Whilst the majority of my components are being shipped over from China (transcievers, MCUs, vibrating motor) I thought I would see how far I could get with configuring the piezo sensor.

A circuit diagram and code will follow. However, the sensor itself will hopefully be powered by an ATTiny85. In the meantime I shall be using an ATMega168-20PU as that is all I have to hand.

Having wired up the piezo sensor in a voltage divider setup (1MΩ resistors) and connected it to the Analog Digital Converter of the ATMega the piezo sensor could pick up fairly loud sounds (as indicated by a flashing LED) when taped to my kitchen table.

However, the setup was nowhere near sensitive enough. Swapping out the resistors for 10MΩ resistors did the trick too well to the extent that it would pick up the workmen next door with their incessant hammering and off-tune singing (honestly guys - it's 11pm - go home already!).

Sensitivity is clearly going to be an issue and will obviously depend upon what device the sensor is attached to. Conclusion - I need to order some potentiometers so that sensitivity can be altered on the fly. Back to eBay I go.