Power Conversion Guide
Voltage & Frequency
Current Capacity
Wattage Ratings
UL Listing
Transformer Class
Transformer vs. Solid-state
Types of Conversion
Safety Warnings
Abbreviations & Glossary
Conversion FAQ's
AC to AC Converters
AC to DC Adapters
DC to AC Inverters
DC to DC Adapters

 RadioShack Guide to Understanding Power Conversion

AC to DC Power Conversion (AC Adapters)

Purpose of Converter / Explanation of Operation

AC-to DC adapters (generally just called AC adapters) are generally used to provide low-voltage DC power for small electronic devices, such as answering machines, scanners and hand-held computers. RadioShack offers two types of AC adapters: single voltage adapters, which provide a fixed output voltage, and multi-voltage adapters, which have a switch that allows you to select from several output voltages. In addition to the standard AC Adapters, there is a special type of single-voltage AC to DC adapter called a 12-volt Power Supply. A 12-volt power supply is an adapter that is specifically designed to provide 12V DC vehicle power in order to run vehicle-powered devices (such as mobile scanners or car radios) off of AC power, and usually includes a cigarette lighter socket for connecting the devices.

Selecting an Adapter

When selecting an AC adapter, you need to know the input voltage. current consumption, tip-size and tip polarity for your electronic device. This information is often on a label on the back or bottom of the device, and is usually in the format described at the links below:

The tip size may or may not be provided; however, if it is not listed on the device or in the manual, you can easily determine the correct tip by taking the device into your local RadioShack, where a full range of our Adaptaplug tips is available. There are "test tips" corded and attached to the display area for power converters in order to allow customers to determine which plug fits their device(s). If you need assistance, a store employee can help you.

When selecting your AC adapter, you need to match the voltage, tip polarity and tip size exactly; however, the adapter only needs to match the current consumption as a minimum. Because a device will only pull as much current as it needs, and because adapters are rated at the maximum current that they can provide, there is no problem using an adapter which is rated at a higher current than is required by your device.

If you have a number of devices that need AC adapters, we have a worksheet that will make the selection process easier. Print out the worksheet, fill it in as much as the information is available, then take the worksheet to your local RadioShack store, along with any devices for which you do not have a plug size.


  • Do not use a power converter of any type for critical equipment such as medical devices unless so advised by the equipment manufacturer.
  • Do not use a power converter of any type if you are not sure of your equipment's power ratings; contact the manufacturer for this information.

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