Sometimes you get a chance to combine helping out your family with a nice hobby project..
In this case my father in law was looking for a lighting system for his bird breeding cages. A daylight simulation system to be exact. He asked me to take a look at a website which sells such systems, since he wanted to know what he needed to order. After a quick look at those websites and seeing their pricing.. I convinced my father in-law I would develop and install the system myself.. He would get his lighting, I would have a new hobby project!
The requirements for a daylight simulation system are simple: lights should gradually (say in 20 minutes) increase to a set high intensity in the morning, stay at that intensity during the day, gradually decrease to a set lower intensity in the evening, and stay at the low intensity during the night.
Other 'non-functional' requirements of such systems: the light should not flicker (this is stressful for the birds), the dimming should be smooth (again related to stress), the system should be reliable..
This instructable describes how I built this system based on an Arduino, some N-channel NPN transistors, a real time clock, a character LCD and some cheap LEDs from eBay.
A sidenote: The birds are only in the cages for breeding, the remainder of the year they are in an outside bird sanctuary. So no animals were harmed for making this instructable!
I've submitted this project to the 123D Circuits Contest and the 2014 makerlympics (both pending approval). So if you like this project: please vote for it! Thanks!