What electrical converters to work chargers are needed for Android 7 and IPad?
If you look at your existing chargers, you will see in small print, "120-240 VAC, 50-60 HZ"
You just need a plug adaptor, and the "standard" European continental 2 prong plug works fine.
For Switzerland, a Type C (two Prong) or Type J (three prong) adapter will work.
https://www.ricksteves.com/travel-tips/phones-tech/electric-adapters-converters
Today's gadgets are "dual voltage," which means they work on both
American and European current. If you see a range of voltages printed
on the item or its plug (such as "110–220"), you're OK in Europe.
No converter (transformer) needed for multi-voltage "chargers". Just plug adapters to fit:
Ungrounded (two conductors) Type C (two round pins): http://www.iec.ch/worldplugs/typeC.htm
Grounded (two conductors plus ground pin) Type J (three round pins in a "triangle) pattern: http://www.iec.ch/worldplugs/typeJ.htm