You probably remember those fun Light Bright boxes that were so much fun to play with. This one looks a lot different than the plain white wedge that I had when I was young, but the concept is the same. Over at Mean PC you can see how a simple Lite Brite was turned into a Lite Brite LED Clock. You can see the numerous build videos that take you from the beginning to end.
Thanks for sending this in Lonnie.
“The Arduino lite brite clock basically consists of an Arduino, 46 LED’s, 12 resistors, a Lite Brite and a few other odds and ends. I have the LED’s multiplexed like this: all of the cathodes on each row are soldered together. All of the anodes on each column are soldered together. The LED’s making up the colon are stand alone. Since there are 5 rows and 10 columns, the digits take up 15 pins on the Arduino, and the colon takes up 2 pins for 17 pins total. “