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TDS AND CONDUCTICITY METER 7TH SEMESTER E&C

PAGE 1 OF 49 INDUS INSTITUTE OF TECHNOLOGY AND ENGINEERING

PROJECT REPORT

ON

TDS ND CONDUCTIVITY METER

Submitted

In Partial Fulfillment of the Requirements

For the Degree of

BACHELOR OF ENGINEERING

2013-14

Under the able guidance of

Prof. Vrushank Shah

By

Dhruv Patel

(100250111051)

Kevin Bhavsar

(100250111025)





Department of Electronics and Communication Engineering

INDUS INSTITUTE OF TECHNOLOGY AND ENGINEERING

RANCHARADA, AHMEDABAD.

DECEMBER-2013

ABSTARCT

Conductivity meter principle is a digital representation of solution conductivity with

conduction current capacity. The electrical conductivity of the water and the

inorganic acid, alkali, salt content have a certain relationship, when their low

concentration, conductivity increases with concentration, therefore, the index is used

to speculate that the total concentration of ions in the water or salt content.

Conductivity ( G ) is a invers resistance ( R ). So when the two electrodes (usually platinum or platinum black ) into the solution, can be used to measure the resistance

between two electrodes R. According to the Ohm's law, certain temperature, the

value of this resistor and electrode spacing of L ( cm ) is proportional to the cross-

sectional area, and the electrode A ( cm^2 ) inverse, which depends on the nature of

the material. According to the type, the electrical conductor ( G ) can be expressed as

the type : G=1/R= (1/ !) x ( A/L ) =K "( 1/J ), K=1/ ! called conductivity, J=L/A

called electrode constant electrolyte solution conductivity refers to the distance of1cm between two parallel electrodes is filled with 1cm3 solution with conductance.

Based on the formula of visible, when known electrode constant ( J ), and to test the

solution resistance or conductance ( R ) ( G ), can be obtained by conductivity, after

the measurement of conductivity we can simply convert it to TDS(Total Dissolved

Solid).Calculation between conductivity and TDS depends on the nature of water and

temperature so we also have used temperature sensor to sense the temperature and toaccurate the required output as per our need.

Application of conductivity meter conductivity meter is laboratory measurements ofelectrical conductivity of water solution necessary equipment, it is widely used in

petroleum, chemical, biological, pharmaceutical, sewage treatment, environmental

monitoring, mining smelting and tertiary institutions and scientific research units and

TDS meter is most widely used to measure the water impurities and petroleum

impurities and also used in industries of water bottler where water purity is more

needed.





ACKNOLWLEDGEMENT

It is indeed a proud moment for us to present our project TDS and Conductivity

Meter.

However it would be incomplete without rendering our heartily thanks to the various

people, who guided us throughout this hardworking task.

We take this opportunity to express our deep sense of gratitude and regard to

Prof. Vrushank Shah, Department of Electronics and Communication Engineering,

IITE, Indus University, Ahmedabad for his continuous encouragement and able

guidance, we needed to complete our desired work for the project.

We render our sincere most thanks to our H.O.D Prof. R. N. Mutagi (Department of

Electronics and Communication Engineering, IITE, Indus University, Ahmedabad)

for their valuable comments and suggestions that have helped us to make it a success

and also thankful to our Department Co-ordinator Prof. Bhavin Gajjar (Department

of Electronics and Communication Engineering, IITE, Indus University, Ahmedabad)

for the valuable and fruitful discussion with him and it was of immense help without

which it would have been difficult to present this TDS and Conductivity Meter

Project in its present form.

Finally we are also grateful to our beloved parents for their encouragement and help,

which made this project seen much easier than it really was.

Dhruv Patel_____________

Kevin Bhavsar_____________





Certificate

TO WHOM IT MAY CONCERN

This is to certify that project titled

“ TDS ND CONDUCTIVITY METER”

Submitted by:

1. Dhruv Patel

2. Kevin Bhavsar

Of B.E 7 th semester, Electronics & Communication Engineering, in partial fulfillment of the requirement for the Degree of Bachelor of Engineering in

Electronics & Communication Engineering by the Gujarat TechnologicalUniversity (GTU), Gujarat.

During the academic year 2013-14 is their original endeavor carried outunder my supervision and guidance and has not been presented anywhere

else.

GUIDE H.O.D CO-ORDINATOR EXAMINER

Prof. Vrushank Shah Prof. R.N.Mutagi Prof. Bhavin Gajjar





Table of Contents

Pages

Abstract 2Acknowledgments 3

Certificate 4

Table of Contents 5

Table of figure 6

Chapter 1: Introduction 71.1 Purpose of This Document 8

Chapter 2: Description of Project 9

2.1 What is project.? 9

2.2 Definitions 92.2a Conductivity 9

2.2b TDS(Total Dissolved Solid) 10

2.3 Applications of the project 11

2.4 Novelty in our project 11

Chapter 3: Block diagram and each block description 12

3.1 Frequency selection circuit 13

3.2 Oscilattor and Driver circuit 13

3.3 Measuring conductivity cell 14

3.4 Current sensing circuit 153.5 Rectifiers and Filter 16

3.6 Temperature PROBE 173.7 Temperature Sensing circuit 17

3.8 Analog to digital converter 17

3.9 Multiplexer 18

3.10 Microcontroller/Microprocessor 19

3.11 Display 20

Chapter 4: List of components used for TDS and Conductivity meter 21

Chapter 5: Circuit Design & description 22Chapter 6: Future work 36

6.1 Overall schedule of project 37

References 38

Appendix 39





List of Figures

Figure Title

1 Conductivity measuring cell 9

2 Block diagram of TDS and Conductivity meter 12

3 Working of measuring cell 14

4 Polarization effect 16

5 2-to-1 Multiplexer 18

6 Used measuring cell in project 287 Circuit diagram of Rectifier and filter 29

8 Circuit diagram of ADC(Analog to Digital convertor) 30

9 Circuit diagram of Timing circuit 31

10 PT100 Temperature PROBE 31

11 Circuit diagram of Temperature sensing circuit 32

12 Circuit diagram of Multiplexer 33

13 Circuit diagram of Microcontroller 34

14 Circuit diagram of Display selection 34

15 Circuit diagram of interfacing with 7-segment LED display 35





Chapter 1Introduction

! Conductivity is the ability of a material to conduct electric current. The

principle by which instruments measure conductivity is simple—two plates are

placed in the sample, a potential is applied across the plates (normally a sine

wave voltage), and the current is measured. Conductivity (G), the inverse ofresistivity (R), is determined from the voltage and current values according to

Ohm’s law.

G = 1/R = amps/volts

!

Where TDS (Total Dissolved Solid) is the measurement of water impuritieslike salt, silicon, any solid impurities Conductivity and TDS are

mathematically relates each other by the simple calculation of multiplication,

and also correlates to the ability of water to conduct electricity.

! TDS and Conductivity depends on the temperature of room or environment

where the device is in the working situation. So we also have to take care of

temperature on our measurement and to overcome that problem we have taken

temperature sensing circuit and temperature PROBE to measure and control

the effect of temperature on the result of measured conductivity and TDS. We

can calculate the degree to which temperature affects conductivity varies from

solution to solution and can be calculated using the following formula:

Gt = Gtcal{1 + a(t-tcal)}

! Mostly all meters in the market have fixed temperature compensation and it

will not give us accurate result so we have taken adjustable automatic

temperature compensation explained above.

! And we also have to calibrate our device for accurate results in our

measurement so we have to only calibrate the result of conductivity

measurement cell because as above explained TDS only depends onconductivity of liquid and this is the method and techniques by which we will

calibrate our device. First conductivity meters and cells should be calibrated to

a standard solution before using. Selecting a standard that is closest to the

conductivity of the solution to be measured. A polarized or fouled electrode

must be replatinized or cleaned to renew the active surface of the cell. In most

situations, hot water with a mild liquid detergent is an effective cleanser.

Acetone easily cleans most organic matter, and chlorous solutions will remove

algae, bacteria, or molds. Do not use abrasives to clean an electrode.





1.1 Purpose of this Document

! This project report is prepared as the part of B.E final year project in

Electronics and Communication Department, IITE, Ahmedabad.! The purpose of this project report is to give the detailed description of the

algorithms used for TDS and Conductivity measurement, hardware forconductivity measurement and software programs used for the calibrationmethod, selection of frequency as per liquid, for input current required bymeasuring cell and temperature effect which effects to the measurements.

! And in this project report of TDS and Conductivity meter we also have shownour work out in 7 th semester.





Chapter 2Description of Project

2.1 What is project.?

! The project targets the measurement and practical implementation of TDS and

Conductivity. In this project we measure TDS in ppm(parts per million) and

Conductivity in mS(milliSiemens) and µS(microSiemens).

! Conductivity and TDS are mathematically relates to the each other because

TDS correlates the ability of water to conduct electricity through it and passing

electricity is the conductivity of the liquid.

2.2 Description:

2.2a Conductivity

! The electrical conductivity of a solution of an electrolyte is measured by

determining the resistance of the solution between two flat or cylindrical

electrodes separated by a fixed distance.

! An alternating voltage is used in order to avoid electrolysis. A conductivity

meter also measures the resistance. Typical frequencies used are in the range

1–3 kHz.

! The dependence on the frequency is usually small, but may become

appreciable at very high frequencies, an effect known as the Debye–

Falkenhagen effect.

! Consider two vertical plates each of area A, separated by a distance L,

immersed in a liquid. If a potential difference V is applied across the plate, thecurrent I flowing through the plates has a relation as shown in below figure.

!

Figure 1





! V=IXR or R=V/I, Where R is the resistance between the two plates. The

resistance R is given by

R = (L/A) X Resistivity of the liquid.

! We know,

Resistivity = 1 / Conductivity (G) Therefore,

R = (L/A) X (1/G) or V/I = (L/A) X (1/G) , or G = (L/A) X (I/V).

! Thus, for a given value of A, L, and V, conductivity C is calculated by

measuring the current I flowing between the two plates.

! The two plates constitute what is called a conductivity cell. The plates as such

are called electrodes of the conductivity cell.

2.2b TDS(Total Dissolved Solid)

! TDS(Total Dissolved Solids) is the measuring of the amount of salts in asolution.

! TDS correlates to the ability of water to conduct electricity.

! It is also an index used to determine the concentration of dissolved minerals.

The more minerals that are dissolved, the more conductive the water will be.

! A TDS meter is calibrated to read in parts per million (PPM). TDS is the

concentration of a solution as the total weight of dissolved solids. (1 ppm = 1

milligram/liter. TDS is a mass estimate and is dependent upon the mix of

nutrients as well as the concentration.

! TDS is depended on the conductivity, so after the a measurement of

conductivity by meter we can easily calculate TDS by simple mathematical

operation.

! To convert the electrical conductivity of a water sample into the approximate

concentration of total dissolved solids, the conductivity(mS/cm) is multiplied

by a simple conversation factor.

! The conversation factor depends on the chemical composition of the TDS and

can very between 0.54-0.96. A value of 0.67 is commonly used as an

approximation if the actual factor is not known.





2.3 Applications of the project

! To measure the amount of salt in inductive of the levels of other stuff in a

solution.

! TDS/PPM meters used for gardening and aquariums figure the amount of salt

in Parts Per Million by measuring the Electrical Conductivity of the solution

under test.

! A conductivity meter also measures the resistance so we can also use it for

electric purpose.

! Conductivity and TDS measurements are used to monitor quality in public

water supplies, in hospitals, in boiler water and industries, which depend on

water quality such as brewing and petrol pump or petroleum industries. ! TDS meter is used in controlling dissolved solid in boiler .If TDS value is high

then it caused carryover and if TDS value is low then it caused Priming.

2.4 Novelty in our project

! Most widely using meters have to use different current selection circuit for the

current as AC input for the conductivity measurement cell because the

polarization effect but we are using Microcontroller to generate AC pulse code

signal for the conducting cell.

! Our system offers automatic temperature correction in measurement of

conductivity and we also can adjust desired temperature for measurement.

! Conductivity Range of our device: 0.1 µS to 200 mS.

!

TDS Range of our device : 0.1 ppm to 200 ppm.! We can change Temperature range automatically and manually according to

our requirement.

! TDS and Conductivity meter is having accuracy of +/-1% of the F.S , +/-1

digit.





Chapter 3

Block diagram and each block description

! The block diagram of the proposed system for the TDS and Conductivity meter

is shown in Figure.Fi ure 2





3.1 Frequency selection circuit

! Frequency selection circuit is used in our project for the required selection of

the frequency which is used for oscilattor to generate required sine wave forfurther operations.

! This selection of required frequency is managed by microcontroller/

microprocessor.

! A frequency selection circuit which is equivalent to an LCR series resonantcircuit, though not provided with inductance and which can adjust resonant

frequency, selectivity or quality factor Q and circuit impedance at resonance

independently of one another, merely by adjusting resistance.

!

The circuit comprises an operational amplifier connected to receive an inputsignal at its non-inverting input, a band rejection filter connected to an output

of the operational amplifier, a positive feedback resistor connected between an

output of the band rejection filter and the non-inverting input of the operational

amplifier, and a voltage divider connected between the output of the band

rejection filter and the output of the operational amplifier and connected at its

output to an inverting input of the operational amplifier. The band rejection

filter comprises a series combination of a first resistor and a first capacitor anda parallel combination of a second resistor and a second capacitor.

!

The first and second resistors have the same resistance, and the first and second

capacitors have the same capacitance.

! The resonant frequency of the frequency selection circuit depends solely on the

resistance of the first and second resistors and the capacitance of the first and

second capacitors in the band rejection filter.

! The circuit impedance at resonance depends solely on the feedback resistor,

and the selectivity solely on a dividing factor of the voltage divider.

3.2 Oscilattor and Driver circuit

! Oscilattor is used to generate repeatative sine wave for the conductivity

measuring cell of the project.

! There are any types of oscillators as Crystal oscilattor, Bridge oscilattor, Wein

bridge Oscilattor, Linear oscilattor, Relaxation oscilattor etc.





! Bt we are going to use wein bridge oscilattor for our project because of its

small size and easy fabrication over the PCB and its also very greatful to

generate repeatative sine wave with large range of frequency.

!

The wein bridge oscilattor can be consider as a combination of diffrentialamplifier and wein bridge,connected in a positive loop between the op-amp

output and diffrential input.

! At the oscilatting frequency the bridge is almost balanced and has very small

transfer ratio.

! The loop gain is product of very high op-amp gain and very small bridge ration

as discussed above.

! And driver circuit is used to drive the current to the measuring cell as per

requirment.

! Driver circuit is used to drive a controllable amount of current through the

measuring cell, and enabling as short current rise and fall times as possible for good

performance.

3.3 Measuring conductivity cell

! Measuring cell is used to measure the conductivity of Liquid and it transfers it

to Microcontroller for further calculation.

! In this project we are using Conductivity measuring cell of cell constant c =

0.8cm-1 as shown in below figure.

!

! Measured conductivity of liquid is in digital form and is given tomicrocontroller/microprocessor for the calculation of effect of temperature onthe conductivity of liquid, which is done by also measuring temperature ay-

same time.

Fi ure 3





! And we cannot measure conductivity by measuring cell by applying DC voltage directly to the measuring cell because of the polarization effect takeplace.

! We simply apply AC voltage generated by wein bridge oscillator in sine wave,square wave or triangular wave.

! Working of the measuring cell is already defined in the above topics of thereport.

3.4 Current sensing circuit

! A current sensing circuits sensor is a device that detects and converts current to

an easily measured output voltage, which is proportional to the current through

the measured path.

! In our project current passed through liquid by conductivity measuring cell isapplied as input to current sensing circuit.

! And converted voltage by current sensing circuit is further used for thecalculation of TDS and then applied to other devices.

! There are a wide variety of sensors, and each sensor is suitable for a specific

current range and environmental condition. No one sensor is optimum for all

applications.

! Among these sensors, a current sensing resistor is the most commonly used. It

can be considered a current- to-voltage converter, where inserting a resistor

into the current path, the current is converted to voltage in a linear way of

V = I " R.

! Current sensing cuircuit is most widely by register because of advantages like

Low-cost, High measurement accuracy, Measurable current range from very

low to medium.

!

Current passed through conductivity measuring cell is very low in value then

input because of the resistance and other impurities of water or any liquid, so

current sensing circuit have to use low side current sensing technique for

conversion.

! In low current sensing technique sensing register is connected between load

and ground and sensed voltage is very low in value so we have to amplifies

that voltage for measurable voltage output.

!

Main advantage of register current sensing circuit is that it is very low in costand it eliminates ground disturbances which will very our measured output

voltage.





3.5 Rectifiers and Filter

! Rectifier and filter is used to convert AC voltage to DC voltage.

!

Rectifiers are most widely used in voltage convertor and here we are going touse wein bridge rectifier for voltage conversion and filter is used here to filter

only required voltage output form the rectifier and both are internally

connected.

! We are converting AC voltage to DC voltage here because of polarizationeffect of measuring operation.

! And here a question arise that “Why we are not using DC voltage from the

starting of the circuit instead of AC”

! Polarization effect in our project is described by below figure.

!

! And answer is that we cannot measure conductivity of salt using DC current

because it will rip the molecules apart, and since the molecules are what

conducts the electricity you get a constantly changing reading that is useless.

! And so that polarization takes place and we will get very different output at

instance time so rectifier and filter are used to convert AC to DC, because in

further work of device DC voltage is required.

!

A full-wave rectifier converts the whole of the input waveform to one of

constant polarity (positive or negative) at its output. Full-wave rectification

Figure 4





converts both polarities of the input waveform to pulsating DC (direct current),

and yields a higher average output voltage. Two diodes and a center

tapped transformer, or four diodes in a bridge configuration and any AC source

(including a transformer without center tap), are needed. Single semiconductor

diodes, double diodes with common cathode or common anode, and four-diode

bridges, are manufactured as single components.

! For single-phase AC, if the transformer is center-tapped, then two diodes back-

to-back (cathode-to-cathode or anode-to-anode, depending upon output

polarity required) can form a full-wave rectifier. Twice as many turns are

required on the transformer secondary to obtain the same output voltage than

for a bridge rectifier, but the power rating is unchanged.

3.6 Temperature PROBE

! As discussed in above topics that temperature is effecting parameter on the

measurement of the conductivity and TDS both, we have to manage it for

accurate result.

! And to overcome that problem of temperature effect we have made newmethod to manage it so for that we have to measure temperature first by

temperature PROBE.! We are going to use PT-100 temperature PROBE for the simple measurement

of temperature.

! PT100 temperature sensor have platinum resistor thermometer, which offers

the best overall advantage in measurement.

! Platinum resistance temperature sensor is built into steel tube V4A, 1/2 inch,

suitable for installation in pipes. Thermal response time T0,9 in the air 255 s,

in water 45 s.

!

2-wire transmission technique is used in our project for PT100.

3.8 Analog to digital converter

! Analog to digital convertor are used to convert analog signal to digital signal.

! In our system for further calculations of the measurement we have used

microcontroller/microprocessor, and as we know from our study that

microprocessor or controller both needs digital data or signal for theirexecution so we have used A to D convertor.





! A/D converters are electrical circuits that have the following characteristics.

! The input to the A/D converter is a AC or DC voltage, and as discussed above

that we have used DC Voltage in our circuit so our A/D converters may be

designed for voltages from 0 to 10v, from -5 to +5v, etc., but they almostalways take a voltage input. (Some rare exceptions occur with current inputs!)

! In any event, the input is an analog voltage signal for most cases. The output of

the A/D converter is a binary signal, and that binary signal encodes the analoginput voltage. So, the output is some sort of digital number.

! A comparator can be used as a simple one-bit A/D converter. Although a

converter with just one bit isn't particularly useful in our project, so we have

used integrated circuit as A/D convertor.

! And this converted binary or digital data is directly given to the

microcontroller or microprocessor, which we have used.

3.9 Multiplexer

! We are using multiplexer here to rest the load on our device in selection of

measurement between conductivity measurement cell or tempreture sensing

device which is more complex.

! So we have to use 2-to-1 multiplexer for our desired work.

! Multiplexers can implement arbitrary functions.

! A 2^n-to-1 multiplexer sends one of 2^n input lines to a single output line.

! A multiplexer has two sets of inputs, one is for 2^n data input lines and second

one is for n select lines, to pick one of the 2^n data inputs.

! As defined above that we are going to use 2-to-1 multiplexer.this is the

common block diagram of pin connection.!

! Here D1 is Temperature sensor PIN and D0 is Conductivity cells PIN, and

when S=0 then D1 PIN input is as Output and S=1 then D0 PIN input is as

output. This is very good decision to use multiplexer in our project circuit

which will mostly rest down the complex building blocks and load on our

microprocessor or microcontroller.

Figure 5





3.10 Microcontroller/Microprocessor

! Microcontroller/processor are core devices which are used to simplify the

calulation of very large or complex digits.! Here we are going to use microcontroller instead of microprocessor because of

lots of advantages of microcontroller over microprocessor as below.

! Microprocessor have diffrent memory storage of RAM and ROM, so it is very

bulky and complex design for our circuit and it also need much more large

integrating space on PCB.

! So we are using microcontroller in our project device, now its very irritating

desicion in selection of which microcontroller we have to use.? Because there

are many types and family of microcontroller like 8051, 89S52, 8053 etc.! 8051 and 89S52 both microcontroller are best suited for our circuit design as

both are compatible for our calculation.

! But we are using 89S52 instead of 8051 because the 89S51 has an RISC

structural design and holds fewer no of codes which makes it easy for

programming through SPI as compared with a microcontroller such as the

8051.

! However as compared to other microcontrollers they have very few differences

but 89S52 is best microcontroller for our requirement.! This below listed are specs of AT89S52

- 8K bytes of In-System Programmable(ISP) flash memory.

- 4.0 to 5.5V operating range.

- Fully static operation: 0 Hz to 33 MHz.

- Three level program memory lock.

- 256*8-bit internal RAM.

-

32 programmable I/O lines.

- Three 16-bit timers/counters.

- Eight interrupt source.

- Low power idle and power down modes.

- Watchdog timer(WDT) and dual data pointer.

- Fast programming time.

- Power off flag and flexible ISP programming(Byte and page mode).





3.11 Display

! Display is used to show down our result of the measurement.

!

Mainly 2-types of display are present 1>LCD(Liquid Crystal Display)

2>LED Display(Light Emitting Diode)

! For not more complex output of our device we are using LED display instead

of LCD.

! The decimal outputs of digital instruments such as digital voltmeter (DMDS)

and frequency counters are often displayed using 7-segment indicators.

! Such indicators are constructed by using fluorescent bars, liquid crystal bars or

LED bar for each signal.! LED type indicators are convenient because they are directly compatible with

TTL circuits , and do not require higher voltage for the work.

! A LED display is nothing but a light output to shown an information in the

visual form.

! This displays are divided into two categories, 1> Character display-which will

give visual indication of numbers and letters. 2>Graphical display-which will

give pictorial as well as alphanumeric information.

!

This displays are in response to digital signals given by microcontroller.! Here we are using Character display to display our measured outputs.





Chapter 4

List of components used for TDS and Conductivity meter

!

Semiconductor:

- AT89S52

- ICL7135

- NE555

- 76LS138

- 76LS164

- 4052

! Resistors(±5% Carbon):

- Resistor (Quantity-70)

! Capacitors

- Capacitors(Quantity-65)

! Miscellaneous:

- PCB(Programmable Circuit Board)(Quanity-3)

- 7-segment LED(Quantity-8)

- Diodes(Quantity-20)

- Transistors(Quantity-10)





POWER SUPPLY

! Introduction

! There are many types of power supply. Most are designed to convert high

voltage AC mains electricity to a suitable low voltage supply for electronics

circuits and other devices. A power supply can by broken down into a series of

blocks, each of which performs a particular function. For example a 5V

regulated supply can be shown as below

! Similarly, 12v regulated supply can also be produced by suitable selection of

the individual elements. Each of the blocks is described in detail below and the

power supplies made from these blocks are described below with a circuit

diagram and a graph of their output:

! Transformer

! A transformer steps down high voltage AC mains to low voltage AC. Here we

are using a center-tap transformer whose output will be sinusoidal with 36volts

peak to peak value.

! The low voltage AC output is suitable for lamps, heaters and special AC

motors. It is not suitable for electronic circuits unless they include a rectifier

and a smoothing capacitor. The transformer output is given to the rectifier

circuit.





! Rectifier

! A rectifier converts AC to DC, but the DC output is varying. There are several

types of rectifiers; here we use a bridge rectifier.

! The Bridge rectifier is a circuit, which converts an ac voltage to dc voltage

using both half cycles of the input ac voltage. The Bridge rectifier circuit is

shown in the figure. The circuit has four diodes connected to form a bridge.

The ac input voltage is applied to the diagonally opposite ends of the bridge.

The load resistance is connected between the other two ends of the bridge.

! For the positive half cycle of the input ac voltage, diodes D1 and D3 conduct,

whereas diodes D2 and D4 remain in the OFF state. The conducting diodes

will be in series with the load resistance R L and hence the load current flows

through R L. For the negative half cycle of the input ac voltage, diodes D2 and

D4 conduct whereas, D1 and D3 remain OFF. The conducting diodes D2 and

D4 will be in series with the load resistance R L and hence the current flows

through R L in the same direction as in the previous half cycle. Thus a bi-

directional wave is converted into unidirectional.

!

!

! The varying DC output is suitable for lamps, heaters and standard motors. It is

not suitable for lamps, heaters and standard motors. It is not suitable for

electronic circuits unless they include a smoothing capacitor .





! Smoothening of filter

! The smoothing block smoothness the DC from varying greatly to a small ripple

and the ripple voltage is defined as the deviation of the load voltage from its

DC value. Smoothing is also named as filtering.

! Filtering is frequently effected by shunting the load with a capacitor. The

action of this system depends on the fact that the capacitor stores energy during

the conduction period and delivers this energy to the loads during the no

conducting period. In this way, the time during which the current passes

through the load is prolonging Ted, and the ripple is considerably decreased.

The action of the capacitor is shown with the help of waveform.





! Regulator

! Regulator eliminates ripple by setting DC output to a fixed voltage. Voltage

regulator ICs are available with fixed (typically 5V, 12V and 15V) or variableoutput voltages. Negative voltage regulators are also available Many of the

fixed voltage regulator ICs has 3 leads (input, output and high impedance).

They include a hole for attaching a heat sink if necessary. Zener diode is an

example of fixed regulator which is shown here.





5.1 Measuring Cell

! We are going to use a platinum 4-plate conductivity probe with integrated

fixed cable.! Nominal cell constant: 0.80 /cm.

! We have selected welltronix conductivity measuring cell for our project and

description of measuring cell is as shown below.

! Shaft material of measuring cell is glass and temperature is between 0-100C.

! Cable lenght of measuring cell is 1.0m and connector is mini-DIN connector.

Figure 6





5.2 Rectifier & Filter

! As explainded above that it converts AC voltage to DC voltage and in some

cases it also converts current.! In this project we are using Wien-Bridge Rectifier for the voltage converter

and Filter as shown in the below figure.

! It is connected between current sensing circuit and multiplexer.

! We are using wein bridge convertor because of its easy fabrication method on

PCB and small space for fabrication.

5.3 ADC (Analog to Digital Converter)

! In this project we are using ADC to convert signal to Digital form and thenapplying it to Microcontroller.

! Here we are converting our Analog signal to Digital signal because

Microcontroller only accept the Digital signal. And we are using ICL7135 IC

as ADC as shown in the figure.

! In ICL7135, we are applying power supply of -Vcc to pin 1 and power supply

of +Vcc to pin 11, signal input is given to pin 9 from any sensor like

temperature sensor or conductivity measuring cell.

! Pin 24 is grounded and clocked signal is applied to pin 22 , and pins from 12 to

20 and 23 are connected to 7-segment LED display decoder as shown in the

figure.

Figure 7





!

! Input of ICL7135 is from multiplexer, and we have used 120kHz clocked pulse

to clock our ADConvertor and PIN 3 is gronded.

5.4 Timing Circuit

! We are using NE555 IC in timing circuit.

! It used as frequency generator, and it will generate 100Hz and 1kHz as per our

requirement.

! Here we have created frequency for the use of our measurement in different

types of liquid.

!

We are using NE555 IC because of its applications like below.

- Precision timing.

- Required pulse generation.- Time Delay generation.

- Sequential timing.

! This is the circuit diagram of timing circuit where we are using NE555 timer in

our project.

Figure 8





!

! In NE555IC PIN 1 is grounded.

PIN 2 is trigger pin.

PIN 3 is output pin.

PIN 4 is reset pin.

PIN 5 is power input of +Vcc.

PIN 6 is discharge pin.

PIN 7 is threshold pin.

PIN 8 is control voltage pin.

5.5 Temperature Sensing Circuit and Temperature PROBE

! Output of temperature sensor PROBE PT100 is directly given as input to

temperature sensing circuit as shown above.

! Working of temperature sensing circuit is to convert the measured output ofPT100 PROBE to voltage unit.

!

And we are using PT100 as temperature sensing PROBE and the figure of themeasuring PROBE of temperature is as below.

!

Figure 9

Figure 10





! A conductor is a material in which the electrons of the outer orbit of the atom

are less bonded. If the energy of the material is increased, for example byheating up, the atoms will move more and more and at a certain moment these

electrons can leave their orbit and move freely in the space between the atoms.

!

The resistance increased due to movement of electron around material, this infact means that the resistance of the material has increased. So this tells that

there is a relationship between temperature and resistance.

! And due to the relation between resistance and temperature we can easily

measure the temperature of the liquid or any material.! And output of temperature PROBE PT100 is given to the temperature sensing

circuit and the circuit diagram of temperature sensing circuit of our project is

as shown below.

!

! Output from PT100 Probe is given to inverting and non-inverting terminal of

the Op-Amp as shown in the figure and we have used AD509SH Operational

Amplifier for the current sensing circuit.! And output of temperature sensing circuit is directly given to the multiplexer

which will select between two inputs.

Figure 11





5.6 Multiplexer

! We have already explained that why we have used multiplexer in our device

circuit.

!

In our project we have used IC 4519BD as 2-to-1 multiplexer.! Temperature output from temperature sensing circuit and conductivity

measurement form measurement cell are given as input of the IC.

!

!

Output from temperature PROBE and measuring cell is given to the IC4519BDvia PIN 6 and PIN 7.

! PIN 10 is output of IC and PIN 14 is grounded.

5.7 Microcontroller

! ATMEL 89S52 Microcontroller.

!

Here we are using 89S52 microcontroller in our project for digital calculation. ! Pins of microcontroller are connected with the other circuits of our project as

described below.

! PIN Connection

- P0.0 to P0.7 are connected with the 10! register network.

- P3.4 is directly connected with the Clock cycle.

- P3.5 is connected with the multiplexer.

- P1.3 and P1.4 are connected with the Crystal oscillator to

generate the sine wave.

-

P4.0 is power input of +Vcc.- P2.0 is grounded.

Figure 12





! Circuit diagram and PIN connection are as below shown diagram.

!

5.8 Display selection segment

! As described above that we are using LED screen display, here we will show

the circuit diagram and connection of LED display in our Project.

! For the interfacing between Microcontroller and 7-segment LED display wehave used IC 74LS1380 as shown in the figure.

!

Figure 13

Figure 14





! Pins of IC 74LS1380 1 to 4 are directly connected with the microcontrollers

Pin P0.0 to P0.3 after the register network of 10 # registers.! Output pins of IC 74LS1380 are connected to 7-segment LED display through

transistors as shown in the figure.

!

In transistor base is connected directly with the output pins of IC, Emitter isconnected with the 7-segment LED display and Collector is connected with the

power supply +Vcc.

! This LED display will display the character output on the Display like error,

temperature, wait, etc.

5.9 Interfacing with 7-segment LED display

!

For 7-segment LED’s display segment we have used IC 74LS164D. ! IC pin 1 is directly connected with the microcontrollers pin P0.4 after the

register network, pin 2 is connected with the power supply +Vcc, pin 7 is

connected to ground, and pin 9 is connected with the clock.

! Output pins of IC 3 to 6 and 10 to 13 are connected to 7-segment LED through

registers R1 to R8 as shown in the figure.

!

Figure 15





Chapter 6

Future work

6.1 8th

semester workout plan

! Now we already have finalized the required hardware for project and also we

have made circuit diagram of TDS and conductivity meter in OrCAD and NI

Multisim 12.0.! In future we have to first make program codes for our project and then we will

start hardware implementation of project.

! After successful hardware implementation of our project we will start using it

and suppose any error in coded program or in hardware implementation of

project occurs then we will troubleshoot it and hardly try to solve it.





Work Schedule of Project

Task 1- Component selection and circuit design

Task 2- To study different type of sensor for conductivity and temperature

Task 3- To study control of 230V-12V step down transformer

Task 4- To study about Temperature sensor and Temperature PROBE

Task 5- To study microcontroller AT89S52

Task 6- To study Current sensing and Range selection circuit using relays

Task 7- To study Rectifiers & filters and Scaling Circuit

Task 8- To study ADC(ICL7135 IC) and Multiplexer

Task 9- To study Kell C Programming

Task 10- Hardware implementation

Task 11-Troubleshooting

Task 12- Demonstration





References

! Dean G Jarrett, IEEE Trans. Instrumentation and Measurement, 46(325).

!

V. G. Kher, C S Adgankar Ind. J. Pure & Appl. Physics.10(902).

! Oliver B. M. and Cage J. M. Electronics Measurement and

Instrumentation(McGraw Hill).

! Jung W. G. “IC Op-Amp Cookbook”, BPB publication, New Delhi.

! Roychaudhary D & Jain Shail, Linear integrated circuits(New Age

International).

!

M.S. Lanjewar, S.M. Sawarkar, C.S. Adgaonkar & A.R. Khobragade,

Proceeding of International conf. on Micro-wave and Opto Electronics,

Abad(M.S.) India 2007.

! Keithly “Data acquisition and control hand book, a guide to hardware and

software for computer based measurement and control”.

! Muhammad Ali Mazidi, Janica G. Mazidi “The 8051 microcontroller and

embedded system” Pearson Publication.! IC Control applications notes, Volume-4.2

http://www.iccontrols.com/files/4-2.pdf

! http://www.filtersfast.com/HM-TDS-Guide.pdf





AppendixPin Diagrams of Different Electronic Components

PIN DIAGRAM OF ATMEL89S52





74LS1380





4519BD_5V





ICL7135





NE555





LM7805/7809

project-tds meter

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