The most important part of a burglar alarm system is  the  control panel or motherboard. The motherboard acts as the brains to the system. Most of the programming of a burglar alarm system, as well as the wiring connections, occur at the motherboard. The motherboard typically is located in a secure location within a home and usually requires very little interaction from the home owner. Also, a burglar alarm battery backup is housed inside this box and is kept at full strength by the motherboard via a built in trickle charger. In the event of a loss of power the battery backup automatically keeps the burglar alarm system operating for a few hours up to a couple of days. The duration of the battery backup is dependent on the size, type and age of the battery, the number of power consuming devices connected in the burglar alarm system, and the state of the alarm (i.e. on/off etc)


The next  component of a burglar alarm system is the keypad. Keypads typically are located near entry doors for convenience and often times in bedroom areas such as the Master Suite.  The keypad is used to turn the system on and off. The keypad also can tell the user when an intrusion alarm occurs, which door or window has been violated. Many keypads also have a Chime feature built in. The Chime feature is a very useful feature because it allows parents of small children to keep track when they’re coming and going from home. The way that it keeps track is the keypad(s) will beep when a door or window are opened. More sophisticated systems will have a computerized voice that will tell a home owner which window or door is open.

Door or Window Contacts

Window Contact

The next important component of a burglar alarm system are the door and window contacts. The purpose of the door & window contacts is to determine when a door or window is opened. The way that these devices typically work if by the use of a magnetic contact. A magnet is the embedded in the door, or in the case of wireless, fastened to the door. When the door or window is opened the open circuit is sensed at the motherboard and  that signifies the door or window is open.

Motion Detector

Motion sensors are a part of burglar alarm systems. Typically a motion sensor is a second line of defense inside a home. The motion sensor typically is only turned on when the house is vacant. The motion sensor however can be turned on when the home is occupied if the entire alarm system has been designed for this feature. When the house is vacant and  the motion sensor is turned on the motion sensor will be track when a person walks into the room where the motion sensor is located. Typically this is done by sensing body heat; however, this is not the only method of motion detection available. Motion sensors today have been designed to ignore the heat signature of small pets such as cats and small to medium sized dogs with certain limitations. A limitation for example would be how close can a pet get to the motion sensor, too close and even a house pet can trip today’s newest motion sensors. The way a motion detector is able to ignore a pet is because the heat signature of the human body is different from the heat signature of most pets and the motion sensor can distinguish the heat patterns.

Glass Break Detector

Glass breaks sensors are also part of burglar alarm systems today. Glass break sensors perform the function of what their name suggest, they detect breaking glass. Unfortunately the technology utilized for detecting breaking glass has not kept pace with other alarm device technologies. There are four general types of glass break detection devices:

  1. There is the old style silver tape that you see on windows. This style has gone away. 
  2. The most predominant style used today is a frequency detection glass break detector. When glass shatters it emitts a certain frequency which trips many glass break sensors. Other things such as crying babies, loud music, banging dishes etc can trip these sensors.  
  3. Dual frequency glass break sensors work on the principle that before glass breaks it must bend ever so slightly. When the glass bends it emits a frequency different from the frequency emitted when it breaks. This initial frequency triggers the dual frequency glass break sensor to measure for the immediate glass breaking frequency and when that occurs in the millisecond or so then this sensor will trip. 
  4. The last type of glass break sensor is a shock sensor. It is attached to the glass and breaking glasses opens the internal contact thus tripping the alarm however thunder storms and birds flying against the window can cause this to false alarm.

Alarm Siren

Another part of a burglar alarm system is the siren. Typical home alarm systems have a siren inside the house. A siren serves two basic functions. One function is to let any how occupants that a burglar is occuring but more importantly the siren usually scares the burglar away. The other type of siren is an outside siren. The benefit of an outside siren is to notify the neighborhood or people in the area that the alarm has been violated. This too will typically cause the burglar to flee. The benefit of the outside siren is that when the homeowners are away from a home, and a burglary is occurring, the outside siren notifies people around the house of the burglary.

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