This video shows you how to make a security device out of a door bell. The concept is that most thefts happen when people are away from home. To make sure of this the thief rings the door bell to make sure that nobody is home, if nobody answers then they will break in. A lot of people have dogs and alarm systems which will scare off the thieves, but this alarm system combines both. To make this devise you have to buy a speaker system that connects to your door bell. When the door bell rings it triggers the speaker, which triggers an audio recording from the PC that is connected to the speaker. The audio recording is of a barking dog, So if a thief rings the door bell he will hear a dog barking and run off. If I where to do this, I would make it sound like people were in the house so the thief would think actual people were there.