How Burglar Alarms Work

The concept of burglar alarms was introduced to the world by Edwin Holmes. Holmes made these alarms an important component of business and residential security. In 1905, after enjoying several years of successful business, Holmes sold the concept of burglar alarms and his company to American Telephone and Telegraph Company (AT&T). AT&T then went a step further and connected burglar alarms to emergency call systems at both fire and police departments.

Since then, a lot of people sleep easy as they know that if someone breaks into their homes and offices, the alarm will ring and alert the police. However, how many of us know how these wonderful machines that have brought us better sleep, work? Not many. For those of you who are not aware of the working of burglar alarms and wish to know so, this article is a must-read.
The functioning of a burglar alarm resembles that of a simple electric light bulb. While the basic concept is the same, the difference is in how to turn them on. To turn on a light bulb, a person needs to press the light switch. In contrast, a burglar alarm goes off when an unauthorized movement is detected. For example, if the door of your office is opened after you have set the burglar alarm and left for the night, and an intruder walks in, the movement will be detected and the alarm will start ringing and the nearby police and fire departments will be alerted.

A burglar alarm can be classified into two categories depending on the type of electric circuit system used: closed-circuit alarm or open-circuit alarm. In a closed-circuit alarm, the circuit is completed only when the door is closed. That is, when the door is closed, electricity can pass through the circuit. However, when the door is opened, the flow of electricity in the circuit is interrupted and the circuit becomes open. This triggers the alarm to start ringing. In an open-circuit alarm, the opposite is true. That is, the alarm is triggered when the circuit is closed.

Also, the ringing of the alarm is dependent on the movement of the intruder. So, how would a burglar alarm detect movement? The alarm system has a set of magnetic sensors that sense movement. A magnetic sensor is composed of a battery that functions as the power source, a magnet that is embedded in the door, a spring switch, and a buzzer. As soon as some motion is detected, a magnetic sensor transmits signals to the alarm device through the control box. Upon receiving these signals, the alarm starts ringing. The shrill sound of the alarm is supposed to scare the intruder away.

Also, as these alarms are connected to emergency call lines at the nearby police and fire stations, as soon as an alarm starts ringing, these departments are alerted and the police and firemen are on their way to get hold of the intruders. Therefore, with these alarms installed at your place of business and residence, you can sleep easy at night and let these systems worry about the intruders.