TransformersTransformers are the heaviest and most costly voltage conversion options. Even a small one can cost at least $25 and weigh half a pound. There are 1500W transformers available for high wattage devices that weigh 20 pounds and cost more than a hundred dollars.
Unless you're planning to move to the UK, you don't need to worry about those. But, smaller ones, used for electronic and motorized devices, are surprisingly heavy.
A transformer can be used for electric shavers, radios, CD players, camcorders running on AC and other small, non-heating appliances that draw 40 to 45W. They too can overheat and have circuit breakers to prevent damage to your appliances when this happens.
The Bottom Line Frankly, unless you are completely addicted to your gaming console and can't go anywhere without it, transformers and voltage converters make little sense on vacation. They add cost to your travel budget and weight to your luggage that is out of proportion to their use for a typical vacationer. Battery chargers -- for your CD player and camcorder can almost always operate at US or UK voltages and the selection of dual voltage devices - most likely including all your electronic gear - is easy to find and constantly increasing.
All you really need to carry is an adaptor plug or two and your collection of dual voltage appliances and you're ready to rock and roll.