  A simple and inexpensive system capable of displaying relevant power quality
data of a residential voltage signal is presented, and it is based on Arduino,
Python and Kivy. A circuit for adjusting the voltage signal for sampling is
suggested. The software of the system allows the transmission of data with any
device capable of serial communication at a 2000000 Baud rate, although an
Arduino NANO/UNO board is recommended A board based on an Arduino NANO R3 was
used. The software plots the last 6 cycles contained in the data by default,
but lets analyze any amount of cycles. It provides the RMS voltage, the peak
voltage and the total harmonic distortion of the scrutinized cycles, up to the
25th harmonic. The software is also capable of calculating the fast Fourier
transform of the studied cycles, and returning the corresponding plot. A sample
of data captured at Maracaibo, Venezuela is shown.
