re: Leaving for Austria/Switzerland in 2 weeks. This question may be for tech board...

"Electronics" is different than cell phones and computers. You need to understand the US uses 110/120volt plus different plugs, most if not all of Europe is 220/240 volt. So you need a plug adapter to fit in to wall socket, then anything like a hair dryer or low end American electronics need a converter to reduce the 220 to 110. Does this make sense? So it's a two part process.

iPhones, most cell phones, most tablets, and most computers are built to run on both 110/220 Volts. So you just need a plug adapter.

Things like hair dryers you usually need both, and my wife always burns something up she brought because she only plugged the appliance into a plug adapter and not into an adapter/ converter. Some are both, some are just adapters and you usually know by price. Under $10 is usually just an adapter and more than that is usually both. Obviously the packaging will tell you but that's a good quick reference.

If you see a USB plug in Europe, that will be 220v. So that's fine and great for phones, but double check your other items like portable battery chargers, fans, clocks, etc.