Project Report : Speed Limit Alert
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Project Report : Speed Limit Alert

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Project report on : Speed Limit Alert

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Project Report : Speed Limit Alert Project Report : Speed Limit Alert Document Transcript

  • DEPARTMENT OF ELECTRONICS & TELECOMMUNICATION ENGINEERING A Project report on SPEED LIMIT ALERT Submitted by ASHTEKAR SWAPNIL TUKARAM BARAWKAR ADITYA AVINASH CHETAN ARVIND PATIL T-3053008 T-3053013 T-3053022 PUNE INSTITUTE OF COMPUTER TECHNOLOGY DHANKAWADI, PUNE 411043 2009-2010
  • DEPARTMENT OF ELECTRONICS & TELECOMMUNICATION ENGINEERING PUNE INSTITUTE OF COMPUTER TECHNOLOGY DHANKAWADI, PUNE 411043 2009-2010 CERTIFICATE This is to certify that the project report entitled SPEED LIMIT ALERT “ ” Submitted by ASHTEKAR SWAPNIL TUKARAM BARAWKAR ADITYA AVINASH CHETAN ARVIND PATIL T-3053008 T-3053013 T-3053022 Is a bonafide work carried out by them under the supervision of and it is approved for the partial fulfillment of the requirement of ESD & MP Third Year of Engineering University of Pune. Internal Guide (Prof. S.S. Dudam) Place: Pune Date: H.O.D, E&TC Dept. (Prof. S.S. Narkhede)
  • ACKNOWLEDGEMENT We express our heartfelt gratitude to all the people who, in some way or the other have lent us a helping hand in the successful completion of the project. Their contribution to the project has made our task much simpler. We thank our internal guide, Prof. S.S. Dudam for his guidance and assistance in times of need. Without their inspiration, the mammoth task of the completion of the project was impossible. We extend a token of thanks to all our friends who have helped us to make this project a success. Last, but not the least, we thank the library staff for providing us all the books we needed to refer.
  • LIST OF FIGURES FIGURE NUMBER DESCRIPTION PAGE NUMBER Fig 1 Block Diagram 8 Fig 2 Circuit Diagram 10 Fig 3 Inductive Pick Up 11 Fig 4 Square wave shaping circuit 12 Fig 5 Amplifier 13 Fig 6 Frequency discriminator block 14 Fig 7 Waveform of frequency discriminator 15 Fig 8 Configuration of frequency discriminator 17 Fig 9 LED,Buzzer driving circuit 18 Fig 10 Output on DSO 20 Fig 11 Comparator circuit 21 Fig 12 Input waveform of comparator 22 Fig 13 Implementation of circuit on Bread board 23 Fig 14 Schematic of PCB 24 Fig 15 Layout and 3-D view of PCB 25
  • TABLE OF CONTENTS 1 Introduction…………………………………………………………………………….7 1.1Aim &Project definition……………………………………………………………...7 1.2Brief History………………………………………………………………………….7 1.3Recent trends and developments in field…………………………………………….7 2 Block Diagram………………………………………………………………………......8 2.1 Block Diagram…………………………………………………………………........8 2.2 Block Diagram description………………………………………………………….9 3 System Design..............................................................................................................10 3.1 Understanding the system………………………………………………………….11 3.2 Inductive Pick up……………………………………………………………..…....11 3.3 Differential Amplifier………………………………………………………..........12 3.4 Amplifier…………………………………………………………………………..13 3.5 Monostable Multivibrator..……………………………………………..………....14 3.6 Amplifier to drive LED and BUZZER ………………………………..………….18 4 Circuit Operation……………………………………………………………………...19
  • 5 Implementation,Testing And Debugging…………………………………………….20 5.1 First Phase…………………………………………………………………….……20 5.2 Second Phase…….…………………………………………………………………20 5.3 Third Phase………………………………………………………………………...21 5.4 Fourth Phase……………………………………………………………………….22 5.5 Fifth Phase…………………………………………………………………………24 5.6 Final Phase………………………………………………………………………...25 6 List of Components……………………………………………………………………26 7 Results and conclusion……………………………………………………………….27 8 Future enhancements………………………………………………………………...28 9 Applications…………………………………………………………………………...29 10 References…………………………………………………………………………...30 11 Datasheets…………………………………………………………………………...31
  • 1. INTRODUCTION 1.1 AIM & PROJECT DEFINITON: The project is aimed to provide a circuit for speed limit alert for which the input will be given from the engine spark plug without any physical contact. It will give speed limit equipment which will be useful for all those low priced vehicles which do not come fitted with speed limit alert system. This circuit with some slight modification can give more services in low cost. 1.2 BRIEF HISTORY: Speed has been an important and dangerous issue in vehicles. Over the years, most of the accident and life lost are due to over speeding of vehicles. In the thrill of high speed the driver does not understand that he/she has crossed the limit of vehicle and the vital components like brakes are not designed for such high speeds and at such high speed distraction of driver by looking into the speedometer leads to fatal accidents. So there is need for equipment which can alert the driver well in advance with visual and audio indication for crossing the safe speed limit. 1.3 RECENT TRENDS AND DEVELOPMENTS IN FIELD: High end vehicles are equipped with much more advanced hardware in which speed in automatically decreased after crossing the safe speed limit. There are sensors in the vehicles which read the line on the road and if driver is approaching the curve with high speed then these sensors inform to slow down and accidents are avoided. But such equipment cost more and can’t be fitted in low cost vehicles. Considering the safety issue these low cost vehicles should be provided with low cost without altering the parts of the vehicle. 7
  • 2. BLOCK DIAGRAM Fig. 1 Block Diagram 8
  • 2.1 BLOCK DIAGRAM DESCRIPTION: The block diagram shows operation of our system which we will be implementing. As shown in block diagram the electromagnetic pulses generated by the engine are picked up by inductive coil. The pulses picked up are applied to OP-AMP (comparator) and from there it is applied to amplifier (Hex Inverter). After getting proper pulse output from amplifier the pulse is applied to monostable multivibrator. In the last stage of operation the input is given to timing circuit for LED and thus our implementation for SPEED LIMIT ALERT is achieved. 9
  • 3. SYSTEM DESIGN Fig. 2 Circuit Diagram 10
  • 3.1 UNDERSTANDING THE SYSTEM: In any of the internal combustion engine, there is a spark plug which initiates the expansion cycle (one of the four cycles of IC engine). The spark in the spark plug is generated by giving a high voltage of about 30 Kv. As the revolution per second of the crank shaft increases, the frequency at which the spark are generated increases i.e. there is a fixed relation between the rpm of the engine (speed of vehicle ) and the high voltage pulses provided to the spark plug. This voltage is supplied through cables which produces electromagnetic waves. Hz= (Number of cylinders * RPM) / 120 3.2 INDUCTIVE PICK UP: The pulses which are produced are picked up in the circuit with the help of inductor. Just as primary and secondary of the transformer are coupled i.e. the varying current in primary produce electromagnetic waves which produces varying current in the secondary. The same way spark plug produces electromagnetic waves which are captured by the inductor which is placed nearby. Thus we get our input signal for our circuit in form of voltage across the inductor. The pulses obtained from the vehicles are very weak and not suitable for the operation of the circuit. As the pulses for the spark plug are of high voltage of about 30Kv, we require a coil with low value inductance. Here we selected a 10mH inductor coil. Electromagnetic Coupling Spark Plug Inductor Fig. 3 Inductive Pick Up 11
  • 3.3 OP-AMP (Difference Amplifier): As the pulses from the inductor are not clean for operation of circuit. So we use an OP-AMP, as a comparator to shape the pulses the desired output of the OP-AMP is clean square wave. We are using CA3140 4.5 MHz,BIMOS Operational Amplifier with MOSFET Input/Bipolar output for our purpose. Features: Very high input impedance, very low input current, wide common mode input voltage range, output swing complements input common mode range etc. As the pulses from the inductive pickup are not clean. We require a differential amplifier to shape them into square wave. Fig. 4 Square wave shaping circuit Output Voltage Vo = (-Rf/R1)*V1 + [1+(Rf/R1)][Rf/(R2+Rf)] If R1=R2 Vo = (Rf/R1) (V2-V1) Rf=100K R1=1K 12
  • Therefore , Vo = 100(V2-V1) And Gain = 100 As gain is very high and voltage of input is of the order of volts . Therefore, output of the circuit will be Vsat. i.e. Vo=Vsat=Vcc 3.4 AMPLIFIER: We have used 6 hex inverters for the amplification as directly connecting the OP-AMP output to the next stage may lead to loading of the IC. We have used 4 stages of hex inverters connected in cascade. We select a Hex inverter IC as our amplifier. It means our requirements of 1) High noise immunity. 2) Low power dissipation. 3) Capable of driving two low-power TTL loads. We select IC MC14069 as hex inverter. It has 6 inverters in a package. Fig. 5 Amplifier A 50 Kohm potentiometer is used to fine tune output voltage of the inverter. 13
  • 3.5 MONOSTABLE MULTIVIBRATOR: Here we use CD4098BMS dual monostable multivibrator which provides stable retriggerable/resettable one shot operation for any fixed voltage timing application. The output of the hex is connected to the pin number 4 which is +TR (rising edge trigger). When the speed limit exceeds, we get pulses at 60 Hz at output of Hex inverter, the pin number 6 which is the output is held permanently high as the monostable multivibrator is set in retriggerable mode. The second monostable multivibrator act as timing circuit for the LED and BUZZER. We need to design a circuit which would detect the desired frequency i.e it would discriminate the high frequencies (High speed of vehicle) from the low frequencies (normal speed of vehicle) For this we choose a monostable multivibrator which could operate in retrigerable mode. Input frequency Frequency Output frequency=+vcc(High) =0 (Normal) Discriminator Fig. 6 Frequency discriminator block 14
  • Low Frequency: (Normal Operation) I/p Vtg 5v t Pulse width decided by Rx Cx O/p vtg High Frequency: (Speed Limit crossed) I/p Vtg 5v t Retriggering O/p vtg Fig. 7 Waveform of frequency discriminator 15
  • Deciding values of Rx and Cx As per datasheets, the period of the pulse is given by Tx = (1/2)(Rx*Cx) Deciding critical frequency For testing purpose we design the system at moderate speeds. Later on the speed limit can be increased by decreasing the value of Rx Cx. We select, 3600 rpm to 4800 rpm as our range for speed limit. We select Cx as 330nF Max value of Cx that can be selected is 100uF (As per data sheet). Freq= (Number of cylinders * RPM)/120 We tested the circuit for two wheeler with single cylinder. Therefore, Freq= (1*3600)/120 =30 Hz Freq=(1*4800)/120 =40 Hz Calculating Rx For 30 Hz T= 1/30=0.033 sec T=(1/2)Rx*Cx 0.033 = (1/2)*Rx*330nF 16
  • Rx = 220Kohm for 30 Hz i.e 3600 rpm For 40 Hz T= (1/2)Rx*Cx 0.025 = (1/2) Rx*330 nF Rx = 150 k for 40 Hz i.e. 4800 rpm Therefore the given values of Rx and Cx we configure the monostable multivibrator as. Fig. 8 Configuration of frequency discriminator 17
  • 3.6 AMPLIFIER TO DRIVE LED AND BUZZER The timer output is at pin number 10 of the 2nd monostable multivibrator. It cannot be used to directly drive the LED or the circuit may get loaded. We use a transistorized amplifier to drive the LED and BUZZER through Vcc. Vcc Ds Buzzer 1k 22k Fig. 9 LED,Buzzer driving circuit Neglecting the drop across the transistor and LED Therefore Current through the LED = (9K)/(1K) = 9 mA Therefore, Current through LED is less than 9mA. Rb is high value i.e. 22K has no base current flowing through it. 18
  • 4. CIRCUIT OPERATION The OP-AMP (differential amplifier) amplifies the difference between the leads of the inductor (pick up) and give an output which is a square wave (positive pulses) with output Vsaturation and with highest output value which is saturation value of the OP-AMP. To avoid the loading of OP-AMP we used hex inverter as a buffer. The use of the inverters keeps the voltage level high around 8.2 V and sources sufficient current. We have used 6 hex inverters for the amplification as directly connecting the OP-AMP output to the next stage may lead to loading of the IC. We have used 4 stages of hex inverters connected in cascade. The monostable multivibrator acts as a frequency discriminator. We have configured it in retrigger able mode so that when the input frequency increases (speed limit exceeds) the output is a DC signal of around 8 V. When the output of frequency discriminator is a DC level the second monostable multivibrator does not reset and works as timing circuit for the LED and buzzer to sound at a frequency of 1 Hz. 19
  • 5. IMPLEMENTATION , TESTING AND DEBUGGING 5.1 FIRST PHASE: First we implemented the 1st phase of our circuit in which we checked the actual working of circuit with input from spark plug of Bike (Two Wheeler) to get the frequency which is generated by spark plug. We also implemented circuit on MULTISIM but the output were not as desired. So we decided to move on Bread Board to check the response of circuit. 5.2 SECOND PHASE: In this phase of our project we purchased the components and implemented it on Bread Board and saw the output with the help of signal generator and DSO. Then after getting desired frequency response on DMM we got assurance that the first phase of our circuit is working. The way we implemented is as shown below: Fig. 10 Output on DSO 20 5.3 THIRD PHASE:
  • Then we moved on and implemented the rest of the circuit and in similar fashion we saw the output on DSO and observed the result. In this part we encountered with lots of issues and problems which we worked on and debugged it after consultation with our internal guide we designed below circuit using OP-AMP so as to get desired output. Now, our aim was to design a circuit which would glow a LED when the output of the frequency discriminator is a DC level and the LED should be off when the output should be off in form of the pulses. We charge a capacitor (4.7 uF) with high value resistance (100 K) in series with it so that the rise time exceeds 27 msec which is the maximum pulse width of the frequency discriminator. The discharging of capacitor takes place through low value of resistance (560 ohm) so that it is discharged instantly. When the output of frequency discriminator is high the voltage across capacitor will exceed an offset voltage which can be adjusted by pot and the OP-AMP output will go high making the LED to glow. Comparator: Vcc 7 I/P from A pin no. 6 of 4098 100 K 10 K B 560 K 4.7 uF 63 V 4 5.2 V 560 ohm 1K Fig. 11 Comparator circuit 21
  • Waveform: op of freq. discriminator (Monostable Multivibrator pin no. 6) Low Frequency 7.2 V 5.2 V 4.4 V High Frequency (Speed limit crossed) Output of comparator ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Fig. 12 Input waveform of comparator 22
  • 5.4 FOURTH PHASE: In this phase of our project we implemented the rest of the requirement from project on general purpose board and finished with the implementation of the circuit. The Bread Board after mounting all components is as shown below: Fig. 13 Implementation of circuit on Bread board 23
  • 5.5 FIFTH PHASE: After confirming the necessary result we decided to move on PCB designing. We started to build schematic of the circuit on Protel 2004, the software which we used to create PCB layout. Our PCB schematic layout looked like this: Fig. 14 Schematic of PCB 24
  • 5.6 FINAL PHASE: Here we designed the PCB layout with the help of above schematic Fig. 15 Layout and 3-D view of PCB 25
  • 6. LIST OF COMPONENTS R1, R2, R19_____________________________________________________ 1K 1/4W Resistors R3-R6, R13, R17_______________________________________________ 100K 1/4W Resistors R7, R15_________________________________________________________1M 1/4W Resistors R8______________________________________________________50K 1/2W Trimmer Cermet R9____________________________________________________________470R 1/4W Resistor R10___________________________________________________________470K 1/4W Resistor R11____________________________________________________100K 1/2W Trimmer Cermet R12___________________________________________________________220K 1/4W Resistor R14, R16_______________________________________________________68K 1/4W Resistors R18____________________________________________________________22K 1/4W Resistor R20___________________________________________________________150R 1/4W Resistor C1, C7_____________________________________________100µF 25V Electrolytic Capacitors C2, C3________________________________________________330nF 63V Polyester Capacitors C4-C6________________________________________________4µ7 25V Electrolytic Capacitors D1, D5_________________________________________________________Red LEDs 3 or 5mm D2, D3__________________________________________________1N4148 75V 150mA Diodes D4____________________________________________BZX79C7V5 7.5V 500mW Zener Diode IC1____________________________________________________CA3140 or TL061 Op-amp IC IC2___________________________________________________________4069 Hex Inverter IC IC3_____________________________________4098 or 4528 Dual Monostable Multivibrator IC Q1, Q2___________________________________________BC238 25V 100mA NPN Transistors L1_________________________________________________________10mH miniature Inductor BZ1_______________________________________Piezo sounder (incorporating 3 KHz oscillator) SW1___________________________________________________________SPST Slider Switch B1________________________________________________________________9V PP3 Battery Clip for PP3 Battery 26
  • 7. RESULTS AND CONCLUSION The system we have designed and implemented which can be used in any of the automobile with no physical contact and the frequency can be calculated changed from the formula according to the vehicle where we are implementing this circuit with fine adjustment of potentiometer. Hz= (Number of cylinders * RPM) / 120 It can work on any engine without any physical contact or alteration in the engine. 27
  • 8. FUTURE ENHANCEMENTS We can use a frequency to voltage convertor to drive a bar graph display for graphical representation of RPM. With microcontroller interface we can instruct optimum gear shift which will ultimately lead to better fuel usage. We are also exploring and thinking for any other future scope and any suggestion will be appreciated too. 28
  • 9. APPLICATIONS In its current form our project can be packaged and marketed as a high tech tachometer for low priced vehicles which do not come with company fitted tachometer. As this design do not demand any physical alteration in design of the engine or alterations in wiring and thus it can be used for testing purpose in laboratories. 29
  • 10.REFERENCES INTERNET: 1. Google 2. http://www.alldatasheets.com 3. http://www.discovercircuits.com BOOKS: 1. Analog Integrated circuits and design by U A Bakshi and A P Godse 2. Op-amps and linear integrated circuits –Ramakant A Gayakwad 30