Here is a nice, simple instructable for anyone just starting out with LEDs, soldering and electronics. It uses basic parts, with no mucking about with microcontrollers or timers (as fun as those are!) You can build one in an evening if you have all the parts ready to go.
But what is it? The LED Disco Light in a Jar is exactly what the name implies. Over a dozen RGB LEDs in a mason jar, frantically changing colour in a completely random pattern. It's a neat light effect for your next party, or you can use it to entertain a baby for quite a while!
See the last page for videos.
Step 1: Parts
1 mason jar, jam jar or anything with a suitably wide neck and a metal cap
1 4xAA battery holder, in a 2x2 configuration
1 9V battery snap (mates with the battery holder)
24 RGB fast or slow-change LEDs*
12 10 ohm resistors
some solid 22 gauge wire
perfboard or make your own printed circuit board**
some 25mm aluminum standoffs and matching screws
Glass Frosting Spray (optional)
- These LEDs have only two pins, and when power is applied they automatically cycle between red, green, blue, and combinations thereof. You can find them on eBay from various sellers in Hong Kong and elsewhere.