I am just starting to collect parts to build a House power usage system. I find that there three common methods to convert and read the 120 vac with regular analog input.
A. Step-down transformer (9vac) to voltage splitter and full sign wave placed at + 2.5 v offset. Advantage - able to read full wave.
B. Step-down transformer to full wave bridge, cap to average, voltage splitter and 5.1 v zener to protect. advantage -- average RMS DC delivered.
C. Step-down transformer to one diode, voltage splitter. Measure + peak only. Advantage low part count. easy arithmetic to account for .2 v diode drop and 1/2 wave.
Are there other methods? What are your thoughts?