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How to Choose An AC/DC Adapter?

Date:2016-07-05 Hits:276
How to Choose An AC/DC Adapter?
With an increasing number of new electronic gadgets - phones, music players, PDAs, handheld games and other toys - comes an increasing number of AC Adapters needed to charge and power those gadgets. Often the adapteris lost or broken, and choosing a replacement can be confusing because of the variety of selections available

1.Determine the desired output specifications of the AC adapter. This can usually be found on the old adapter, the electronic device, or the instruction manual of the electronic device. There are two components to this: the voltage, measured in volts, and the current, usually measured in milliamps (ma). When selecting an adapter, you will want to match these as closely as possible.
If an exact match is not available, it is better to err on the side of the new adapter having a lower voltage and higher current than the specifications require. For example, if the device calls for 6 volts at 500 ma, it is preferable for the new adapter to provide 5 volts at 600 ma (lower voltage, higher current) than it would be for the new adapter to provide 9 volts at 333 ma (higher voltage, lower current), as the excess voltage could damage the electronic device.

2.Determine whether the adapter should be regulated or unregulated. Simply put, an unregulated adapter does not always produce the rated voltage while a regulated adapter does. Because of this, regulated AC adapters are also generally more expensive than unregulated ones.

It is possible to substitute a regulated adapter for an unregulated one (the downside being added cost), but it is not advisable to substitute an unregulated adapter in place of a regulated adapter as this could cause the electronic device being powered to fail.

3.Determine the polarity of the adapter, which will either be positive or negative. The following image shows how polarity is usually represented.
Polarity determines the direction that current flows; if the current from the adapter flows the wrong way for the intended electronic device, the device may be damaged. It is important to be sure that the polarity of the adapter and the device match.

4. Determine the size of the adapter plug. Plug sizes are normally measured in millimeters.If the plug size is the only thing wrong with an adapter, meaning that its voltage and current ratings, whether it is regulated or unregulated, and its polarity all match, it is possible to splice a new plug onto the adapter, as many electronics stores do sell just the plug in different sizes. However, care must be taken to ensure that the new plug maintains the same polarity as the old one, meaning that the wire that connected to the outside surface of the old plug still connects to the outside of the new plug, and that the wire that connected to the inside surface of the old plug still connects to the inside surface of the new plug

5. Choose an adapter that meets all of the above four requirements: proper output voltage and current, regulated voltage if required, proper plug size, and proper polarity