I have seen circuits for "fading eyes" where 2 LEDs fade in and then out over a period of time (NE555). I have 10 LEDs and would like to build a circuit to fade in and out over a 12 hour period (LEDs go in fish tank and I would like to simulate a moon cycle - I know, a little much...). Any ideas? Can I modify the fading eyes circuit w/ resistor/capacitor to increase period? Thanks for your help.