I'm going to reduce my current draw assumption down to 100 mA max, 80 nominal. Should have plenty of margin for my purposes.
With regard to transformers, I'm going to pursue the possibility of using one. I may not, but I at least want to see what the analysis looks like.
I think it might be difficult to select parts/components with 120VAC running across it, but if I can transform it down to 12 VAC that should be much easier to deal with.
Also...I'm concerned about the floating ground on the DC voltage side. Even when I remove the R1 resistor, there is still a diode between the Arduino GND pin and actual GND (never mind the current sense resistor. <= 1 mOhm). What I'm wanting to do is take the voltage across the current sense resistor (which is in the AC side of the circuit), run my -20 to +20 mV through an OpAmp, and get it into the 0-5 VDC range the Arduino needs. Because the Arduino's GND is floating, that means I'll need to not only raise my -20 to +20 mV signal to 0-40 mV, but I'll also need to add in the floating ground as an offset. Are there any good examples on how to do this? Can I simply add a level shift for the Arduino's GND on the DC side to my OpAmp circuit, or will the DC/AC be an issue? Imgur: The magic of the Internet (Also, I understand this circuit does not correct the -20 mV to +20 mV to 0-5V. I'm not there yet)
Am I off base here?