piezo signal conditioning circuit

Other Hardware General Electronics
10

  1. Putting a capacitor in series with the piezo will make the signal smaller, not larger.

  2. Ideally you should choose R3 and R4 so that the total resistance seen by each input of the op amp is the same. That way, the effects of input bias current cancel out, minimising the offset voltage at the output when there is no input. Currently, pin 2 sees 410K and pin 3 sees about 8K (10K in parallel with 33K). So you should increase R4 to about 1.6M and R3 to about 510K, aiming for R3*R4/(R3+R4) = R1+R2.