Hello, i need an idea for my project. So i wanted to put a TVS diode and a RC supressing network before the transformer, the thing is the system will be working on 110vac and 220vac, and a switch will be used to change the input of the transformer from 110v to 220v. My initial idea was to simple put a TVS and RC network on the line like this.



A simple two position switch would be used to change the input voltage. But i don't know if this is going to work properly, because taking a first look it seems that every line is connected actually and that may or may not be true. Any help ?

 

Just design the TVS and RC nework for 220Vac and put at the switch input. That should also be sufficient for 110Vac.
Otherwise put the suppression on the output of the transformer.

 

A TVS rated for the 15Vac of the output of my transformer? Good ideia and thr RC behind the switch