HALL EFFECT SENSOR BASED TACHOMETER

DIGITAL TACHOMETER2014

ACKNOWLEDGEMENTThis project is the first creditable achievement of our student life and it is our prime duty to acknowledge the persons who helped us in this project.

We take this opportunity to heartily thanks our project in charge respected Mr. M.S.Patel for her valuable guidance with a touch of inspiration and motivation throughout the course of this project work.

At Last thanking all

PREFACE

The idea of undertaking this project came to our mind due to our keen interest in the field of hardware. This project is our practical knowledge which is very useful particularly for the technical student. So we have decided to take this project of Digital Tachometer. This project report is not just the copying of material from the books but a great deal of material developed by ourselves.

It has been a long hard journey on this novel expedition for us and we have tried to put in our best effort into the accomplishment of this project. However we are bound to be erroneous due to inexperience and hence we request the readers to please bear with us and analyze any project report.

ABSTRACT

The working principles of IR sensor has been introduced in this paper. To the defects of traditional methods, it proposed the designing strategy of motor speed measurement system based on single chip microcontroller with integrated chip. The hardware circuits including power module, data processing module and data display module have been described and it focuses on the analysis speed measurement module. The speed data can be obtained through counting impulse signals and displayed on LED or LCD. Experience shows that the system have high stability, it can meet the needs of DC motor speed measurement.

Sr. No.ContentsPage no.

1.Introduction 5

2.Block Diagram6

3.Circuit diagram 7

4.PCB layout bottom view10

5.PCB layout top view11

6.Component list12

7.Component Explanation13

8.Project Model30

9.Merits & Demerits & Application31

10.Conclusion33

11. References34

INDEX

1.INTRODUCTIONMethod of Operation

Non-contacting speed sensors of the FAH11... series are basically designed for speed sensing. The rotation of ferromagnetic toothed wheels is sensed by means of a difference-Hall-effect sensor chip and converted by a signal amplifier into a rectangular signal. The frequency of the rectangular signal is proportional to the speed. Apart from speed, the sensors are adapted to sense any movement of ferromagnetic parts. The rectangular signal lends itself to evaluation or transformation by a variety of devices.

The output signal is a noise-immune, rectangular signal whose frequency is proportional to the speed. The voltage range is within the load voltage and load-dependent. The geometry of the passing object determines the pulse duty factor. In the case of a toothed wheel, it corresponds to approx. 50 %. The output circuit is a push-pull stage. Short circuit protection is provided by a 60 PTC-resistor. Spurious pulses are intercepted by an internal varistor against minus. The push-pull output stage can be used as a NPN output (current sinking) as well as a PNP output (current sourcing). The output voltage is galvanic ally coupled to the load voltage.

2.BLOCK DIAGRAM

3. CIRCUIT DIAGRAM

4. PCB LAYOUT BOTTOM VIEW:

5. PCB LAYOUT TOP VIEW:

6. COMPONENTS LIST:1. RESISTOR2. CAPACITOR

3. DIODE

4. 7805 VOLTAGE REGULATOR

5. 7812 VOLTAGE REGULATOR

6. COMPARATOR LM 392

7. IR TRANSMITTER AND SENSOR

8. DC MOTOR9. 16x2 LCD Display10. AT89S52 Micro Controller7.COMPONENTS EXPLANATION :7.1 RESISTORS:-

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 = IRResistors are elements of electrical networks and electronic circuits and are ubiquitous in most electronic equipment. Practical resistors can be made of various compounds and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel/chrome).

The primary characteristics of a resistor are the resistance, the tolerance, maximum working voltage and the power rating. Other characteristics include temperature coefficient, noise, and inductance. Less well-known is critical resistance, the value below which power dissipation limits the maximum permitted current flow, and above which the limit is applied voltage. Critical resistance depends upon the materials constituting the resistor as well as its physical dimensions; it's determined by design.

Resistors can be integrated into hybrid and printed circuits, as well as integrated circuits. Size, and position of leads (or terminals) are relevant to equipment designers; resistors must be physically large enough not to overheat when dissipating their power.

7.2 CAPACITOR:-A capacitor or condenser 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. The effect is greatest between wide, flat, parallel, narrowly separated conductors.

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.

Capacitors are widely used in electronic circuits to block the flow of direct current while allowing alternating current to pass, to filter out interference, to smooth the output of power supplies, and for many other purposes. They are used in resonant circuits in radio frequency equipment to select particular frequencies from a signal with many frequencies.

7.3 DIODE:-

Diodes are two terminal components used to block current in one direction while passing current in the opposite direction. This effect, which converts AC (alternating current) to DC (direct current) is also called "rectifying" current, hence diodes are also called "rectifiers".

The symbol for diode is an arrow and line, indicating passing electricity in only one direction.

A stripe on the component indicates the "perpendicular line on the schematic.

Diode ratings

Diodes have two important ratings and several more subtle ratings. The most important ratings are:

PIV - peak inverse voltagethis is the voltage above which the diode is likely to be damaged, because it stops blocking the flow of electricity in one direction.

Current rating in amps or milliamps. This is the amount of current the diode can safely dissipate. It is based upon the physical size of the diode and the amount of heat that the component can dissipate.

Uses for diodes

Conversion of AC into DC (rectification)

Blocking inverse polarity pulses from inductive loads (solenoids, motors etc)

Reverse polarity protection with batteries

Voltage doublers (with AC current)

DC to DC conversion

logic and switching matrices

7.4 7805 VOLTAGE RECULATOR :-7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at input and output pins depending upon the respective voltage levels.

Pin Description:

Pin NoFunctionName

1Input voltage (5V-18V)Input

2Ground (0V)Ground

3Regulated output; 5V (4.8V-5.2V)Output

7.5 7812 VOLTAGE RECULATOR :-7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at input and output pins depending upon the respective voltage levels.

Pin Description:

Pin

NoFunctionName

1Input voltage (5V-25V)Input

2Ground (0V)Ground

3Regulated output; 5V (11.8V-12.2V)Output

7.6 LM-392 COMPARATOR:-

The LM392 consists of two independent building-block circuits. One is a high-gain internally-frequency-compensated Operational Amplifier and the other is a precision voltage Comparator Both the Operational Amplifier and the voltage Comparator are designed to operate from a single power supply over a wide range of voltages. Both circuits have input stages that force the common-mode input down to ground when operating from a single power supply. Operation from split power supplies also is possible, and the low power-supply current is http://circuits.datasheetdir.com/37/LM392-pinout.jpgindependent of the magnitude of the supply voltage7.7 IR SENSOR:-

An infrared sensor is an electronic instrument that is used to sense certain characteristics of its surroundings by either emitting and/or detecting infrared radiation. It is also capable of measuring heat of an object and detecting motion. Infrared waves are not visible to the human eye.

In the electromagnetic spectrum, infrared radiation is the region having wavelengths longer than visible light wavelengths, but shorter than microwaves. The infrared region is approximately demarcated from 0.75 to 1000m. The wavelength region from 0.75 to 3m is termed as near infrared, the region from 3 to 6m is termed mid-infrared, and the region higher than 6m is termed as far infrared.

Infrared technology is found in many of our everyday products. For example, TV has an IR detector for interpreting the signal from the remote control. Key benefits of infrared sensors include low power requirements, simple circuitry, and their portable feature.

Principles of OperationWe have already discussed how a light sensor works. IR Sensors work by using a specific light sensor to detect a select light wavelength in the Infra-Red (IR) spectrum. By using an LED which produces light at the same wavelength as what the sensor is looking for, you can look at the intensity of the received light. When an object is close to the sensor, the light from the LED bounces off the object and into the light sensor. This results in a large jump in the intensity, which we already know can be detected using a threshold.

Depiction of the operation of an IR Sensor

Detecting Brightness

Since the sensor works by looking for reflected light, it is possible to have a sensor that can return the value of the reflected light. This type of sensor can then be used to measure how "bright" the object is. This is useful for tasks like line tracking.

Depiction of the operationof an IR Sensor to measure brightness

7.8 DC MOTOR:-An electric motor uses electrical energy to produce mechanical energy. The reverse process, that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo. The principle of conversion of electrical energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821.

DC Motor Operation.

7.9 16x2 LCD DisplayLCD display is an inevitable part in almost all embedded projects and this article is about interfacing 162 LCD with 8051 microcontroller. Many guys find it hard to interface LCD module with the 8051 but the fact is that if you learn it properly, its a very easy job and by knowing it you can easily design embedded projects like digital voltmeter / ammeter, digital clock, home automation displays, status indicator display, digital code locks, digital speedometer/ odometer, display for music players etc etc. Thoroughly going through this article will make you able to display any text (including the extended characters) on any part of the 162 display screen. In order to understand the interfacing first you have to know about the 162 LCD module.

162 LCD module.

162 LCD module is a very common type of LCD module that is used in 8051 based embedded projects. It consists of 16 rows and 2columns of 57 or 58 LCD dot matrices. The module were are talking about here is type number JHD162A which is a very popular one . It is available in a 16 pin package with back light ,contrast adjustment function and each dot matrix has 58 dot resolution. The pin numbers, their name and corresponding functions are shown in the table below.

Pin No:Name Function

1VSSThis pin must be connected to the ground

2VCCPositive supply voltage pin (5V DC)

3VEEContrast adjustment

4RSRegister selection

5R/WRead or write

6EEnable

7DB0Data

8DB1Data

9DB2Data

10DB3Data

11DB4Data

12DB5Data

13DB6Data

14DB7Data

15LED+Back light LED+

16LED-Back light LED-

VEE pin is meant for adjusting the contrast of the LCD display and the contrast can be adjusted by varying the voltage at this pin. This is done by connecting one end of a POT to the Vcc (5V), other end to the Ground and connecting the center terminal (wiper) of of the POT to the VEE pin. See the circuit diagram for better understanding.

The JHD162A has two built in registers namely data register and command register. Data register is for placing the data to be displayed , and the command register is to place the commands. The 162 LCD module has a set of commands each meant for doing a particular job with the display. We will discuss in detail about the commands later. High logic at the RS pin will select the data register and Low logic at the RS pin will select the command register. If we make the RS pin high and the put a data in the 8 bit data line (DB0 to DB7) , the LCD module willrecognizeit as a data to be displayed . If we make RS pin low and put a data on the data line, the module will recognize it as a command.

R/W pin is meant for selecting between read and write modes. High level at this pin enables read mode and low level at this pin enables write mode.

E pin is for enabling the module. A high to low transition at this pin will enable the module.

DB0 to DB7 are the data pins. The data to be displayed and the command instructions are placed on these pins.

LED+ is the anode of the back light LED and this pin must be connected to Vcc through a suitable series current limiting resistor. LED- is the cathode of the back light LED and this pin must be connected to ground.

162 LCD module commands.

162 LCD module has a set of preset command instructions. Each command will make the module to do a particular task. The commonly used commands and their function are given in the table below.

Command Function

0FLCD ON, Cursor ON, Cursor blinking ON

01Clear screen

2Return home

4Decrement cursor

06Increment cursor

EDisplay ON ,Cursor ON

80Force cursor to the beginning of 1st line

C0Force cursor to the beginning of 2nd line

38Use 2 lines and 57 matrix

83Cursor line 1 position 3

3CActivate second line

0C3Jump to second line, position3

OC1Jump to second line, position1

LCD initialization.

The steps that has to be done for initializing the LCD display is given below and these steps are common for almost all applications.

Send 38H to the 8 bit data line for initialization

Send 0FH for making LCD ON, cursor ON and cursor blinking ON.

Send 06H for incrementing cursor position.

Send 01H for clearing the display and return the cursor.

Sending data to the LCD.

The steps for sending data to the LCD module is given below. I have already said that the LCD module has pins namely RS, R/W and E. It is the logic state of these pins that make the module to determine whether a given data input is a command or data to be displayed.

Make R/W low.

Make RS=0 if data byte is a command and make RS=1 if the data byte is a data to be displayed.

Place data byte on the data register.

Pulse E from high to low.

Repeat above steps for sending another data.

Circuit diagram.

Interfacing 16x2 LCD module to 8051

The circuit diagram given above shows how to interface a 162 LCD module with AT89S1 microcontroller. Capacitor C3, resistor R3 and push button switch S1 forms the reset circuitry. Ceramic capacitors C1,C2 and crystal X1 is related to the clock circuitry which produces the system clock frequency. P1.0 to P1.7 pins of the microcontroller is connected to the DB0 to DB7 pins of the module respectively and through this route the data goes to the LCD module. P3.3, P3.4 and P3.5 are connected to the E, R/W, RS pins of the microcontroller and through this route the control signals are transffered to the LCD module. Resistor R1 limits the current through the back light LED and so do the back light intensity. POT R2 is used for adjusting the contrast of the display.

7.10 8051 MICROCONTROLLER

When we have to learn about a new computer we have to familiarize about the machine capability we are using, and we can do it by studying the internal hardware design (devices architecture), and also to know about the size, number and the size of the registers.

A microcontroller is a single chip that contains the processor (the CPU), non-volatile memory for the program (ROM or flash), volatile memory for input and output (RAM), a clock and an I/O control unit. Also called a "computer on a chip," billions of microcontroller units (MCUs) are embedded each year in a myriad of products from toys to appliances to automobiles. For example, a single vehicle can use 70 or more microcontrollers. The following picture describes a general block diagram of microcontroller.

89s52: The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmels high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory pro-grammer. By combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller, which provides a highly flexible and cost-effective solution to many, embedded control applications. The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM con-tents but freezes the oscillator, disabling all other chip functions until the next interrupt

The hardware is driven by a set of program instructions, or software. Once familiar with hardware and software, the user can then apply the microcontroller to the problems easily.

The pin diagram of the 8051 shows all of the input/output pins unique to microcontrollers:

The following are some of the capabilities of 8051 microcontroller.

Internal ROM and RAM

I/O ports with programmable pins

Timers and counters

Serial data communication

The 8051 architecture consists of these specific features:

16 bit PC &data pointer (DPTR)

8 bit program status word (PSW)

8 bit stack pointer (SP)

Internal ROM 4k

Internal RAM of 128 bytes.

4 register banks, each containing 8 registers80 bits of general purpose data memory

32 input/output pins arranged as four 8 bit ports: P0-P3

Two 16 bit timer/counters: T0-T1

Two external and three internal interrupt sources Oscillator and clock circuits.

8. PROJECT MODEL

9. MERITS & DEMERITS & APPLICATIONMERITS:-1. It is non-contact type sensor which is very reliable.2. Because IR sensor is non-contact type, there is no friction or energy loss during speed measurement.

3. IR sensor based speed measurement is accurate and cheaper. DE-MERITS:-

1. If there is any magnetic interference around tachometer, it can generate errors in output. APPLICATIONS:-1. Electric tachometers are utilized in machinery and automobiles

2. Tachometers are used in aircraft, automobiles and other vehicles for indicating the rotation rate of the crankshaft of the engine3. Tachometers are used in vehicles such as trucks and tractors4. Used in stationary engines5. Used in rail vehicles6. Used in analog audio recording10. CONCLUSION:-

IR Sensor Based Tachometers are devices that measure the speed of rotation of a disk or shaft in motors or other machines. It works on the principle that a motor which is operated as a generator produces a voltage according to the velocity of the shaft. Available electrical outputs of tachometers include switch or alarm, analog modulated frequency, analog current and analog voltage.11. REFERENCES:-

www.efymag.comwww.projectguidance.comwww.google.comwww.wikipedia.comDATASHEETSPAGE A.V.PAREKH TECHNICAL INSTITUTE-RAJKOTPage 21