Battery-powered devices such as radios and MP3 players utilise direct current electrical energy. Even though the battery-powered device may be portable, in many cases the device is kept in one place at all times.
Over the lifespan of a battery-powered device, batteries may be changed hundreds of times. If the battery operated device is kept in the same place at all times, and there is a nearby wall outlet, it may be more convenient and cost=effective to convert the device into an outlet-powered device.
Open the battery compartment of your device and snip off the battery clip interface. Strip 1/4 inch of insulation from the exposed wires. Snip the connector end off the DC adaptor and mark the positive DC adaptor wire with a piece of tape.
Strip 1/4 inch of insulation off the DC adaptor wires. Pull the wires apart so that there is approximately four inches of separation between the wires. Twist the positive DC adaptor wire to the red battery wire on the electrical device. Solder the connection and cover the joint with electrical tape.
Twist together the black battery wire with the remaining DC adaptor wire and solder the connection. Wrap the joint with electrical tape. Clip a small piece off from the battery compartment cover, and run the adaptor wire through the resulting hole. Replace the battery cover (making sure that the covered electrical joints remain in the battery compartment).