The goal of this project is to modify a "Projectables" brand plug-in projection night light with a Joule thief so that partially dead AA batteries can be used to light it up, while maintaining plug-in functionality. Basically, I wanted an excuse to make a Joule thief and to use up a bunch of partially-dead AA's. You can buy these from Amazon, Home Depot, directly from the manufacturer, and other places. I have the solar system one that I picked up from Home Depot for $10.

You can see the light sensor (photoresistor) here

They work by shining an LED through a image and a lens, all of which is located in the globe, which can be rotated 360 degrees thanks to springy-metal contacts. The following pictures detail the take-apart process.

It's held together with three TA20 (triangle) right-hand threaded screws. These puzzled me for a bit because I figured they'd be standard threaded, but nope...they have reverse threads.

Lots of patents

Insides:

The LED under the globe is for making the globe glow.

Spring contacts allow for 360 degree rotation. Clever

 To disassemble it more, you have to take needle nose pliers and pull out the little gray piece of plastic holding the wall plug contacts in. Then you can push the wall plug contacts out.

Bottom: gray piece that holds in plug contacts. The clear piece is the photoresistor protector.

I'll map out the circuit later. It seems pretty simple. I want to be able to tie the Joule thief circuit into the two LED's. I'm hoping to be able to add a simple switch somewhere to allow me to switch between wall mode and battery mode.

Circuit

Popping open the globe (snaps together like one of those plastic Easter eggs) reveals the projector. It was a bit more complicated than I thought it would be and splits into a few pieces. Starting from right and moving left: lens, tube, solar system picture (the tabs keep the picture in place), lens, tube, LED.

The projector