This circuit is used for automating a day/night scheduled security system which, best of all, could only cost cost you $0.25 a YEAR to run. (All electricity prices based on a 2009 national average cost found here .) If you have a security system circuit you would like to run for a long time, then you probably don’t want to pay more than you need to pay nor do you want to have to switch it on and off manually in order to save money and have it run at nighttime. This circuit takes care of both those problems. The circuit can be changed around to run on a daytime or nighttime schedule and is low cost to run along with the other circuit. (I’ll explain how to calculate these prices of run time in the last step).
Security System Power Saver – [Link]