1. GOVT WOMEN ENGINEERING COLLEGE AJMER
SEMINAR PRESENTATION ON
LASER BASED SECURITY SYSTEM

2. INTRODUCTION OF ORGANISATION
DRDO was formed with 10 establishments or laboratories.
Today it is a network of 50 laboratories which are deeply engaged in developing defence technologies covering various disciplines like aeronautics, electronics, missiles etc.
Presently the organization is backed by over 5000 scientists

3. INTRODUCTION OF PROJECT
Laser based security system can protect from thieves or trespasses in bank, jewelry shop, shopping malls etc.
Burglar, fire and safety alarms are electronic alarms designed to alert the user to a specific danger.
In these types of security systems, sensors are connected to a control unit via low voltage wiring or a narrowband RF signal which is used to interact with a response device.

4. CIRCUIT DIAGRAM

5. PRINCIPLE
Any trespasser interrupts laser beam path, an electronic circuit should generate alarm.
We have designed and developed this circuit using transistor, diode and alarm.
A laser beam may be placed around the required area by proper area by proper placing mirrors.

6. LIST OF COMPONENTS Resistor Capacitor Transistor Transformer LDR Diode
Laser light
Relay
PCB

7. RESISTOR
Resistors are electronic components that are used for resisting the flow of electrons
Types of resistors
i. Carbon resistors
powdered carbon + powdered clay
tolerence 10% and 20%
ii. Film resistors
more precise
tolerence 0.5%, 0.25% and 0.1%
iii. Wire wound
special wire wounded around a non conducting core

8. CAPACITOR Capacitors are used to store electric charges.
These are also used as filters and smoothing.
Measured in farads.
There are many types of capacitors.
Electrolytic capacitor is used where larger capacitance values are needed.
These capacitors are polarised .

9. TRANSISTOR
A transistor is a device used to amplify and switch electronic signals.
It has two p-n junction inside it so known as bi-junction transistor.
BJT consists of three differently doped semiconductor regions.
It is a three terminal device.
According to doping transistors are of two types: NPN and PNP.

10. DIODE
In electronics, a diode is a two terminal component that conducts electric current in only one direction.
This is a crystalline piece of semiconductor material connected to two electrical terminals.
The most common function of a diode is to allow an electric current to pass in one direction while blocking current in the opposite direction.

11. RELAY Relays are mostly used for switching purpose.
Normally we use five terminal relays.
We deal with mainly two states of relay: NO and NC
NO(normally open): contacts connect the circuit when the relay is activated.
NC(normally closed): contacts disconnect the circuit when the relay is activated.

12. TRANSFORMER
The transformer is based on two principles: first, that an Electric current can produce a magnetic field (electromagnetism), and, second that a changing magnetic field within a coil of wire induces a voltage across the ends of the coil (electromagnetic induction). Changing the current in the primary coil changes the magnetic flux that is developed. The changing magnetic flux induces a voltage in the secondary coil

13. LASER
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons.
The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation. The emitted laser light is notable for its high degree of  coherence

14. LDR It is light dependent resistor.
It is a resistor whose resistance decreases with increasing incident light intensity.
A photoresistor is made of a high resistance semiconductor. If light falling on the device is of high enough frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electron conduct electricity, thereby lowering resistance.

15. PCB
The miniaturization in electronic equipment design has introduced a new technique known as
PRINTED CIRCUIT BOARD.
It is used to interconnect the various electronic components. Basically it is a piece of insulating material with circuit printed on it and provided with holes.

16. CASE 1 : LASER BEAM IS FALLING ON LDR
In this case, when laser beam is shined on LDR. LDR resistance will be very low around some Ohm.
Both switches S1& S2 are closed, through transformer X1, 12V is passing through the diode D2 and capacitor C1.
LDR illuminated by Laser beam, the LDR resistance will be low, hence base current of transistor T1 is high, so it will drive the Transistor T1 in saturation mode and Vce saturation is 0.3V. Because of this low Vce sat voltage the relay RL1 is in OFF condition i.e. contact will be open and there will be a path break for alarm as well as for transformer X2.
Hence transformer X2 is also OFF and no current is flow towards relay RL2.
And alarm is in OFF condition.

17. CASE 2: LASER BEAM IS INTERRUPTED
When laser light off/Hindrance due to tress pass. LDR resistance will be high around 100Kohm.
Due to hindrance in laser beam path, LDR resistance at base of transistor T1 is high, so the base current will be current will be low enough to cut off the trasistor and 12V DC will be applied to relay RL1 and relay will be in ON condition i.e. contact will be made at N/C.
And alarm is started to ring.
Due to this the transformer X2 is ON and so 12V is passing through C2 and D6 and relay RL2 is ON.

18. CASE 3: AGAIN LASER BEAM SHINED ON LDR
1. When again laser beam is shined on LDR, transistor T1 is OFF.
2. So, RL1 is OFF
3. Alarm will not OFF, because circuit is completed through transformer X1 and RL2.
4. Therefore Switch S2 should be open to OFF the alarm.

19. THANKS !

20. QUERIES???