The quality of the AC powerline voltage is something that worries more people than you would think. It is said that in most countries the line frequency is extremely stable, but that does not mean that there are no variations. Because of its rather low repetition rate measuring the grid’s frequency seems easy enough. However, doing it accurately requires a stable and accurate time reference and a stable trigger point. The author of this project has been working on the subject for several years now and he recently posted new software for his grid frequency meter. Read more on Elektor.Labs…