Modification of Sonoff Pow R2 to connect CT sensor and measure AC power.
It might be useful when measuring higher power than 15A Sonoff can handle or when you can not cut AC line wires. Original Sonoff shunt circuit inside can be left untouched, need to solder only two wires inside.
Circuit diagram, left is CT sensor circuit and right part of original Sonoff circuit chip CSE7759B. During calibration you can connect some know loads like 40W bulb and coffee water heater 1KW, in both cases in eWelink app you should get as much as possible close values, if values not close enough CT sensor resistors might need to be changed.
