Desktop Power supplies such as those found within our Power Supplies - External/Internal (Off-Board) | AC DC Desktop, Wall Adapters | DigiKey category include a filter for positive or negative centers on the output barrel plug.
If you are replacing a power supply, the easiest way to identify which one you need is to look at the label for one of the following symbols:
Its important to note when looking for a replacement: That the part number and polarity legend on the label is correct 99.9% of the time. There are some very less often times where a manufacturer will get a custom order for an adapter with a different connector overmolded onto the cable for use with their equipment. This can cause confusion when trying to identify the polarity and connector size because the adapter manufactuerer does not always change the label. Again this is rare, but we have seen this cause confusion in the past.
Here are some examples of where to find this graphic:
Please Also See