This connector converter can convert a 7.4 x 5.08mm male connector with center pin to a 5.5 x 2.1mm male connector.
The back end of this converter is a 7.4 x 5.08mm female jack:
It can plug to a 7.4 x 5.08mm male connector, convert it to a 5.5 x 2.1mm male connector like this:
Note: 7.4 x 5.08mm connector is widely used on Compaq, Dell and HP laptop power adapters.
Overall Rating for Y61 Power Connector - 7.4 x 5.08mm Round Shape Female Jack to 5.5 x 2.1mm Male Plug