For $30 or less you can quickly and easily install a door security alarm, whether it's intended to alert you in case a small child wanders into an enclosed pool area or to provide an additional level of nighttime security. Home security systems often place a magnetic door sensor at every point of entry to a house. The principle is the same with a door security alarm, but whereas a sensor will signal the system control panel to sound the alarm, a door security alarm includes the siren in its design.
Door Alarm Design
Comprised of two parts, a door security alarm installs on virtually any type of door and its adjacent frame. The bigger part contains the battery, electronics, siren and any controls, while the smaller part holds the opposing magnet. When in place and with the door closed, the magnets in each part attract each other and form a contact point. Once the door alarm is activated, any break in that contact will sound the alarm, alerting you to the fact that the door has been opened.
Door security alarms are battery powered and typically feature an on/off switch. Some units include a keypad to arm or deactivate the alarm. Other features may include a panic button and automatic reset.