Power problems are a major pain in the you-know-what for travelers. Every country seems to have its own voltage and requires its own adapters, accounting for power as well as outlet shape. Even more confusingly, not all adapters work for all devices -- we've often found, for example, the converters that work for laptops won't work for hair dryers. Even the technology for chargers and plugs have changed. Here's what you need to know. 

It's a brave new electric world.

For the last several years, every power brick-and-wall charger for consumer electronics has been made to handle anything from 100 volts to 240 volts -- the range of voltages you'll get around the world -- says Dave Dean, co-founder of Too Many Adapters, a tech-focused website for travelers. These days, as long as you can make the plugs physically fit the wall socket, you don't have to worry.

But what about all of those rules about input/output and converters? For electronics from the past few years, those rules are outdated. Once upon a time, this was a problem when traveling abroad, because the voltage coming out of wall sockets in North America were in the 100V to 120V range -- and chargers were made accordingly. In the rest of the world, that input is in the 220V-240V range. Naturally, damage often happened when you plugged a 100V-120V charger into an outlet that was feeding 220V-240V of electricity.

(If you want to get more technical, here's how Dean lays it out: "Every power adapter will have both an input and output voltage. The input is AC, or the alternating current, and the output is DC, or direct current. The power adapter converts one to the other -- it will give the device only what it needs -- but it has a particular range of input voltages that it can handle.")

The reason for the change in what input voltages chargers can handle? “With the number of different countries their gear was being used in, it was just cheaper and easier [for manufacturers] to design chargers that would work anywhere -- rather than supplying different versions for different countries and dealing with the warranty claims and irate customers who took their gear somewhere new and blew it up,” Dean explains. Long story short, chargers are now made with worldwide use in mind, no matter where they're manufactured or sold.

Of course, travelers still have to deal with differently shaped sockets when they go abroad, hence the multitude of "universal" converters today. One example is the Smart Travel Router & Adapter ($50), a compact charger-router that works in more than 150 countries and even creates a private, wireless network when there's a direct internet connection.

So what about our hair?

Unlike ubiquitous computers and phones, hair dryers and other smaller electronics aren't used consistently in different countries around the world -- and they're not often packed for trips either, Dean says. And because these gadgets go for cheaper, manufacturers try to save money wherever they can to boost their profit margins -- “in this case, that means cheap power bricks that can't handle a change in voltage from (e.g.) 110V-120V in the U.S. to 220V-240V in the UK,” says Dean. To avoid that lovely smell of melted plastic, you'll need a voltage converter as well as a plug adapter. The good news is that those aren't particularly expensive or heavy; they're just another item you'll have to account for.

But there is one solution: dual voltage travel hair dryers. Travel style blogger Kristin Francis says, “In my prior experience, a converter technically does work on a regular hair dryer, but it also reduces the airflow to a level that makes it pretty much useless." You'll just want to make sure to flip the voltage switch to avoid any hazards, but Francis adds that you can always pickup an inexpensive dryer at the local drugstore, as she's done before in London.