Security Door Alarm using Magnetic Reed Switch
Security door alarms are simple electronic devices that trigger when an intruder
or trespasser tries to gain access to any designated area. They are a necessary
part of today’s home security systems. There are a number of electronic
configurations available to implement such home security alarms. Here, we will
take a look at implementing using a reed switch. The heart of this circuit is a
magnetic reed switch. A reed switch comprises two ferromagnetic blades,
separated by only a few microns. When another magnet comes close to these
blades, the two blades pull towards one another. Once touching, the blades close
the normally open (NO) contacts, allowing electricity to flow. Some reed
switches also contain a non-ferromagnetic contact, which forms a normally closed
(NC) output. Any approaching magnet will disconnect the contact and pull away
from the switching contact.
Door Security Alarm Circuit
