For some reason, baby swings dont come with wall chargers or winders like the one I rode in. They like to eat D batteries by the truck load. So, I had to modify the swing to take AC power from the good ol' wall. Since we might wanna take the swing out in the yard for some reason, I put in a switch that would let it run on batteries or AC.
This is a simple on/off DPDT switch from Radio Shack.
In this pic you can see the old cell phone charger cord concealed coming out of the back of the housing. The swing takes 4D batteries at 1.5v each. So the power adapter I am using is a 5.8v supply. It's almost exactly the right amount of voltage with loss.