PROJECT REPORT ON

“Contactless Tachometer - using HALL EFFECT sensor”

Minor Project Report

Submitted in partial fulfillment of the Requirement ofDegree of

BACHELOR OF ENGINEERING (RAJIV GANDHI PROUDYOGIKI VISHWAVIDYALAYA, BHOPAL)

Submitted By:

Satyam Jain (0812EX081050)

Under the Guidance of:

Prof: AMRITA MANTRI

Prof: SANJIV JAIN (DEPTT. OF ELECTRICAL AND ELECTRONICS)

April - May 2011

Electrical and Electronics Department

MEDI-CAPS INSTITUTE OF TECHNOLOGY

AND MANAGEMENT INDORE-453331

2011

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MEDI-CAPS INSTITUTE OF TECHNOLOGY

AND MANAGEMENT, INDORE

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGG.

CERTIFICATE

This is to certify that the project entitled “Contactless Tachometer - using

HALL EFFECT SENSOR” presented by “SATYAM JAIN” of B.E. III year

(VI Semester) of branch Electrical and Electronics Engineering have completed

there project. They have submitted this project report towards the partial

fulfillment for the requirement of the degree of bachelor of engineering of Rajiv

Gandhi Proudyogiki Vishwavidhyalaya, Bhopal during the academic year 2010-

11.

INTERNAL EXAMINER EXTERNAL EXAMINER

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DATE: DATE :

MEDI-CAPS INSTITUTE OF TECHNOLOGY

AND MANAGEMENT, INDORE

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGG

CERTIFICATE

This is to certify that the project entitled “Contactless tachometer -using HALL

EFFECT SENSOR” presented by “SATYAM JAIN” of B.E. III year (VI

Semester) of branch Electrical and Electronics Engineering have completed there

project. They have submitted this project report towards the partial fulfillment for

the requirement of the degree of bachelor of engineering of Rajiv Gandhi

Proudyogiki Vishwavidhyalaya, Bhopal during the academic year 2010-11.

CERTIFIED BY:

(Dr. S. K. SOMANI) (Prof. SANJIV K. JAIN)

DIRECTOR HOD, EX DEPTT.

MITM, INDORE MITM, INDORE

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(Prof. AMRITA MANTRI)

Project Guide

ACKOWLEDGEMENT

We feel great pleasure in submitting this report on the project “Contactless

Tachometer - using HALL EFFECT sensor”

We would like to take this opportunity to express our gratitude to our project

guide, Prof. Amrita mantri for her support and constant encouragement along

with her expert guidance that helped us to complete this project successfully. Her

everlasting patience and wholehearted inspiration guided us on the right path to

achieve what we have achieved today.

We are thankful to Prof. Sanjiv K. Jain, Head of Electrical and Electronics

Department, MITM Indore for his invaluable guidance and support We are

indebted to our director Dr. S.K. Somani for giving us the opportunity to work

on the project and providing the necessary facilities for the same.

We express our thanks to professors and lecturer of the department for extending

every possible help to us. We are also thanking full to the sub-ordinate staff that

offered us their help and stood by us.

In the end we would like to express our thanks to our friends and fellows who

helped us in many ways and encouraged us.

Satyam Jain Shashank Gupta

(0812EX081050) (0812EX081053)

Surbhi Khandelwal

(0812EX081058)

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CONTENTS

Subject Page No.

1. Design Objective 6

2. Physical & Technical Specifications 7

3. Introduction 8

4. Circuit Block Diagram 9

4.1. Power Supply 10

4.2 Hall Effect Sensor 11

4.3 Seven Segment Decade Counter 12

4.4 Seven Segment LED Display 13

5. Schematic Circuit Diagram 14

6. PCB Layout 15

7. List of Components 16

8. Future Enhancement 18

9. Conclusion 19

10. References and Bibliography 20

11. Annexure 21

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DESIGN OBJECTIVE

The main objective of designing contactless tachometer is just to level up the

generation of measuring instruments which actually reduces the human efforts

and makes the work easier. Technology today is seeing heights in all the areas

especially in the field of embedded system. It’s true that every electronic gadget

that is used in our daily life right from pc keyword to refrigerator is based on

embedded system. This project just gives the basic idea of designing contactless

tachometer. Tachometer is a device that gives you the information about the

rotational speed of any shaft or disc. It usually measures the speed in revolutions

per minute (RPM). We have made a simple tachometer that could measure the

rotation speed of a disk without making any physical contact (that's why it is

contact less) with the rotating object. The range of this tachometer is 0 - 99 RPM

and displays the RPM on a multiplexed 2-digit seven-segment display. Of course,

we are going to do this project on our usual PIC16F628A development board.

However the range of this instrument can easily be increased by just adding

another seven segment display.

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TECHNICAL SPECIFICATIONS

power supply requirement : 5V DC

power source : 5V DC power supply

operating temperatures : 40 to + 85 °C

nature of display : digital

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INTRODUCTION

A tachometer is an instrument designed to measure the speed of a rotating object. The

word is formed from Greek roots tachos, meaning speed, and metron, meaning

measure. The traditional tachometer is laid out as a dial, with a needle indicating

the current reading and marking safe and dangerous levels. Recently, digital

tachometers giving a direct numeric output have become more common. In its

most familiar form, a tachometer measures the speed at which a mechanical

device is rotating. A common example is the tachometer found on automobile

dashboards. In this application, the tachometer measures the revolutions per minute (RPMs) of

the engine drive shaft. A tachometer used in this application can be built in

multiple ways. It may be a small generator attached to the engine drive shaft,

where the RPM measurement is scaled to the electric current generated by the

device. Alternately, it may simply measure the rate at which the ignition system

sends sparks to the engine. The traditional tachometer requires physical contact

between the instrument and the device being measured. In applications where this

is not feasible for technical or safety reasons, it may be possible to use a Contact

less tachometer to take measurements from a distance. A Contact less tachometer

works by attaching a small magnet to the rotating element. Every rotation

generates the pulse which will be detected by Hall Effect sensor and every pulse

will be counted. This instrument uses 4033 7-segment decade-counter, a 7

segment LED display and 72xx Hall Effect sensor to detect the rotation of the

shaft whose speed is being measured. This instrument can be operated on 12volt

dc supply rechargeable battery or power supply of 5 volt months of regular use of

this device before it needs to be recharged. A Contact less tachometer can be a

permanent part of the system, or it can be handheld for occasional spot

measurements.

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BLOCK DIAGRAM AND DESCRIPTION

PRINCIPLE OF OPERATION

T h e p r i n c i p l e i s b a s e d u p o n t h e H a l l E f f e c t s e n s o r ; w h i c h

d e t e c t s a n y c h a n g e i n m a g n e t i c f i e l d o r p o l e in front of it, and

thus, give an output pulse for each and every r o t a t i o n o f t h e s h a f t .

T h e s e v o l t a g e p u l s e s a r e f e d t o t h e 4 0 3 3 s e v e n s e g m e n t

d e c a d e c o u n t e r a n d c o u n t e d . A n d t h u s w e w i l l g e t t h e o / p i n

t h e f o r m o f g l o w o f s e v e n s e g m e n t L E D d i s p l a y .

POWER SUPPLY

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A power supply is a device that supplies electrical energy to one or more electric

loads. A regulated power supply is one that controls the output voltage or current

to a specific value; the controlled value is held nearly constant despite variations

in either load current or the voltage supplied by the power supply's energy source.

A DC regulated power supply usually uses a transformer to convert the voltage

from the wall outlet (mains) to a different, nowadays usually lower, voltage. If it

is used to produce DC, a rectifier is used to convert alternating voltage to a

pulsating direct voltage, followed by a filter, comprising one or

more capacitors, resistors, and sometimes inductors, to filter out (smooth) most of

the pulsation. A small remaining unwanted alternating voltage component at

mains or twice mains power frequency (depending upon whether half- or full-

wave rectification is used)—ripple—is unavoidably superimposed on the direct

output voltage.  A linear regulator may be used to set the voltage to a precise

value, stabilized against fluctuations in input voltage and load.

HALL EFFECT SENSOR

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The heart of this tachometer is Hall Effect sensor. A Hall Effect sensor is

a transducer that varies its output voltage in response to changes in magnetic

field. Hall sensors are used for proximity switching, positioning, speed detection,

and current sensing applications.

The Hall Effect sensor is one of the most common applications for a Hall Effect

Sensor. The magnetic flux required to operate the sensor may be furnished

by individual magnets mounted on the shaft or hub or by a ring magnet

frequently, a Hall sensor is combined with circuitry that allows the device to act

in a digital (on/off) mode, and may be called a switch in this configuration. Hall

sensors are commonly used to time the speed of wheels and shafts, such as

for internal combustion engine ignition timing, tachometers and anti-lock braking

systems. They are used in brushless DC electric motors to detect the position of

the permanent magnet.

SEVEN SEGMENT DISPLAY

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A seven-segment display, or seven-segment indicator, is a form of

electronic display device for displaying decimal numerals that is an alternative to

the more complex dot-matrix displays. Seven-segment displays are widely used

in digital clocks, electronic meters, and other electronic devices for displaying

numerical information. A seven segment display, as its name indicates, is

composed of seven elements. Individually on or off, they can be combined to

produce simplified representations of the Arabic numerals.

SEVEN SEGMENT DECADE COUNTER

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This synchronous decade, or divide-by-10, counter provides internal decoding to

drive a 7-segment display. It does not have internal count storage, nor does it

provide enough output current to directly drive high-current display types. A

divide-by-10 square-wave output is also available.VDD = +3 TO +15V. In normal

operation, reset and clock enable are held at ground and the ripple blanking input

is connected to ground or a more-significant count stage. The counter advances

one count on each ground-to-positive (positive edge) transition of the clock . The

counter is reset to zero by bringing the RST terminal high. This results in an a-b-

c-d-e-f low, along with a high on the ÷ 10 output. The RST input must be

returned to ground when counting is to continue. A high on the Test input puts all

outputs high for lamp or display test input.

SCHEMATIC CIRCUIT DIAGRAM

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PCB LAYOUT

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LIST OF COMPONENTS

1. +5V DC Power Supply

2. IC 4033:Seven segment display and decade counter

3. Hall Effect Sensor: 72XX15

4. Seven Segment Display LED

5. LED as load

Hall Effect Sensor(72XX)

When a current-carrying conductor is placed into a magnetic field, a voltage will

be generated perpendicular to both the current and the field. This principle is

known as the Hall Effect.

These sensors provide an output voltage that is proportional to the magnetic field

to which it is exposed. The sensed magnetic field can be either positive or

negative. As a result, the output of the amplifier will be driven either positive or

negative. But the digital sensor has an output that is just one of two states: ON or

OFF.

The principal input/output characteristics are the operate point, release point and

the difference between the two or differential. As the magnetic field is increased,

no change in the sensor output will occur until the operate point is reached. Once

the operate point is reached, the sensor will change state. Further increases in

magnetic input beyond the operate point will have no effect. If magnetic field is

decreased to below the operate point, the output will remain the same until the

release point is reached.

At this point, the sensor’s output will return to its original state (OFF). The

purpose of the differential between the operate and release point (hysteresis) is to

eliminate false triggering which can be caused by minor variations in input.

IC 4033

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CD4033BMS consists of a 5 stage Johnson decade counter and an output decoder

which converts the Johnson code to a 7 segment decoded output for driving one

stage in a numerical display. This device is particularly advantageous in display

applications where low power dissipation and/or low package count is important.

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 one cycle every ten CLOCK INPUT cycles and 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 o/p goes high on selection.

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FUTURE ENHANCEMENT

This device can be built on an AT89S52 (or AT89C52) microcontroller, an alpha-

numeric LCD module and a proximity sensor to detect the rotation of the shaft

whose speed is being measured.

The idea behind most digital counting device, frequency meters and tachometers,

is a micro-controller, used to count the pulses coming from a sensor or any other

electronic device. 

In the case of this tachometer, the counted pluses will come from proximity

sensor, which will detect any reflective element passing in front of it, and thus,

will give an output pulse for each and every rotation of the shaft, as show in the

picture. Those pulses will be fed to the microcontroller and counted.

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CONCLUSION

The HALL effect sensor counts the number of revolution of motor with the help

of counter IC 4033 . This sensor generates voltage pulses with the change in

magnetic field or poles.

The main drawbacks of this project is that it can count upto 99 revolution. This

drawback can be over come easily by cascading IC 4033 along with the 7

segment display to the carry out pin of the preceeding counter also it can not be

operated on multi pole motor. Its distance range of operation is very less and is

about 3cm only.

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BIBLIOGRAPHY

*Edward ramsden “Hall effect sensor: theory and application”,second

edition newness publication.

* Contactless tachometer “EE herald(E-magzine)”,

http://www.eeherald.com

*http://www.ikalogic.com/ contactless tachometer Last update: 25/4/11

* http://www.esskayinstitute.com/

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ANNEXURE

1. HALL EFFECT SENSOR:

ABSOLUTE MAXIMUM RATINGS at TA = +25°C

Supply Voltage, VCC ...........................30 V

Reverse Battery Voltage, VRCC ........ -30 V

Magnetic Flux Density, B ....... Unlimited

Output OFF Voltage, VOUT ................ 28 V

Reverse Output Voltage, VOUT ........ -0.5 V

Continuous Output Current, IOUT ... 25 mA

Operating Temperature Range, TA

Suffix ‘E–’ ................. -40°C to +85°C

Suffix ‘L–’ ............... -40°C to +150°C

Storage Temperature Range,

TS .............................. -65°C to +170°C

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FEATURES and BENEFITS

_ Superior Temp. Stability for Automotive or Industrial Applications

_ 4.5 V to 24 V Operations … Needs Only An Unregulated Supply

_ Open-Collector 25 mA Output … Compatible with Digital Logic

_ Reverse Battery Protection

_ Activate with Small, Commercially Available Permanent Magnets

_ Solid-State Reliability … No Moving Parts

_ Small Size

_ Resistant to Physical Stress

2.IC4033

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DC Supply Voltage Range, (VDD) . . . . . . . . . . . . . . . -0.5V to +20V(Voltage Referenced to VSS Terminals)Input Voltage Range, All Inputs . . . . . . . . . . . . .-0.5V to VDD +0.5VDC Input Current, Any One Input . . . . . . . . . . . . . . . . . . . . . . . . ± 10mAOperating Temperature Range. . . . . . . . . . . . . . . . -55°C to +125°CPackage Types D, F, K, HStorage Temperature Range (Tstg) . . . . . . . . . . . -65°C to +150°CLead Temperature (During Soldering) . . . . . . . . . . . . . . . . . +265°C

Reliability Information

Thermal Resistance . . . . . . . . . . . . . . . . θja θjc

Ceramic DIP and FRIT Package . . . . . 80°C/W 20°C/W

Flat pack Package . . . . . . . . . . . . . . . . 70°C/W 20°C/W

Maximum Package Power Dissipation (PD) at +125°C

For TA = -55oC to +100oC (Package Type D, F, K) . . . . . . 500mW

For TA = +100oC to +125oC (Package Type D, F, K) . . . . .Derate Linearity at

12mW/°C to 200mW

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Device Dissipation per Output Transistor . . . . . . . . . . . . . . . 100mW

For TA = Full Package Temperature Range (All Package Types)

Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +175°C

Features

• High Voltage Types (20V Rating)

• Decoded 7 Segment Display Outputs and Ripple Blanking

• Counter and 7 Segment Decoding in One Package

• Easily Interfaced with 7 Segment Display Types

• Fully Static Counter Operation DC to 6MHz (typ.) at VDD =10V

• Ideal for Low-Power Displays

• “Ripple Blanking” and Lamp Test

• 100% Tested for Quiescent Current at 20V

• Standardized Symmetrical Output Characteristics

• 5V, 10V and 15V Parametric Ratings

•Schmitt- Triggered Clock Inputs

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3.Seven Segment Display LED

Parameters Red Colored LED

Reverse voltage Vr 5v

Forward voltage If 20A

Peak current Ipeak 150

Power consumption Pt 120

Operating temperature Ta -40 to 80℃Storage temperature Tsta -40 to 85℃

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