To top my tree, I wanted an illuminated angel with flapping wings. When I couldn't find one, I made my own using a flapping butterfly (scientificsonline.com) and a "Direct LED G4" from earthled.com. I started with an angel topper from KMart and went from there.
To supply the LED light, you need a power source. The power supply can be anything from 10 volts to 15 volts, AC or DC, 150 milliamps or more. You can hook either wire to either terminal on the LED light.
Because the LED light is very bright and annoying even from the ground, a shield is necessary to prevent visibility from the human eye level. I took a short piece of the 1/2 inch stainless steel and formed a tight (ends touching) "U" shape. Pressure fit this over the LED light and the light should all go upward.
While the angel is still on the ground, adjust the bracket until the light shines where you want it. If you wait until this is wired up on top of the tree, you will not be happy while precariously standing on a chair or stool and trying to adjust the pattern.
You will have two power supplies, one for the butterfly (angel wings) and one for the light. Take your time and thread these deep into the tree. Support these wall transformers, or they will drop at an inopportune time, taking part of the angel with them.