Designing bandpass filters for harmonics Project

Discussion in 'The Projects Forum' started by PMB917, Mar 7, 2006.

  1. PMB917

    Thread Starter New Member

    Mar 7, 2006
    I'm putting together a project for school (ITT Tech Woburn MA) that deals with harmonics of certin tyes of waves. (square, triangle,sawtooth ect.) I need to design variable gain bandpass filters for 2kHz, 4kHz, 6kHz, 8kHz and 10kHz.

    There are a few ways to do this, and I've found one way to do this with only one op amp.

    The only problem here is that they dont give any formulas for setting the center frequency or Q.

    Anyone farmilure with this design?

    I also had another thought to use a multiple feedback bandpass filter design.
    But that would mean I'd need twice the number of op amps to be able to vary the gain.

    I could go sallen key but then I'd be upto 3 op amps per harmonic totaling 14 and theres only so much room on a breadboard.

    anyone got suggestions?
  2. aac

    Active Member

    Jun 13, 2005
    The circuit you posted looks like a version of a twin-t filter. I'm sure you can find the formulas quickly if you do a search on twin-t bandpass.