage for amplifiers B and D."
    2. Relevant equations

    Voltage gain = change in output voltage divided by change in input voltage.

    3. The attempt at a solution

    To use B as an example. I've tried finding the voltage gain (rise over run or the formula above) to get 8.33. I then use that as the voltage gain and rearrange the above formula but alas it didn't work. If it helps, the book shows (for B) a peak voltage of 1.8v and a trough of 1.8v.

    Any help would be appreciated.
  2. jcsd
  3. May 10, 2010 #2


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    For B, your rise over the run approach is the way to go. :approve: But you might want to redo the math. :frown: The way I see the figure (which isn't too easy, it's kind of squashed), the output voltages seems to around 5.0 V for an input voltage of around 0.55 V. That doesn't give a gain of 8.33.
  4. May 11, 2010 #3
    It's 5v and 0.6v. :p

    5/0.6 = 8.33.
  5. May 11, 2010 #4


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    Yeah, it's kind of hard for me to see because the figure is squished up. On the other hand, if you use 5/0.55 = 9.09, you'll get the answer in the book. I'm not sure if the book made a mistake in the figure, or the answer, or if it's just because I just can't interpret the figure very well myself.
  6. May 12, 2010 #5
    Thanks for your help.

    I went through with a tutor today and it turns out my system was right in the way of getting it and on an exam I will get a 10% range for graph style questions. I re-drew the graph on graph paper and ended up getting the correct answer.

    Thanks for helping!
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