BRIEF DESCRIPTION: This simple touch sensitive alarm is developed by using NE-555 timer IC, operated as a monostable vibrator. This touch alarm circuit will sound when somebody touches the trigger plate. Touch the sensing plate of the alarm with your finger and it starts beeping and then stops. Touching it again and it goes again! Here the stable stage is low, so the timer outputs low after the trigger is removed. Basically the circuit has a led which turns on when we touch a pin of timer. The led will be on for the time during which the trigger is present. Once the trigger is removed the led turns off. This is a little and flexible circuit consists of a touch sensor and a NE-555 IC with a small buzzer as the output load. Two touch sensor strips of metal are mounted side by side & connected to the input of the circuit. TEAM MEMBERS SHAHRUKH JAVED MOHAMMED MUZAFAR N For more log on to: http://shahrukhjaved.webs.com/apps/blog/ E-mial: shahrukh.tjit14@gmail.com

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A Mini Project Report on
SIMPLE TOUCH ALARM
Submitted to
T JOHN INSTITUTE OF TECHNOLOGY
Bangalore.
Bachelor of Engineering
In
Electronics and Communication Engineering
By
Shahrukh Javed BEE141570
Mohammed Muzafar N BEE141557
Session: 2016-2017
Date of submission 13th
Oct 2016
UNDER THE ESTEEMED GUIDANCE OF
PROF. BASAVANAGOUDA
DEPARTMENT OF ECE.
Department of Electronics and Communication Engineering
T JOHN INSTITUTE OF TECHNOLOGY
(Visvesvaraya Technological University)
(Approved by AICTE, Affiliated to VTU & Accredited by NAAC)
86/3, Gottigere, Bannerghatta Road, Bangalore - 560083

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PREFACE
This project provides complete information on the topic “SIMPLE TOUCH
ALARM” and maximum efforts have been taken to make the project more
comprehensive and lucid to understand.
This project covers a variety of sub topics like basic information, its working,
day to day uses in life and different aspects of basic touch alarm System. One
may notice a perceptible change in written in an easy dialogue style engaging
the readers constantly and included with more informatics comments.
I assure you to go through this project thoroughly to know a bit more and facts
about touch alarm system.

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Declaration
I hereby declare that the project entitled “SIMPLE TOUCH ALARM”
submitted by us to T. John Institute of Technology, Visvesvaraya
Technological University during the degree of Bachelor of Engineering in
Electronics & Communication Engineering is a record of bonafide project
work carried out by us under the guidance of Mr. Basavanagouda.
I further declare that the work reported in this mini project has not been
submitted & will not be submitted either in part or in full for award of any
degree in this institute.
SHAHRUKH JAVED
MOHAMMED MUZAFAR N

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Acknowledgement
The satisfaction that accompanies the successful completion of the
task would be put incomplete without the mention of the people who made
it possible, whose constant guidance and encouragement crown all the
efforts with success.
It is my greatest pleasure to thank Dr. Arun Vikas Singh Head of
Department of Electronics and Communication, T.John Institute of
Technology for providing us heart full encouragement support and
allowing us to work in such a resourceful lab of this esteemed institute &
thereby fulfilling one of my dreams.
I whole heartedly thank my project guide Mr. Basavanagouda (Asst.
Professor Electronics & Communication Department) for his consistent
guidance, expert academic and support throughout the project, without his
great concepts & inspiration it would have been impossible.
I’m very much thankful to Mr.Chethan for his help in the laboratory for
practical guidance during this project.
I thank my parents for their emotional and financial support which they
provided during this project.
We show gratitude to our Honourable Principal Dr. H.N Thippeswamy,
for having provided all the facilities and support.
I thank to all faculties who directly and indirectly helped us in the
completion of this projects.

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INTRODUCTION
This simple touch sensitive alarm is developed by using NE-555 timer IC, operated as
a monostable vibrator.
This touch alarm circuit will sound when somebody touches the trigger plate. Touch
the sensing plate of the alarm with your finger and it starts beeping and then stops.
Touching it again and it goes again!
Here the stable stage is low, so the timer outputs low after the trigger is removed.
Basically the circuit has a led which turns on when we touch a pin of timer. The led
will be on for the time during which the trigger is present. Once the trigger is removed
the led turns off.
This is a little and flexible circuit consists of a touch sensor and a NE-555 IC with a
small buzzer as the output load. Two touch sensor strips of metal are mounted side by
side & connected to the input of the circuit.

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COMPONENTS USED
SR.NO. COMPONENT NAME SPECIFICATION QUANTITY
1. INTEGRATED CIRCIUT NE555 IC
1
2. METAL PLATES TOUCH SENSITIVE
4
3. LED GREEN
1
4. PIEZO BUZZER SOUND LEVEL
85dB (minimum)
1
5. BATTERY 9V
1
Table 1. List of the Components Used.
MAJOR COMPONENT DESCRIPTION
1. NE555 IC
Fig 2. Pin configuration of NE555 IC
The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation,
and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and
as a flip-flop element.

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Pin description
The connection of the pins for a DIP package is as follows:
PIN NAME PURPOSE
1 GND Ground reference voltage, low level (0 V)
2 TRIG
OUT will be high as long as the trigger is kept at low voltage.
Output of the timer totally depends upon the amplitude of the
external trigger voltage applied to this pin.
3 OUT This output is driven to approximately 1.7 V below +VCC, or
to GND.
4 RESET
A timing interval may be reset by driving this input to GND,
but the timing does not begin again until RESET rises above
approximately 0.7 volts. Overrides TRIG which overrides
THR.
5 CTRL Provides "control" access to the internal voltage divider (by
default, 2/3 VCC).
6 THR The timing (OUT high) interval ends when the voltage at THR
("threshold") is greater than that at CTRL (2/3 VCC if CTRL is
open).
7 DIS Open collector output which may discharge a capacitor
between intervals. In phase with output.
8 VCC Positive supply voltage, which is usually between 3 and 15 V
depending on the variation.
Table 2.
Features Applications
Timing From Microseconds to Hours. Fingerprint & Iris Biometrics.
Astable or Monostable Operation. RFID Reader.
Adjustable Duty Cycle. Pulse width modulation.
TTL-Compatible Output Can Sink or
Source Up to 200 mA.
Precision timing and pulse generation.
Table 3.

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CIRCUIT DIAGRAM
Fig 1.
Working
As shown, the touch sensitive circuit is connected on the breadboard as per the
schematic diagram, and power is turned ON.
The main part of this circuit is the 555 timer IC which is set as a monostable
multivibrator, the metallic loop (here we used as a pin) to pin-2 of 555 and it is active
low, when the pin 2 is grounded the latch output will be set to 1 and when pin 4 is
grounded the latch is reset, the output of the latch is given to a buzzer.
Trigger determines the output of IC NE-555; this trigger pin sets the flip-flop inside
the 555 TIMER. When this pin is high the output will be high and when this pin is low
the output is low.
As said earlier since this pin is very sensitive it will pull the 555 output high by touch.
LED will not turn on as the trigger is not given. The trigger pin in the timer is a high
impedance one and is very sensitive. This pin can merely be pulled high by human

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body potential. So on touch the trigger pin forces the internal flip-flop to SET mode
and so the output goes high.
Touch the sensor plate of the alarm with your finger and it starts beeping.
Touching it again and it starts beeping!!

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Advantages
 Easy to operate & Fast response.
 Smaller in size.
 Low power consumption and sophisticated security.
 The cost is cheap and difficult to detect by burglars / intruders.
Disadvantages
 Unexpected alert i.e., Accidental alarm
 The prototype version can only be attached with conductors.
 Doesn’t provide wireless control to systems
Some Of Our Most Common Applications Involve:
 Car alarms.
 Locker system.
 Electrical Control Rooms.
 Heat Treating Furnaces.
 Historical places- Antique Statues & monuments.
 Unauthorized access to Military bases ammunition resource notification alarm.
 It can be used simple burglar alarm for security, the plate can be place in any
metal such our doors or in metal knobs.

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CONCLUSION
Here is a simple alarm device it generates a loud alarm when there is an attempt
of unauthorized access. When the intruder opens the door, the circuit senses the
attempt of theft & the alarm will be activated.
Circuit of the simple touch sensor alarm is built around a couple of readily
available cheap components. Working of this circuit is straight forward and self-
explanatory. When the circuit is powered by a 3V compact battery, Touch the
sensor of the alarm with your finger and it starts beeping. In this two sensor
strips of metal are mounted side by side and connected to the input of the
circuit, the active piezo-sounder at the output of IC starts beeping.
The circuit requires 3V dc supply and can power from a standard 3V alkaline
battery.