This document describes a laser security alarm system. It includes a circuit diagram and list of components used, which are resistors, transistors, an LDR light dependent resistor, battery, buzzer, and laser. The system is designed to detect intrusion using a laser that is invisible to the naked eye in bright light but visible in dark light to alert people of any burglary. It has advantages of being easy to construct, light weight, economical, and able to easily alert people during a burglary. Applications mentioned include use in homes, businesses, prisons and vehicles.

1. VALLURUPALLI NAGESWARA RAO VIGNANA JYOTHI
INSTITUTE OF ENGINEERING & TECHNOLOGY
AN AUTONOMOUS INSTITUTE
(Approved by AICTE, New Delhi and Govt. of A.P. & affiliated to JNTUH)
Vignana Jyothi Nagar, Bachupally, Nizampet (S.O.) Hyderabad – 500090.A.P. India.
Tel: +91-40-23042758, 23042759, 23042760, Fax: 91-40-23042761
E-mail: postbox@vnrvjiet.ac.in, Website: www.vnrvjiet.ac.in
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING
2013-2014

2. In guidance with
G.C.Prabhakar sir........................

3. LASER Security alarm system
• A security alarm is a system designed to detect
intrusion – unauthorized entry – into a building or
area. Security alarms are used in residential,
commercial, industrial, and military properties for
protection against burglary (theft) or property
damage, as well as personal protection against
intruders. Car alarms likewise protect vehicles and
their contents. Prisons also use security systems for
control of inmates.

4. But we are working on a security alarm with
laser, there are many types of security alarm.
Now in our daily life we are mostly using
security alarm with help of laser, they can be seen
in dark light but in brightness we can’t see with
naked eye.

5. Advantages of security alarm with laser:
 It is easy in construction.
 It lights in weight.
 Light weight as compared to other security systems.
 It economical.
 If any burglary happens people will alert easily.

6. Applications of laser security alarm:

8. Circuit diagram:

9. Components used:
 Resistors -330Ω - 2no
-1kΩ- 2no.
 Transistors -BC547- 2no
-BC109-1no.
 LDR (light dependent resistor)
 9V battery
 Buzzer
 General PCB board
 LASER ( light amplification by stimulated emission of radiation).

10. Resistor
 The current through a resistor is in directly proportion to
the voltage across the resistor's terminals. This relationship is
represented by Ohm's law:
Resistor is a device which
opposes the flow of electrons

11.  where I is the current through the conductor in units of amperes, V is the
potential difference measured across the conductor in units of volts, and R is
the resistance of the conductor in units of ohms (symbol: Ω).
 In this circuit we are using the resistor to limit the current into the transistors
and the buzzer.

12. LASER
Light Amplification by Stimulated Emission of
Radiation is an electronic device that produces light
(electromagnetic radiation) through a process of optical
amplification. These radiation have very special
properties that makes them used in a wide variety of
applications.
It is used to manufacture a wide range of electronic
devices including CD ROMs, Bar code readers, etc. The
light emitted by these devices is thin and coherent.

13. Applications of LASER:
 It is used in CD and DVD ROMs.
 They are also used in barcode scanners
 Used as an integral part of nuclear fusion reactors
 In devices used for alignment, cutting, soldering, drilling,
surface treatment, welding etc.
 In medical equipments for dentistry, cosmetic treatment
etc
 In military equipments like anti missiles devices
 In Laser Printers for printing