Reliable readings from Arduino voltmeters

Abstract Modern instruments use sensors, analogue and digital electronics, and digital processing to measure almost any kind of physical quantities. Arduino is a very useful and widely used platform to build such systems in a school environment. Since it has analogue voltage inputs, it can be used as a digital voltmeter or even as a chart recorder. However, the ways of ensuring the required level of accuracy or just the right estimation of accuracy are often unknown or misunderstood. In this paper we try to fill this gap to aid reliable school experimentation.