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Homework Help: Help designing a RC passive high pass filter

  1. Feb 7, 2007 #1
    1. The problem statement, all variables and given/known data

    I was asked to desing a RC passive high pass fiilter with a cutoff of 3KhZ.

    2. Relevant equations
    The formula for Fc = 1/(2piRC)

    3. The attempt at a solution

    I set 3kHz = (1/(2piRC)) but am not sure what to do next. Do I pick a random cap or resistor value and solve?
  2. jcsd
  3. Feb 7, 2007 #2
    Is that it? Nothing else, no mention of impedances, voltages, anything?
  4. Feb 7, 2007 #3


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    Since resistors cover a larger range of commercial values, you should pick a reasonable value for the capacitor and calculate the corresponding resistor.
  5. Feb 7, 2007 #4
    Look up the standard ranges for electronic components, E12, E24 etc...
  6. Oct 21, 2007 #5
    Sorry to dig up a really old thread... I found this site via Google.

    I want to use this formula:

    Fc = 1/(2piRC)

    to determine the corner frequency of a passive 'tone control' circuit as commonly used in electric guitars (a low-voltage AC circuit).

    What I don't know about the formula is what the proper units are for R and C.

    Is R in ohms? Thousand ohms?

    Is C in farads? Microfarads?

    An example would be a very common one:

    A 500k ohm potentiometer, and a .022uf capacitor.

    Plugging the numbers into a the formula isn't a problem - I just don't know what the units are supposed to be...
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