After purchasing SEN-09196 Piezo Vibration Sensor, I decided the use the below circuit with the help of LM393 as the voltage comparator so that the digital input signal can be sent to the arduino.
https://img.alicdn.com/imgextra/i4/3611 … 121710.jpg
However, after I replace the vibration sensor at the position 傳感器, there is no digital output signal come out from the DO pin when I try to deflect the sensor. Can anyone explain the reason? Is it the signal voltage too low for the LM393?