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Homework Help: Wien Bridge Help

  1. Sep 15, 2018 at 11:59 AM #1
    1. The problem statement, all variables and given/known data

    When testing the circuit of FIGURE 1 (a) it was found that the output shown in FIGURE 1 (b) was obtained when the input was connected to ground.

    upload_2018-9-15_15-18-18.png
    upload_2018-9-15_15-18-50.png


    explain why this was so and attempt an estimate of the capacitance values of C.


    2. Relevant equations


    3. The attempt at a solution
    estimating the waveform as 7ms the formula f = 1/T was used to get the frequency of 142.857Hz

    assuming C1 = C2 and R1 = R2

    the formula f = 1/2πCR was used, rearranged into C= 1/2πfR to give capacitance as 111uF.

    any help is much appreciated in giving me any advice as to whather this is correct.
     

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    Last edited by a moderator: Sep 15, 2018 at 2:20 PM
  2. jcsd
  3. Sep 16, 2018 at 1:14 PM #2

    Merlin3189

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    Homework Helper
    Gold Member

    I don't see T = 7 ms
    I count about 10 peaks in the last 30 ms , or about 3&a bit cycles between 20 and 30 ms.
    I see no R!, R2, C1, C2
    The two R values are given and the two capacitors are marked the same, C , so no assumptions needed.
    Ok formula, but I don't get 111 uF, with either your frequency or mine.
     
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