This hackable version of holiday card is based on an ATtiny13A and a few LEDs that play a short light show in the tree upon pushing the button. From the small Atmel ATtiny13A microcontroller, one pin ...

Designed for power button (not tact one) and one Li-Ion cell. Should work with ATtiny45 and ATtiny85, but untested. PB0 - one AMC7135 PB1 - two AMC7135's PB2 - devider 19k1 and 4k7 between VCC and GND ...