@anon33391-- I believe what you need is a voltage converter. The US uses 110v for devices whereas Europe uses 220v. A converter helps convert one to the other and will allow you to use American bought devices in Europe and vice versa.
Many electronics these days are made to suit both of these voltage systems. If you check the electrical plug of your electronic device or its manual, it will tell you if it is adapted for both 110v and 220v. Usually, there is a small switch that allows you to switch back and forth to these voltages. If it is made to suit both, you don't need to buy a voltage regulator circuit or converter.