This low cost module measures the short-term accuracy of 60 Hz sources. A bright bargraph indicator displays variations around the ideal frequency.
Many devices make use of the 60 Hz waveform from the local power utility
as a timing standard. While the long-term accuracy of this source is assured
through periodic adjustments made to the power grid, there is significant
drift above and below the expected norm throughout the course of a typical
day. This useful tool shows at a glance whether the power line frequency
is currently above or below 60 Hz in 0.005 Hz increments (1 part in 12000).