Balanced microphone input solves clicks and noise. R6 and R13 should be equal to R5 and R12, respectively. Typical values ​​are 10kΩ to 22kΩ.
While some meters may provide only amperes or voltage, a panel mounted power meter delivers additional value by providing real-time, true-RMS measurements of current, power, voltage, energy and many other parameters.
Panel Mounted Power Meter,Digital Panel Power Meter,Led 3 Phase Panel Power Meter,Three Phase Power Meter Jiangsu Sfere Electric Co., Ltd , https://www.elecnova-global.com
Photocoupler 
