“VOLTAGE AND CURRENT SENSING CARD

FOR DAQ 6008”

PROJECT REPORT

Submitted in partial fulfillment of the requirements for the award of degree of

BACHELOR OF TECHNOLOGY

IN

ELECTRICAL AND ELECTRONICS ENGINEERING

By

C.JAYASREE (08241A0212)

CH.RAMYA KRISHNA (08241A0237)

N.S.S SAAI SARVANI (08241A0242)

K.SWAPNA (08241A0250)

Department of Electrical and Electronics Engineering GokarajuRangaraju Institute of Engineering and Technology

(Affiliated to Jawaharlal Nehru Technological University)

Bachupally, Hyderabad 2011

GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING AND

TECHNOLOGY

Hyderabad, Andhra Pradesh.

DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

CERTIFICATE

This is to certify that the project entitled “VOLTAGE AND SENSING CARD FOR DAQ 6008”has been submitted by

C.JAYASREE (08241A0212)

CH.RAMYA KRISHNA (08241A0280)

N.S.S SAAI SARVANI (08241A0242)

K.SWAPNA (08241A0250)

in partial fulfillment of the requirements for the award of degree of Bachelor of Technology in Electrical and Electronics Engineering from

Jawaharlal Nehru Technological University, Hyderabad.

The results embodied in this project have not been submitted to any other University or Institution for the award of any degree or diploma.

Internal Guide Head of Department

G.Sapna P.M.Sarma

Associate Professor Professor& HOD

Dept. of Electrical Engg. Dept. of Electrical Engg.

ACKNOWLEDGEMENT There are many people who have helped us directly or indirectly in the successful

completion of our project. We would like to take this opportunity to thank one and all.

First of all we would like to express our deep gratitude towards our project guide

Miss G.Sapna(Assistant Professor, EEE) for her valuable guidance during our project.

We are also grateful to Mr.M.Chakravarthy (Associate Professor, EEE) for always being

available whenever we required his guidance as well as motivating us throughout the

project work.

We express our sincere gratitude to Professor P.M.Sarma, Head of EEE Department,

GRIET, for his deep interest in the progress of the project right from the beginning and

constructive criticism, which gave us all the motivation required to complete this project.

We are also thankful to Dr.S.N.Saxena, Professor of EEE Department, GRIET, for providing

us constant guidance and giving us regular feedback on the work done by us, which helped us

a great deal to complete our project in time with the desired outputs.

ABSTRACT

This project is basically designed to sense the input voltage and hence protect system

equipment and circuitry from voltage that is hazardous or unsuitable for operation.

Voltage Sensors are designed to operate in a wide variety of military and industrial

environments. Models are available for operation with single or three phase voltage systems

and for DC, 50, 60, or 400 Hz. applications.

The measurement capabilities of different voltage transducers differ widely due to the many

ranges of their usage, from computer circuitry to large transformer circuits.

The voltage sensor under consideration includes three major components namely potential

divider circuit, isolation amplifier HCPL-7800A and TLE2082CP.

The potential divider circuit is used to step down the input voltage that is to be sensed (0-

340V) to the order of millivolts, since the recommended operating range for the input voltage

applied to HCPL-7800A lies in the range -200 mV to +200mV.

The output voltage of the sensor circuit lies in the range 0-5V.

General Circuit board(GCB) and Printed Circuit Board(PCB) were made and tested.

ABBREVIATIONS

POT: Potentiometer GCB: General Circuit Board PCB: Printed Circuit Board

EAGLE: EASILY APPLICABLE GRAPHICAL LAYOUT-EDITOR

ACKNOWLGEMENT

ABSTRACT

ABBREVIATIONS

CONTENTS

Chapters Page. No. 1. Introduction

1 1.1 Working of the sensor

2. Block diagram and Circuit diagram 3

2.1 Description 4

3. Details about HCPL-7800A 7

3.1 Isolation amplifier 7

3.2 Block diagram 9

3.3 Functional diagram 11

3.4 Features 13

3.5 Applications 15

4. Details about TLE2082CP 17

4.1 Description 18

4.2 Functional diagram 19

4.3 Recommended Operating Conditions 21

5. Power supply circuit 22

5.1 5V Power supply circuit 22

5.2 15V and -15V Power supply circuit 23

6. Offset Compensation circuit 26

7. Calculation of output voltage for the sensor 31

7.1 Output voltage of potential divider circuit 32

7.2 Output voltage of HCPL-7800A 33

7.3 Output voltage of TLE2082CP 34

7.4 Results at each stage of the sensor for varying input voltages 34

8. Simulation of the sensor circuit using Multisim software 35

8.1 Description of Multisim software 36

8.2 Simulation Circuits 37

8.2.1 Simulation Circuit for AC input 38

8.2.2 Simulation Circuit for DC input 39

8.3 Simulation Results 40

9. PCB Design 41

9.1 PCB testing 42

9.2 Results 43

10. Conclusion and scope for future work 44

References

Appendix A: Data sheet of HCPL-7800A 45

Appendix B: Data sheet of TLE2082CP 57

Appendix C: Data sheet of 1N4740 63

CHAPTER - 1

INTRODUCTION

VOLTAGE SENSOR:

AC Voltage Sensors are designed to protect system equipment and circuitry from voltage that

is hazardous or unsuitable for operation. Models are available for operation with single or

three phase voltage systems and for DC, 50, 60, or 400 Hz. applications. They can be used to

monitor for under-voltage, over-voltage, or a voltage window. In the event that the sensor

detects an undesirable voltage condition, the output of the sensor can be used to activate

alarms, shed loads, or shutdown systems. The measurement capabilities of different voltage

transducers differ widely due to the many ranges of their usage, from computer circuitry to

large transformer circuits.

CURRENT SENSOR:

The current sensor we are using in our project is TLE2082CP. The TLE208x series of JFET-

input operational amplifiers more than double the bandwidth and triple the slew rate of the

TL07x and TL08x families of BiFET operational amplifiers. The TLE208x also have wider

supply-voltage rails, increasing the dynamic-signal range for BiFET circuits to ±19 V. On-

chip zener trimming of offset voltage yields precision grades for greater accuracy in dc-

coupled applications. The TLE208x are pin-compatible with lower performance BiFET

operational amplifiers for ease in improving performance in existing designs. This signal is

given to a current to voltage converter. From the current to voltage converter it is given to a

low pass filter for further conditioning. The output voltage obtained is proportional to input

line current up to a certain current value then the output voltage becomes saturated.

Accordingly the current sensor can be used for its applications.

1.1 WORKING OF THE SENSOR

The voltage sensor under consideration includes three major components namely, potential

divider circuit, isolation amplifier HCPL-7800A and TLE2082CP.

The potential divider circuit is used to step down the input voltage that is to be sensed (0-

340V) to the order of millivolts, since the recommended operating range for the input voltage

applied to HCPL-7800A lies in the range -200 mV to +200mV.

HCPL-7800A is used for precision applications with a gain tolerance of ±1%. The mean gain

value of HCPL-7800A is 8.

The gain of TLE2082CP is set to 3.9 by using 1kΩ resistor at its inverting input and 3.9kΩ as

the feedback resistor.

The output voltage of the sensor circuit lies in the range 0-5V.

CHAPTER - 2

BLOCK DIAGAM AND CIRCUIT DIAGRAM

VOLTAGE SENSOR:

The block diagram of the voltage sensing card is shown in fig 2.1.

2.1 DESCRIPTION

The voltage sensing card under consideration can be used for both ac and dc voltage

measurements. The input voltage to be measured lies in the range (0-340VPeak, range can be modifed). It is given to the potential divider circuit which brings down the voltage to be

measured to the order of millivolts. The potential divider circuit consists of four 470kΩ resistors and a 1kΩ POT in series. The voltage across the 1kΩ POT setting gets applied

between the input terminals of HCPL-7800A. Since, the output voltage should lie in the range (0-5V), the POT setting is set to 0.9kΩ which is connected to pins 2 and 4 of HCPL-7800A. The +5V power supply to the pins 1 and 8 are isolated. Therefore, they are represented by

two +5V voltage regulators (LM7805) in the block diagram as in fig 2.1.

The recommended operating range for the input voltage applied to HCPL-7800A lies in the range -200 mV to +200mV. The mean gain value of HCPL-7800A is 8. Hence, the output of HCPL-7800A lies between +1.6V to -1.6V. For the sensor under consideration, the maximum output of HCPL-7800A is 1.2992VPeak which is the maximum value of input voltage to TLE2082CP. The gain of TLE2082CP is set to 3.9 by using 1kΩ resistor at its inverting input and 3.9kΩ as the feedback resistor. Hence, the maximum value of the output of TLE2082CP which is also the output of the sensor is 1.2992 * 3.9 = 5.06V.

The circuit diagram of the voltage sensing card is shown in fig 2.2

Modifications in the component values of the sensor circuit in fig 2.2 Circuit Component to be Replaced with Resistors 499kΩ470kΩ 4.99kΩ 4.7kΩ R136 (6.81kΩ) 3.9kΩ Capacitors 68pF 100Pf

CURRENT SENSOR:

The block diagram of the currentsensing card is shown in fig 2.3.

The circuit diagram of the current sensing card is shown in fig 2.4

CHAPTER – 3

DETAILS ABOUT HCPL-7800A

3.1 ISOLATION AMPLIFIER

Isolation amplifiers provide electrical isolation and an electrical safety barrier. They protect data

acquisition components from common mode voltages, which are potential differences between

instrument ground and signal ground. Instruments without an isolation barrier that are applied in

the presence of a common mode voltage allow ground currents to circulate, leading in the best

case to a noisy representation of the signal under investigation. In the worst case, assuming that

the magnitude of common mode voltage and/or current is sufficient, instrument destruction is

likely.

Amplifiers with an isolation barrier allow the front-end of the amplifier to float with respect to

common mode voltage to the limit of the barrier's breakdown voltage, which is often 1,000 VDC,

peak AC, or more. This action serves to protect the amplifier and the instrument connected to it,

while still allowing a reasonably accurate measurement.

3.2 BLOCK DIAGRAM

Figure 3.1 below shows the primary functional blocks of the HCPL-7800A.

In operation, the sigma-delta analog-to-digital converter converts the analog input signal into a

high-speed serial bit stream, the time average of which is directly proportional to the input signal.

This high speed stream of digital data is encoded and optically transmitted to the detector circuit.

The detected signal is decoded and converted into accurate analog voltage levels, which are then

filtered to produce the final output signal.

To help maintain device accuracy over time and temperature, internal amplifiers are chopper

stabilized. Additionally, the encoder circuit eliminates the effects of pulse-width distortion of

the optically transmitted data by generating one pulse for every edge (both rising and falling) of

the converter data to be transmitted, essentially converting the widths of the sigma-delta

output pulses into the positions of the encoder output pulses. A significant benefit of this coding

scheme is that any non-ideal characteristics of the LED (such as non-linearity and drift overtime

and temperature) have little, if any, effect on the performance of the HCPL-7800A.

3.3 FUNCTIONAL DIAGRAM

Fig 3.2 below shows the functional diagram of HCPL-7800A. It is an 8-pin integrated circuit. There are two terminals each for input (pins 2, 3) and output (pins 7,8) connections.

+5V

Fig 3.1 Block Diagram of HCPL-7800A

3.4 FEATURES

15 kV/ms Common-ModeRejection at VCM = 1000 V*

Compact, Auto-Insertable Standard 8-pin DIP Package

4.6 mV/°C Offset Drift vs.Temperature

0.9 mV Input Offset Voltage

85 kHz Bandwidth

0.1% Nonlinearity

Worldwide Safety Approval: UL 1577 (3750 V rms/1 min), VDE 0884 and CSA

Advanced Sigma-Delta (SD)A/D Converter Technology

Fully Differential CircuitTopology

1 mm CMOS IC Technology

3.5 APPLICATIONS

Motor Phase Current Sensing

General Purpose Current Sensing

High-Voltage Power Source Voltage Monitoring

Switch-Mode Power Supply Signal Isolation

General Purpose Analog Signal Isolation

Transducer Isolation

CHAPTER – 4

DETAILS ABOUT TLE2082CP

4.1 DESCRIPTION

The TLE208x series of JFET-input operational amplifiers more than double the bandwidth and

triple the slew rate of the TL07x and TL08x families of BiFET operational amplifiers. The

TLE208x also have wider supply-voltage rails, increasing the dynamic-signal range for BiFET

circuits to ±19 V. On-chip zener trimming of offset voltage yields precision grades for greater

accuracy in dc-coupled applications. The TLE208x are pin-compatible with lower performance

BiFET operational amplifiers for ease in improving performance in existing designs.

BiFET operational amplifiers offer the inherently higher input impedance of the JFET-input

transistors, without sacrificing the output drive associated with bipolar amplifiers. This makes

these amplifiers better suited for interfacing with high-impedance sensors or very low level ac

signals. They also feature inherently better ac response than bipolar or CMOS devices having

comparable power consumption.

Because BiFET operational amplifiers are designed for use with dual power supplies, care must

be taken to observe common-mode input-voltage limits and output voltage swing when operating

from a single supply. DC biasing of the input signal is required and loads should be terminated to

a virtual ground node at mid-supply.

The TLE208x are fully specified at ±15 V and ±5 V.

4.2 FUNCTIONAL DIAGRAM

The functional diagram of TLE2082CP is shown in fig 4.1.

Pin 1 represents the ouput terminal for the input at pins 2, 3. Pin 7 represents the ouput terminal for the input at pins 5, 6. There are two pins for power supply. +VCC supply is given to pin 8 and –VCC supply is given to pin 4. For the voltage sensor under consideration +VCC = +15V and –VCC = -15V.

4.3 RECOMMENDED OPERATING CONDITIONS

The supply voltage(VCC) range lies between ±2.25V to ±19V.

Differential input voltage range, VID lies between VCC+ and VCC-

Maximum input current, II (each input) = ±1mA

Maximum output current, IO (each input) = ±80mA

The common-mode input voltage (VIC) for VCC = ±15V lies between -10.9V and 15V.

The operating free-air temperature range (TA) is 0˚C to 70˚C.

CHAPTER – 5

POWER SUPPLY CIRCUIT

5.1 5V POWER SUPPLY CIRCUIT

The 5V power supply circuit of fig 5.1 consists of a step down transformer. 230V AC is applied

to the primary side of the transformer and the voltage obtained on the secondary side is 9V AC.

The 9V AC is converted to DC using a bridge rectifier comprising of four 1N4007 diodes. The

capacitors are used for the removal of ripples in the circuit. The voltage regulator used is

LM7805 which produces a steady 5V regulated DC. This 5V DC is given to the isolation

amplifier HCPL-7800A. Since the input and output side of HCPL-7800A are isolated, two such

5V power supplies are required.

Fig 5.1 5V Power Supply Circuit

5.2 15V AND -15V POWER SUPPLY CIRCUIT

The 15V and -15Vpower supply circuit of fig 5.2 consists of a centre tapped step down

transformer. 230V AC is applied to the primary side of the transformer and the voltage obtained

on the secondary side is 15-0-15V AC. The 15-0-15V AC is converted to DC using a bridge

rectifier comprising of four 1N4007 diodes. The capacitors are used for the removal of ripples in

the circuit. The voltage regulators used are LM7815 and LM7915. LM7815 produces a steady

15V regulated DC and LM7915 produces a steady -15V regulated DC with respect to the centre

tap of the transformer. 15V and -15V DC is given to TLE2082CP.

Fig 5.2

Fig 5.2 15V and -15V Power Supply Circuit

CHAPTER 6

OFFSET COMPENSATION CIRCUIT

Fig 6.1 Offset Compensation Circuit

Input offset voltage (Vio) is the differential input voltage that exists between two input terminals

of an operational amplifier without any external inputs applied. In other words, it is the amount of

the input voltage that should be applied between two input terminals in order to force the output

voltage to zero. Let us denote the output offset voltage due to the input offset voltage Vioas VOO .

The output offset voltage VOO is caused by mismatching between two input terminals.

Before we apply external input to the op-amp, with the help of an offset voltage compensating

network we reduce the output offset voltage VOO to zero; the op-amp is then said to be nulled or

balanced.

The adjustment of the 1kΩ POT as shown in fig 6.1 will null the output.

Zener diodes are used to obtain symmetrical voltages. The 200Ω resistors are chosen so as to

supply sufficient current for the diodes to operate in avalanche mode.

In the voltage sensing card circuit, the ouput of the offset compensating network (Off_VA) is

given to pin 3 of TLE2082CP as seen from fig 2.2.

CHAPTER -7

CALCULATION OF OUTPUT VOLTAGE FOR THE SENSOR

Let us consider an ac input of 220V (RMS). Then the peak value of input equals 220√2 that is equal to 311.126V.

7.1 OUTPUT VOLTAGE OF POTENTIAL DIVIDER CIRCUIT

As seen from fig 2.2, the voltage across 0.9kΩ setting of the POT or the capacitor C282 (470pF)

is the input to HCPL-7800A. This represents the output of the potential divider circuit(VPD).

Hence VPD = [0.9kΩ/(470kΩ*4)+0.9kΩ] * 220

= 105.268mV

7.2 OUTPUT VOLTAGE OF HCPL -7800A

The gain of HCPL-7800A is 8.

Hence the output of HCPL – 7800A( VOUT1) is 8 * VPD .

VOUT1 = 8 * 105.268mV

= 0.8421V

7.3 OUTPUT VOLTAGE OF TLE2082CP

The output of TLE2082CP is the output of the voltage sensing card which is observed at pin1 of

TLE2082CP.

The differential input voltage to TLE2082CP is the output of HCPL -7800A.

The gain of TLE2082CP is set to 3.9 by using 1kΩ resistor at its inverting input and 3.9kΩ as the

feedback resistor.

Hence, the output of TLE2082CP (VOUT2) equals 3.9 * VOUT1

VOUT2 = 3.9 * 0.8421V = 3.2841V (RMS)

VOUT2 in terms of peak value equals 3.2841V * = 4.6445V

CHAPTER – 8

SIMULATION OF THE SENSOR CIRCUIT USING

MULTISIM SOFTWARE

8.1 DESCRIPTION OF MULTISIM SOFTWARE

Simulation is a mathematical way of emulating the behavior of a circuit. With simulation,

you can determine much of a circuit's performance without physically constructing the circuit

or using actual test instruments. Although Multisim makes simulation intuitively easy-to-use,

the technology underlying the speed and accuracy of the simulation, as well as its ease-of-

use, is complex.

To view the results of your simulation, you will need to use either a virtual instrument or run

an analysis to display the simulation output. This output will include the combined results of

all Multisim simulation engines.

When you use interactive simulation in Multisim (by clicking on the Run Simulation button),

you see the simulation results instantly by viewing virtual instruments such as the

oscilloscope. The dual-channel oscilloscope displays the magnitude and frequency variations

of electronic signals. It can provide a graph of the strength of one or two signals over time, or

allow comparison of one waveform to another.

During simulation, you can change the values of "interactive" components (those whose

behavior can be controlled through the keyboard) and view the effect immediately.

Interactive components include such devices as the potentiometer, variable capacitor,

variable inductor, and multiple switcher.

The Multisim component database is designed to hold the information necessary to describe

any component. It contains all the details needed for schematic capture (symbols), simulation

(models) and PCB layout (footprints), as well as other electrical information.

There are three levels of database provided by Multisim. The master database is read only,

and contains components supplied by Electronics Workbench. The user database is private to

an individual user. It is used for components built by an individual that are not intended to be

shared. The corporate database is used to store custom components that are intended to be

shared across an organization. Various database management tools are supplied in order to

move components between databases, merge databases, and edit them.

Fig 8.1 Potential Divider simulation circuit for AC input in Multisim window

8.2 SIMULATION CIRCUITS

8.2.1 Simulation Circuit for AC input

The voltage sensing card circuit was simulated for an AC input of 240V (rms). 0.9kΩ setting

of the POT was considered. Fig 8.1 represents the potential divider circuit. Fig 8.2 represents

the voltage sensing card circuit after HCPL-7800A as can be seen from Fig 2.2.

Since HCPL-7800A is not available in the Multisim Library, it was replaced by an AC

voltage source whose magnitude equals eight times the output of the potential divider circuit

as the gain of HCPL-7800A is 8. This can be seen in Fig 8.2.

Fig 8.3 represents the output of the voltage sensing card circuit in oscilloscope.

Fig 8.2 Voltage Sensing Card Simulation Circuit (ac)

Fig 8.3 Voltage Sensing Card simulation output (ac) in oscilloscope

8.2.2 Simulation Circuit for DC input

The voltage sensing card circuit was simulated for a DC input of 339.411V.

0.9kΩ setting of the POT was considered.

Fig 8.4 represents the potential divider circuit.

Fig 8.5 represents the voltage sensing card circuit after HCPL-7800A as can be seen from Fig

2.2.

Since HCPL-7800A is not available in the Multisim Library, it was replaced by a DC voltage

source whose magnitude equals eight times the output of the potential divider circuit as the

gain of HCPL-7800A is 8. This can be seen in Fig 8.5.

Fig 8.6 represents the output of the voltage sensing card circuit in oscilloscope.

Fig 8.4 Potential Divider simulation circuit for DC input

8.3 SIMULATION RESULTS

Table 8.3.1 below shows the results of the voltage sensing card circuit simulation

Table 8.3.1 Simulation results for AC input

CURRENT SENSING:

Input of HCPL

Output of TLE2082CP (V)

Shunt Resistance ( R)

Output of sensor ( I= V/R)

0.09 0.29694 0.04 7.4

0.07 0.23094 0.04 5.75

0.06 0.19794 0.04 4.75

0.04 0.13197 0.04 3.25

0.03 0.09896 0.04 2.25

0.02 0.06599 0.04 1.5

0.01 0.03299 0.04 0.75

0 0 0.04 0

TABLE 8.3.2 simulation results for AC input

Input of HCPL Output of TLE2082CP (V)

Shunt Resistance ( R)

Output of sensor ( I= V/R)

0.09 0.298 0.04 7.25

0.07 0.232 0.04 5.8

0.06 0.199 0.04 4.97

0.05 0.166 0.04 4.15

0.04 0.133 0.04 3.32

0.02 0.067 0.04 2.66

0.01 0.034 0.04 1.675

TABLE 8.3.3.simulation results for DC input

CHAPTER 9

PCB DESIGN USING EAGLE SOFTWARE

9.1 DESCRIPTION OF EAGLE SOFTWARE

EAGLE software stands for Easily Applicable Graphics Layout Editor.

Version 4.1 of Eagle has been used.

System Requirements

EAGLE is a powerful graphics editor for designing PC-board layouts and schematics. In

order to run EAGLE the following hardware is required:

IBM-compatible computer (586 and above) with

Windows 95/98/ME, Windows NT4/2000/XP or

Linux based on kernel 2.x, libc6 and X11 with a minimum color depth of 8 bpp,

a hard disk with a minimum of 50 Mbyte free memory,

a minimum graphics resolution of 1024 x 768 pixels, and

preferably a 3-button mouse.

Control Panel and Editor Windows

From the Control Panel you can open schematic, board, or library editor windows by using

the File menu or double clicking an icon.

EAGLE Files

The following table lists the most important file types that can be edited with EAGLE:

Type Window Name

Board Layout Editor *.brd

Schematic Editor *.sch

Library Editor *.lbr

Script File Text Editor *.scr

User Language Program Text Editor *.ulp

Any text file Text Editor *.*

Backup Files

EAGLE creates backup data of schematic, board, and library files. They will be saved with

modified file extensions:

.brdbecomes .b#1,

.schbecomes .s#1, and

.lbrbecomes .l#1.

There can be a maximum number of 9 backup files.

It is also possible to have EAGLE files saved in a certain time-interval. In this case the files

get the extension b##, s## or l##. The files can be used again after renaming them with the

original file extension. All settings concerning backups can be done in the Options/Backup

menu of the Control Panel.

9.2 SCHEMATIC OF THE SENSOR IN EAGLE

Fig9.1 and Fig 9.2 below gives the schematic of the Voltage Sensing Card in Eagle window.

Fig 9.1

Drawing a Schematic :

Fig 10.3 gives the command toolbar for the Schematic Editor in Eagle.

Create a Schematic File Use File/New and Save as to create a schematic with a name of your

choice. Load a Drawing Frame Load library FRAMES with USE and place a frame of your

choice with ADD.

Place Symbols Load appropriate libraries with USE and place symbols (see ADD, MOVE,

DELETE, ROTATE, NAME, VALUE). Where a particular component is not available, define a

new one with the library editor.

Draw Net Connections Using the NET command, connect up the pins of the various elements on

the drawing. Intersecting nets may be made into connections with the JUNCTION command.

Fig 9.3 Command toolbar of the Schematic Editor( left) and the Layout Editor( right)

Fig. 9.3.1. Routing PCB

Multimeter displaying output while testing PCB for an DC input of 33V(rms)

Multimeter displaying 0 volts output for 0 volts input

9.4 PCB CIRCUIT (HARDWARE) The input to the PCB is given through a 0-240V (rms) autotransformer. For different AC inputs the output of the sensor was noted. Fig 10.6 below gives the PCB of the voltage sensing card.

CHAPTER – 10

CONCLUSION AND SCOPE FOR FUTURE WORK

10.1 PROBLEMS FACED DURING THE PROJECT WORK

The PCB results were showing deviations from the calculated values. The 1kΩ TRIM POT used had to be replaced as it was not showing steady values.

10.2 SCOPE FOR FUTURE WORK

The output of the voltage sensing card circuit changes with the POT setting on the input side,

with the value of the feedback resistor used in the circuit of TLE2082CP and the resistor at the inverting input (pin 6) of TLE2082CP. It can also be changed by varying the power supply to TLE2082CP. Hence a voltage sensing card as per one’s own requirement can be designed by changing any of the above mentioned parameters.

REFERNCES 1. Ramakant A. Gayakward, Op-Amps and Linear Integrated Circuits, Fourth Edition, PHI, 1987 2. William Hayt and Jack E. Kimmerly, Engineering Circuit Analysis, McGraw Hill Company, Sixth Edition 3. http://en.wikipedia.org/wiki/voltage_sensor

4. www.datasheeetcatalog.com

5. http://www.globalspec.com/Electrical _Voltage sensors