This document summarizes a student project that designed an anti-theft alarm system for bikes. The circuit uses a 555 timer, 7805 voltage regulator, 7473 JK flip-flop, and LM311 comparator. It has a transmitter section with an IR LED attached to the front mudguard and a receiver section with an IR sensor. When the mudguard is moved, the sensor detects the IR signal and sounds the bike horn through a relay. The system provides security for vehicles in a low-cost and effective way.

1. VARDHAMAN COLLEGE OF ENGINEERING
ANTI-THEFT ALARM FOR BIKES
Mini Project
By
B. Ajitha (09881A0462)
E. Vinod kumar (09881A04B3)
Under the Guidance of
Ms. C. Padmini
Senior Assistant Professor
Department of ECE

2. OUTLINE
Introduction
Circuit diagram
Implementation of Project
Advantages & Limitations
Applications
Conclusion and Future Scope
References

3. INTRODUCTION
 Automobiles appearance impacts and changes people's life,
it's becoming the progressive symbol of modern society.
 However, as the sharp rise of the automobile quantity,
vehicle thief case is increasing.
 Vehicle theft is common in present time and physical
protection is not much enough. So to protect vehicles from
thieves some electronic techniques should be used.

4.  When anyone tries to steal the bike then this circuit will
starts conducting and the buzzer starts sounding.
 This sound indicates that somebody is trying to steal the
bike, so this circuit is used to protect the vehicles from
thieves.
 We can also use different types of anti theft guards for
different applications, like the home doors and car doors
for security purpose. These are low cost and effective.

5. CIRCUIT DIAGRAM

6. 555 TIMER IN ASTABLE MODE
Astable, in which the circuit is not
stable in either state
It continually switches from one
state to the other. It does not
require an input such as a clock
pulse.

7. IC 7805
IC 7805 is a voltage regulator
integrated circuit.
It maintains the output voltage at
a constant value
7805 provides +5V regulated
power supply

8. IC 7473
The circuit can be made to change state by signals applied to one or
more control inputs and will have one or two outputs.

9. IC LM311
The LM311 series is a low input
current voltage comparator.
It can drive lamps or relays,
switching voltages up to 50V at
currents as high as 50 mA.

10. IMPLEMENTATION OF PROJECT
 Usually, a handle lock is used on the handle bar for the safety of bikes, with
the front mudguard in a slanted position. When the handle lock is freed,
the front mudguard can be aligned with the body of the bike.
 This circuit consists of transmitter and receiver sections. The transmitter
(IR LED1) is fitted on the back end of the front mudguard and the receiver
sensor (IRX1) is fitted on the central portion of the crash guard of the bike
such that IR rays from the transmitter directly fall on the sensor when the
front mudguard comes in line with the body of the bike.

11.  The transmitter section is built around timer 555 (IC2),
which is wired as an astable multivibrator with a
frequency of around 38 kHz.
 The output of IC2 is further amplified by transistor T1 and
given to an infrared light-emitting diode (IR LED1), which
continuously transmits the IR frequency.
 The receiver section uses IR receiver module TSOP 1738
(IRX1), which is normally used in TV receivers. The
receiver module senses the IR modulated frequency
transmitted by the IR LED.

12. The input voltage at pin 2 of IC3 is fixed by using the
voltage-divider network comprising resistors R7 and
R8.
When IR rays are not incident on the IR receiver
module, the voltage at pin 3 of IC3 is greater than the
voltage at pin 2. As a result, the output of comparator
IC3 is low.
 But when the receiver senses IR rays from IR LED1,
the voltage at pin 3 of IC3 is lower than the voltage at
pin 2. As a result, the output of the comparator goes
high.

13.  The output of the comparator is given to a latch made up
of JK flip-flop (IC4). The low-to-high going pulse from the
comparator makes the output of IC4 high until it is reset.
 The output of IC4 is latched and used to energise relay
RL1 via transistor T2.
 The relay is connected to the negative terminal of the
mobike’s horn, while the positive terminal of the horn is
connected to the positive terminal of the battery .

14.  The energised relay drives the horn, which continues sounding until
you press reset switch S2 momentarily. At night, lock your bike using
the handle lock and switch on the circuit using switch S1.
 Since the IR transmitter (IR LED1) and the receiver (IRX1) will not be
in line of sight, IR rays from IR LED1 will not be incident on the
sensor.
 This will make the output of the comparator (IC3) high. The pulse
from the comparator will make the output of latch IC4 high and
transistor T2 will conduct to sound the horn via relay RL1.

15. ADVANTAGES & APPLICATIONS
 Advantages:
This circuit is easy and simple to understand.
This circuit is used wherever security needed.
 Limitations:
Continuous power supply is needed to the circuit for operation.
 Applications:
To provide security for vehicles.
To provide security for house doors.

16. CONCLUSION &FUTURE SCOPE
 Conclusion:
It is cost-effective anti theft system, which can be expected to
drastically reduce the automobile thefts, are entirely feasible as
factory installed devices.
Also a wide range of theft methods have been used, the most
prevalent current methods include the use of a door lock
mechanism. The project "anti theft alarm for bikes " system has
successfully designed and tested. Integrating features of all
hardware components used have developed it.
 Future Scope:
Vehicle alarms
Mechanical and Electronic immobilizer
Vehicle tracking

17. REFERENCES
 http://www.electronicsforu.com
 http://www.engineersgarage.com
 http://www.en.wikipedia.org/wiki/filerelay-parts.jp