9. Wiring precautions for vibration sensors

The electrical signals generated by most of these transducers are, before amplification, extremely tenuous: typically, the sensitivity of a small piezoelectric accelerometer of the "Tonpilz" type is only a few picocoulombs per "g", so the charges involved in a current measurement are barely of the nanocoulomb order! Admittedly, this still represents an appreciable number of electrons (whose elementary charge is equal to - 1.6 × 10 ^-19 C), but remains an extremely weak signal for the electron scientist.

In particular, it is of the same order of magnitude as a number of parasitic phenomena:

• the generation of electrical charges by temperature fluctuation (thermoelectricity);

• the generation of electrical charges by relative movements between...