dc42:
- You need a resistor in parallel with the piezo, or alternatively from pin 1 of the op amp to ground. See my previous email. Without this, the circuit won't work at all, the output will go to +5v after a short while and stay there. Your simulation is incorrect because you have simulated the piezo as a voltage source, instead of a voltage source in series with a capacitor.
- today i tried again and i got that unknown error (singular matrix): i tried putting and removing many components, but it seems that it comes out whenever i put that capacitor in series, that's why i couldn't simulate the piezo correctly, as you adviced me. Thanks again for the corrections, il'll put a resistor in parallel with the piezo. are 100k, 470k or 1M good values, or it has to be smaller? also, why is it needed?
dc42:
unless you hit it
- that's what i'll do
