cutoff frequency of low pass filter

Discussion in 'Homework Help' started by rondo1994, May 1, 2014.

  1. rondo1994

    Thread Starter New Member

    Apr 6, 2014
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    how do i determine the cutoff frequency of this circuit, the answer given is fc=4.226 Hz
     
    Last edited: May 1, 2014
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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    hi,
    I guess you meant the title to be high pass filter.?

    What do calculate the Low frequency -3dB point to be .?

    E
     
  3. rondo1994

    Thread Starter New Member

    Apr 6, 2014
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    Ya, high pass sorry about that.
     
  4. ericgibbs

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    no problem:)

    Post your answer, we can check it for you.?
     
  5. rondo1994

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    Apr 6, 2014
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    Yes, i don't know how the resistor connected in parallel with the capacitor affects the value.
     
  6. ericgibbs

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    Do you know how to calculate the impedance Xc of the 10uF cap.?
     
  7. rondo1994

    Thread Starter New Member

    Apr 6, 2014
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    yes 1/(2pifc)
     
  8. ericgibbs

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    Ok,
    As this is homework I cannot give you the answer, but consider.

    What the attenuation in the Output when the Freq=0 , also whats the attenuation when the Freq > 1000Hz.??

    This should give you a clue that some value of Xc will give an attenuation of 0.5.
     
  9. rondo1994

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    Apr 6, 2014
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    what does the resistor connector in parallel to the capacitor do then?
     
  10. ericgibbs

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    At Freq=0 the Xc is infinite, so the attenuation ratio from input to output is 1:0.5

    At Freq > 1000Hz, the Xc can be assumed close to zero, so the attenuation ratio is 1:1
     
  11. atferrari

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    Jan 6, 2004
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    Hola Eric,

    I am surprised I completely forgot how to suscribe to a thread (this one in particular now) other than posting in it. (?)

    Could you please tell? Gracias.
     
  12. ericgibbs

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    Jan 29, 2010
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    Hola Agustin.
    I am sorry I dont know.:(

    Perhaps a Mod may point us both in the right direction.

    Eric
     
  13. rondo1994

    Thread Starter New Member

    Apr 6, 2014
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    Ok solved it using transfer function thx.
     
  14. ericgibbs

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    hi,
    Could you post your calculations, it could help other students.:)

    E
     
  15. atferrari

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    Hola rondo,

    Out of curiosity I would like to see that!

    Gracias.
     
  16. anhnha

    Active Member

    Apr 19, 2012
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    Hi.
    You may try this.
    [​IMG]
     
    atferrari likes this.
  17. atferrari

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    Jan 6, 2004
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    As usual, just in front of me.

    Gracias!
     
  18. jjw

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    Dec 24, 2013
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    3dB point is at 1/sqrt(2) ~ 0.707
     
  19. jjw

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    Dec 24, 2013
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    Did you get the same answer 4.226 Hz as in your first message?
    I got a different answer.
     
  20. WBahn

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    Mar 31, 2012
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    When viewing a thread, go to the top of the first post on a page and select "Thread Tools". One option is to subscribe to the thread.
     
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