1 1. INTRODUCTION Many analysts and policy makers have argued that building more highways is an Ineffective response to congestion: specifically, that it is infeasible to add enough highways Capacity in large urban areas to provide much relief. But this making of highways is just showing the path for accidents because of no speed limits in these highways. In order to overcome this problem we have designed equipment called as “SPEED CHECKER ON HIGHWAYS”. This kit investigates differentiated design standards as a source of capacity additions that are more affordable. Here we consider the average speed and high speed with which the vehicles are moving. We also consider the implications of differing accident rates. All these consideration were taken and the design of this equipment is done. This design helps to find the vehicles which are moving with high speed in spite of a speed limit board is present in that highway. The cops then can take necessary action on that culprit. The design mainly
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Transcript
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1. INTRODUCTION
Many analysts and policy makers have argued that building more highways is an
Ineffective response to congestion: specifically, that it is infeasible to add enough highways
Capacity in large urban areas to provide much relief. But this making of highways is just
showing the path for accidents because of no speed limits in these highways. In order to
overcome this problem we have designed equipment called as “SPEED CHECKER ON
HIGHWAYS”. This kit investigates differentiated design standards as a source of capacity
additions that are more affordable. Here we consider the average speed and high speed with
which the vehicles are moving. We also consider the implications of differing accident rates.
All these consideration were taken and the design of this equipment is done. This design
helps to find the vehicles which are moving with high speed in spite of a speed limit board is
present in that highway. The cops then can take necessary action on that culprit. The design
mainly uses a timer, counter, logic gates and 7-segment display. Using these components we
design the speed checker on highways and observed that it is working more efficiently than
expected.
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2. BLOCK DIAGRAM AND DESCRIPTION OF EACH BLOCK
2.1 Block Diagram
Fig 2.1 Block Diagram
2.2 Block Description
There are totally four sections in the block diagram. They are Counter circuit, timer &
control circuit, triggering circuit and 7-segment display. Each block has its own functionality.
The 7-segment display is used for displaying the output. The counter circuit is the one
count the number of times an event has occurred in accordance with the clock signal. The is
received from the timer and control circuit. The timer and control circuit consists of a timer
IC and another IC which receives input signal from triggering circuit according to the
ON/OFF condition of the two switches present there.
A circuit having a delay circuit provided with a gate for converting the output signal of an SR
flip-flop into a signal with a delay equal to or more than the clock pulse width enough for
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count operation and leading the logical addition between the signal and system clock and the
logical multiplication between the signal and counter write signal to the direct reset input of a
transparent latch 7 and for realizing read-on-the-fly or write-on-the-fly operation even if
timer input does not synchronize with the system clock is called as Timer & Control circuit.
A circuit or network in which the output changes abruptly with an infinitesimal change in
input at a predetermined operating point. Also known as trigger. A circuit in which an action
is initiated by an input pulse.
CIRCUIT DIAGRAM WITH OPERATION DETAILS
2.3 Circuit Diagram
Fig 2.3 Circuit Diagram
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2.3.1 MAIN CIRCUIT DIAGRAM:
Fig 2.3.1 Main Circuit Diagram
2.4 circuit Operation:
The circuit mainly consists of a supply circuit, control circuit and a 7-segment display. The
control circuit consists of a counter ON/OFF circuit, timer & control circuit amd triggering
circuits connected to the switches.
When a supply is given to the secondary of the transformer, it steps down the 220v
AC supply to 18v AC. This 18v is fed to the bridge rectifier in order to convert AC to DC.
The bridge rectifier provides same polarity of output voltage for either polarity of input
voltage. It’s most common application is conversion of AC input to DC output. A capacitor
is connected across the output of bridge rectifier in order to reduce noise and fluctuations in
the output voltage. The 18v dc acts as input to the voltage regulator which reduces the
voltage to 12v,as only 12v is required to the circuit. This regulator uses a resistor to
maintain the voltage constant throughout the operation. This voltage is now fed to the
whole circuit.
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The kit mainly consists of two laser transmitter-LDR sensor pairs which are installed on
the highway 100m apart such that the transmitter and LDR sensor of each pair on the
opposite sides of the road. This kind of arrangement is shown in the figure below.
Fig 2.4 Circuit Operation
When any vehicle crosses the first laser beam LDR1 goes high for the time set to cross
100mts with the selected speed (60KMPH) and LED1 glows during this period. When the
vehicle crosses the second laser light beam, the output of IC2 goes high and LED2 glows
for this period. Pezo buzzer sounds an alarm if the vehicle crosses the distance between the
laser setups at more than selected speed(lesser period than preset period).The counter starts
counting when the first laser beam is intercepted and stops when the second laser beam is
intercepted. The time taken by the vehicle to crop both the laser beams is displayed on the
7-segment display.
2.5 Supply Details:
Input supply to the transformer 220v AC
Input supply to the Bridge Rectifier 18v AC
Input supply to the Regulator 18v DC
Supply to the PCB 12v DC
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3 COMPONENT DESCRIPTION
3.1 Transformer:
Transformer is static equipment which transforms power from one circuit to another by
stepping up or stepping down the primary voltage without any change in the frequency.
Fig 3.1 Transformer
A transformer is an energy device it has an input side (primary) and an output side
(secondary).electrical energy applied to the primary is converted to a magnetic field which in
turn, induces a current in the secondary which carries energy to the load connected to the load
connected to the secondary. The alternating current that flows through the primary winding
establishes a time –varying magnetic flux, some of which links to the secondary winding and
induces a voltage across it. The magnetic of this voltage is proportional to the number of
turns on the primary winding to the number of turns on the secondary winding this is known
as “turn’s ratio”.
The basic working principle of transformer is based on mutual induction between
two coupled coils. According to this principle by changing flux creates on induced emf in
turn equal to the derivative of the flux so that the total induced emf across ‘N’ turns is
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E= N d@/dt :- (@=fi)
A transformer consists of at least two sets of windings wound on a single magnetic
core. There are two main purposes for using transformers. The first is to convert the energy
on the primary side to a different voltage level on the secondary side. This is accomplished
by using differing turn’s counts on primary and secondary windings. The voltage ratio is the
same as the turn’s ratio. The second purpose is to isolate the energy source from the
destination, either for personal safety, or to allow a voltage offset between the source and
load.
Fig 3.1.1 Step Down Transformer
A step down transformer has less turns of wire on the secondary coil which makes a smaller
induced voltage in the secondary coil. Decreasing the voltage does not decrease the power.
As the voltage goes down, the current goes up. It is called a step down transformer because
the voltage output is smaller than the voltage input. If the secondary coil has half as many
turns of wire then the output voltage will be half the input voltage.
3.2 Rectifier
Rectifier circuits are found in all dc power supplies that operate from an ac voltage
source. They convert the ac input voltage to a pulsating dc voltage. The most basic type of
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rectifier circuit is the half-wave rectifier. Although half-wave rectifiers have some
applications, the full-wave rectifiers are the most commonly used type in dc power supplies.
These are two types of full-wave rectifiers:
(1) full-wave center-tapped rectifier
(2) full-wave bridge rectifier
Here in this particular design we are using a bridge rectifier which is discussed as
follows.
3.2.1 Full-wave Bridge Rectifier
The full –wave bridge rectifier uses four diodes, as shown in below figure. When the input
cycle is positive, diodes D1 and D2 are forward-biased and conduct current through RL.
During this time, diodes D3 and D4 are reverse-biased.
Fig 3.2 Full-wave Bridge Rectifier
During positive half-cycles of the input, D1 and D2 are forward-biased and conduct current, D3
and D4 are reverse-biased.
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When the input cycle is negative as shown in below figure , diodes D3 and D4 are
forward-biased and conduct current in the same direction through RL as during the positive
half-cycle. During the negative half-cycle, D1 and D2 are reverse-biased. A full-wave rectifier
output voltage appears across RL as a result of this action.
During negative half-cycles of the input, D3 and D4 are forward-biased and conduct current
D1 and D2 are reverse-biased.
The above two figures explain the full-wave Bridge Rectifier.
The output graph of a full-wave rectifier is as shown
below
:
Fig 3.2.1 Diode Operation and waveform of current
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3.2.2 IN4007 Diode
These diodes are used to convert AC into DC these are used as half wave rectifier or full
wave rectifier. Three points must he kept in mind while using any type of diode.
1. Maximum forward current capacity
2. Maximum reverse voltage capacity
3. Maximum forward voltage capacity
Fig 3.2.2 IN4007 Diode
The number and voltage capacity of some of the important diodes available in the market are
as follows:
Diodes of number IN4001, IN4002, IN4003, IN4004, IN4005, IN4006 and IN4007
have maximum reverse bias voltage capacity of 50V and maximum forward current
capacity of 1 Amp.
Diode of same capacities can be used in place of one another. Besides this diode of
more capacity can be used in place of diode of low capacity but diode of low capacity
cannot be used in place of diode of high capacity. For example, in place of IN4002;
IN4001 or IN4007 can be used but IN4001 or IN4002 cannot be used in place of
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IN4007.The diode BY125made by company BEL is equivalent of diode from IN4001
to IN4003. BY 126 is equivalent to diodes IN4004 to 4006 and BY 127 is equivalent
to diode IN4007.
3.3 Voltage Regulator
A voltage regulator is an electrical regulator designed to automatically maintain a constant
voltage level. It may use an electromechanical mechanism, or passive or active electronic
components. Depending on the design, it may be used to regulate one or more AC or DC
voltages.
Fig 3.3 Voltage Regulator
With the exception of passive shunt regulators, all modern electronic voltage regulators
operate by comparing the actual output voltage to some internal fixed reference voltage. Any
difference is amplified and used to control the regulation element in such a way as to reduce
the voltage error. This forms a negative feedback servo control loop; increasing the open-loop
gain tends to increase regulation accuracy but reduce stability (avoidance of oscillation, or
ringing during step changes). There will also be a trade-off between stability and the speed of
the response to changes. If the output voltage is too low (perhaps due to input voltage
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reducing or load current increasing), the regulation element is commanded, up to a point, to
produce a higher output voltage - by dropping less of the input voltage (for linear series
regulators and buck switching regulators), or to draw input current for longer periods (boost-
type switching regulators); if the output voltage is too high, the regulation element will
normally be commanded to produce a lower voltage. However, many regulators have over-
current protection, so entirely stop sourcing current (or limit the current in some way) if the
output current is too high, and some regulators may also shut down if the input voltage is
outside a given range (see also: crowbar circuits).
The voltage Regulator used in this design is LM 7812.
3.3.1 LM78xx Regulator
The LM78XX series of three terminal regulators is available with several fixed
output voltages making them useful in a wide range of applications. One of these is local on
card regulation, eliminating the distribution problems associated with single point regulation.
The voltages available allow these regulators to be used in logic systems, instrumentation,
Hi-Fi, and other solid state electronic equipment.
Although designed primarily as fixed voltage regulators these devices can be used with
external components to obtain adjustable voltages and currents. The LM78XX series is
available in an aluminum TO-3 package which will allow over 1.0A load current if adequate
heat sinking is provided. Current limiting is included to limit the peak output current to a safe
value. Safe area protection for the output transistor is provided to limit internal power
dissipation.
If internal power dissipation becomes too high for the heat sinking provided, the thermal
shutdown circuit takes over preventing the IC from overheating. Considerable effort was
expanded to make the LM78XX series of regulators easy to use and minimize the number of
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external components. It is not necessary to bypass the output, although this does improve
transient response. Input bypassing is needed only if the regulator is located far from the filter
capacitor of the power supply.
For output voltage other than 5V, 12V and 15V the LM117 series provides an output voltage
range from 1.2V to 57V.
Features
- Output current in excess of 1A
- Internal thermal overload protection
- No external components required
- Output transistor safe area protection
- Internal short circuit current limit
- Available in the aluminum TO-3 package
Voltage Range
LM7805C 5V
LM7812C 12V
LM7815C 15V
3.4 IC 555 TIMER
The 555 Timer IC is an integrated circuit (chip) implementing a variety of timer and multi-
vibrator applications. The IC was designed and invented by Hans R. Camenzind. It was
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designed in 1970 and introduced in 1971 by Signe tics (later acquired by Philips). The
original name was the SE555/NE555 and was called "The IC Time Machine".
The 555 gets its name from the three 5-kohm resistors used in typical early implementations.
It is still in wide use, thanks to its ease of use, low price and good stability. As of 2003, 1
billion units are manufactured every year. Depending on the manufacturer, it includes over 20
transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line
package (DIP-8). The 556 is a 14-pin DIP that combines two 555s on a single chip.
The 558 is a 16-pin DIP that combines four slightly modified 555s on a single chip (DIS &
THR are connected internally; TR is falling edge sensitive instead of level sensitive). Also
available are ultra-low power versions of the 555 such as the 7555 and TLC555. The 7555
requires slightly different wiring using fewer external components and less power.
The 555 has three operating modes:
• Monostable mode: in this mode, the 555 functions as a "one-shot". Applications
include timers, missing pulse detection, bounce free switches, touch switches, frequency