I would like to do some monitoring of power line conditions. To start with, I just want to monitor and record the voltage wave form on the two split phases. I would dedicate a small computer to the purpose. The idea is to reduce the voltage from the power line in a safe way and feed that through the audio input of the computer. A program would then capture that audio input, compress it in a lossless manner (a 60 Hz sine wave should be very compressible), and store it on disk space to be fetched by another computer over the network on a regular basis. I'm not sure what I will get out of it. But I just want to tackle the issue of getting it in a reliable and safe way for now. In particular, I want to know what method might be best for reducing the voltage and still not alter the waveform any more than would be acceptable. Would a transformer be adequate for this, especially if it is kept well away from the saturation level? Or would it be best to have a resistor divider network? I don't even know what impedance and levels the audio inputs have, yet. But I know I don't want to go buy the off-the-shelf device I once saw, since it could not be automated as I would want (had to manually move a memory device from the unit to the storage computer, which would apparently also mean a gap in measuring), and it would cost $3500.00 for this inconvenience. I figure I could do better with $50 of parts and an old used netbook worth maybe $100 today (and feel safe about fetching the data via wifi). One motivation to do this is that at different times, I detect behavior of different devices changing, presumably due to changes in the electricity. Sometimes my UPS clicks over to battery and back off again. Was there a transient? A couple lost cycles? Sometimes my lights just dim for a while. Sometimes my fan in the floor pumping air into a small room I use for a couple computers will slow down and speed up. These different things do NOT happen at the same time so I am curious about this. Voltage change? Transient? Frequency change? Any suggestions to set up power line monitoring like this?