Sensing Sound – Knock Sensor

We can use a simple piezo contact as a sensor as well as a speaker – that is – it is a microphone as well as a speaker and we can use it to detect sound. This work very well as a movement sensor and the little piezo work very well to detect quite low level vibrations when sticky taped to a floor or on a mat.

The one thing to watch out for is that they are also sensitive little components that have a ceramic surface that can crack if stepped on or bent in anyway. They are all very very cheap and so are a great sensor to experiment with.

As analog sensors they are also very rich in the data they provide – but that means we will have to map the values – that is work out what the important threshold levels are that we’d like to trigger particular events.

Its connection and code is very much like the photoresistor although in the case we will use a 1M Ohm resistor.

Check out the details here.