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Understanding how door alarms work is not very difficult. There are quite a few different types though so I'll start with the one I like the most, which is the door stop alarm. This one is my favorites because it not only alerts you that someone is trying to break in but also stops the door from opening. There is a pressure sensitive switch in the base that triggers the alarm when anyone tries to push open the door. This unit is also very flexible. Take it with you on business trips, vacation or the office as well as using it at home.
Next let's talk about a unit that's not only a portable door alarm but also a window alarm as well. When looking into how door alarms work this warning device functions the way many of them do. It has an attachment with a sprung metal clip that you slide between the door and the jam (or the window and the sill). With the door (or window) closed the connection between the two pieces of metal are held in place completing an electrical circuit. When the door (or window) is opened the contacts spring apart, breaking the electrical circuit, and the alarm is sounded. Really, understanding how door alarms work is not that difficult.
What you may think of when you think "door alarm" is 2 contacts, 1 mounted to the door, the other mounted to the frame, connected by wiring to a box or keypad, like you would get form ADT or any of the big alarm companies. This type works exactly the same way as the one in the last paragraph does. When the d
or is opened, and the contacts separate, the connection is broken which causes the alarm to go off. The only difference is it can't be moved.
Another type of alarm, although not technically a door alarm, is a PIR (Passive InfraRed) motion sensor. These sensors can be connected to a base unit either by wire or wireless transmitter. They operate by detecting variances between a persons body heat and the normal background temperature. Let's complete our understanding of how door alarms work by looking at an instant door alarm which can also be used as a personal alarm. This one works by creating an incomplete electrical circuit. It comes with a chain that is placed on any metal door knob. It sends an electrical signal through the chain, to the knob, which has no where to go until someone touches it. When anyone touches the door knob they become the ground, completing the electrical circuit, and the alarm is instantly triggered. A disadvantage of this alarm is that it can not be used on a metal door because the door would ground the circuit and the alarm would go off constantly.
About the authur:
My name is Mark Strong and I live in Loveland Ohio with my lovely wife Patricia. We hope that everyone will benefit from the information and products we provide and have a safer, happier more secure life.