220V to 110V - Converter or Transformer?

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(see also: 110V vs. 220V Appliances)

Converters and transformers are electric conversion products that enable safe operation of electric devices in foreign countries. Electric devices that are designed for use with 110V systems require foreign 220V current to be "stepped-down." Devices that are designed for use with 220V systems require foreign 110V current to be "stepped-up."

The choice between a converter or a transformer depends on several things.

First, is your device an electric appliance with a high power heating element or mechanical motor such as a hair dryer or iron? If you are using an electric appliance, you need a converter. Or is your device electronic, using electronic chips or circuits, such as a computer, printer or VCR? If you are using an electronic device, you need a transformer. When in doubt about the type of device, use a transformer. Both electric appliances and electronic devices work with a transformer, but only electric appliances work with a converter.

Second, is your use continuous and long-term or is it sporadic and short term? Transformers are designed for long term, continuous use. Converters are designed to operate for only an hour or two at a time.

What's the difference between a converter and a transformer? It lies in how the device converts voltage current. AC power is supplied in alternating bursts that are in a shape called a "sine wave." To reduce 220V to 110V, for example, a converter chops off the sine waves in half whereas a transformer alters the length of the sine waves. This is a critical difference because electronic devices require a full sine wave for operation thus can operate only with a transformer. Electric appliances function with either a full or a half sine wave so can be operated with either a converter or a transformer.

The converter's short-term use and "chopping" off of sine waves are relatively simple and compact functions. The transformer's continuous use and alteration of sine waves are relatively sophisticated functions and require more space. As a result, transformers are generally larger, heavier and much more expensive than converters. Thus if you are going to travel with an electronic device you should purchase one that is dual voltage if it is available.

Most converters and transformers that are available to the consumer do not alter or convert the "cycles," shown as "Hz" on most devices. Although cycle differences may not cause a problem with many devices, they do with some. See our Cycles / Hz Tech Note for further explanation.