Originally Posted by aprebyl

Hi,

I'm not an electronics guru but I remember just a bit from my high-school class.

Project background: My wife is trying to breed a particularly finnicky (no pun intended) type of aquarium fish. Supposedly, these fish have behavioural patterns tied to lunar illumination. So, what I'd like to build for her is some sort of light that will provide low-level illumination that varies in intensity on a 30 day cycle. The idea is to simulate moonlight filtering through the water during the monthly waxing and waning of the moon.

My concept here is to use one or more LED's as the light source, but I'm looking for suggestions on two topics:

1) How do I get the thing to automatically adjust the voltage going to the LED's? I mean, how do I add a step in voltage every day for 30 days and then start over at 0?

2) Is there a way to get this whole thing to come on automatically when the main aquarium light (on a timer) turns itself off at the end of the day?

Any thoughts appreciated. Thanks!