Back to Course Home

System Components

Burglar alarm systems have become commonplace in both domestic and commercial environments, due to the especially high crime rate in our country. They offer protection of both assets, as well as personal protection while on the premises. It is, therefore, a good idea to understand the components that form an alarm system.

The basic components of any burglar alarm system are as follows:

  • The control unit:
    • This is the “brain” of the system.
    • All wired component devices are wired into the control units PC board, as are any wireless receiver units.
    • The battery is housed in the same housing box as the control unit.
    • The control unit also has the siren, transformer, communicator and other outputs, as well as the keypad connections.
    • It is important that the control unit is installed in a protected area of the home, such as in a cupboard (not in the ceiling or roof space), and protected by an infra-red sensor.  

  • The keypad:
    • This is a device from which one can access the functions of the system, such as arming, disarming, bypassing, viewing alarm memory etc. This should be installed in an area that is protected by an infra-red sensor.

  • The backup battery:
    • This takes over the running of the system in the event of a power loss, and is fitted into the same box housing the control unit

  • The siren:
    • Sounds an alarm tone when the system is activated.

  • The transformer:
    • Gives the system its power.
    • It plugs into a wall socket.

  • PIR detectors:
    • These are the “eyes” of the system.
    • There are many different types available, working in many different ways. They measure a change in the ambient air temperature, or movement, or a combination of the two.
    • They also come in
      • standard,
      • pet friendly,
      • wired,
      • or wireless.
    • Their range is dependent on the type of sensor.

  • Magnetic contact points:
    • These are fitted to the external doors, and windows.
    • They are mechanical devices, which keep a reed switch closed on one side of the door or window by means of magnetism. If the door or window is opened, the magnetism is lost, and the alarm, if armed, will activate.
    • Larger ones, with a greater magnetic force are also available, for wider gap doors, roller doors etc.
    • Also available wired or wireless.

  • Remote controls:
    • Systems can operate via remote control, as well as keypads. These have rolling code technology, making them almost impossible to clone.
    • A receiver unit picks up the signal from the remote control, and the panel is programmed to perform the function, i.e. arm, disarm, panic etc.
    • They are also linked to gate and garage doors and lights, to allow for full functionality on one remote control.

  • Panic buttons:
    • These should be dotted around the home, in strategic places.
    • They are either wired or wireless.

  • Links:
    • The alarm system can (and should) be connected to a control room for monitoring thereof.
    • Telephone links, radio links and GSM radios, or a combination of them, are used for this purpose.
    • Self-monitoring is also available on many systems, by means of SMS modules or cell phone apps, which give an alert on the cell phone on an activation.
    • A cell phone can be used to remotely arm, disarm, bypass zones etc. anywhere in the world as long as there is cell phone reception.

  • Perimeter beams and perimeter PIR sensors:
    • They can also form part of an alarm system.

These are the main components of a burglar alarm system, although there are many more that can be added. In the next reading, we will discuss layers of system protection, as well as system design.