I just wanted to express my satisfaction with the 8x8 module with the voltage sensor on the Mac. It took about 30 minutes to figure out the connections and the necessary xcode to connect and display the input voltage. I'm mounting a Mac Mini in my vehicle and wanted to make sure the Mac would hibernate automatically when the car is tuned off. By monitoring the voltage from the system I can determine it dropped (alternator) and cause the Mac to sleep. A separate box automatically shuts off the inverter 15 minutes after the car is turned off - plenty of time to issue the hibernate command to Finder.
I will say there was no "explicit" examples of how to use the voltage sensor but the documentation by Phidgets gave enough hints to figure it out with little trouble.