This is my entry for the 555 contest. I didn’t have much time to make something so the entry isn’t much.
This design is a fan controller. The base of it is a simple pwm circuit with the 555 timer. The problem with fan’s is that they don’t start at low voltages. So I added a capacitor (C2) to give it a little voltage boost at the startup.
The circuit can also be easily adjusted to have a soft start. This can be useful when driving led’s etc. This way the light is not instantly bright.