Project Documentation - Final

8/10/2019 Project Documentation - Final

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TABLE OF CONTENTS

TITLE PAGE i

TABLE OF CONTENTS ii

LIST OF TABLES iii

LIST OF FIGURES iii

Part 1. INTRODUCTION 1

1.1 Concept/Theories of the Design

1.2 Previous Research and Studies1.3 Applicable Standards

Part 2. Design Specification 42.1 Design Prototype

2.2 Design Block Diagram2.3 Design Schematic Diagram

2.4 Circuit Description/Operation

Part 3. Experiment Activities 9

3.1 (Theoretical and practical passive output verification of the design)

3.2 (Signal Filtering through CapacitorsArbitrary Circuit Effects)

3.3 (AC-DC Signal ConversionSupply Rectification)

Part 4. Results and Discussion 154.1 (Results of Experiment 1Design Verification)

4.2 (Results of Experiment 2Signal filtering through Capacitors)

4.3 (Results of AC-DC Signal ConversionSupply Rectification)

Part 5. Summary and Conclusion 21

References 22


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Part I

INTRODUCTION

1.1 Theories/Concept of the Design

The need to construct a steady and reliable DC power supply is given by the fact that

most electronic devices and components run on direct current and also require varying amounts

of voltages. This type of power is very different from the Alternating current that can be

harnessed from the common wall outlet and as such, the process of signal rectification, through

the power supply unit is necessary.

The design the researchers intend to do for this project is an AC-DC Regulated Power

Supply which is capable of producing 6 output voltages for 1.5v, 3v, 4.5v, 5v, 6v and 9v. This is

achieved through the use of a system of diodes, capacitors and resistors which, when working

together, would be able to produce the warranted voltage specified in the design. The mostimportant aspect of the design is the use of a variable IC regulator which eliminates the need for

individual regulators for the specified output voltages above. Another important concept involves

the use of a 6 position rotary switch in order to vary the voltage supplied by the circuit.

The design follows the primary process of AC-DC conversion which involves stepping

down the AC voltage to a lower level through the use of a transformer, rectifying the signal using

diode rectifiers, filtering through capacitors and RC filters and regulating the voltage through a

regulator. Although our design adds additional functionalities such as an indicator LED light, a

safety fuse and the ability to manipulate voltage output, nevertheless everything is still compliant

to the primary concept of AC-DC signal conversion.

1.2 Previous Research and Studies

In his paper for the engineering journal Proceedings of the IREentitled Basic Theory

and Design of Electronically Regulated Power Supplies, A. Abate of Raytheon Manufacturing

Corporation wrote about the importance of understanding the process of voltage regulation in

designing power supply units. This is because the regulation process in power supply design,

more often than not, and in most practical applications, is only seen as an additional process

instead of being an essential part of the design itself. What results is a circuit design that is

unregulated in nature but only becomes regulated through the unwelcome addition of an IC

regulator. This increases the likelihood of a design failure with the circuit not being able to hold

on to the regulated voltage for a significant period of time. Our design circumvents this common

mistake by making sure that the regulator we use is well suited for the circuit design and that

filters are also added in the circuit after the regulator.


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Another research supplemental to our study is about switching power supply ripple

rejection written by Yu-jie Fang, Bing-hua Su and Ling-xia Hang, students from the Beijing

Institute of Technology School of Optoelectronics. Their study discusses the process of ripple

rejection in high current power supplies. Based on a special switching power supply, this text

describes the problem of output stability as the ripple of the switching power supply is defined

and analyzed, how it is generated and several solutions have been proposed. The researchers

studied several methods of ripple rejection such as adding a filter in multiple parallel

configurations and so on, in order to reduce output ripple and improve stability especially in high

current applications. In text, the integrated power supply is formed by the two direct current

modules in parallel. The processes they employed in this study is primarily the same with the

ones we used as we employed a system of capacitor and RC filters to stabilize the DC power

output produced by the supply.

Figure 1.1 (Simple RC Filter)

The image above shows how the researchers mentioned above employed the use of a

capacitor and series filter in order to reduce the ripple factor in the signal and stabilize the output

of the laser mechanism which they ought to power. This concept is very similar to what we hope

to achieve in our design which is the stability and consistency of the DC power signal that we are

to produce through the power supply unit.


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Part II

DESIGN SPECIFICATION

2.1 Design Prototype

Figure 2.1 (Design PrototypePopulated Value)

Figure 2.2 (Design PrototypeUnpopulated Value)


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Figure 2.3 (Design PrototypeFinal Output)

Figure 2.4 (Design PrototypeInternal Parts)

Transformer

Selector Switch

Resistor Series

Brid e Rectifier

Ca acitor Filter

RC Filter

Regulator

Out ut Terminals

LED Li ht

Switch


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2.2 Block Diagram

Figure 2.5 (Block Diagram)

1. 220 VAC InputDescribes the input AC input which the power supply will obtain from

the common wall outlet.

2. 12v Step-down transformerSteps down the voltage input from 220v to 12v of AC.3. Bridge Rectifiercomposed of four diodes arranged in a bridge type configuration which

will convert the AC sinusoidal signal to a full-wave signal to enable easy circuit filtering.

4. Capacitor Filter Primary filter of the circuit which eliminates most of the ripple from

the rectifier output.5. LM317 Variable IC RegulatorReceives input from the potentiometer and the resistor in

order to determine the output voltage to produce and regulate.

6. Potentiometeridetermines the voltage output produced by the variable IC regulator.

7. 6 Position Selector SwitchAllows the user to manipulate the output voltage by varyingthe amount of resistance encountered by the regulator.

8.

RC Filterfurther stabilizes the voltage output produced by the regulator and eliminatesmost of the ripple voltage.

9. Output Voltages allows the output terminals to produce 1.25V to 14.5V voltages

depending upon the requirement imposed by the user.

2.3 Schematic Diagram

12v Step-down

Transformer

Bridge

RectifierCapacitor Filter

Variable

IC Regulator

Resistor Series6 Position

Selector Switch

RC Filters1.5v, 3v, 4.5v,

5v, 6v, 9v DCOutput

220v AC Input


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Figure 2.6 (Schematic Diagram)

2.4 Circuit Description and Operation

After the input AC voltage goes through a step down transformer to reduce it to a lower

12v voltage, a bridge rectifier will then convert the 12VAC signal to a full-wave signal in order

to make the job of filtering it easier. Given the internal resistances of the diodes in the bridge

rectifier, the maximum deliverable voltage from the transformer goes down to approximately 9

volts after it has passed the rectifier which is why our design for the power supply does not

exceed 9 volts of output. After the rectification process, a 3,300 microfarad capacitor does the

primary filtering of the circuit which eliminates most of the ripple voltage from the output signal.

A 2000 ohm resistor and a 10 microfarad RC circuit then helps further reduce the signal

fluctuations. It is then passed onto the LM317T IC Variable regulator which regulates the signal

relative to a load. What dictates the output voltage to the regulator is the amount of resistancethat it encounters in the circuit which is the reason why the regulators adjustable terminal

receives input from a series of switches and resistors that dictate the output voltage needed. After

the signal needed for output has been selected, it is then passed onto another series of RC filters

before being subsequently passed onto the output terminals.


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Shown below is the method of computation used to obtain the value of the resistors used

in the resistor series. The formula is obtained from the specifications of the regulator.

Figure 2.7 Resistor Series Function

In order to find the amount of resistance required by the regulator to produce a certain

voltage, the researchers used the formula above. The required voltage is represented as V outand

the resistance parallel to the adjustment terminal, which in this case is 100 ohms, is represented

as R1in the equation above, with the required resistance being R2.

( ) ( ) ( ) (

)

( ) ( )

R1


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Part III

EXPERIMENT ACTIVITIES

3.1. Theoretical and practical passive output verification of the design

Objective: 1. To be able to check whether or not the power supply provides the

designed capacity in theory and in real-life applications without regard tothe stability of the supply signal.

2. To be able to compare the difference, if any exists, of the theoretical

expectation and the practical data obtained from the finished device.

Materials: 1. NI MultiSim 13.0

2. Power Supply Prototype3. Multimeter

4. Computer Unit

Procedures: PART I (MultiSim)

1. Construct the circuit as indicated in the schematic diagram in Figure 2.6

above. Ensure that the correct values for the resistors and capacitors areused and that the correct model and build for the diodes and the IC

regulator is observed.

2. Use the built-in oscilloscope function and tap the input terminals to theoutput connection in. Ensure the correctness of the wire polarity.

TAP HERE


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3. Run the simulation then slowly turn the designed selector switch to go

through the various voltages provided. Take good note of the

measurements of the voltage.

Table 3.1.1 Voltage output relative to Resistance values (Selector Switch)

Resistance Theoretical Output Voltage(Preset Switch Position)

Position 2

Position 3

Position 4

Position 5

Position 6

PART II (Actual Prototype)

4. Construct the circuit as indicated in the schematic diagram in Figure 2.6



5. Set the multimeter to read DC voltage and tap its terminals to the output

terminals of the power supply as indicated in figure 2.4. Ensure the

correctness of the polarity of the wires of the multimeter to that of theoutput terminals.

6. Slowly turn the rotary switch, going through all the designed voltagesand measure the supply output. The selector switch is as indicated in

figure 2.4, with the leftmost position being the 1.5 volts output and theswitch turning clockwise in 5 positions.


Resistance Actual Output Voltage

0 Ohms (Preset Switch Position)

Position 2

Position 3

Position 4

Position 5

Position 6

6. Compute the percentage difference between the theoretical and practical

output values. Take note of them in the table below.


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Table 3.1.3 Percentage Difference between practical and theoretical output

Resistance Actual Output MultiSim Percentage

Difference

Position 1

Position 2

Position 3Position 4

Position 5

Position 6

Questions: 1. Did the power supply design in MultiSim performed exactly as expected?

Describe the values obtained.

2. When the design was executed practically. Did the finished Power Supply

replicate the performance of the simulation design in MultiSim?

3. Describe the discrepancies between the two obtained figures if thereexists some. What couldve caused them if so?

4. What factors affect the performance of a circuit in computer simulation

and in real-life?

Conclusions:

3.2. Theoretical and practical active output verification of the design

Objective: 1. To verify whether the design power supply will give a stable andaccurate voltage with the presence of a current-drawing load.

2. To understand the operation of an IC voltage regulator.

Materials: 1. NI MultiSim 13.0

2. Power Supply Prototype3. Multimeter

4. Computer

Procedures: PART I (MultiSim)

1. Construct the circuit as indicated in the schematic diagram in figure 2.6




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2. Add a 12v1w lamp at the output side of the circuit similar to the first

experiment and wire a voltmeter parallel with the lamp in order to measure

the voltage drawn by the load.

3. Run the circuit starting from 1.5v up to the 5v position and record the

voltage reading. Take good note of the stability of the DC voltage by usingthe oscilloscope function. Record the results in the table below.

5

.

6

4

PART II (Actual Prototype)

4. Set the power supply to the lowest output then wire a 12v lamp to theoutput side of the supply. Consequently, use a voltmeter to measure the

voltage across the lamp. Use the table below to record observations. Take

good notice of the performance of the lamp and the stability of the voltage.

Questions: 1. Is the supply provided by the power supply stable? Can the supply

provide adequate current to run the electrical component required?

2. Are the values obtained from measuring using the computer software and

from the finished product the same? If it is not, what can cause these

deviations?

3. What is the maximum power rating and voltage of an electrical

component which the device can theoretically run? Explain the logic behind

the answer.

4. Why is the IC regulator important in the performance of a power supply

circuit?

Table 3.2.1 Voltage Reading (MultiSim)

Expected Voltage Active Voltage (With Load)

1.5v

3v

4.5v

5v

6v

9v

Table 3.2.2 Voltage Reading (Practical)

Expected Voltage Active Voltage (With Load)

1.5v3v

4.5v

5v

6v

9v


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3.3. AC-DC Signal ConversionSupply Rectification

Objective: 1. To be able to observe the process of AC Signal Rectification and toverify the DC signal consistency of the finished power supply

2. To understand the operation of the diode bridge rectifier

Materials: 1. Oscilloscope

2. Power Supply Prototype

3. Multimeter4. Connecting wires

Procedures: 1. Tap the Oscilloscope to the output terminals of the finished power

supply. Ensure that the Oscilloscope is affixed to the correct settings andthe power supply is turned off.

2. Turn on the Power Supply and observe the signal visualization on theOscilloscope. Draw the output waveform below.

3. Tap the Oscilloscope terminals on the position identified on the figure.This is to see the signal output after the rectification process.

TAP HERE


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4. Observe the output waveform produced through the oscilloscope and

draw the output waveform in the space provided below.

5. Tap the oscilloscope terminals in the identified points below. This

would show the waveform before rectification. Ensure that correct

oscilloscope settings are observed in order to prevent damage to thedevice.

6. Draw the output waveform in the space provided below.

Questions: 1. Differentiate the output waveforms of the three points measured using

the Oscilloscope. Identify below what caused these waveforms.

2. State the importance of the rectification process in the production of

power supply units.

3. What happens if the power supply would not be able to provide

consistent DC voltage.

TAP HERE


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Part IV

RESULTS AND DISCUSSIONS

4.1 Results of Experiment 1: Resistance input for Variable IC Regulator

Results of Table 1

Results of Table 2

Results of Table 3


Resistance Theoretical Output Voltage

0 Ohms (Preset Switch Position) 1.504 Volts

Position 2 3.012 Volts






Resistance Practical Output Voltage

0 Ohms (Preset Switch Position) 1.50 Volts






Table 4.1.3 Percentage Difference between practical and theoretical output

Resistance PracticalOutput

TheoreticalOutput

PercentageDifference

Position 1 1.50 1.504 0.27%

Position 2 3.00 3.012 0.41%

Position 3 4.51 4.521 0.24%

Position 4 5.00 5.010 0.20%

Position 5 6.04 6.038 0.03%

Position 6 9.09 9.037 0.58%


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Questions: 1. Did the power supply design in MultiSim performed exactly as expected?

Describe the values obtained.

Answer: The circuit performed as expected as it prudently produced the

desired voltages that correspond to the resistor amounts with very little

deviation from the expected outputs.

2. When the design was executed practically. Did the finished Power Supply

replicate the performance of the simulation design in MultiSim?

Answer: Yes. Similar to the design simulation in MultiSim, the actual

prototype successfully replicated the performance of the simulation with

very little deviation from the output.

3. Describe the discrepancies between the two obtained figures if there

exists some. What couldve caused them if so?

Answer: There were very little discrepancies and differences between the

two obtained values; All of them never exceeding one percent deviation.

The very slight differences couldve been caused by a rounding error orimprecise calibration of the multimeter used to read the practical values.

4. What factors affect the performance of a circuit in computer simulation

and in real-life?

Answer: Several factors exist which will likely cause the values obtainedfrom practical and theoretical observations to deviate from each other. First

is the level of calibration of the multimeter used to measure real-life values.

It is because the software used to simulate the circuit is highly precise andany deviation will likely come from the multimeter. Also, discrepancies

could come from the circuit build given that the materials and circuit

components that the researchers use arent perfect and that they may beharboring discrepancies. Finally, other factors like the environment to which

the testing is performed and the quality of the instruments used all affect the

values although by only a small factor. There is also the factor of the

ambient temperature of the device and that of the regulator which may causesignificant deviations if not controlled. This is because as the temperature of

the unit and the room rises, the components behave differently from the

standards.

Conclusion: The device is able to supply the correct voltage as per required by the

design. This is with the use of exact values of components as much aspossible in order to replicate the performance of the design. Also, the

theoretical obtained values can and would vary from the practical output

because of already mentioned factors and environmental considerations.


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4.2 Results of Experiment 2: Theoretical and practical active output verification of the

design

(Figure 4.1-4.2 Circuit performance at 5v and 4.5v respectively)

Results of Table 1

Table 4.2.1 Voltage Reading (MultiSim)

Resistance Theoretical Output Voltage

1.5v 1.504 Volts

3v 3.012 Volts4.5v 4.521 Volts

5v 5.010 Volts

6v 6.038 Volts

9v 9.037 Volts


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Results of Table 2

Questions: 1. Is the supply provided by the power supply stable? Can the supply

provide adequate current to run the electrical component required?

Answer: The power provided by the supply is stable given that in both

instances of experimentation, MultiSim and practical, the circuit did not

exhibit any signs of instability e.g. signal fluctuations in oscilloscope for

MultiSim and flickering for Practical. It can also be verified that the supplycan provide adequate current to run the electrical component specified given

that it has a very able transformer at 2A.

2. Are the values obtained from measuring using the computer software and

from the finished product the same? If it is not, what can cause these

deviations?

Answer: There were slight deviations from the computer simulator obtained

values. These can be caused by the accuracy of the multimeter used, the

quality of the bulb load powered by the circuit and other external factorswhich would likely cause any deviation from the ideal, theoretical amount.

3. What is the maximum power rating and voltage of an electricalcomponent which the device can theoretically run? Explain the logic behind

the answer.

Answer: Theoretically, the power supply can power a device with a voltagerating of 9v and a power rating of 18w in full capacity. This is because the

device is equipped with a 2A transformer which, when multiplied with the

maximum voltage provided at 9v, can provide for an 18w device. This is

without taking into consideration other factors such as the heat dissipationability of the regulator.

4. Why is the IC regulator important in the performance of a power supplycircuit?

Table 4.2.2 Voltage Reading (Practical)

Resistance Practical Output Voltage1.5v 1.491 Volts

3v 2.994 Volts

4.5v 4.55 Volts

5v 5.064 Volts

6v 6.071 Volts

9v 9.14 Volts


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Answer: The IC regulator plays an important role in a linear power supply

because it allows the supply to provide a consistent voltage regardless of

whether a current-drawing load is powered by the device or not. This isbecause, without the regulator, the voltage deliverable by the device would

fluctuate heavily and would cause damage to the device or simply wouldnt

be able to power the device anymore.

Conclusion: It is important to know the exact specifications of the device by performing

an analysis of the power and voltage ratings of the components used anddetermining the maximum tolerable values for the output load. The voltage

regulator performs an important job of ensuring the stability of the voltage

and making sure that the device receives a consistent amount of voltage.

4.2 Results of Experiment 3: AC-DC Signal Conversion Supply Rectification

After Filtering After Rectification


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Before Rectification

Questions: 1. The output waveform before rectification, that is, through the transformer isthat of an AC signal which is sinusoidal in nature with peak voltage of 12

13 volts. After the signal has passed through the bridge rectifier, the signal is

then converted to a full-wave signal in order to begin the process of DCconversion. After it has passed through the main capacitor filter and the RC

filters, it is now a straight line which signifies full DC conversion.

2. Signal rectification is a very important process in the production of powersupply units because it is important that AC electricity be effectively

converted to DC signals in order to power electrical components

consistently. Rectifiers form the backbone of DC Power supplies and areessential in their functions in converting signals.

3. If the power supply would not be able to provide DC voltage consistently,damage could be sustained by the load device because most devices are

designed to perform with DC electricity than AC power. If in the case that

the device is not damaged, it wouldnt be able to perform its specification

effectively because incorrect electricity is being provided.


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REFERENCES

Abayte, A. (1945, July). Basic Theory and Design of Electronically Regulated Power

Supplies.Proceedings of the IRE. Retrieved December 20, 2013, from

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=1696888&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F10933%2F35749%2F01696888

Agelidis, V.G. "The future of power electronics/power engineering education: challenges

and opportunities", Power Electronics Education, 2005. IEEE Workshop

Doval-Gandoy, J.; Castro, C.; Martinez, C. "Line input AC to DC conversion and filter

capacitor design", Industry Applications Conference, 2002. 37th IAS Annual Meeting.

Conference Record of the, On page(s): 2530 - 2535 vol.4 Volume: 4, 13-18 Oct. 2002

Cartwright, K.V. "Further results related to power supply design and analysis in the

undergraduate curriculum", IEEE Transactions on Education, Volume.44, Issue.3,

pp.262, 2001, ISSN: 00189359,

Doval-Gandoy, J.; Castro, C.; Martinez, M.C. "Line input ac-to-dc conversion and filtercapacitor design", IEEE Transactions on Industry Applications, Volume.39, Issue.4,

pp.1169, 2003, ISSN: 00939994,

G. Rizzoni, Principles and Applications of Electrical Engineering, 1993

A. S. Sedra and K. C. Smith, Microelectronic Circuits, 1991. Saunders College

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