piezo signal conditioning circuit

hi and thanks for your help! i've applied the modifications you suggested me, but i noticed i wasn't able to simulate the circuit due to a "singular matrix" error. however, here's some thoughts:

  1. i forgot to say i will use the LM324, also because it come in a convenient package of 4 op-amps :slight_smile:
  2. i've increased the value of R$, but do i really need to remove C1? i would like to smooth the incoming signal non to get a series of pulses on the output
  3. despite reading this point many times, i haven't understood
  4. D1 removed :slight_smile:
  5. thanks for the advice, i've put a resistor between the output and the diode to limitate the current

following your advices and messing a bit with the circuit, i end up with this:

as you can see, i put R4 to limitate the input current, i reduced the gain to about 6, i added the current limiting resistor to the output as well as a filtering capacitator. on the simulation everything looks fine, what you you think?