Some time ago I wrote a short article on a small circuit I made to power on and off my garden lights using only a handful of components and some patience. Since then, however, I’ve dug deeper and found out some other good solutions to the problem.
A quick recap of the problem: At dusk and dawn I’d like my garden lights (powered by 12V DC batteries) to switch themselves on and off without me doing anything: a first step towards total automation ;)
My first try at accomplishing this task was using a simple BJT with a voltage divider specifically design to allow a certain bias current when it gets dark. See here for more information on this first raw trial.