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| How to Pick the
Right AC to DC Power Adapter Before you purchase an AC adapter, you need to find out some information to make the right choice. On the power adapter you wish to replace, or on the equipment that you are purchasing the power adapter for, there should be a label indicating the following: Input: This is the AC voltage the adapter can use. US standard is 120V at 60Hz. If an adapter indicates it's 100V to 240V, that means it can be used worldwide without any extra equipment. (See Countrycode for a list of the voltage difference around the world) Output Voltage: The voltage the adapter will convert the AC input such as 120V to a stable DC voltage for electronic device. When we say a 3 volt power adapter, we are referring to the 3 volt DC output. The output must be close to the voltage required by the device. For example, if your equipment uses a 9.3 volt power supply, a 9 volt power supply will still work. However, it's best that you do not use a power supply that is more than 0.5 volt off than the required voltage. Using a 15 volt power supply on a device needing only 3 volt will cause a permanent damage. (You'll see smoke coming out) Output Amperage: The power supply must provide sufficient amount of amps to power your equipment. If your equipment needs 3 amps, you need a power adapter with at least 3 amps, and not less. Any power adapter with greater than 3 amps output will work. (Doesn't have to be close) *Note - if an exact match is unavailable, it is better to chose a slightly lower voltage and higher current (amps) than what is required. For example, if your old adapter is 5 volt 2 amp, it's better to replace it with a 4.5 volt 3 amp adapter than to chose a 6 volt 1 amp adapter. Polarity: Polarity of the AC power adapter must be the same as required by the device. (Most of the equipment today uses positive polarity.) When we mean by positive polarity, we mean center positive, or the inside of the plug is positive. You will also see a diagram below on your device or the power adapter you need to replace:  Connector: This is the hardest part when choosing the right adapter as there are so many types of connectors. The "standard", or most common, if there is one, is the 2.1mm x 5.5mm plug. There are also various proprietary or customize plug in which large corporation uses so you must purchase their replacement adapters. (However, that seems to be less now) Most of the plugs are of following coaxial type:  The diagram shows a plug with 2.1mm diameter inside and 5.5mm diameter outside. Other commonly use plug size are 2.5mm x 5.5mm, 1.7mm x 4mm, and 6.4mm x 4.4mm (for laptop). Since most of the adapters and electronic equipments do not indicate plug size, it's best that you measure it to determine the right size. If you cannot find a power adapter with the right connector, we do have conversion connector which at one end will connect to 2.1mm x 5.5mm (the most type we carry) to other types of connector. We carry roughly 10+ types of connector which should cover over 80% of the products used today. Otherwise you can always go to local electronic store and ask an engineer to change the plugs for you. Besides the above crucial point you also need to consider the following when purchase a power adapter. Regulated/Unregulated: Unregulated AC adapters are not stable and does not always produce the rated voltage while regulated adapter does. For example, an unregulated 12V adapter when first plug in the wall, it might produce 13+ volt, and as you turn on your electronic equipment and use up current, than it'll drop down to 12 volt. Such instability, in the long run, may hurt your equipment. Regulated adapters, however, are much more expensive. *Many of the AC adapters sold or use in the market today are unregulated. Original Manufacture Adapters or not: Most of us received our power adapters when we purchase our electronic equipment, be it electronic keyboard, cordless phone, laptop, etc.. So intuitively we believe the best replacement adapter is from the original manufacture. The reality is that manufactures we bought our device from do not make adapters. They source it from some other factory, mostly in Asia to their specifications. Depending on how competitive the industry is, when manufacture wants to cut down cost to their product power adapter usually is a good component to do so. A poor quality power adapter can cost half of high quality ones. For example, an external hard manufacture (and I used to work in one many years ago) may only have $15 margin for a drive retail at over $100. Using a cheap adapter could save between $3 to $5 over high quality ones. The incentive to cost down is always there. We are not implying that original manufacture's adapters are all bad. However, there is a reason why some manufacture has good reputation while others don't. | |
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