Here’s a cool star clock project that takes advantage of bunch of great Adafruit gear, created by Eric Scott:

A Christmas gift I made for my wife from an Arduino Leonardo,
2×16 LCD I2C Shield, ChronoDot, 12mm diffused LED pixel strand, and 5V power supply. Hour and nearest 5 minutes are indicated on the clock face with separate colors, a third color when they overlap. The five points fade from purple to blue over 1 minute, when all are blue the minute hand ticks over.

She likes things that light up, and I have a “star” theme going this year.  Perusing my favorite electronic supply sites I came upon these Adafruit addressable LED strings.  Very similar to a product I’d used in the past (ThingM BlinkM) but cheaper, and you don’t need to set each unit’s address.

It took me a couple of days to work out a concept to take advantage of the lights.  What I would do is to make a clock with the LEDs changing color to indicate the position of the hands.  12 of the LEDs will make up the face, and then 5 additional ones will occupy the points of the star, pulsing to indicate seconds, similar to the way the light on my Macbook Pro pulses while sleeping.

To make the major portion of the clock I used a piece of white delrin plastic.  This part is just slightly smaller than the table travel of the mill.  Additionally both sides of the part need to be machined, which further complicates the setup and fixturing.  To begin, I cut the holes in the back side of the clock to hold the LEDs.  The 12 central holes are for the “hand” display, and the 5 peripheral holes for the pulsing star points.  The large central cavity provides a convenient place to stash the RTC (real time clock) chip which keeps track of date and time with a battery backup.

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Featured Adafruit Products!

12mm Diffused Thin Digital RGB LED Pixels (Strand of 25) – WS2801: RGB Pixels are digitally-controllable lights you can set to any color, or animate. Each RGB LED and controller chip is molded into a ‘dot’ of silicone. The dots are weatherproof and rugged. There are four flanges molded in so that you can ‘push’ them into a 12mm drill hole in any material up to 1.5mm/0.06″ thick. They’re typically used to make outdoor signs. We also have flat-backed pixels that are essentially the same, but are not as long and thin. (read more)

ChronoDot – Ultra-precise Real Time Clock – v2.1: The ChronoDot RTC is an extremely accurate real time clock module, based on the DS3231 temperature compensated RTC (TCXO). It includes a CR2016 battery (not shown, but included in the product) which should last at least 8 years if the I2C interface is only used while the device has 5V power available. No external crystal or tuning capacitors are required.
(read more)