Our third year analog project

1. PROJECT REPORT
ON
“SECURITY ALARM”
Submitted By
VISHRAM ANANT (24), JOEL MENDONCA (33),
GLEVITA MENDONSA (34), JAESON NAZARETH (36)
Under The Guidance Of
Prof: ManaliTayade
Department of Electronics & Telecommunication
Xavier Institute Of Engineering, Mahim.
MUMBAI UNIVERSITY, MUMBAI
2012-2013

2. CERTIFICATE
This is to certify that this Project Report entitled
“SECURITY ALARM”
Is satisfactorily completed by
VISHRAM ANANT (24), JOEL MENDONCA (33),
GLEVITA MENDONSA (34), JAESON NAZARETH (36)
Of T.E(E.X.T.C) class as specified in syllabus.
This report represents their bonafide work in year 2012-2013.
Prof. ManaliTayade Prof. SupravaPatnik
(Project Guide) (H.O.D. –EXTCDepartment)
Prof. Y.D. Venkatesh (External Examiner)
(Principal)

3. Security Alarm
Joel Mendonca, GlevitaMendonsa, Vishram Anant, Jaeson Nazareth.
Electronics and Telecommunication Engineering
Xavier Institute of Engineering, Mahim
Abstract- This design provides an inexpensive yet effective B. WORKING
form of protection against intruders as well as it can be
easily used during festivals for novel applications. When a The circuit consist of a transformer which is a step
ray of light is interrupted, the power output is switched on down transformer. It gives 12V supply to all
for a variable duration of 5-55 seconds to operate the components on the circuit. Besides there are
relay components like Relay switch, IC 555 used as a
monostablemultivibrator, LDR (Light Dependent
I. INTRODUCTION
Resistor) which serves as the primary component of the
The circuit illustrated here is used as an Burglar alarm. LDR circuit whose role will be given in detail.
is kept at such a place that when thief enters our house then a
shadow will fall on the LDR. A small beam of light source is 1.IC 555-The operation and output of the 555
also needed to supply continuous signal to LDR. For best Monostable is exactly the same as that for the
Light source we can use Laser diode which will work for few transistorised one. The difference this time is that the
KMs. For home use Infra Red LED’s will be good and will be two transistors have been replaced by the 555 timer
tricky to thief and works with same efficiency at night. device. Consider the 555 Monostable circuit below
II CIRCUIT DIAGRAM
Fig 1. Circuit Diagram
A. COMPONENTS USED Fig 2. Working of monostable IC 555
The components used are :
IC 555 When a negative ( 0V ) pulse is applied to the trigger
Centre tap X’former 230-12V input (pin 2) of the Monostable configured 555 Timer
LDR oscillator, the internal comparator, (comparator No1)
Transistor T1,T2 BJT 547 detects this input and "sets" the state of the flip-flop,
T3 BJT 557 changing the output from a "LOW" state to a "HIGH"
Diode D1, D2 Zener diode state. This action inturn turns "OFF" the discharge
R1,R2,R3,R4,R5,R6,R7 transistor connected to pin 7, thereby removing the
C1,C2,C3 short circuit across the external timing
Bulb 11 watts capacitor, C1.This action allows the timing capacitor to
Relay switch start to harge up through resistor, R1 until the voltage
across the capacitor reaches the threshold (pin 6)
Potentiometer
voltage of 2/3Vcc set up by the internal voltage divider
network. At this point the comparators output goes
"HIGH" and "resets" the flip-flop back to its original

4. state which inturn turns "ON" the transistor and multiple operating coils are used to protect electrical
discharges the capacitor to ground through pin 7. This circuits from overload or faults; in modern electric
causes the output to change its state back to the original power systems these functions are performed by digital
stable "LOW" value awaiting another trigger pulse to instruments still called "protective relays".
start the timing process over again. Then as before, the Small "cradle" relay often used in electronics. The
MonostableMultivibrator has only "ONE" stable "cradle" term refers to the shape of the relay's armature.
state.The Monostable 555 Timer circuit triggers on a A simple electromagnetic relay consists of a coil of
negative-going pulse applied to pin 2 and this trigger wire wrapped around a soft iron core, an iron yoke
pulse must be much shorter than the output pulse width which provides a low reluctance path for magnetic flux,
allowing time for the timing capacitor to charge and a movable iron armature, and one or more sets of
then discharge fully. Once triggered, the 555
contacts (there are two in the relay pictured). The
Monostable will remain in this "HIGH" unstable output
armature is hinged to the yoke and mechanically linked
state until the time period set up by the R1 x C1 network
to one or more sets of moving contacts. It is held in
has elapsed. The amount of time that the output voltage
place by a spring so that when the relay is de-energized
remains "HIGH" or at a logic "1" level, is given by the
following time constant equation. there is an air gap in the magnetic circuit. In this
condition, one of the two sets of contacts in the relay
2.Relay switch-A relay is an electrically operated pictured is closed, and the other set is open. Other
switch. Many relays use an electromagnet to operate a relays may have more or fewer sets of contacts
switching mechanism mechanically, but other operating depending on their function. The relay in the picture
principles are also used. Relays are used where it is also has a wire connecting the armature to the yoke.
necessary to control a circuit by a low-power signal This ensures continuity of the circuit between the
(with complete electrical isolation between control and moving contacts on the armature, and the circuit track
controlled circuits), or where several circuits must be on the printed circuit board (PCB) via the yoke, which
controlled by one signal. The first relays were used in is soldered to the PCB.
long distance telegraph circuits, repeating the signal When an electric current is passed through the coil it
coming in from one circuit and re-transmitting it to generates a magnetic field that activates the armature,
another. Relays were used extensively in telephone and the consequent movement of the movable
exchanges and early computers to perform logical contact(s) either makes or breaks (depending upon
operations. construction) a connection with a fixed contact. If the
set of contacts was closed when the relay was de-
energized, then the movement opens the contacts and
breaks the connection, and vice versa if the contacts
were open. When the current to the coil is switched off,
the armature is returned by a force, approximately half
as strong as the magnetic force, to its relaxed position.
Usually this force is provided by a spring, but gravity is
also used commonly in industrial motor starters. Most
relays are manufactured to operate quickly. In a low-
voltage application this reduces noise; in a high voltage
or current application it reduces arcing.
3.LDR-A photoresistor or light dependent resistor
Fig 3. Relay Switch (LDR) is a resistor whose resistance decreases with
increasing incident light intensity; in other words, it
A type of relay that can handle the high power required
exhibits photoconductivity.Aphotoresistor is made of a
to directly control an electric motor or other loads is
called a contactor. Solid-state relays control power high resistance semiconductor. If light falling on the
circuits with no moving parts, instead using a device is of high enough frequency, photons absorbed
semiconductor device to perform switching. Relays by the semiconductor give bound electrons enough
with calibrated operating characteristics and sometimes energy to jump into the conduction band. The resulting

5. free electron (and its hole partner) conduct electricity, components, EAGLE already supplies the
thereby lowering resistance. Device Set so we don’t have to spend
timerecreating devices from scratch every time
we wish to use it. First things first, look
through yourdesign and list all of the
components that you expect to use and look
through the libraries that comeprepackaged
with EAGLE.
Fig 4.LDR
A photoelectric device can be either intrinsic or
extrinsic. An intrinsic semiconductor has its own
charge carriers and is not an efficient semiconductor,
for example, silicon. In intrinsic devices the only FIG 5. Schematic of security Alarm
available electrons are in the valence band, and hence B. BOARD
the photon must have enough energy to excite the Creating the board from a schematic is one of
electron across the entire bandgap. Extrinsic devices the easiest tasks with EAGLE.
have impurities, also called dopants, added whose The Board command creates a new window
ground state energy is closer to the conduction band; with all the parts arranged next to a default
board outline. All the nets from the schematic
since the electrons do not have as far to jump, lower
are shown as air wires. The Move command
energy photons (that is, longer wavelengths and lower allows you to pick up each part and move it to
frequencies) are sufficient to trigger the device. If a its desired position. You can also move entire
sample of silicon has some of its atoms replaced by groups of parts. The right mouse button rotates
phosphorus atoms (impurities), there will be extra the current part or group.
electrons available for conduction. This is an example The Ratsnest command recalculates the air
of an extrinsic semiconductor.Photo resistors are wires.Manual routing is done with
the Route command. You simply pick up an
basically photocells.
air wire, adjust the angle with the right mouse
button, and select the layer with the center
III. TECHNOLOGY USED button. Via will be added automatically as
IC 555 is used in monostable state and triggers needed. You can also let the Auto router do
theRelay circuit. the routing.
A. SOFTWARE USED
1. Schematic Designed on Eagle
2. Board prepared on Eagle
EAGLE(Easily Applicable Graphical Layout Editor)
IV. PCB LAYOUT
A. SCHEMATIC
Library CreationEAGLE only knows of
components that exists in its libraries, if it isn’t
contained in one of themany default libraries
you will have to create the device yourself.
For standard components andmany typical

6. Etching at ambient temperature might take
over an hour, it is better to heat up the etching
solvent to about 35-45 degrees Celcius. The
etching solution heating up could be done in a
magnetron, this takes about 40 to 60 seconds
in a 850W magnetron depending on the initial
temperature of the etching solution (hint: first
try this with just water to determine the timer
setting of the magnetron). The etching -
rocking the etching tray - takes about 15-30
minutes at this temperature. If you have a
heated, air-bubble circulated etching fluid tank
available, this is probably the fastest way to
etch. At higher temperatures the etching
performance decreases. The etching process is
C. PCB UV Exposure an exothermic reaction, it generates heat. Take
The protective plastic layer is removed - care, cool your etching tray when necessary!
peeled back - from the photosensitive PCB. You should minimize the amount of copper to
The toner side of the greased layout is placed etch by creating copper area in your PCB
on the copper of the PCB. Captured air- layout as much as possible. When starting the
bubbles are gently pressed away from etching process and little to etch it is difficult
underneath the layout. The PCB with the to keep the etching solution at 35-45 degrees
layout is now covered with an appropriate Celsius. It helps to fill for example the kitchen
sized windowpane and placed on a piece of sink with warm water and rock the etching
plain polished tile or marble. The tile or tray in the filled kitchen sink.
marble absorbs the heat coming from the UV
bulb, which is significant. Three to four
minutes 300W bulb UV exposure from a V. CONCLUSION
distance of 30-40 cm will do the photo The LDR and R1 form a potentialdivider. With light
process. Take care when finished and focused on LDR, the resistance of LDR becomes very
removing the PCB, it gets hot! low – of the order of 500 ohm to 1k.Hence, the voltage
across R1 is sufficient to keep T1 in conduction which
D. PCB Development in turn keeps T2 in conduction. Underthis condition IC
The PCB is developed with a 1% solution of 555 is triggered. The output of themonostable stage is
sodium hydroxide NaOH. You can make this low and relay is unable to trigger.When the beam is
solvent by adding 10 gram of sodium interrupted momentarily by the coin orby an intruder
hydroxide pellets to 1 litter of water and mix it the resistance of LDR suddenly rises to 1M.Now the
until everything is dissolved. Use a brush to voltage across R1 is insufficient to keep T1
speed up the developing and clean the PCB inconduction and hence T1 and T2 are cut off and the
during this process if the PCB is still greasy bulb glows.
due to the applied sunflower-seed oil. The
developing process takes about 1 minute. It is ACKNOWLEDGMENT
sometimes difficult to guess when the It is our privilege to acknowledge with deep sense of
developing is finished. The traces should gratitude to our project guide, Prof. Manali Tayade
become clear and the exposed photosensitive for her valuable suggestions and guidance throughout
layer has dissolved (during the brushing you our course of study and timely help given to us in the
see darker `cloud' coming off the PCB completion of our project.
surface).
We are highly obliged to the entire staff of Electronics
and Telecommunication Department for their kind help
E. PCB Etching

7. and co-operation. We also take this opportunity to
thank all my colleagues for offering all possible help.
REFERENCES
1. http://www.wikipedia.org
2. http://www.kpsec.freeuk.com/components
3. http://www.electronics-tutorials.ws
4. http://electronics.howstuffworks.com
5. http://www.mp3car.com/the-faq-emporium
6. http://www.testech-elect.com/cadsoft/
7. http://sfprime.net/pcb-etching/index.htm