Security Alarm Curcuit

A security alarm is a system designed to detect intrusion, such as unauthorized entry, into a
building or other areas such as a home or school. Security alarms used in residential,
commercial, industrial, and military properties protect against burglary (theft) or property
damage, as well as personal protection against intruders. Security alerts in neighborhoods show a
connection with diminished robbery. Car alarms likewise help protect vehicles and theircontents.
Prisons also use security systems for the control of inmates.Some alarm systems serve a single
purpose of burglary protection; combination systems provide fire and intrusion protection.
Intrusion-alarm systems are combined with closed-circuit television surveillance (CCTV)
systems to record intruders' activities and interface to access control systems for electrically
locked doors. There are many types of security systems. Homeowners typically have small, self-
contained noisemakers. These devices can also be complicated, multirole systems with computer
monitoring and control. It may even include a two-way voice which allows communication
between the panel and monitoring station

Circuit Diagram of Security Alarm.

 · Circuit Components:
· 74LS00

· BUTTON

· BUZZER

· LED- YELLOW

· RESISTOR

· SPEAKER

· TIP41

· TORCH_LDR

Resistor
Resistors are the passive device with two terminals. They are mainly used in the circuit to
restrict the flow of current across any of the circuits. The current flow from the resistor is
directly proportional to the voltage that is given across the terminals of the resistor. In the
market resistors are mainly available in two broad categories: Fixed resistor– It actually
means that the resistor whose value cannot be change and remain

what its mark on it.

Variable Resistor- It means that the value of resistance can vary within the range marked
over it.

For e.g. If the value of 5k is marked on it then it implies that the value of the resistor can
vary from 0-5k.

The value of the resistor can be calculated either with the help of multimeter or with the
help of color code over the resistor.

Diodes
It is a device with two terminals and have a asymmetric attribute which means that it
permit the flow of current in one of the directions while the flow of high resistance is from
another direction. Hence in it flow of current is in one way only and block the other .way
for the current flow. The two terminals in diode named as anode and cathode. AC current
can be converted into DC with the help of diode unidirectional behaviour.

Transistor
transistor is a three terminal electronic device used to amplify weak input signals. A
transistor consist of two PN junction diode connected back to back. Transistor are of
different type such as bipolar junction transistor, Field effect transistor and photo
transistor. They are mostly used in electrical appliances due their smaller size and light
weight. In addition they posses less power hence have greater efficiency.

Speaker
it is a transducer which creates sound in reaction of the electrical auditory signal given in
the input

How Alarm Systems Work

Alarm Systems work by sending out signals to a central monitoring station when sensors
are faulted. The central hub of an alarm system is the alarm control panel. All system
sensors and other equipment communicate with the panel. The panel needs a
communicator to send outbound signals.The purpose of an alarm system is to let the user
and the appropriate authorities know whenever there is an emergency. This includes an
intrusion, fire, environmental problem or medical crisis. The system identifies these
emergencies using various sensors. Some popular sensors for security systems include door
and window contacts, motion detecting sensors, glass break sensors, smoke and heat
detectors, flood sensors, temperature sensors and security key fobs. Sensors can be
hardwired into a security system, or they can communicate wirelessly through the use of a
wireless receiver.When a sensor is activated or faulted, it sends an alert to the alarm control
panel. The system will then respond based on the programming settings for that zone. For
example, one sensor might only cause alarms if activated while the system is Armed, while
others may cause alarms at any time, regardless of the current system status. Making sure
that your sensors have the correct programming settings is very important. Zones can also
be programmed to have a delay period, which gives the user a short period of time to
Disarm the system before an alarm signal is sent out.When an alarm does occur, the system
sends out an alert to a central monitoring station. Most alarm systems today use an internet
communicator or a cellular communicator to send out signals. There are also dual-path
modules that use both IP and cellular communication. The central monitoring station
operates around the clock, 24/7. A trained dispatcher will immediately notice the alarm and
begin contacting the end user and/or the local authorities. If the dispatcher does not receive
verification that the alarm was false, then the appropriate authorities will be sent out to the
premises as soon as possible.There is also what is referred to as self-monitoring. In this
case, the alarm system does not contact a central monitoring station. Instead, it alerts the
end user directly through a text message or email. This is done using an interactive service
platform like Total Connect 2.0 or Alarm.com. It is then up to the end user to contact the
appropriate authorities. This can be a good option if the user is confident that they can
quickly and consistently respond to texts or emails letting them know that something may
be wrong. For more information about our monitoring plans, please review our alarm
monitoring page.

Advantanges of security alarm system

· Protects valuables.

· Deters crime.

· Allows remote access to your home.

· Lowers homeowner's insurance.

· Notifies you of fire or gas problems.

· Helps keep tabs on kids.

· Improves electricity management.

 · Makes room for peace of mind.

Advantage – Constant Protection

If you install a monitored alarm system in your home, you and your family have roundthe-
clock the protection against break-ins. Some systems also have fire alarms built in, which
provides additional reassurance. The constant protection of an alarm system is particularly
comforting when you may be away from your home for an extended period or you must
leave your children home alone for an evening. It also means that your home is protected
while you are sleeping so you can have peace of mind about your family's safety and get a
good night's sleep.

Advantage – Deterrent to Criminals

Most home alarm systems provide small lawn signs or placards for your window that
indicate that your home is protected by a security company. In many cases, the presence of
this type of sign alone may persuade burglars and other criminals to pass over your home
and move on to a dwelling that is not protected by a security system. Be sure to clearly
display the decals and signs from your monitoring company to fully advertise your home's
security.

Advantage – Lower Insurance Rates

While there is a significant cost to install a home alarm system, it can mean a financial
advantage as well. Your insurance company may actually adjust the rate on your
homeowners insurance policy if you have a system installed in your home. Because your
home is protected from theft – and in many cases, fire – costly incidences that might
require you to make a claim are less likely to occur in your home. As a result, your
insurance company can lower your rate.

Disadvantage – Cut Phone Line

If your alarm system is connected to your security company by phone line only, you can
run into problems. A burglar may cut your phone line before entering your home and all
monitoring and communication with your alarm company is terminated. As a result, it is a
good idea to have a cellular radio installed with your system, which will allow
communication with the security company even if the phone line is cut.

Disadvantage – False Alarms

While a home alarm system can provide security and peace of mind, it has the potential to
become fairly annoying as well. It is not uncommon for false alarms to occur with your
system. In some cases, the police or fire department may be dispatched to your home before
you have a chance to explain the mistake to your security company. Some police
departments may charge you if they are repeatedly called to your home without reason. To
avoid false alarms, consult with your alarm company to determine what might be causing
them so you can make adjustments.

Disadvantage – Expense
The primary disadvantage of a home alarm system may be its expense. It is costly to have
the system installed in the first place, but security companies charge a daily or monthly fee
to provide monitoring services as well. These fees can quickly add up, so if you are on a
budget, it may put a strain on your finances.