I have some questions regarding my assembly and especially on the role of the capacitor within the circuit.
Before I added the capacitor I encountered 2 issues:
- when the piezo was squeezed (a pulse is generated) then the pressure was maintained for some time and then released, the piezo generated a positive pulse that I wished to get rid of.
- when the pressure was maintained on the piezo film, I had such a sensitivity that the LED was still flashing. The brightness was weak though.
Adding the capacitor fixed these issues but I can’t explain why for the 1st one or rather I don’t know why. Of course, why I added the capacitor was for the 2nd point, I wanted to discharge this phenomenon through a capacitor. And it's working well.
And also I don’t get why since I’ve added the capacitor, the voltage seen on the oscillator is different. It’s pretty low now around 20mV while without the capacitor I have an input voltage of 20 mV to 800 mV depending on the pressure applied on the piezo film and an output voltage (right after the op amp) around 2.5V-2.8V.
Thanks in advance ;)