Thought about that, but i don't have one and my project is super temporary--hence 0 cost is ideal.
Basically my fridge is running odd and i want to monitor temperature and when the compressor is on. I've got a thermistor measuring temp and plotting temp every min on an LCD display (and saving the data to and SD card so I can plot temp vs time over say 3 days), but i'd like to plot compressor on/off with temp as well--hence why i need to determine when it's powered up.
I'll just give it a shot.
Thanks for responding.