SPEED CHECKER FORSPEED CHECKER FOR HIGHWAYSHIGHWAYS

A Project Report Submitted In Partial Fulfillment of the Requirement for the Degree

Of Master of Science (Electronics)

By

PRAMOD CHOUDHARY

2006-2007

Jai Narain Vyas University Jodhpur(Accredited As “A” Grade Institution by NAAC-UGC)

ACKNOWLEDGEMENT

It is a matter of great privilege for me to submit thisIt is a matter of great privilege for me to submit this review on “SPEED CHECKER FOR HIGHWAYS”. I amreview on “SPEED CHECKER FOR HIGHWAYS”. I am highly obliged by Dr. S. K. Sharma for his unfailinghighly obliged by Dr. S. K. Sharma for his unfailing encouragement and constant inspiration and I extendencouragement and constant inspiration and I extend my gratitude and thanks to him whose valuablemy gratitude and thanks to him whose valuable guidance and keen interest made it possible to completeguidance and keen interest made it possible to complete the project. I am deeply indebted for the positivethe project. I am deeply indebted for the positive feedback regarding contribution to my work and for hisfeedback regarding contribution to my work and for his unfailing and ungrudging help at every step of thisunfailing and ungrudging help at every step of this project.project.

Turning the aspiration into realities is easier whenTurning the aspiration into realities is easier when quality people supportive to your effects. Among suchquality people supportive to your effects. Among such persons are my parents to whom I deeply indebted forpersons are my parents to whom I deeply indebted for the positive feedback regarding contribution to my workthe positive feedback regarding contribution to my work and for unfailing and ungrudging help at every step ofand for unfailing and ungrudging help at every step of this project.this project.

Pramod ChoudharyPramod ChoudharyM.Sc. FinalM.Sc. FinalElectronicsElectronics

PREFACE

Not only theoretical knowledge but also practicalNot only theoretical knowledge but also practical knowledge is essential for a technical student. And thusknowledge is essential for a technical student. And thus the Project work is very beneficial for him to learn morethe Project work is very beneficial for him to learn more and more about practical works.and more about practical works.

An excellent practical work and knowledge makesAn excellent practical work and knowledge makes a M.sc. student practically good, successful in everya M.sc. student practically good, successful in every field and these qualities are very important for a M.sc.field and these qualities are very important for a M.sc. student.student.

This report consists of details about “SPEEDThis report consists of details about “SPEED CHECKER FOR HIGHWAYS”. This report gives goodCHECKER FOR HIGHWAYS”. This report gives good knowledge about project work. I will never say that it isknowledge about project work. I will never say that it is complete in it our self. We had tried to do my best incomplete in it our self. We had tried to do my best in preparing this report will be taken as reference bypreparing this report will be taken as reference by coming students.coming students.

CERTIFICATE

This is to certify that Mr. Pramod Choudhary of class MSc.This is to certify that Mr. Pramod Choudhary of class MSc. (Final year) from New Campus (J.N.V.U.) has completed his(Final year) from New Campus (J.N.V.U.) has completed his Electronics Project Work Titled “SPEED CHECKER FORElectronics Project Work Titled “SPEED CHECKER FOR HIGHWAYS” and he has submitted a satisfactory report inHIGHWAYS” and he has submitted a satisfactory report in this volume for partial fulfillment of the requirement for thethis volume for partial fulfillment of the requirement for the degree of Master of Science (Electronics) and this is adegree of Master of Science (Electronics) and this is a record of his own work carried out by him under guidance ofrecord of his own work carried out by him under guidance of Dr. S. K. Sharma.Dr. S. K. Sharma.

Date:Date: Dr. S. K. SharmaDr. S. K. SharmaPlace: JodhpurPlace: Jodhpur New CampusNew Campus

Jai Narain Vyas University Jai Narain Vyas University JodhpurJodhpur

CONTENTS

1) INTRODUCTION

2) CIRCUIT DESCRIPTION

3) CONSTRUCTION AND WORKING

4) PRECAUTIONS

5) COMPONENTS

6) CIRCUIT DIAGRAM

7) LIST OF COMPONENTS

Introduction

While driving on highways, motorists should not exceed the maximum speed limit permitted for their vehicle. However, accidents keep occurring due to speed violations since the drivers tend to ignore their speedometers.

This speed checker will come handy for the highway traffic police as it will not only provide a digital display in accordance with a vehicle’s speed but sound an alarm if the vehicle exceeds the permissible speed for the highway.

The system basically comprises two laser transmitter-LDR sensor pairs, which are installed on the highway 100 meters apart, with the transmitter and the LDR sensor of each pair on the opposite sides of the road. The installation of lasers and LDRs is shown fig below. The system displays the time taken by the vehicle in crossing this 100m distance from one pair to the other with a resolution of 0.01 second from which the speed of the vehicle can be calculated as follows:Speed (kmph) = Distance/Time = 0.1 km

(Reading x 0.01)/3600Or,Reading (on display) =36000/Speed

As per the above equation for a speed of 40 kmph the display will read 900 (or 9 second), and for a speed 60 kmph the display will read 600 (or 6 seconds). Note that the LSB of the display equals 0.01 second and each succeeding digit is tem times the preceding digit. You can similarly calculate the other readings (or time).

Circuit description

This circuit has been designed assuming that the maximum permissible speed for highways is either 40 kmph or 60 kmph as per the traffic rule.

The circuit is built around five NE555 timer ICs (IC1 through IC5), four Cd4026 counter ICs (IC6 through IC9) and four 7-segmint displays (DIS1 through DIS4). IC1 through IC3 function as monostables with IC1 serving as count –start mono, IC2 as count –stop mono and IC3 as speed-limit detector mono, controlled by IC1 and IC2 outputs. Bistable set-reset IC4 is also controlled by the outputs of IC1 and IC2 and it (IC4), in turn controls switching on/off of the 100Hz (period=0.01 second) astable IC5.

The time period of timer NEE555 (IC1) count –start monostables multivibrator is adjusted using preset VR1 or VR2 and capacitor C1.For 40kmph limit the period is set for 9 seconds using preset VR1, while for 60kmph limit the time period is set for 6 seconds using preset VR2 .Slide switch S1 is used to select the time period as per the speed limit (40 kmph and 60 kmph, respectively). The kmph and 60 kmph, respectively) .The junction of LDR1 and resistor R1 is coupled to pin 2 of IC1.

Normally, light from the laser keeps falling on the LDR sensor continuously and thus the LDR offers a low resistance and pin 2 of IC1 is high. Whenever light falling on LDR is interrupted by any vehicle, the LDR resistance goes high and

hence pin 2 of IC1 goes low to trigger the monostables .As a result, output pin 3 goes high for the preset period (9 or 6 seconds) and LED1 glows to indicate it. Reset pin4 is controlled by the output of NAND gate N3 at power or whenever reset switch S2 is pushed.

For IC2, the monostables is triggered in the same way as IC1 when the vehicle intersects the laser beam incident on LDR2 to generate a small pulse for stopping the count and for use in the speed detection.LED2 glows for the duration for which pin 3 of IC2 is high.

The outputs of IC1 and IC2 are fed to input pins 2 and 1 of NAND gate N1, respectively. When the outputs of IC1 and IC2 go high simultaneously (meaning that the vehicle has crossed the preset speed limit), output pin 3 of gate N1 goes low to trigger monostables timer IC3. The output of IC3 is used for driving piezobuzzer PZ1, which alerts the operator of speed –limit violation .Resistance R9 and capacitor C5 decide the timer period for which the piezobuzzer sounds.

The output of IC1 triggers the bistable (IC4) through gate N2 at the leading edge of the count-start pulse. When pin 2 of IC4 goes low, the high output at pin 3 enables clock generator IC5, since the count-stop pulse output of IC2 is connected to pin 6 of IC4 via diode D1, it resets clock generator IC5. IC5 can also be reset via diode D2 at power-on as well as when reset switch S2 is pressed.

IC5 is configured as an astable multivibrator whose time period is decided by preset VR3, resistor R12 and capacitor C10. Using preset VR1, the frequency of astable multivibrator is set as 100 Hz. The output of IC5 is fed to clock pin 1 of decade counter/7-segment decoder IC6 CD4026.

IC CD4026 is a 5-stage Johnson decade counter and an output decoder that converts the Johnson code into a 7-segment

decoded output for driving DIS1 display. The counter advances by one count at the positive clock signal transition.

The carry–out (Count) signal from CD4026 provides one clock after every ten clock inputs to clock the succeeding decade counter in a multidecade counting chain. This is achieved by connecting pin 5 of each CD4026 to pin of the next CD4026.

A high reset signal clears the decade counter to its zero count. Pressing switch S2 provides a reset signal to pin 15 of all CD4025 ICs also IC1 and IC4. Capacitor C12 and resistor R14 generate the power-on-reset signal.

The seven decoded outputs ‘a’ through ‘g’ of CD4026 illuminate the proper segment of the 7-segment displays (DIS1 through DIS4) used for representing the decimal digits ‘0’ through ‘9’ .Resistor R16 through R19 limit the current across DIS1 through DIS4, respectively.

Fig. above shows the circuit of the power supply. The AC main is stepped down by transformer X1 to deliver the secondary output of 15 volts, 500 mA. The transformer output is rectified by a bridge rectifier comprising diodes D3 through D6, filtered by capacitor C15 bypass regulated 12V supply. Capacitor C15 bypasses any ripple in the regulated output. Switch S3 is used as the ‘on’/’off’ switch. In mobile application of the circuit, where mains 230V AC is not available, it is advisable to use an external 12V battery .For activating the lasers used in conjunction with LDR1 and LDR2, separate batteries may be used.

Construction and working

Assemble the circuit on a PCB. Before operation, using a multimeter check whether the power supply output is correct, if yes apply power supply to the circuit by flipping switch S3 to ‘on’. In the circuit, use long wires for connecting the two LDRs, so that you can take them out of the PCB and install on one side of the highway, 100 meters apart. Install the two laser transmitters (such as laser torches) on the other side of the highway exactly opposite to the LDRs such that laser light falls directly on the LDRs. Resets the circuit by pressing switch S2, so the display on the LDRs. Resets the circuit by pressing switch S2, so the display shows ‘0000’. Using switch S1, select the speed limit (say, 60 kmph) for the highway. When any vehicle crosses the first laser light, LDR1 will trigger IC1. The output of IC1 goes high for the time set cross 100 meters with the selected speed (60 kmph) and LED1 glows during for period. When the vehicle crosses the second laser light, the output of IC2 goes high and LED2 glows for this period.

Piezobuzzer PZ1 sounds an alarm if the vehicle crosses the distance between the laser set-ups at more than the 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 vehicle to cross both the laser beams is displayed on the 7-segment display. For 60 kmph speed setting, with timer frequency set at 100 Hz, if the display count is less than ‘600’. It means that the vehicle has crossed the speed limit (and simultaneously the buzzer sounds). Reset the circuit for monitoring the speed of the next vehicle.

Precautions

To make sure that ambient light dose not falls on LDRs, house the LDRs is black tube pointing to wards the light sources. The ICs should be soldered carefully. It is better to use IC bases and plug in the ICs later. The solder to IC pin should not be dry or loose.

Components

LDR

Electronic optosensors are devices that alter their electrical characteristics, in the presence of visible or invisible light. The best-known devices of these types are the LDR (light dependent resistor), the photodiode, and the phototransistor.

LDR operation relies on the fact that the conductive resistance of a film of cadmium sulphide (Cds) varies with the intensity of light falling on the face of the film. This resistance is very high under dark conditions and low under bright conditions.

The device consists of a pair of metal film contacts separated by a snake-like track of cadmium sulphide film, designed to provide the maximum possible contact area with the two metal films. The structure is housed in a clear plastic or resin case, to provide free access to external light.

LDRs are sensitive, inexpensive, and readily available devices. They have good power and voltage handling capabilities, similar to those of a conventional resistor. Their only significant defect is that they are fairly slow acting, taking tens or hundreds of milliseconds to respond to sudden changes in light level. Useful practical LDR applications include light- and dark- activated switches and alarms, light beam alarms, and reflective smoke alarms etc.

VARIABLE RESISTANCE

Variable resisters are those resisters in which resistance value can be varied, with in a pre determined range. These are three terminal devices. Two terminals are fixed while the third one is connected to a moveable tap which slides along the resistive element, changing the resistance between ends tap terminal Variable resistance are also called as potentiometer

PCB

A printed circuit board properly known as PCB is a piece of plastic electronic circuit consisting of copper or special photo engraving process prints silver –conducting path. On the other side of the PCB electric components are mounted like resistors, capacitors, diodes, transistors, transformers, tubes, and IC’s. Suitable holes are punched in the PCB for mounting the components, which are connected to the conducting paths by soldering.

LED

A light-emitting diode (LED) is a semiconductor device that emits incoherent monochromatic light when electrically biased in the forward direction. The color of the emitted light depends on the chemical composition of the semiconducting material used, and can be near-ultraviolet, visible or infrared.

RESISTORS

The circuit elements which offers an opposition to electric current flowing in a circuit is known as resister and its value of resistance is expressed in ohms. The Ohm is denoted by Greek letter Omega ().

CAPACITORS

The capacitors are the most widely used passive element next to resistors. Capacitor is made up of two parallel plates separated by insulating materials called as dielectric. Capacitance is defined as the ability of capacitor to store charge.

PUSH TO ON SWITCH

They are used for makes the connection only when switch is pressed. On releasing button the connection must be break down.

IC’S BASE

They are for mounting of IC’s on PCB i.e. they help us to remove or put IC’s on PCB with very easy push or pull action. They are available according to the numbers of pins of IC’s used.

SEVEN SEGMENT LED DISPLAY

LTS543 is common cathode 7- segment LED display. These display devices are used in application where the viewer is within 6 m of display. This type of LED fits into standard dip sockets with 1.52 cm pin rows it also has a decimal point on the lower right hand side.

8

NE555

Description

The NE555 is a highly stable controller capable of producing accurate timing pulses. With a monostable operation, the time delay is controlled by one external resistor and one capacitor. With an astable operation, the frequency and duty cycle are accurately controlled by two external resistors and one capacitor

Features

• High Current Drive Capability (200mA) • Adjustable Duty Cycle • Temperature Stability of 0.005%/°C • Timing From µSec to Hours • Turn off Time Less Than 2µSec

Internal Block Diagram

Application Information

Monostable Operation

Figure illustrates a monostable circuit. In this mode, the timer generates a fixed pulse whenever the trigger voltage falls below Vcc/3. When the trigger pulse voltage applied to the #2 pin falls below Vcc/3 while the timer output is low, the timer's internal flip-flop turns the discharging Tr. off and causes the timer output to become high by charging the external capacitor C1 and setting the flip-flop output at the same time.The voltage across the external capacitor C1, VC1 increases exponentially with the time constant t=RA*C and reaches 2Vcc/3 at td=1.1RA*C. Hence, capacitor C1 is charged through resistor RA. The greater the time constant RAC, the longer it takes for the VC1 to reach 2Vcc/3. In other words, the time constant RAC controls the output pulse width.When the applied voltage to the capacitor C1 reaches 2Vcc/3, the comparator on the trigger terminal resets the flip-flop, turning the discharging Tr. on. At this time, C1 begins to discharge and the timer output converts to low.In this way, the timer operating in the monostable repeats the above process. Figure 2 shows the time constant relationship based on RA and C.It must be noted that, for a normal operation, the trigger pulse voltage needs to maintain a minimum of Vcc/3 before the timer output turns low. That is, although the output remains

unaffected even if a different trigger pulse is applied while the output is high, it may be affected and the waveform does not operate properly if the trigger pulse voltage at the end of the output pulse remains at below Vcc/3.

Astable Operation

In the astable operation, the trigger terminal and the threshold terminal are connected so that a self-trigger is formed, operating as a multi vibrator. When the timer output is high, its internal discharging Tr. turns off and the VC1 increases by exponential function with the time constant (RA + RB) x C. When the VC1, or the threshold voltage, reaches 2Vcc/3, the comparator output on the trigger terminal becomes high, resetting the F/F and causing the timer output to become low. This in turn turns on the discharging Tr. and the C1 discharges through the discharging channel formed by RB and the discharging Tr. When the VC1 falls below Vcc/3, the comparator output on the trigger terminal becomes high and the timer output becomes high again. The discharging Tr. turns off and the VC1 rises again. In the above process, the section where the timer output is high is the time it takes for the VC1 to rise from Vcc/3 to 2Vcc/3, and the section where the timer output is low is the time it takes for the VC1 to drop from 2Vcc/3 to Vcc/3.

The explanations of terminals coming out of the timer IC is as follows:

Pin 1: Ground terminal: It is a common ground terminal. All the voltages measured with respect to this terminal.

Pin 2: Trigger terminal: This pin is an inverting input to comparator, which is responsible for transition of flip flop from set to reset. The output stage of timer depends on the amplitude on external trigger pulses applied to this pin.

Pin 3: Out put terminal: Output of timer is available as this pin. Normally its level remains low and only during timing interval it goes high. There are two ways to connect the load to this terminal .One is to connect the load between pin-3 and pin-8, which is called floating supply load. Since in the case of floating supply load, current only flows during low state of output and during high state of output and during high state of output, there is on current i.e. when output is off, load current is on, therefore floating supply load is also known as “normally on load”, Science in case of floating supply load, load current flows through load into output terminal therefore this current is known as sink current while in case of grounded load, load current flows of output terminal. Therefore it is called source current.

Pin 4: Reset terminal: To disable or reset the timer a negative pulse is applied at this pin due to which it is called reset terminal.

Pin 5: Control voltage terminal: Function of the control voltage terminal is to control the threshold and trigger level and that is why this terminal is called control terminal .This either the external voltage or a potentiometer connected at this pin can also be used to modulate the output waveform. When this pin is not used for the above purpose, it should be connect to ground through a 0.01 microfarad capacitor to bypass noise

and ripple voltage from the power supply so as to minimize their effect on threshold voltage.

Pin 6: Threshold terminal: It is a non –inverting terminal of comparator, which compares the voltage applied at this terminal with a reference voltage of 2Vcc/3. Thus the amplitude of the voltage at threshold terminal is responsible for the set of flip flop.

Pin 7: Discharge terminal : At this pin ,collector of a transistor is connected internally and mostly a capacitor is connected externally between this terminal and ground .It is called as discharge terminal because when a transistor saturates , capacitor discharges through the transistor is in cutoff, the capacitor charges at a rate of determined by the external resistor and capacitor.

Pin 8: Supply terminal: A supply voltage Vcc of +5 V is applied to this pin with respect to ground. Due to such a large range of Vcc from +5 V existing digital logic supplier, linear IC supplies and automatic on dry cell batteries can power 555.

IC 555 timer finds very useful application in many other projects such as:

Precision timing, sequential timing.

Pulse shaping.

Pulse generator.

Missing pulse generator.

Time delay generator.

Frequency division.

Traffic light control.

Infrared remote control timer.

DIODE 1N4148 (Small-Signal Diode) AND 1N4007

Diode 4148 performs switching operation here. Whenever the logical level at their anode is 1 they switch on and provide a positive pulse to the circuit connected to them. Diode 4007 is a rectifying diode used in bridge rectifier.

IC 7812 3-Terminal 1A Positive Voltage Regulator

DescriptionThe LM7812 three terminal positive regulators are available in the TO-220/D-PAK package and with several fixed output voltages, making them useful in a wide range of applications. Each type employs internal current limiting, thermal shut down and safe operating area protection, making it essentially indestructible. If adequate heat sinking is provided, they can deliver over 1A output current. Although designed primarily as fixed voltage regulators, these devices can be used with external components to obtain adjustable voltages and currents.

Features• Output Current up to 1A• Output Voltages of 12V• Thermal Overload Protection• Short Circuit Protection• Output Transistor Safe Operating Area Protection

Internal Block Diagram

IC CD4011 Quad 2-Input NAND Buffered B Series Gate

General Description

The CD4011BC quad gates are monolithic complementary MOS (CMOS) integrated circuits constructed with N- and P-channel enhancement mode transistors. They have equal source and sink current capabilities and conform to standard B series output drive. The devices also have buffered outputs which improve transfer characteristics by providing very high gain. All inputs are protected against static discharge with diodes to VDD and VSS.

Features

Low power TTL

5V–10V–15V parametric ratings

Symmetrical output characteristics

Max input leakage 1A at 15V over full temperature. range

Connection Diagrams

IC CD4026

CD 4026 consist of a 5-stage Johnson decade counter and an output decoder which converts the Johnson code to a 7-segment decode output for driving one stage in a numerical display.These devices are particularly advantageous in display applications where low power dissipation and/or low package counts are important.Input is CLOCK INHIBIT, common outputs are CARRY OUT and the seven decoded outputs (a, b, c, d, e, f, g). Additional inputs and outputs for the CD 4026 include DISPLAY ENABLE input and DISPLAY ENABLE and UNGATED "C-SEGMENT" outputs.A high RESET signal clears the decade counter to its zero count. The counter is advanced one count at the positive clock signal transition if the CLOCK INHIBIT signal is low. Counter advancement via the clock line is inhibited when the CLOCK INHIBIT signal is high. The CLOCK INHIBIT signal can be used as a negative-edge clock if the clock line is held high. Antilock gating is provided on the JOHNSON counter, thus assuring proper counting sequence. The CARRY-OUT (Cout) signal completes. The cycle every ten CLOCK INPUT cycles and it is used to clock the succeeding decade directly in a multi-decade counting chain. The seven decoded outputs (a, b, c, d, e, f, g) illuminate the proper segments in a seven segment display device used for representing the decimal numbers 0 to 9. The 7-segment outputs go high only when the DISPLAY ENABLE IN is high.

List of componentsSemiconductors:

IC1-IC5 NE555 timerIC6-IC9 CD4026 decade counter/7segment decoderIC10-CD4011 NAND gateIC11 7812 12 V regulatorD1, D2 1N4148 switching diodeD3-D6 1N4007 rectifier diodeLED1 Green LEDLED2, LED3 Red LEDDIS1-DIS4 LTS543 common-cathode, 7 segment

display

Resistors:

R1, R4 100-kilo-ohmR2, R5, R6, R8,R10, R11, R14 10-kilo-ohmR3, R7, R13, R16-R19 470-ohmR9 470-kilo-ohmR12, R15 1-kilo-ohmVR1, VR2 100-kilo-ohm presetVR3 20-kilo-ohm preset

Capacitors:

C1 100µF, 25v electrolyticC2, C4, C6C8, C11 0.01µF ceramic diskC3, C13, C15 0.1µF ceramic diskC5 10µF, 25v electrolyticC7 0.47µF, 25v electrolyticC9 0.2µF ceramic diskC10 1µF, 25v electrolyticC12 47µF, 25v electrolyticC14 1000µF, 35v electrolytic

Miscellaneous:

X1 230V AC primary to 0-15V, 500mA secondary transformer

PZ1 PiezobuzzerLDR1, LDR2 Light Dependent ResistorsS1 Double side single through switchS2 Push-to-on switchS3 On/Off switchPointed laser light