Automatic IN/OUT Indicator with Doorbell Manual

1. AUTOMATIC IN/OUT INDICATOR WITH DOORBELL
A PROJECT REPORT
Submitted To
Department of Electronics & Communication Technology
North Lakhimpur College (Autonomous)
For the partial fulfillment of the
Degree of Bachelor of Science in Electronics
Submitted By
SAMIRAN DAS
BSc. 6TH Semester (Electronics)
Roll-no: 13BS257
North Lakhimpur College
Khelmati 787031, Lakhimpur, Assam

2. DEPARTMENT OF ELECTRONICS
NORTH LAKHIMPUR COLLEGE
(COLLEGE WITH POTENTIAL FOR EXELLENCE)
DR. JITEN DUTTA, P.O- Khelmati
Head of the Department N.Lakhimpur, 787031
Mobile- +91- 9435277377 Phone: 03752-222174
E-mail- nlcollege.autonomous@gmail.com Website - nlc.ac.in
Ref.No. NLC/Elect/Proj/2016/01
From : Dr. Jiten Dutta, MSc. PhD
Head, Department of Electronics
North Lakhimpur College
North Lakhimpur
TO WHOM IT MAY CONCERN
This is to certify that the project entitled as “AUTOMATIC IN/OUT INDICATOR WITH
DOORBELL“ is a record of independent laboratory work done by SAMIRAN DAS (Roll-
13BS257) under my supervision during 2011-2012, submitted to the department of
Electronics, North Lakhimpur College in partial fulfillment for the award of degree of
BACHELOR OF SCIENCE IN ELECTRONICS and the report has not previously formed the basis
for the award of any other degree, diploma or other title.
(Dr. Jiten Duta)
Head, Department of Electronics
North Lakhimpur College

3. ACKNOWLEDGEMENT
The credit for the successful completion of this project goes to number of people without
the help of whom this would not have been a successful one.
My heart full thanks also goes to Dr. Jiten Dutta Sir, Mr. D.Das Sir, Mr. J. Mudoi Sir, Mr.
Bhaben Sir, Mr. Pranjal Sir, my guide who gave me continous guidance and help to
accomplish this project.
Finally, I would like to thank all my friends and Mr. Gajen Hiloidari (Dept. of Elect.) for their
helpful suggestion and respond.
Mr. Samiran Das
BSc. 6th
Semester
Roll: 13BS257
Reg no: S133289
N.L College

4. ABSTRACT
Now a day the electronics technology is changing a lot. In the present work an
attempt has been made to improve the technology of modern electronics
home and office appliances. Here the circuit has been designed in such a way
that it is simple, highly reliable and easy to assemble. It is a circuit that
automatically changes its displays from IN to OUT in the presence and absence
of any individual. The circuit totally works on the basis of touch plate or key
plate.

5. CONTENTS
1.0 INTRODUCTION--------------------------------- 1
2.0 OBJECTIVE OF THE PROJECT----------------- 2
3.0 COMPONENTS DETAILS----------------------- 3
3.1 RESISTORS--------------------------------------- 4
3.2 CAPACITOR--------------------------------------- 5
`3.3 TRANSISTOR------------------------------------ 6
3.4 DIODE --------------------------------------------- 7
3.5IC NE555 TIMER--------------------------------- 8
3.6 IC CD4017---------------------------------------- 9
3.7 SPEAKERS--------------------------------------- 10
3.8 BATTERY----------------------------------------- 11
3.9 PCB---------------------------------------------- 12
3.10 TOUCH PLATE--------------------------------- 13
3.11 CONNECTING WIRES------------------------ 14
4.0 CIRCUIT DAIGRAM---------------------------- 15
5.0 CIRCUIT OPERTATION------------------------ 16
6.0 WORKING PRINCIPLE------------------------- 17
7.0 INSTALLATION---------------------------------- 18
8.0 RESULTS------------------------------------------ 19
9.0 CONCLUSION------------------------------------ 20
10.0 BIBLOGRAPHY--------------------------------- 21

6. INTRODUCTION
Our main motto is to make a model pf a circuit that will automatically
turns and displays whether a person is in or out with a calling bell
ringing. Generally, whether a person is ‘in’ or ‘out’ is indicated
through a cardboard indicator which has to be turned for each arrival
or departure. Instead of this, electronic indicators can also be used.
However, these also need to be set for changing the display. So, if we
forget to change the display the indicator becomes useless. The
proposed circuit solves this problem. It does not need any setting or
adjustment for each change. It automatically changes the display
when we enter or leave our office or home.

8. COMPONENTS DETAILS
3.01 RESISTORS
Special components called resistors are made for the express purpose of creating a precise
quantity of resistance for insertion into a circuit. They are typically constructed of metal
wire or carbon, and engineered to maintain a stable resistance value over a wide range of
environmental conditions. Unlike lamps, they do not produce light, but they do produce
heat as electric power is dissipated by them in a working circuit. Typically, though, the
purpose of a resistor is not to produce usable heat, but simply to provide a precise quantity
of electrical resistance.
The most common schematic symbol for a resistor is a zig-zag line:
Resistor values in ohms are usually shown as an adjacent number, and if several resistors
are present in a circuit, they will be labeled with a unique identifier number such as R1, R2,
R3, etc. As you can see, resistor symbols can be shown either horizontally or vertically:
Real resistors look nothing like the zig-zag symbol. Instead, they look like small tubes or
cylinders with two wires protruding for connection to a circuit. Here is a sampling of
different kinds and sizes of resistors:
In keeping more with their physical appearance, an alternative schematic symbol for a
resistor looks like a small, rectangular box:
Resistors can also be shown to have varying rather than fixed resistances. This might be for
the purpose of describing an actual physical device designed for the purpose of providing

9. an adjustable resistance, or it could be to show some component that just happens to have
an unstable resistance:
In fact, any time you see a component symbol drawn with a diagonal arrow through it, that
component has a variable rather than a fixed value. This symbol “modifier” (the diagonal
arrow) is standard electronic symbol convention.
Variable resistors must have some physical means of adjustment, either a rotating shaft or
lever that can be moved to vary the amount of electrical resistance. Here is a photograph
showing some devices calledpotentiometers, which can be used as variable resistors:
Because resistors dissipate heat energy as the electric currents through them overcome the
“friction” of their resistance, resistors are also rated in terms of how much heat energy they
can dissipate without overheating and sustaining damage. Naturally, this power rating is
specified in the physical unit of “watts.” Most resistors found in small electronic devices
such as portable radios are rated at 1/4 (0.25) watt or less. The power rating of any resistor
is roughly proportional to its physical size. Note in the first resistor photograph how the
power ratings relate with size: the bigger the resistor, the higher its power dissipation
rating. Also note how resistances (in ohms) have nothing to do with size!
Although it may seem pointless now to have a device doing nothing but resisting electric
current, resistors are extremely useful devices in circuits. Because they are simple and so
commonly used throughout the world of electricity and electronics, we’ll spend a
considerable amount of time analyzing circuits composed of nothing but resistors and
batteries.
In schematic diagrams, resistor symbols are sometimes used to illustrate any general type
of device in a circuit doing something useful with electrical energy. Any non-specific
electrical device is generally called a load, so if you see a schematic diagram showing a

10. resistor symbol labeled “load,” especially in a tutorial circuit diagram explaining some
concept unrelated to the actual use of electrical power, that symbol may just be a kind of
shorthand representation of something else more practical than a resistor.
To summarize what we’ve learned in this lesson, let’s analyze the following circuit,
determining all that we can from the information given:
All we’ve been given here to start with is the battery voltage (10 volts) and the circuit
current (2 amps). We don’t know the resistor’s resistance in ohms or the power dissipated
by it in watts. Surveying our array of Ohm’s Law equations, we find two equations that give
us answers from known quantities of voltage and current:
Inserting the known quantities of voltage (E) and current (I) into these two equations, we
can determine circuit resistance (R) and power dissipation (P):
For the circuit conditions of 10 volts and 2 amps, the resistor’s resistance must be 5 Ω. If we
were designing a circuit to operate at these values, we would have to specify a resistor with
a minimum power rating of 20 watts, or else it would overheat and fail.
3.02 CAPACITORS
There are two common ways to draw a capacitor in a schematic. They always have two
terminals, which go on to connect to the rest of the circuit. The capacitors symbol consists
of two parallel lines, which are either flat or curved; both lines should be parallel to each
other, close, but not touching (this is actually representative of how the capacitor is made.
Hard to describe, easier to just show:

11. (1) and (2) are standard capacitor circuit symbols. (3) is an example of capacitors symbols in
action in a voltage regulator circuit.
The symbol with the curved line (#2 in the photo above) indicates that the capacitor
is polarized, meaning it’s probably an electrolytic capacitor. More on that in the types of
capacitors section of this tutorial.
Each capacitor should be accompanied by a name – C1, C2, etc.. – and a value. The value
should indicate the capacitance of the capacitor; how many farads it has. Speaking of
farads…
Capacitance Units
Not all capacitors are created equal. Each capacitor is built to have a specific amount of
capacitance. The capacitance of a capacitor tells you how much charge it can store, more
capacitance means more capacity to store charge. The standard unit of capacitance is called
the farad, which is abbreviated F.
It turns out that a farad is a lot of capacitance, even 0.001F (1 milifarad – 1mF) is a big
capacitor. Usually you’ll see capacitors rated in the pico- (10-12
) to microfarad (10-6
) range.
Prefix NameAbbreviationWeightEquivalent Farads
Picofarad pF 10-12
0.000000000001 F
Nanofarad nF 10-9
0.000000001 F
Microfarad †F 10-6
0.000001 F
Milifarad mF 10-3
0.001 F
Kilofarad kF 103
1000 F
When you get into the farad to kilofarad range of capacitance, you start talking about
special caps called super orultra-capacitors.
Capacitor Theory
Note: The stuff on this page isn’t completely critical for electronics beginners to
understand…and it gets a little complicated towards the end. We recommend reading
the How a Capacitor is Made section, the others could probably be skipped if they give you
a headache.
How a Capacitor Is Made
The schematic symbol for a capacitor actually closely resembles how it’s made. A capacitor
is created out of two metal plates and an insulating material called a dielectric. The metal
plates are placed very close to each other, in parallel, but the dielectric sits between them
to make sure they don’t touch.

12. The dielectric can be made out of all sorts of insulating materials: paper, glass, rubber,
ceramic, plastic, or anything that will impede the flow of current.
The plates are made of a conductive material: aluminum, tantalum, silver, or other metals.
They’re each connected to a terminal wire, which is what eventually connects to the rest of
the circuit.
The capacitance of a capacitor – how many farads it has – depends on how it’s constructed.
More capacitance requires a larger capacitor. Plates with more overlapping surface area
provide more capacitance, while more distance between the plates means less capacitance.
The material of the dielectric even has an effect on how many farads a cap has. The total
capacitance of a capacitor can be calculated with the equation:
Where εr is the dielectric’s relative permittivity (a constant value determined by the
dielectric material), A is the amount of area the plates overlap each other, and d is the
distance between the plates.
How a Capacitor Works
Electric current is the flow of electric charge, which is what electrical components harness
to light up, or spin, or do whatever they do. When current flows into a capacitor, the
charges get “stuck” on the plates because they can’t get past the insulating dielectric.
Electrons – negatively charged particles – are sucked into one of the plates, and it becomes
overall negatively charged. The large mass of negative charges on one plate pushes away
like charges on the other plate, making it positively charged.
The positive and negative charges on each of these plates attract each other, because that’s
what opposite charges do. But, with the dielectric sitting between them, as much as they
want to come together, the charges will forever be stuck on the plate (until they have
somewhere else to go). The stationary charges on these plates create an electric field,
which influence electric potential energy and voltage. When charges group together on a
capacitor like this, the cap is storing electric energy just as a battery might store chemical
energy.
Charging and Discharging
When positive and negative charges coalesce on the capacitor plates, the capacitor
becomes charged. A capacitor can retain its electric field – hold its charge – because the

13. positive and negative charges on each of the plates attract each other but never reach each
other.
At some point the capacitor plates will be so full of charges that they just can’t accept any
more. There are enough negative charges on one plate that they can repel any others that
try to join. This is where the capacitance (farads) of a capacitor comes into play, which tells
you the maximum amount of charge the cap can store.
If a path in the circuit is created, which allows the charges to find another path to each
other, they’ll leave the capacitor, and it will discharge.
For example, in the circuit below, a battery can be used to induce an electric potential
across the capacitor. This will cause equal but opposite charges to build up on each of the
plates, until they’re so full they repel any more current from flowing. An LED placed in
series with the cap could provide a path for the current, and the energy stored in the
capacitor.
3.03 TRANSISTOR
Transistors make our electronics world go ‘round. They’re critical as a control source in just
about every modern circuit. Sometimes you see them, but more-often-than-not they’re
hidden deep within the die of an integrated circuit. In this tutorial we’ll introduce you to the
basics of the most common transistor around: the bi-polar junction transistor (BJT).
In small, discrete quantities, transistors can be used to create simple electronic
switches, digital logic, and signal amplifying circuits. In quantities of thousands, millions,
and even billions, transistors are interconnected and embedded into tiny chips to create
computer memories, microprocessors, and other complex ICs.
Symbols, Pins, and Construction
Transistors are fundamentally three-terminal devices. On a bi-polar junction transistor
(BJT), those pins are labeled collector (C), base (B), and emitter (E). The circuit symbols for
both the NPN and PNP BJT are below:

14. The only difference between an NPN and PNP is the direction of the arrow on the emitter.
The arrow on an NPN points out, and on the PNP it points in. A useful mnemonic for
remembering which is which is:
NPN: Not Pointing iN
Backwards logic, but it works!
Transistor Construction
Transistors rely on semiconductors to work their magic. A semiconductor is a material
that’s not quite a pure conductor (like copper wire) but also not an insulator (like air). The
conductivity of a semiconductor – how easily it allows electrons to flow – depends on
variables like temperature or the presence of more or less electrons. Let’s look briefly
under the hood of a transistor. Don’t worry; we won’t dig too deeply into quantum physics.
A Transistor as Two Diodes
Transistors are kind of like an extension of another semiconductor component: diodes. In a
way transistor are just two diodes with their cathodes (or anodes) tied together:
The diode connecting base to emitter is the important one here; it matches the direction of
the arrow on the schematic symbol, and shows you which way current is intended to
flow through the transistor.
The diode representation is a good place to start, but it’s far from accurate. Don’t base your
understanding of a transistor’s operation on that model (and definitely don’t try to
replicate it on a breadboard, it won’t work). There’s a whole lot of weird quantum physics
level stuff controlling the interactions between the three terminals.
Transistor Structure and Operation
Transistors are built by stacking three different layers of semiconductor material together.
Some of those layers have extra electrons added to them (a process called “doping”), and
others have electrons removed (doped with “holes” – the absence of electrons). A
semiconductor material with extra electrons is called an n-type (n for negative because
electrons have a negative charge) and a material with electrons removed is called a p-
type (for positive). Transistors are created by either stacking an n on top of a p on top of
an n, or p over n over p.

15. Simplified diagram of the structure of an NPN.
With some hand waving, we can say electrons can easily flow from n regions to p regions,
as long as they have a little force (voltage) to push them. But flowing from a p region to
an n region is really hard (requires a lot of voltage). But the special thing about a transistor
– the part that makes our two-diode model obsolete – is the fact that electron scan easily
flow from the p-type base to the n-type collector as long as the base-emitter junction is
forward biased (meaning the base is at a higher voltage than the emitter).
The NPN transistor is designed to pass electrons from the emitter to the collector (so
conventional current flows from collector to emitter). The emitter “emits” electrons into
the base, which controls the number of electrons the emitter emits. Most of the electrons
emitted are “collected” by the collector, which sends them along to the next part of the
circuit.
A PNP works in a same but opposite fashion. The base still controls current flow, but that
current flows in the opposite direction – from emitter to collector. Instead of electrons, the
emitter emits “holes” (a conceptual absence of electrons) which are collected by the
collector.
3.04 DIODE
A diode is an electrical device allowing current to move through it in one direction with far
greater ease than in the other. The most common kind of diode in modern circuit design is
the semiconductor diode, although other diode technologies exist. Semiconductor diodes
are symbolized in schematic diagrams such as Figure below. The term “diode” is
customarily reserved for small signal devices, I ≤ 1 A. The term rectifier is used for power
devices, I > 1 A.

16. Semiconductor diode schematic symbol: Arrows indicate the direction of electron current
flow.
When placed in a simple battery-lamp circuit, the diode will either allow or prevent current
through the lamp, depending on the polarity of the applied voltage. (Figure below)
Diode operation: (a) Current flow is permitted; the diode is forward biased. (b) Current flow
is prohibited; the diode is reversed biased.
When the polarity of the battery is such that electrons are allowed to flow through the
diode, the diode is said to be forward-biased. Conversely, when the battery is “backward”
and the diode blocks current, the diode is said to be reverse-biased. A diode may be
thought of as like a switch: “closed” when forward-biased and “open” when reverse-biased.
Oddly enough, the direction of the diode symbol’s “arrowhead” points against the direction
of electron flow. This is because the diode symbol was invented by engineers, who
predominantly use conventional flow notation in their schematics, showing current as a
flow of charge from the positive (+) side of the voltage source to the negative (-). This
convention holds true for all semiconductor symbols possessing “arrowheads:” the arrow
points in the permitted direction of conventional flow, and against the permitted direction
of electron flow.
Diode behavior is analogous to the behavior of a hydraulic device called a check valve. A
check valve allows fluid flow through it in only one direction as in Figure below.
Hydraulic check valve analogy: (a) Electron current flow permitted. (b) Current flow
prohibited.
Check valves are essentially pressure-operated devices: they open and allow flow if the
pressure across them is of the correct “polarity” to open the gate (in the analogy shown,
greater fluid pressure on the right than on the left). If the pressure is of the opposite
“polarity,” the pressure difference across the check valve will close and hold the gate so
that no flow occurs.
Like check valves, diodes are essentially “pressure-” operated (voltage-operated) devices.
The essential difference between forward-bias and reverse-bias is the polarity of the
voltage dropped across the diode. Let’s take a closer look at the simple battery-diode-lamp
circuit shown earlier, this time investigating voltage drops across the various components in
Figure below.

17. Diode circuit voltage measurements: (a) Forward biased. (b) Reverse biased.
A forward-biased diode conducts current and drops a small voltage across it, leaving most
of the battery voltage dropped across the lamp. If the battery’s polarity is reversed, the
diode becomes reverse-biased, and drops all of the battery’s voltage leaving none for the
lamp. If we consider the diode to be a self-actuating switch (closed in the forward-bias
mode and open in the reverse-bias mode), this behavior makes sense. The most substantial
difference is that the diode drops a lot more voltage when conducting than the average
mechanical switch (0.7 volts versus tens of millI volts).
This forward-bias voltage drop exhibited by the diode is due to the action of the depletion
region formed by the P-N junction under the influence of an applied voltage. If no voltage
applied is across a semiconductor diode, a thin depletion region exists around the region of
the P-N junction, preventing current flow. (Figure below (a)) The depletion region is almost
devoid of available charge carriers, and acts as an insulator:
Diode representations: PN-junction model, schematic symbol, physical part.
The schematic symbol of the diode is shown in Figure above (b) such that the anode
(pointing end) corresponds to the P-type semiconductor at (a). The cathode bar, non-
pointing end, at (b) corresponds to the N-type material at (a). Also note that the cathode
stripe on the physical part (c) corresponds to the cathode on the symbol.
If a reverse-biasing voltage is applied across the P-N junction, this depletion region expands,
further resisting any current through it. (Figure below)
Depletion region expands with reverse bias.
Conversely, if a forward-biasing voltage is applied across the P-N junction, the depletion
region collapses becoming thinner. The diode becomes less resistive to current through it.
In order for a sustained current to go through the diode; though, the depletion region must
be fully collapsed by the applied voltage. This takes a certain minimum voltage to
accomplish, called the forward voltage as illustrated in Figure below.

18. Increasing forward bias from (a) to (b) decreases depletion region thickness.
For silicon diodes, the typical forward voltage is 0.7 volts, nominal. For germanium diodes,
the forward voltage is only 0.3 volts. The chemical constituency of the P-N junction
comprising the diode accounts for its nominal forward voltage figure, which is why silicon
and germanium diodes have such different forward voltages. Forward voltage drop remains
approximately constant for a wide range of diode currents, meaning that diode voltage
drop is not like that of a resistor or even a normal (closed) switch. For most simplified
circuit analysis, the voltage drop across a conducting diode may be considered constant at
the nominal figure and not related to the amount of current.
3.05 IC NE 555
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. Derivatives provide up to four timing circuits in one package.
Introduced in 1971 by American company Signetics, the 555 is still in widespread use due to
its low price, ease of use, and stability. It is now made by many companies in the
original bipolar and also in low-powerCMOS types. As of 2003, it was estimated that
1 billion units are manufactured every year.
Pins
Pinout diagram
The connection of the pins for a DIP package is as follows:

19. Pin Name Purpose
1 GND Ground reference voltage, low level (0 V)
2 TRIG
The OUT pin goes high and a timing interval starts when this input falls below
1/2 of CTRL voltage (which is typically 1/3 VCC, CTRL being 2/3VCC by default if
CTRL is left open).
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, 2/3VCC).
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.
Pin 5 is also sometimes called the CONTROL VOLTAGE pin. By applying a voltage to the
CONTROL VOLTAGE input one can alter the timing characteristics of the device. In most
applications, the CONTROL VOLTAGE input is not used. It is usual to connect a 10 nF
capacitor between pin 5 and 0 V to prevent interference. The CONTROL VOLTAGE input can
be used to build an astable multivibrator with a frequency-modulated output.
Modes
Bistable mode or Schmitt trigger – the 555 can operate as a flip-flop, if the DIS pin is not
connected and no capacitor is used. Uses include bounce-free latched switches.
Monostable mode – in this mode, the 555 functions as a "one-shot" pulse generator.
Applications include timers, missing pulse detection, bounce-free switches, touch switches,
frequency divider, capacitance measurement, pulse-width modulation(PWM) and so on.
Astable (free-running) mode – the 555 can operate as an electronic oscillator
include LED and lamp flashers, pulse generation, logic clocks, tone generation, security
alarms, pulse position modulation and so on. The 555 can be used as a simple ADC,
converting an analog value to a pulse length (e.g., selecting a thermistor as timing resistor
allows the use of the 555 in a temperature sensor and the period of the output pulse is
determined by the temperature). The use of a microprocessor-based circuit can then
convert the pulse period to temperature, linearize it and even provide calibration means.
Specifications
These specifications apply to the NE555. Other 555 timers can have different specifications
depending on the grade (military, medical, etc.).

20. Supply voltage (VCC) 4.5 to 15 V
Supply current (VCC = +5 V) 3 to 6 mA
Supply current (VCC = +15 V) 10 to 15 mA
Output current (maximum) 200 mA
Maximum Power dissipation 600 mW
Power consumption (minimum operating) 30 mW@5V, 225 mW@15V
Operating temperature 0 to 75 ŠC
3.06 IC CD4017
The CD4017 is the one of the most popular Decade Counter (Divided by 10 Counter). It is a
5 Stage Divide by 10 Johnson Counter with 10 Decoded outputs. It has a wide supply
voltage range from 3V to 15V and is compatible with TTL. It has a medium speed of
operation, typically 5 MHz. Their application includes industrial electronics, remote
metering, automotive, medical electronics, and instrumentation and alarm systems.
CD4017
Pin Diagram
CD4017 Pin Diagram
The above diagram shows the pin out of CD4017B, Dual-In-line package.
Pin Functions
Vcc
It is the supply voltage terminal of the IC. Being a CMOS IC it has a wide supply voltage
range from 3V to 15V.
Vss
It is the ground pin or common pin of the IC CD4017. It should be connected to the negative
terminal of the DC Power supply or battery.
Q0 – Q9
These are the 10 decoded outputs of the CD 4017 IC. One of the 10 decoded outputs may
be high at a time.
Clock
It is the clock pin of the counter. Q0 goes high during the rise of the first clock cycle. Q0
goes low and Q1 goes high during the rise of the second clock cycle, and so on..

21. Clock Enable
This is the active low enable pin for clock input. If this input is high the counter will not
count clock cycles.
Carry Out
This pin is used to indicate that the count exceeds 10. This pin goes low when the output
Q5 goes high and goes high when the output Q0 goes high.
Reset
This is the reset pin of the IC. When this pin goes high, the output pin Q0 will go high.
Timing Diagram – CD4017
CD4017 Timing Diagram
Clock is applied to the terminal continuously. When RESET signal is applied the IC will reset
and the output Q0 will become HIGH. During the positive transaction of next clock cycle Q0
goes LOW and Q1 goes HIGH, and so on.. The output Carry Out becomes LOW and HIGH
when the output Q5 goes HIGH and Q1 goes HIGH respectively. Clock Enable input is an
Active Low input pin, when it is high the counter will not count clock cycles.
3.07 SPEAKERS
A loudspeaker (or loud-speaker or speaker) is a device containing one or more electro
acoustic transducers; which convert an electrical audio signal into a
corresponding sound. The first primitive loudspeakers were invented during the
development of telephone systems in the late 1800s, but electronic amplification
by vacuum tube beginning around 1912 made loudspeakers truly practical. By the 1920s
they were used in radios, phonographs, public address systems and theatre sound systems
for talking motion pictures.

22. The most widely used type of speaker today is the dynamic speaker, invented in 1925
by Edward W. Kellogg and Chester W. Rice. The dynamic speaker operates on the same
basic principle as a dynamic microphone, but in reverse, to produce sound from an
electrical signal. When an alternating current electrical audio signal is applied to its voice
coil, a coil of wire suspended in a circular gap between the poles of a permanent magnet,
the coil is forced to move rapidly back and forth due to Faraday's law of induction, which
causes diaphragm (usually conically shaped) attached to the coil to move back and forth,
pushing on the air to create sound waves. Besides this most common method, there are
several alternative technologies that can be used to convert an electrical signal into sound.
The sound source (e.g., a sound recording or a microphone) must be amplified with
an amplifier before the signal is sent to the speaker.
Speakers are typically housed in an enclosure which is often a rectangular or square box
made of wood or sometimes plastic, and the enclosure plays an important role in the
quality of the sound. Where high fidelity reproduction of sound is required, multiple
loudspeaker transducers are often mounted in the same enclosure, each reproducing a part
of the audible frequency range .In this case the individual speakers are referred to as
"drivers" and the entire unit is called a loudspeaker. Drivers made for reproducing high
audio frequencies are called tweeters, those for middle frequencies are called mid-
range drivers, and those for low frequencies are called woofers. Smaller loudspeakers are
found in devices such as radios, televisions, portable audio players, computers,
and electronic musical instruments. Larger loudspeaker systems are used for music, sound
reinforcement in theatres and concerts, and in public address systems.
3.08 BATTERY
In our daily life, we generally use two types of battery; one of them is which can be used
once before it gets totally discharged. Another type of battery is rechargeable which means
it can be used multiple times by recharging it externally. The former is called primary
battery and the later is called secondary battery. Batteries can be found in different sizes. A
battery may be as small as a shirt button or may be so big in size that a whole room will be
required to install a battery bank. With this variation of sizes, the battery is used anywhere
from small wrist watches to a large ship.
We often see this symbol in many diagrams of electrical and electronics network. This is the
most popularly used symbol for battery. The bigger lines represent positive terminal of the
cells and smaller lines represent negative terminal of the cells connected in the battery.
Working Principle of Battery
To understand the basic principle of battery properly, first, we should have some basic
concept of electrolytes and electrons affinity. Actually, when two dissimilar metals or

23. metallic compounds are immersed in an electrolyte, there will be a potential difference
produced between these metals or metallic compounds.
It is found that, when some specific compounds are added to water, they get dissolved and
produce negative and positive ions. This type of compound is called an electrolyte. The
popular examples of electrolytes are almost all kinds of salts, acids, and bases etc.
The energy released during accepting an electron by a neutral atom is known as electron
affinity. As the atomic structure for different materials are different, the electron affinity of
different materials will differ. If two different kinds of metals or metallic compounds are
immersed in the same electrolyte solution, one of them will gain electrons and the other
will release electrons. Which metal (or metallic compound) will gain electrons and which
will lose them depends upon the electron affinities of these metals or metallic compounds.
The metal with low electron affinity will gain electrons from the negative ions of the
electrolyte solution. On the other hand, the metal with high electron affinity will release
electrons and these electrons come out into the electrolyte solution and are added to the
positive ions of the solution. In this way, one of these metals or compounds gains electrons
and another one lose electrons. As a result, there will be a difference in electron
concentration between these two metals. This difference of electron concentration causes
an electrical potential difference to develop between the metals. This electrical potential
difference or emf can be utilized as a source of voltage in any electronics or electrical
circuit. This is a general and basic principle of battery.
All batteries cells are based only on this basic principle. Let’s discuss one by one. As we said
earlier, Alessandro Volta developed the first battery cell, and this cell is popularly known as
the simple voltaic cell. This type of simple cell can be created very easily. Take one
container and fill it with diluted sulfuric acid as the electrolyte. Now immerse zinc and one
copper rod in the solution and connect them externally by an electric load. Now your
simple voltaic cell is completed. Current will start flowing through the external load.
Zinc in diluted sulfuric acid gives up electrons as below:
These Zn+ +
ions pass into the electrolyte, and their concentration is very high near the zinc
electrode. As a result of the above oxidation reaction, the zinc electrode is left negatively
charged and hence acts as cathode. The diluted sulfuric acid and water disassociate into
hydronium ions as given below:
Due to the high concentration of Zn+ +
ions near the cathode, the H3O+
ions are repelled
towards the copper electrode and get discharged by removing electrons from the copper
atoms. The following reaction takes place at the anode:
As a result of the reduction reaction taking place at copper electrode, copper is left
positively charged and hence it acts as the anode.

24. 3.09 PCB
Printed circuit board is the most common name but may also be called “printed wiring
boards” or “printed wiring cards”. Before the advent of the PCB circuits were constructed
through a laborious process of point-to-point wiring. This led to frequent failures at wire
junctions and short circuits when wire insulation began to age and crack.
A significant advance was the development of wire wrapping, where a small gauge wire is
literally wrapped around a post at each connection point, creating a gas-tight connection
which is highly durable and easily changeable.
As electronics moved from vacuum tubes and relays to silicon and integrated circuits, the
size and cost of electronic components began to decrease. Electronics became more
prevalent in consumer goods, and the pressure to reduce the size and manufacturing costs
of electronic products drove manufacturers to look for better solutions. Thus was born the
PCB.
PCB is an acronym for printed circuit board. It is a board that has lines and pads that
connect various points together. In the picture above, there are traces that electrically
connect the various connectors and components to each other. A PCB allows signals and
power to be routed between physical devices. Solder is the metal that makes the electrical
connections between the surface of the PCB and the electronic components. Being metal,
solder also serves as a strong mechanical adhesive.

25. 3.10 TOUCH PLATE
A touch switch/plate is a type of switch that only has to be touched by an object to
operate. It is used in many lamps and wall switches that have a metal exterior as well as on
public computer terminals. A touchscreen includes an array of touch switches on a display.
A touch switch is the simplest kind of tactile sensor.
3.11 CONNECTING WIRES
A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear
mechanical loads or electricity and telecommunications. Wire is commonly formed
by drawing the metal through a hole in a die or draw plate. Wire gauges come in
various standard sizes, as expressed in terms of a gauge number. The term wire is also used
more loosely to refer to a bundle of such strands, as in "multistranded wire", which is more
correctly termed a wire rope in mechanics, or a cable in electricity.
Wire comes in solid core, stranded, or braided forms. Although usually circular in cross-
section, wire can be made in square, hexagonal, flattened rectangular or other cross-
sections, either for decorative purposes, or for technical purposes such as high-
efficiency voice coils in loudspeakers. Edge-wound coil springs, such as the Slinky toy, are
made of special flattened wire.

26. 4.0 CIRCUIT DAIGRAM

27. 5.0 CIRCUIT OPERATION
The circuit works on the basic principle of a touch switch. The input of the circuit carries a
touch plate (key plate). You must place the key of the main door on the surface of this plate
once, before you take it away, so that the display keeps showing ‘OUT’. When power supply
is switched on, the display shows ‘IN’. When you leave home you must take the key. Then,
the touch switch is enabled because the key is placed on the plate. So the display is
changed to ‘OUT’. When you reach home, you place the key on the plate. And again, the
touch switch is activated and the display is flipped to ‘IN’.
The circuit uses two 555 ICs and one decade counter IC 4017. IC1 and IC2 make the clap
switch. The base of transistor T1 carried the touch plate (key plate). IC3 functions as an
oscillator. It produces a frequency of about 1 kHz which is applied to two speakers. If you
are in, then the first speaker (LS1) is enabled. If you are out then the second speaker (LS2) is
enabled.
6.0 WORKING PRINCIPLE
When you touch the key plate, transistor T1 gets biased. So, IC1 is triggered. This changes
the output of IC1 from low to a high state. This high state remains for about 52 seconds.
Since output of IC1 is given to IC2, the output of IC2 also changes from the low to high
state, with change in the output of IC1. This changes the display and rings the bell through
the speaker.
It has the following features:
1. The ‘IN’ and ‘OUT’ signs are indicated by suing LED displays.
2. It displays ‘IN/OUT’ only when a guest presses the calling bell switch. This
will avoid unwanted wastage of energy.
3. If you are inside then a press on the switch displays ‘IN’ and sounds a bell
inside the home for each press of bell switch.
4. If you are out then a press of the switch will display ‘OUT’ and the bell will
ring inside.

28. 7.0 INSTALLATION
The circuits of the internal speaker (LS2) and switch S1 is fitted in a suitable cabinet. This
box may be fixed in place of the calling bell switch or anywhere in the sit-out, so that a
guest may see it at the first look. The external speaker is fixed anywhere inside the house.
The key plate should is also fixed in the house. To make it better the key plate is fitted near
the main door. The key plate is kept at a safe place to avoid unwanted touching. It is fixed
at a height to keep it away from children.

29. 8.0 RESULT
AFTER COMPLETION OF THE PROJECT SUCESSFULLY THE FOLLOWING
RESULTS ARE OBTAINED
1. The device is showing IN indication in presence of anybody with a
bell ringing inside.
2. The device is showing OUT indication in absence of anybody with a
bell ringing outside on the main panel.
3. All the outputs are obtained as required as preferred by the very
system.

30. 9.0 CONCLUSION
The circuit can be easily assembled on a general purpose PCB,
enclosed in a good quality plastic case with provision for touch plate
and loudspeaker.
One of the most denotable advantages of this circuit is its simple
construction and less in cost.
The same circuit model can also be used in construction of various
electronic model by very few modification of the main circuit, such as
parking indicator, notice indicator etc.

31. 10.0 BIBLOGRAPHY
Books & Magazine :
Electronics Projects Vol. 24 – EFY Enterprise Pvt. Ltd.
Simple Projects – EFY Enterprise Pvt. Ltd.
Electronic Gadgets 2nd
Edition – McGraw Hill Education.
Web Helps :
http://www.electronicshub.org
http://www.electronicsproject.org