Piezo vibration sensor board negative values
With this circuit you even can't get the positive values, only a digital signal that tells whether the input signal goes above some fixed threshold level. The threshold can be adjusted by R6.

The LM293 is a comparator that checks whether the negative input (pin 2) is higher than the positive input (pin 3). So the output is purely digital (i.e. 1 or 0).

You could, however, pick up an analog signal at the output of the OpAmp U1B (pin 7).