Audio filter from 1Khz to 7 Khz

Discussion in 'The Projects Forum' started by august, Aug 9, 2009.

  1. august

    Thread Starter New Member

    Aug 8, 2009
    2
    0
    Please help i am newbie here. I need design audio filter which only work in 1 Khz till 7 Khz. Can anyone here help me pls!

    thx!

    august
     
  2. fanie

    Active Member

    Jan 20, 2007
    63
    0
    Nice excuse :D

    Do a search for Filter Lab. You can design a high and low pass filter from that.

    There are about 3 different filter programmes (freeware) you can use. Some just works easier
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    I think you will have to split it up.
    Use a highpass filter of 1 kHz with a lowpass filter of 7 kHz behind it.

    Here is a page from the EDUCYPEDIA with information on filters.
    http://www.educypedia.be/electronics/analogfil.htm

    Greetings,
    Bertus
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,685
    900
  5. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
  6. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,957
    1,097
    Maybe this circuit will be enough
    [​IMG]

    R1=\frac{Q }{2*\Pi*F*C1*Ku}

    R2=\frac{Q }{2*\Pi*F*C1(2*Q^2-Ku)}

    R3=\frac{Q }{\Pi*F*C1}

    Or simplified equations

    R1=Xc*\frac{Q }{Ku}

    R2=Xc*\frac{Q }{2*Q^2-Ku}

    R3=Xc*2Q

    Where:
    C1=C2
    Xc=\frac{1 }{2*\pi*F*C}

    Ku=gain

    B=Bandwidth=Fg-Fd=7KHz-1KHz=6KHz

    Fo=4Khz

    Q=\frac{f0}{B}

    f0=\frac{1}{2*\Pi*C}*\sqr{\frac{1}{R3}*(\frac{1}{R1}+\frac{1}{R2})}

    Or this simple circuit

    [​IMG]

    FL= lower cut-off frequencies = 0.16/(C1*R1)

    FH= upper cut-off frequencies = 0.16/(C2*R2)

    Au=gain=R2/R1​
     
  7. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    You can also read the attached PDF from TI on filter design.

    Greetings,
    Bertus
     
  8. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    It would be useful for you to provide us with some information on your application for this band-pass filter.

    hgmjr
     
  9. august

    Thread Starter New Member

    Aug 8, 2009
    2
    0
    Thx A lot!:)
    I want use this filter for My Swiftlets sound system.
     
  10. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    I favor the approach recommended by bertus.

    hgmjr
     
  11. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,685
    900
    FilterPro by TI and sloa096 (filter design application note by TI) are joined at the hip, so to speak.

    Going through the calculations can be fun. The sequential process for a design described in the note is particularly helpful. FilterPro gives a graphical presentation of the response and calculates the gain bandwidth product (GBP) needed for the op-amp. I found the comparison of filter types and ability to readily observe how the response changes with different variable inputs particularly educational.

    I suggest the OP go through the calculations for a simple design, but then use a program such as FilterPro to finalize his design. Note especially the effect of component tolerances on your actual results. You may need to tweak some values.

    John
     
Loading...