A converter that changes the voltage from American 110V to European 220V is no longer needed for phones, computers and tablets. Most newer appliances sold in the U.S. are dual voltage, meaning they will automatically switch between voltages when plugged in. Some may be marked with 110V-220V, which means they'll work fine in Europe, but may need to be manually adjusted by flipping a switch.
The world keeps getting smaller. I used to lug a voltage converter around.