Battery-operated devices are used in nearly every facet of everyday life. Over a long period of time, a single battery-operated device may require new batteries hundreds of times. If the battery-operated device---such as a battery-operated radio---is set in one place and is only moved when the batteries must be changed, it may be more cost-effective to convert the battery-operated device to use a wired DC adaptor.
Open the battery compartment on the battery-powered device. Remove the batteries.
Snip the tip from the DC adaptor. Pull the wires apart until there are approximately six inches of slack between the wires. Strip 1/2 inch of insulation from each wire end, and mark the positive wire (which was formerly connected to the centre connector on the tip) with a piece of electrical tape.
Twist the negative wire to the spring terminal, which is not connected electrically to any other battery connection. Solder this wire to the spring. Solder the positive wire to the flat battery terminal, which is not connected electrically to any other battery connection.
Break a small corner off the battery cover, and route the electrical cord so it sticks out of the hole in the battery cover. Replace the battery cover. Plug the DC adaptor into the wall socket, and turn on the device.