Figure 1 Basic Active Bandpass Filter Circuit

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Figure 2 Complete Active Bandpass Filter Schematic

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This plot is interesting, because it shows how Q and frequency track each other, resulting in a constant bandwidth regardless of frequency setting. It also shows that gain remains constant as the frequency is tweaked. It is also obvious that the peak frequency varies inversely with the square root of R1b. This means R1b should be an audio taper pot rather than linear for smoothest adjustment.