In this chapter we are going to design a single zone alarm system and learn how the basic components work. We will learn about comparators and how they are used in this case. We will also build and test a simple breadboard circuit that will simulate a single zone alarm. For example, the bell that rings when you enter a store.
A zone is an area that is being protected, and/or a collection of sensors that are protecting the zone. Zones can contain Passive Infrared Sensors (PIR sensors), glass break detectors, window contacts, or a combination of different sensors.
For example, "ground floor windows" could be a zone. Ground floor PIR sensors could be another zone. There are also "special" zones such as fire alarm zones. In commercial installations, the fire alarm zones and CO (carbon monoxide) detectors must have their own zone.
In the following chapters, you will see how we will use these zones to create a layered defense.