thanks for you all
i am working on graduation project and calculating power is a part of it .
i need to connect isolator to protect PIC from high voltage.
i have question about how to connect isolator to protect PIC from high voltage.
i used 4n26 IC but it doesn't work ...

i used a voltage divider to minimize voltage and shunt resistor to sense current
help please

 

Welcome to AAC.

We prefer you to start a new thread for each question. Continuing a previous discussion with a different topic is confusing. Thia is the original thread - http://forum.allaboutcircuits.com/showthread.php?t=12381&page=3.

Not only do you have to keep from applying too much voltage to the input, you also have to insure safety by galvanic isolation. Thia is best done with a transformer. A step down transformer provides a much lower voltage to work with that is also directly related to the input voltage.