A souvenir "Welcome to Las Vegas" sign had broken on me and sat broken for over a year in my office. Finally decided to fix it with the Arduino as both a fun project and a learning exercise for my 12-year old son.
Started with prototyping on an Arduino Uno, using various TIP120 style transistors to switch the 18V LED elements in the sign:
After it was all done and programmed, an ATTiny85 was installed on a breadboard, glued into the base of the sign:
The ATTiny85 fits comfortably into the base, from the outside, the sign looks the same as it came from factory:
Currently, the program is a simple pattern, similar to the actual sign in Vegas.
Down the road, we'll add a button first to cycle through different patterns and ultimately we might switch to a ATMega328 and add Xbee or Ethernet to the mix to use the light as email notifier or something
Code is attached for reference.