If I remember my electrical symbols correctly, the PE adapter is tip postive, so any other adapter you try will need to be. A universal adpater should have its polarity designated on the various tips or in the manual. Make sure the voltage matches too. Regarding STL Droid's question, below, using a 5V for a trickle charge on the PE would likely impact the battery life as it is working harder to draw the current it needs to charge. Any electrical expert out there - feel free to correct if i missed something.