I want to make a small gift for my girl :D
For this i need a LED visualizing a heartbeat (fading up and down)
I'm gonna run the circuit from one single CR2032 (if possible) and it shouldn't fill much, as the circuit should be on the back of the coin-cell.
I have google ALOT, without much of luck.. and I'm down to think that the smallest and simplest circuit is a ATtiny-13 whit one resistor...
Please show me I'm wrong and there's a simpler circuit with only a few extra pieces :)