Myrtle the Mermaid

An easy-to-solder kit for beginners. Uses a 3V CR2032 coin cell to power 5 LEDs with individual resistors in series with the LEDs.

The kit uses 5mm colour-cycling rainbow LEDs which shouldn't really work at 3V according to the specification but they do appear to do so reliably (although the colour cycling may be a little irregular). Other LED colours and sizes can be substituted. 3mm LEDs also look good and are proportionally a better size.

The LEDs are independent of each other and their colour cycling doesn't remain in phase for very long. This gives rise to pleasing multicoloured patterns as they move in and out of synch.

There's a mounting hole for a pin and clip so the badge can be worn on clothing,.

http://www.madlab.org/documents/MyrtleTheMermaid.pdf