This is the actual implementation of the signal input board using an Arduino-based microcontroller.I have chosen Arduino Mega 2560 as the microcontroller board due to the relatively high number of analog inputs built into the main board.
Parts:
Arduino Mega 2560
6.5mm input jack
1MOhm resistor
Other
A sample photo from Arduino edrum project. Another one. Displays the main concept of connecting a piezo sensor to Arduino. This solution also uses multiplexer.