One very common question we receive here at Digi-Key is customers looking for replacement power supplies. The majority of these are AC to DC adapters and can be found in our AC DC Desktop, Wall Adapters Section. The first thing we always ask the customers is if they have a part/model number for their adapter or if they have the voltage and current requirements.
On most adapters this information can be found on a label. On the label below we can find the following information.
Model Number:
Input:
Output:
Note that on this label you also see a symbol showing that the connector is positive center. Even though this is the most common configuration it is important to know as using a positive center when a negative center is called out could result in your products not working and potential damage to circuitry if used.
Looking at this wall mount (also called wall wart) you notice we do not have this model. So we will look at other options. First we know that we need 12VDC out. so I will select 12V
Knowing that I want to order this today I also only want to look at an in stock part. After selecting 12V and now in-stock you will see there are only 338 options available.
The next item you need to look at is the current output of your power supply.On the supply I am using for an example we are needing 1A of output current capability. Since i do not want to limit my options I will choose all power supply that put out at least 1A of current.
On most applications you are able to use a power supply that has the capability to output more current that needed. There are some efficiency losses often noted when a power supply is used for less than its full capacity. ie a power supply being used for designed for 1A will be more efficient at putting out 900mA than a power supply that is designed with a 10A output.
Now the topic that causes the most amount of questions on power supplies, the output connector. Most common is a barrel connector, and there is a large number of possibilities when it comes to size. OD on these connectors is easiest for most people to find. He is a little guide that can help with the most common 2.1 or 2.5 mm ID.
After measurements I know I have a 2.1mm ID and a 5.5mm OD. I also know from my label earlier that I need a Positive Center.
If there are no options that have the correct ends you may want to look at splicing the old end if available onto the new cable.
You may also want to look at barrel connectors you can add to your power supply.
If you have followed the filters to this point most of the available options will work for your application. To narrow it down we will look at some of the remaining specifications.
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Region Utilized
This Category has to do with the power input connector that comes with your power supply. Note here that some of the international models will not come with a blade connector and some come with many. Also some desktop models come with an input cord and some do not. You will select this in the Input type. -
Form
Here you need to decide if you are looking for a Desktop or Wall Mount type power supply. Typically the larger amperage power supplies will come in a desktop model due to package size.
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Input Type
Here you are looking at the input connectors that come on the power supply. On desktop models you need to look at does it come with a cord or is the cord sold separately. On wall mount supplies you can have a fixed blade (one that does not come off), a multi-blade (one that is removeable) and multi-blade that is sold separately.
If you need assistance finding a cable for your desktop power supply here is a post that helps explain how to find a cable.
AC Power Cable Types for Desktop Power Supplies -
No Load power Consumption
Any power supply that is plugged into the wall with use power even when it is not being used. This rating is calling out the maximum amount of power that the power supply will use when it is plugged into the wall and not supplying output power.
