Identification

In today's world, burglar alarm systems are quickly becoming a necessity for keeping our homes and belongings secure. Doors and windows are the obvious points of entry into any enclosure. As garage doors often are the biggest doors to the house, securing them is an essential step towards home security. An alarm system for this type of door is similar to the one used for other entryway doors throughout the home. As with most any alarm set-up, the electrical circuit lies at the heart of the system. The circuit itself is connected to an alarm and a control box. Many also come with a fob-keychain device for remote control operation. The circuit's job is to manage the flow of electricity based on the type of activity taking place. As a precaution, an extra power source is connected to the control box to prevent would-be burglars from disabling the alarm.

Function

An alarm system circuit is made up of a magnetic sensor, a switch, a magnet, a relay and an added power source. It can be set up as an open or a closed system. A closed system would only sound an alarm when the electrical current is interrupted, while an open system would sound when the circuit is completed, or uninterrupted. In the case of open systems, all a burglar would have to do to deactivate it is cut off the main power source. For this reason, closed-circuit systems are the best choice. The alarm circuit is a magnetic device made up of two interdependent circuits--one is connected to an electromagnet and the other is connected to a lever, or switch. In a closed circuit, electricity flows from one circuit to the other when the door is closed. When this flow is broken, the alarm goes off. For a garage door, this device would be mounted right alongside the door frame.

Installation

Since the opening and closing of the garage door determines when electricity moves through the alarm system, the magnet part of the circuit is mounted on the side of the door that slides against the frame. The switch is then positioned on the door frame so the magnet and switch are touching when the door is closed. Switches can be surface-mounted or recessed-mounted, wherein it sits inside the frame itself. The device is then attached to a control box unit that has its own power source. Typically, a control box will include a keypad where the security code can be entered in case of a false alarm. The more expensive systems have added features like motion sensors and wireless remote control access.