Many small battery-operated and other devices use a small AC wall plug, also known as a "wall wart." These small adapters are teamed with a cylindrical plug at the other end, which slides into the device. Although these adapters seem innocuous enough, plugging the wrong one into a device will cause damage or unexpected behavior to the adapter or the component itself. Each device and adapter are marked with ratings indicators, helping you to select the appropriate one.
Examine the sticker on the back of your old adapter, if it's still available. Take it to the store with you, matching the voltage and amperage ratings on the existing adapter with the new one.
Look at the back or base of the device requiring power. Often the device is marked with the voltage and amperage rating. These are needed to match the new adapter to the device.
Look for universal adapters that have a voltage switch. Sliding the switch between 6, 9 and 12 volts, for example, allows use of the adapter with various devices requiring differing voltages.
Look at the size of the AC power jack on the device requiring power. Most new universal AC adapters come with a variety of modular tips to fit a wide array of devices. Plug the correct-sized plug on the adapter to the AC power jack on the device after you select the switch on the universal adapter to the correct voltage.
Contact the manufacturer of the component if a universal replacement adapter is unavailable. It is possible with some devices that a particular voltage and amperage combination is unobtainable with a universal replacement. Devices like laptops often have proprietary power adapters and supplies, necessary for proper operation of the device.
- Determine the voltage and plug style required for a country you are visiting if you need the adapter for travel purposes. Many countries outside of the US operate at 220 volts, lethal to 110 volt electronics if not properly stepped down. Some adapter kits come with a series of plugs packed in, while others sell each plug separately.
- Do not pay attention solely to the voltage rating on a device or adapter. Too much amperage and the adapter or the device may catch fire or melt. Rechargeable batteries may also rupture under excessive amperage.
- Existing AC adapter (if available)
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