Download Automatic NIGHT LAMP WITH MORNING ALARM

minor project report
Automatic night lamp with morning alarm
AUTOMATIC NIGHT LAMP WITH MORNING ALARM
A project report submitted in partial fulfillment of the
requirement of the Diploma of Technology in
Electronics and Communication Engineering
Submitted By
MUKESH JHA
14006100019
Under the guidance of
SH. VIKRAM DOGRA
(Lect. Electronics & Communication Engg.)
Department of Electronics and Communication Engineering
Govt. Polytechnic,MandiAdampur,Hisar (Haryana)
HSBTE, PANCHKULA
minor project report
Automatic night lamp with morning alarm
Introduction
Needs no manual operation for switching ON and OFF. When there is need of light
it automatically switches ON. when darkness rises to a certain value then sensor
circuit gets activated and switches ON and when there is other source of light i.e
day time, the light gets OFF. The sensitiveness of the light can also be adjusted. In
our project we have used four LED for indication of bulb but for high power
switching one can connect Relay (electromagnetic switch) at the output of pin 3 of
ic 555. Then it will be possible to turn ON/OFF any electrical appliances connected
all the way through relay.
This circuit automatically turns on a Light in the evening time and
switched off with rhe coming of the day. the lamp remains on until the light senses
daylight in the morning. A super-bright white LED is used as the night lamp. It
gives bright and cool light in the room. When the sensor detects the daylight in the
morning, a melodious morning alarm sounds.
minor project report
BLOCK DIAGRAM:
Automatic night lamp with morning alarm
minor project report
Automatic night lamp with morning alarm
2.1 LIST OF COMPONENTS
Component name
Descripition
Quantity
Transformer
Step down
1
Resistor
1k,150k,120k,220R,150k 6
IC
555,7809,UM66
3
LDR
2
2
Capacitor
1000uF,0.01uf,0.01uF
3
Diode
1n4001,1n4007,Zener
3.3
diode 3.3
LED
1
1
minor project report
Automatic night lamp with morning alarm
LDR:
LDRs or Light Dependent Resistors are very useful especially in light/dark sensor circuits.
Normally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when
they are illuminated with light resistance drops dramatically.
When the light level is low the resistance of the LDR is high. This prevents current from flowing
to
the
base
of
the
transistors.
Consequently
the
LED
does
not
light.
However, when light shines onto the LDR its resistance falls and current flows into the base of
the first transistor and then the second transistor. The LED lights.
minor project report
Automatic night lamp with morning alarm
Here in our project to avoid the light from led to fall on to LDR we place a box in which we will
keep our jewelry. If any one removes the box the light from led falls directly on to the LDR and
then the transistor will be on which is monitored by the microcontroller.
Light-emitting diode (LED)
Light-emitting diodes are elements for light signalization in electronics. They are manufactured
in different shapes, colors and sizes. For their low price, low consumption and simple use, they
have almost completely pushed aside other light sources- bulbs at first place. They perform
similar to common diodes with the difference that they emit light when current flows through
them.
minor project report
Automatic night lamp with morning alarm
It is important to know that each diode will be immediately destroyed unless its current is limited.
This means that a conductor must be connected in parallel to a diode. In order to correctly
determine value of this conductor, it is
necessary to know diode’s voltage
drop in
forward direction, which depends on
what
material a diode is made of and what
colour
it is. Values typical for the most
frequently used diodes are shown in
table
below: As seen, there are three main
types
of LEDs. Standard ones get ful
brightness at current of 20mA. Low
Current diodes get ful brightness at ten times lower current while Super Bright diodes produce
more intensive light than Standard ones.
Since the 8051 microcontrollers can provide only low input current and since their pins are
configured as outputs when voltage level on them is equal to 0, direct connectining to LEDs is
carried out as it is shown on figure (Low current LED, cathode is connected to output pin).
Resistors :
Example:
Circuit symbol:
Function
Resistors restrict the flow of electric current, for example a resistor is placed in series with
a light-emitting diode (LED) to limit the current passing through the LED.
Connecting and soldering
Resistors may be connected either way round. They are not damaged by heat when soldering.
The Resistor
Colour Code
Colour Number
Black
0
Brown
1
minor project report
Automatic night lamp with morning alarm
Resistor values - the resistor colour code
Resistance is measured in ohms, the symbol for ohm is an omega .
1 is quite small so resistor values are often given in k and M .
1 k = 1000 1 M = 1000000 .
Resistor values are normally shown using coloured bands.
Each colour represents a number as shown in the table.
Most resistors have 4 bands:




Red
2
Orange
3
Yellow
4
Green
5
Blue
6
Violet
7
Grey
8
The first band gives the first digit.
White
9
The second band gives the second digit.
The third band indicates the number of zeros.
The fourth band is used to shows the tolerance (precision) of the resistor, this may be
ignored for almost all circuits but further details are given below.
This resistor has red (2), violet (7), yellow (4 zeros) and gold bands.
So its value is 270000 = 270 k .
On circuit diagrams the is usually omitted and the value is written 270K.
Small value resistors (less than 10 ohm)
The standard colour code cannot show values of less than 10 . To show these small values two
special colours are used for the third band: gold which means × 0.1 and silver which means ×
0.01. The first and second bands represent the digits as normal.
TRANSISTOR
The name is transistor derived from ‘transfer resistors’ indicating a solid state
Semiconductor device. In addition to conductor and insulators, there is a third class of material
that exhibits proportion of both. Under some conditions, it acts as an insulator, and under other
conditions it’s a conductor. This phenomenon is called Semi-conducting and allows a variable
control over electron flow. So, the transistor is semi conductor device used in electronics for
amplitude. Transistor has three terminals, one is the collector, one is the base and other is the
emitter, (each lead must be connected in the circuit correctly and only then the transistor will
function). Electrons are emitted via one terminal and collected on another terminal, while the
third terminal acts as a control element. Each transistor has a number marked on its body. Every
number has its own specifications.
There are mainly two types of transistor (i) NPN & (ii) PNP
minor project report
Automatic night lamp with morning alarm
NPN Transistors:
When a positive voltage is applied to the base, the transistor begins to conduct by allowing
current to flow through the collector to emitter circuit. The relatively small current flowing
through the base circuit causes a much greater current to pass through the emitter / collector
circuit. The phenomenon is called current gain and it is measure in beta.
PNP Transistor:
It also does exactly same thing as above except that it has a negative voltage on its
collector and a positive voltage on its emitter.
Transistor is a combination of semi-conductor elements allowing a controlled current flow.
Germanium and Silicon is the two semi-conductor elements used for making it. There are two
types of transistors such as POINT CONTACT and JUNCTION TRANSISTORS. Point contact
construction is defective so is now out of use. Junction triode transistors are in many respects
analogous to triode electron tube.
A junction transistor can function as an amplifier or oscillator as can a triode tube, but has
the additional advantage of long life, small size, ruggedness and absence of cathode heating
power.
DIODE:
In electronics, a diode is a two-terminal electronic component that conducts
primarily in one direction (asymmetric conductance); it has low (ideally
zero) resistance to the flow of current in one direction, and high (ideally infinite)
resistance in the other. A semiconductor diode, the most common type today, is
acrystalline piece of semiconductor material with a p–n junction connected to two
electrical terminals.[5] Avacuum tube diode has two electrodes, a plate (anode) and
a heated cathode. Semiconductor diodes were the first semiconductor electronic
devices. The discovery of crystals' rectifying abilities was made by German
minor project report
Automatic night lamp with morning alarm
physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's
whisker diodes, developed around 1906, were made of mineral crystals such
as galena. Today, most diodes are made of silicon, but other semiconductors such
as selenium or germanium are sometimes used
Speaker:
SPEAKER, 8OHM, 66MM; Transducer Function:Speaker; Power Rating
RMS:2W; Impedance:8ohm; Resonant Frequency:255Hz; Frequency Response
Min:255Hz; Frequency Response Max:15kHz; External Diameter:61mm; External
Depth:26mm; External Diameter:61mm; Fixing Hole Diameter:4mm; Sound Level
Distance:1m; Sound Level SPL:88dB; Weight:133g
Block Diagram of Power Supply:
Step
down
T/F
Bridge
Rectifier
Filter
Circuit
Regulator
Power supply to all sections
POWER SUPPLY:
The input to the circuit is applied from the regulated power supply. The a.c. input i.e., 230V from
the mains supply is step down by the transformer to 12V and is fed to a rectifier. The output
obtained from the rectifier is a pulsating d.c voltage. So in order to get a pure d.c voltage, the
output voltage from the rectifier is fed to a filter to remove any a.c components present even after
minor project report
Automatic night lamp with morning alarm
rectification. Now, this voltage is given to a voltage regulator to obtain a pure constant dc
voltage.
230V AC
50Hz
D.C
Output
Step down
Bridge
transformer
Rectifier
Regulator
Filter
Fig: Power supply
Transformer:
Usually, DC voltages are required to operate various electronic equipment and these
voltages are 5V, 9V or 12V. But these voltages cannot be obtained directly. Thus the a.c input
available at the mains supply i.e., 230V is to be brought down to the required voltage level. This
is done by a transformer. Thus, a step down transformer is employed to decrease the voltage to a
required level.
Some times transformers make the output voltage bigger than the input voltage, this is
aSTEP UP TRANSFORMER. In a step up transformer there are more coils of wire on the
secondary coil than on the primary coil.
Some times transformers make the output voltage smaller than the input voltage, this is
aSTEP DOWN TRANSFORMER. In a step down transformer there are more coils of wire on
the primary coil than on the secondary coil.
Transformers are used in the national grid.
minor project report
Automatic night lamp with morning alarm
How a transformer works
Alternating current (ac) in the primary coil (input coil) produces a changing magnetic field in
the laminated soft iron core.
The changing magnetic field induces a potential difference (voltage) in the secondary coil(output
coil).
Equations for transformers
We can work out the transformer output voltage if we know the input voltage and the number of
turns (coils) on the primary and secondary coils, using the equation below;
Vp = potential difference (voltage) input on the primary coil
Vs = potential difference (voltage) output on the secondary coil
np = number of turns (coils) of wire on the primary coil
ns = number of turns (coils) of wire on the secondary coil
Transformers are very efficient devices, if we assume they are 100% efficient (no energy
wasted), then the electrical input power will equal the electrical output power and that gives is a
new equation to use;
Where Ipis the current in the primary coil and Is is the current in the secondary coil.
minor project report
Automatic night lamp with morning alarm
Rectifier:
The output from the transformer is fed to the rectifier. It converts A.C. into pulsating D.C.
The rectifier may be a half wave or a full wave rectifier. In this project, a bridge rectifier is used
because of its merits like good stability and full wave rectification.
Filter:
Capacitive filter is used in this project. It removes the ripples from the output of rectifier
and smoothens the D.C. Output received from this filter is constant until the mains voltage and
load is maintained constant. However, if either of the two is varied, D.C. voltage received at this
point changes. Therefore a regulator is applied at the output stage.
Voltage regulator:
As the name itself implies, it regulates the input applied to it. A voltage regulator is an
electrical regulator designed to automatically maintain a constant voltage level. In this project,
power supply of 5V and 12V are required. In order to obtain these voltage levels, 7805 and 7812
voltage regulators are to be used. The first number 78 represents positive supply and the numbers
05, 12 represent the required output voltage levels.
minor project report
Automatic night lamp with morning alarm
WORKING PROCEDURE:
LDR offers Very high Resistance in darkness. In this case the voltage drop across the LDR is
more than 0.7V.
This voltage is more sufficient to drive the transistor into saturation region.
In saturation region, Ic (Collector current) is very high. Because of this Ic, The relay gets
energized, and switches on the lamp.
LDR offers Very low Resistance in brightness. In this case the voltage drop across the LDR is
less than 0.7V.
This voltage is not sufficient to drive the transistor into saturation region. Hence, the transistor
will be in cut-off region.
In cut-off region, Ic (Collector current) is zero. Because of this Ic, The relay will not be
energized, and the lamp will be in ON state only.
Diode is connected across the relay to neutralize the reverse EMF generated.
Reference:
1. WWW. howstuffworks.com
2. EMBEDDED SYSTEM BY RAJ KAMAL
3. 8051 MICROCONTROLLER AND EMBEDDED SYSTEMS BY MAZZIDI
4. Magazines