Jens Hauke designed this charlieplexed 20 LED blinker controlled by an ATTiny45 for the Hackaday Coin Cell Challenge:
This is a small blinky with 20 LEDs powered by one CR2032 coin cell
and with an ATTiny45 brain. The firmware is written in plain C and
compiled with the avr-gcc toolchain. The PCB is a two layer design made
Space efficient daisychained LED placing with shared anode/cathode soldering pads.
Firmware and gerbers are available on GitHub:
Jens has shared the board on OSH Park:
Here is a video of the LED in action:
DanR has shared this motion sensing night light board:
This light is powered by an ATtiny45/85 which powers on the 14 LED lights when motion is sensed and it is in a dark room. The light sensor on the board will not allow the lights to come on if it is in a reasonably lit room.
It is fitted with a barrel plug for power, this model specifically with an L7805CV voltage regulator.