555 Timers are fun and a great way to start learning electronics
UP/DOWN FADING LED Circuit
A Circuit that fades an LED on and off.
These two circuits make a LED fade on and off. The first circuit charges a 100u and the transistor amplifies the current entering the 100u and delivers 100 times this value to the LED via the collector-emitter pins. The circuit needs 9v for operation since pin 2 of the 555 detects 2/3 Vcc before changing the state of the output so we only have a maximum of 5.5v via a 470R resistor to illuminate the LED.
This video walks you through building this circuit using a breadboard.