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Shutting out mains voltage frequency 50/60Hz

Discussion in 'Electronic Basics' started by Ant_Magma, Mar 7, 2006.

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  1. Ant_Magma

    Ant_Magma Guest

    In this application note by ST

    www.st.com/stonline/books/pdf/docs/1752.pdf

    On page 6, section III- Measure on mains, it used the equation:

    Fc=(Rtotal*C*2*pi)=1.1kHz

    But when i calculated the values 6250*2.2e-9*2*pi, i got 8.639e-5.
    What's wrong?

    Another thing, i thought the equation for cutoff frequencies were
    Fc=1/(2*pi*R*C)?
     
  2. w2aew

    w2aew Guest

    The document is wrong, on two counts! The equation for Fc in a simple
    RC circuit is 1/2piRC as you've stated (they left out the 1/ part, or a
    (-1) exponent). Also, they calculated wrong - it should be 11.6KHz,
    not 1.1KHz.
     
  3. Phil Allison

    Phil Allison Guest

    "w2aew"

    ** Not to mention the danger and stupidity of connecting the chassis ground
    of an Spectrum Analyser to the supply neutral.

    I note the article was written by two frogs.

    Beware - they are really toads.




    ......... Phil
     
  4. Ant_Magma

    Ant_Magma Guest

    D**n!

    The blind leading the blind.

    I wonder how many papers and ANs i have that has such mistakes. Don't
    they ever check before they publish?
     
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