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1. INTRODUCTION
The lighting system
of a motor
vehicle consists of lighting and signalling devices mounted or integrated
to the front, sides, rear, and in some cases the top of the vehicle. The
purpose of this system is to provide illumination for the driver to operate
the vehicle safely after dark, to increase the conspicuity of the vehicle, and to
display information about the vehicle's presence, position, size, direction of
travel, and driver's intentions regarding direction and speed of travel.
Driving lamp" is a term deriving from the early days of night time
driving, when it was relatively rare to encounter an opposing vehicle. Only on
those occasions when opposing drivers passed each other would the dipped or
"passing" beam be used. The full beam was therefore known as the driving
beam. Turn signals are required
to blink on and off, or "flash", at a steady rate of between 60 and
120 blinks per minute (Although some operate slower than this). International regulations require that
all turn signals activated at the same time (i.e., all right signals or all
left signals) flash in simultaneous phase with one another; North American regulations also
require simultaneous operation, but
permit side markers wired for side turn signal functionality to flash in
opposite-phase. Worldwide
regulations stipulate an audiovisual telltale when the turn signals are activated;
this usually takes the form of one combined or separate left and right green
indicator lights on the vehicle's instrument cluster, and a cyclical
"tick-tock" noise generated electromechanically or electronically. It
is also required that audio and/or visual warning be provided to the vehicle
operator in the event of a turn signal's failure to light. This warning is
usually provided by a much faster- or slower-than-normal flash rate, visible on
the dashboard indicator, and audible via the faster tick-tock sound.
Turn signals are
in almost every case activated by means of a horizontal lever (or
"stalk") protruding from the side of the steering column, though some
vehicles have the lever mounted instead to the dashboard. The outboard end of
the stalk is pushed clockwise to activate the right turn signals, or
anticlockwise for the left turn signals. This operation is intuitive; for any
given steering manoeuvre, the stalk is pivoted in the same direction as the ateering
wheel must
be turned.
2.
COMPONENTS USED
R1 = 8.2k
R2 = 4.7k
R3 = 10k
R4 = 100
R5 = 470
R6 = 22k
R7 = 33k
IC 555
Capacitor
Transistor
LEDs
3.
CIRCUIT DIAGRAM
WORKING
PRINCIPLE
This
is the signal lamp for safe highway driving. The lamp automatically emits
brilliant tricolour light when a vehicle approaches the rear side of your
vehicle. It emits light for 30 seconds that turns off when the approaching
vehicle overtakes. The ultra-bright blue, white and red LEDs of the signal lamp
emit very bright light to alert the approaching vehicle’s driver even during
the day, giving additional safety during night or when you need to stop your
vehicle on side of the highway. The circuit saves considerable battery power.
The
circuit is built around two timer ICs NE555(IC1& IC2). IC1 is designed as a
standard monostable, while IC2 is designed as an astable. Darlington
Phototransistor L14F1 (T1) is used as a photosensor to activate the monostable.
The collector of Phototransistor T1 is connected to trigger pin 2 of IC1, which
is normally kept high by resistor R1. When headlight from an approaching
vehicle illuminates the phototransistor, it conducts to give a short pulse to
IC1, and the output of IC1 goes high for a 4 period determined by resistor R2
and capacitor C1. The output of IC1 is fed to the base of transistor T2 via
resistor R3. Transistor T2 conducts to
drive transistor T3 and its collector goes high to take reset pin 4 of IC2to
high level. This activates astable IC2, which switches on and off the LED chain alternately. The intermittent
flashing of LEDs gives a beautiful tricolour flashing effect. 12 volt DC supply
to the circuit, can be provided by your vehicle battery with proper polarity.
4.
Components Used
555 IC
The 555 IC is available as an 8-pin metal can, an
8-pin mini DIP(dual in package) or a 14-pin DIP. This IC consists of 23
transistors, 2 diodes and 16 resistors.
Pin 1(Grounded Terminal):- All the voltages are
measured w.r.t this terminal.
Pin 2(Trigger Terminal):- This pin is an inverting
input to a comparator that is responsible for transition of flip-flop from set
to reset.
Pin 3(Output Terminal):- Output of the timer is
available at this pin.
Pin4(Reset Terminal):- To disable or reset the timer a
negative pulse is applied to this pin due to which it is referred to reset
terminal.
Pin 5(Control Voltage Terminal):- The function of this
terminal is to control the threshold and trigger levels.
Pin 6(Threshold Terminal):- This is the non-inverting
input terminal of comparator1, which compares the voltage applied to this terminal
with a reference voltage of +2/3 Vcc.
Pin 7(Discharge Terminal):- This pin is connected
internally to the collector of transistor and mostly a capacitor is connected
between this terminal and ground.
Pin 8(Supply Terminal):- A supply voltage of +5V to
+18V is applied to this terminal w.r.t ground.
.
Fig. 2: IC555
Monostable mode
Monostable multivibrator often called a one shot
multivibrator is a pulse generating circuit in which the duration of this pulse
is determined by the RC network connected externally to the 555 timer. In a
stable or standby state, the output of the circuit is approximately zero or a
logic-low level. When external trigger pulse is applied output is forced to go
high (» VCC). The time for which output remains high is determined
by the external RC network connected to the timer. At the end of the timing
interval, the output automatically reverts back to its logic-low stable state.
The output stays low until trigger pulse is again applied. Then the cycle
repeats. The monostable circuit has only one stable state (output low)
hence the name monostable.
Fig.3: Circuit
Diagram of Monostable Multivibrator
Waveform
Fig.4: Output Waveform of IC555 in Monostable Mode
Astable mode
The
astable multivibrator generates a square wave, the period of which is
determined by the circuit external to IC 555. The astable multivibrator does
not require any external trigger to change the state of the output.
Hence the name free running oscillator. The time during which the output is
either high or low is determined by the two resistors and a capacitor
which are externally connected to the 555 timer. The figure shows the 555 timer
connected as an astable multivibrator. Initially when the output is high
capacitor C starts charging towards Vcc through RA and RB.
Fig.5: Circuit Diagram of 555 timer in
Astable Mode
Waveform
Fig.6: Output waveform of 555 timer in Astable
Mode
Transistor
A transistor is a semiconductor device used to amplify
and switch electronic signals. It is made of a solid piece of semiconductor
material, with at least three terminals for connection to an external circuit.
A voltage or current applied to one pair of the transistor's terminals changes
the current flowing through another pair of terminals. Because the controlled
(output) power can be much more than the controlling (input) power, the
transistor provides amplification of a signal. Some transistors are packaged
individually but many more are found embedded in integrated circuits.The
transistor is the fundamental building block of modern electronic devices, and
its presence is ubiquitous in modern electronic systems.
Fig.7:
Transistor
RESISTOR
A resistor is a
two-terminal electronic component that produces a voltage across its terminals that is proportional to the
electric current through it in accordance with Ohm's law
V = IR
Resistors are
elements of electrical networks and electronic circuits and are ubiquitous in
most electronic equipment.
Fig.8: Resistor
Capacitor
A capacitor is a passive
electronic component consisting of a pair of conductors separated by a
dielectric. When a voltage potential difference exists between the conductors,
an electric field is present in the dielectric. This field stores energy and
produces a mechanical force between the plates. An ideal capacitor is
characterized by a single constant value, capacitance, which is measured in
farads. This is the ratio of the electric charge on each conductor to the
potential difference between them. In practice the dielectric between the plates
passes a small amount of leakage current. The conductors and leads introduce an
equivalent series resistance and the dielectric has an electric field strength
limit resulting in a breakdown voltage.
They are widely used in
electronic circuit to block the flow of direct current while allowing
alternating current to pass, to filter out interferance, to smooth the output
of power supplies, and for many other purposes. They are used in radio
frequency equipment to select particular frequencies from a signal with many
frequencies.
fig.9:Capacitor
LED
A light-emitting diode (LED) is a semiconductor light source. LEDs are used as
indicator lamps in many devices, and are increasingly used for lighting. Introduced as a practical
electronic component in 1962, early
LEDs emitted low-intensity red light, but modern versions are available across
the visible, ultraviolet and infrared wavelengths, with very high
brightness.When a light-emitting diode is forward biased (switched on), electrons are able to recombine with holes within the device, releasing energy in
the form of photons.
This effect is called electroluminescence and the colour of the light (corresponding to the
energy of the photon) is determined by the energy gap of the semiconductor. An LED is often
small in area (less than 1 mm2), and integrated optical
components may be used to shape its radiation pattern. LEDs present many advantages over incandescent light sources
including lower
energy consumption, longer lifetime,
improved robustness, smaller size, faster switching, and greater durability and
reliability
Fig.10:
LEDs
The battery cells
create a voltage difference between the terminals of each cell and hence to its combination in battery.
When an external
circuit is connected to the battery, then the battery drives electrons through
the circuit and electrical work is done. The battery has become a common power
source for many household and industrial applications, and is now a
multi-billion dollar industry.
Fig.11: Battery
PHOTOTRANSISTOR
Phototransistor is
Like diodes,
all transistors
are light-sensitive. Phototransistors are designed specifically to take
advantage of this fact. The most-common variant is an NPN bipolar transistor
with an exposed base
region. Here, light striking the base
replaces what would ordinarily be voltage applied to the base. So, a phototransistor amplifies variations in
the light striking it. Note that phototransistors may or may not have a base
lead (if they do, the base lead allows you to bias the phototransistor’s light
response. Here we use Darlington Phototransistor (L14F1) as a photosensor to
activate the monostable IC1. The collector of phototransistor T1 is connected
to trigger pin2 of IC1, which is normally kept high by resistor R1.When
headlight from an approaching vehicle illuminates the phototransistor. It
conduct to give a short pulse to IC1.
Fig.12: Darling-ton Phototransistor
CONCLUSION
In
this project I have learned a lot about the SIGNAL LAMP scenario in the field
of communication. This circuit is used for safe highway driving. This circuit
inform the driver about the approaching vehicle. It also help the driver if the
driver wants to stop for sometime on highway. It saves battery power.
Note : If u need other project plz write us. or visit us
Deep Groups
97 Nehru Colony,
Thatipur, Gwalior (M.P.)
9826440856
Note : If u need other project plz write us. or visit us
Deep Groups
97 Nehru Colony,
Thatipur, Gwalior (M.P.)
9826440856
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