Faculty of Sciences
Department of Physics
University of Central Punjab
Lahore
Design & Implementation of Variable DC Power Supply Using Adjustable Voltage Regulator
(Session 2018-22)
Submitted By
| Registration No. | Name |
| B1F18BSPH0009 | Samia Asghar |
| B1F18BSPH0013 | Shahzaib Awan |
| B1F18BSPH0026 | Mariam Khalid |
DEPARTMENT OF PHYSICS
FACULTY OF SCIENCES
UNIVERSITY OF CENTRAL PUNJAB
(2022)
University of Central Punjab
FACULTY OF SCIENCES
__________________________________________________
Certificate from Supervisor
The undersigned here by certify that I have read the project title “variable dc power supply using adjustable voltage regulator” bySamia Asghar, Shahzaib Awan and Mariam Khalid. I recommend the submission of the project to the Faculty of Sciences in partial fulfillment of the requirements for the degree of Bachelor Studies.
Supervisor: ____________________
Prof. Dr. Abdul Kareem Khan
Associate Professor
Head of Department
Department of Physics
Faculty of Sciences
UniversityofCentralPunjab
University of Central Punjab
FACULTY OF SCIENCES
__________________________________________________
Project Evaluation Committee
The viva voice examination of Samia Asghar, Shahzaib Awan, and Mariam Khalid (B1F18BSPH0009), (B1F18BSPH0013) and (B1F18BSPH026)session 2018-22 was held on 24-06-2022at at the Faculty of Sciences, University of Central Punjab. The committee recommends the award of the degree of BS Physics.
Project Evaluation Committee:
Names of Members
- Dr. Abdul Kareem Khan 2. Prof. Dr. Tariq Bhatti
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| Muhammad Aurangzeb | |
| Dean | |
| Faculty of Sciences, UCP |
Dedicated to
Our Beloved Parents
Contents
Contents…………………………………………………………………………………..….4
Acknowledgments……………………………………………………………………………6
Abstract………………………………………………………………………………….……7
List of figures…………………………………………………………………………………….8
List of Tables………………………………………………………………………….….…10
Abbreviations…………………………………………………………………………………11
Chapter-01…………………………………………………………………………………….12
- Introduction………………..………………………………….…………………….…13
- Component Description……………….………………………………………………..14
- The transformer…………….…………………………………………………….….…9
- The Rectifier Circuit…………………………….………………………….….…….….9
- Voltage Regulator…………………………….………………………………………………10
- Component List…………………………………………………………………………15
- Charging Formation by Variable Power Supply.….…………………………….….….16
- Applications…………………………………………………………………………….16
- Working…………………………………………………………………………………17
- Working Principle……………………………………………………………….………17
- Battery Charger on the basis of Power Supply…………………………………….……18
- Working………………….…………………………………………………………………..19
- Component Description……………….………………………………………………..14
1.5 Bridge Rectifier……………………………………………………………………….……20
Chapter-02…………………………………………………….…………………….……….21
- Materials and Methodology……………..…………………………………………….15
- Materials……………………………………………………….……………..…………22
- PCB…………………………………………………………………………………….22
- Voltage Regulator…………………………………………………………………………23
- Potentiometer………………………………………………………………..…………23
- Resistors………………………………………………………………..………………25
- Diodes……………………………………………………………………..……………26
- Filter Capacitor…………………………………………………………..…………….27
- Step-Down Transformer ……………………..……………………….……………………29
- Digital Multimeter……………………………………………………..…….…………29
- Materials……………………………………………………….……………..…………22
2.2 Methodology……………………………………………………………..….……………29
Chapter-03……………..……………………………….…………………………..………..31
- Project Work…………………………………………….…………..…..…………….32
- Figures of Project Work …………………………………….……………..……………35
Chapter-04……………………………………..…………………………………………..37
- Results & Discussions……………………………………..…………………………38
- Results…………………………………………………..…………………………….38
- Discussions………………………………………………..………………………….39
- Conclusion…………………………………………………………………………….39
- Future Plan ……………………………………………………………………………40
References…………………………………………………………………………………..41
Acknowledgments
First & foremost, we thank ALMIGHTY ALLAH for the protection and ability to do work & we ask the Almighty to keep showering the blessing upon us, our families, teachers, friends & colleagues as always.
We would like to express our special appreciation & and gratitude towards our tremendous mentor professor Dr. Abdul Kareem Khan. Our deep thanks to for encouraging our research and guidance. His priceless advice on both research & our career made our stumbling journey to go rather smoothly. We are very grateful to Sir Ameer Hamza who helped us in completing our project. We would also like to thank our families, friends & classmates for their productive critics, which made our work challenging & exciting & got our going to hit the final score.
A special thanks to all the staff & leadership of Department of Physics for setting the ground and arrangements in completion of this project report. Words cannot express how grateful we are to our educational institute, University of Central Punjab for taking us in as students $ making us what we are today.
At the end we would like to express appreciation to our beloved parents, siblings who spent most of their time helping & guiding us through every minute of our life to achieve our life’s goal. They literally made our life’s business their own a& supported us day & night practically, economically, socially & emotionally. Their presence by our shoulders never made us reluctant or afraid thus making it possible to coming to its happy ending & moving forward to next step in our life.
Samia Asghar Shahzaib Awan Mariam Khalid
B1F18BSPH0009 BF18BSPH0013 B1F18BSPH0026
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Abstract
Power supplies deliver voltage to each and every constituent in the system, letting them to function. It is the heart beat of the system, and brought power functions similarly as blood in human body. So, we are working on it and making it more useful. We’re making such power supply which is giving the output voltage in such a way that we can charge a battery of any voltage 1.5V to 15V.We had developed our project with electronic material that is cheap and easily available in the market. We want to introduce this technology commercially available in the market. The basic ideaof this project is the whole wave rectification to get the variable power supply, which is done by a bridge configuration. For reducing the voltage according to our requirements, we’re using four diodes to make bridge rectifier which then rectify the output of the step-down transformer.To make availableunremitting input to the regulator, we employ two capacitors, C1 and C2. In addition, it aids in plummeting the strong peaks of output. To decrease the noise and ripples produced by the regulators, 3300 capacitor is operated in order to get the controlled output to have lessripples. We’re toooperatingan Adjustable voltageregulator thatis IC LM317, to offer a steady voltage of 1.5Vs to 15Vs. Now the main purpose is to get the variable voltage, thatis done with the aid of a voltage dividing resistor of 220 and to regulate the output voltage we are using potentiometer of 50 in which the resistance is changeable. As a result, if we vary the rate or value of the resistor, the productive voltage of the regulator also will be changed, given the variable voltage choiceof 1.5V to 15V. Hence the most important benefit of this variable power supply is that we can charge a battery of any voltage range 1.5V to 15V which isn’t done before.
List of Figures
Figure 1.1:Variable Dc Power Supply……………………………………………………14
Figure 1.2: Circuit Diagram of DC Power Supply……………………………….……..…15
Figure 1.3: Working Principle of IC LM317………………………………………………17
Figure 1.4: Rechargeable Batteries………………………………………………………..18
Figure 1.5: Charger of Rechargeable Batteries……………………………………………19
Figure 1.6: Bridge Rectifier……………………………….………………………………20
Figure 2.1: PCB………………………………………………….…………………………22
Figure 2.2: LM317 Voltage Regulator………………………………………………….…23
Figure 2.3: Potentiometer…………………………………………….…………….………23
Figure 2.4: Working of Potentiometer………………………………….………….………24
Figure 2.5: Working Principle of Potentiometer……..…………………………….……..24
Figure 2.6: Resistors……………..……………………………………………….……….25
Figure 2.7: Symbols of Resistors………………………………………………….………25
Figure 2.8: Diodes………………………………………………………………….…..….26
Figure 2.9: Capacitor……………………………………………………………….……….27
Figure 2.10: Step-Down Transformer………………………………………….….….. ….28
Figure 2.11: Multimeter……………………………………………………………….……28
Figure 3.1: Transformer with the bridge Rectifier…………………………………….……32
Figure 3.2: Connection with Capacitor……………………………….…………………….33
Figure 3.3: Connecting IC LM317 with above connections………………………..…………34
Figure 3.4: Final Variable Power Supply Circuit………………………………………………34
Figure 3.5: Rectification of ripples……………………………………………………..….35
Figure 3.6: Project Model………………………………………………….……………….36
Figure 3.7: 3d Diagram of Model………………………………………….……….….….37
Figure 4.2: Graph b/w Variable Resistance & Output Voltage……………….….….…….39
List of Tables
Figure 4.1: Output Voltage Calculation………………………………………………………38
Abbreviations
DC: Direct Current
AC: Alternating Current
PCB: Printed Circuit Board
Chapter-01
Introduction
Chapter-01
- Introduction
A single DC signal is provided by a fixed DC variable power supply. A variable DC supply supplies DC power in a variety of quantities. For instance, if you want 10 Volts DC, you can choose that option. However, if you require 15 volts DC, you can alter the setting to obtain 15 volts DC. One of the most useful equipment on an electronics hobbyist’s workbench is a variable dc power supply. This circuit isn’t groundbreaking, but it’s easy to use, dependable, “rugged,” and short-proof, with variable voltage up to 24V and variable current limiting up to 2A. You can change it to fit your needs. One of the most useful equipment on an electronics hobbyist’s workbench is a variable dc power supply. This circuit isn’t groundbreaking, but it’s easy to use, dependable, “rugged,” and short-proof, with variable voltage up to 1.5V and variable current limiting up to 2A. You can change it to fit your needs. (By &By, 2014)
A voltage regulator that is used in a variable power supply used by linesmen and electrical venture hobbyists to verify the power capacity of any project they have done. The power supply is used as a device to safeguard that the work the person has accomplished can toleratedefinite voltage and current loads. To check the constancy of the circuit the one has produced, tests are usually taken on by put on varied levels of voltage to the accomplished work at a time. These power foundations are also used by summonsartistes to power tattooing armaments and hobbyists to control small microchip technology that require variable voltage.(By & By, 2014)
The variable power source charger is made up of a number of different electrical and electronic components that have been grouped together for ease of understanding:
- Units for power supply
- The circuits that smooth things out
- The regulating unit and
- C. charging units that are regulated
1.1 Component Description
1.1.1 The Transformer
The transformer’s job is to reduce the ac voltage to a level that is safe for humans to handle.
1.1.2 The Rectifier Circuit
Because the battery is a dc component that requires dc voltage to charge, the rectifier circuit transforms ac voltage to dc voltage.
1.1.3 Voltage Regulator
The voltage regulator ensures that the battery is charged at a steady voltage.
1.2 Components List
IC = LM317 EMP Adjustable Voltage Regulator
D1-D4 = 1N4007 Rectifier Diodes
C1 = 3300µF 25V Filter Capacitor
R1 = 220Ω, R2= 50
For variable power supply charger, the above components are connected in the diagram.
1.3 Charging Formation by Variable Power Supply
Charging methods are usually divided into two groups when it comes to battery charging.
Fast charging: is a battery-recharging mechanism that takes one or two hours to recharge.(Parida et al., 2017)
Slow charging: An overnight recharge is commonly described as anindicting current that can be delivered to the battery-operated endlessly short of harming the cell. (Trickle charging is another name for this practice.) When a cell is completely charged, continuing charging reasons gas to develop inside the cell. The maximum degree of dribble charging that is safe for a specific cell sort is dependent on both the battery interaction and the cell structure. All the gas produced essentially be able to recombine internally, or the compression within the cell will accumulates, causing gas to escape through the interioropening (which lessens the life span of the cell). This means that the maximum safe trickle charge rate is greatly dependent on both battery chemistry and internal electrode architecture.(Breitsprecher et al.,2018).
1.3.1 Applications of variable Power Supply
- The individual is able to consider any temperaments or contradictions in the circuit he’s settled by using such a variable power supply, allowing foralterations without having to abandon the whole project. Any experienced with electrical circuitry and components will bargain a variable power supply accessible. It may be used for a lot more than fairchallenging.
- This sort of power supply can also be operated by small hobbyists in addition to testing circuits. People who work with miniature electrical railway sets, for example, frequently employ such gadgets. The train can be speed up or slowed down by adjusting the power supply as it is driven about the pathway by the completed circuit’s power.
- The tattoo business is another typical application for this type of power supply. Tattoo artists utilize variable power supply on a daily basis to modify the strength and speed of the motor on their signal guns so as to get the wanted result with the tattoo pointers they are working with. When a signal artist is exactness a new work, for example, the gun’s speed is raised via the power supply, causing the pointer to travel quicker and create a more reliablerough draft. The power supply is utilized to slow down the needle when the artist is darkening a region of the skin in order to achieve consistent color coverage within the tattoo. (Shafiei et al., 2018)
1.3.2 Working
The voltage that is sent from the actual power source to the circuit is controlled or amplified by a variable power supply. When an electrical train hobbyist starts his train on the track, he doesn’t simply jest a switch and set it on complete blast; as a substitute, he supplies minuteadditions of voltage to the circuit through the controlled variable power supply up until the train reaches the proper speed. The voltage ranges of most conventional variable power supplies range from 1-3volts to 20-30volts, while extensive variable power supplies can have range from 6,000- 20,000 volts, however these power provisions are normally first utilized in manufacturing. (Muniraj, 2016)
1.3.3 Working Principle
The elementary principle of this working is full wave refinement, which is done using a bridge configuration in which four diodes refine the output of a step-down transformer that alters 220 ac volts to 12 ac volts. Here we are employing voltagecontroller that provides a steady voltage, the LM317.
A voltage regulator that outputs 6 volts These controllersoriginate in a variety of outputvoltages, as well as 6 volts, 8 volts, 9 volts, 12 volts and 15 volts.
Now the main mission is to come with variable output. For this, we use a duo of voltage divider resistors to rise the output of the regulator, to each of which has aadjustable resistance, so as we intensification or lessening the value of that resistor, the output voltage of the regulator changes as well, giving us a range of 0 to 12 volts. The filter capacitor is used in this circuit to provide a steady input to the regulator, in addition to decrease the unforeseen peaks in the output. Link the 3300-F capacitor to the input of the regulator and the 100-pF capacitor to the yield because these capacitors help to reduce noise and the ripples that is produced by the regulator, ensuing in a regulated output with lessundulations/ripples. (Fulfilment, n.d.)
1.4 Battery Charger on the basis of Variable Power Supply
A battery charger system collects energy from the grid, stores it in a battery, and thenuses it to power a device. A battery charger is an electrical and electronic expedient that drives an electrical current through a subordinate cell or rechargeable battery-operated to infuse energy into it. The type and the size of battery that is being charged influence the charging mechanism of a battery charger. Approximately battery sorts can be re-energized by linking to a continuous voltage or continuous current basis; simple chargers of this kind require human discontinuation at the end of the charge cycle, or may comprise a timer to turn rotten charging current at a predetermined interval. Additional battery kinds aren’t compatible. This charger might includevoltage and temperature monitoring tours, as well as a microchipregulator to regulate the indicting current and turn off at the end of the charge. A dribble charger delivers a slight amount of current, just sufficient to keep a battery from self-discharging after a long period of inactivity. Slow battery chargers can receipts many hours to charge; high rate chargers, on the other hand, can reinstate most dimensions in minutes or less than an hour, although they normally need battery controlling to avoid overcharging. (Praneeth & Williamson, 2018)
Figure 1.4 fig of rechargeable batteries
1.4.1
Working
Figure 1.5 fig of charger of rechargeable batteries
A battery converts chemical energy stored in the battery into electrical energy. When the electrolyte in the battery runs out, it must be revived. A battery charger is a stratagem that delivers DC to the battery to refill depleted electrolyte. As a result, once all of the electrolytes have been replenished, the battery’s current supply should come to an end. The complete charging process consists of charging, stabilizing (optimizing the charging degree), and dismissing (knowing when to stop charging). The C-rate (Charge Rate) signified the charging and discharging rates of our batteries. It refers to the rate at which a battery is charged or drained in relation to its capacity. If a completely charged 4Ah battery is discharged at a 4-ampere rate, it will income an hour to completely charge. The majority of current electronics, such as cell phones, electric autos, and laptop computers, use lithium When a battery is fully charged, it should stop charging immediately. Standard chargers, on the other hand, have no way of knowing when the battery is fully charged and keep providing power. This is why batteries heat up: it’s their way of releasing the extra power they’ve been given. Overcharging a battery not only harms it, but it also reduces its life span. (De Souza et al., 2021)
Some of the several forms of battery chargers are a dribble, time-based, simple, shrewd charger, pulsation, motion-powered, solar, fast, and three-stage charger. A charger is made for a precise battery based on the quantity of power it can deliver and the amount of while it takes to completely charge it. This means that the charger meant for one battery could not work with another. According to the producers of gadgets, chargers should be purchased from the same brand as the batteries. Avoid charging batteries of different capacities or chemistries together to get the most out of your battery charger. This can damage batteries over time. (De Souza et al., 2021)
1.5
Bridge Rectifier
In general, in comparison to the half-wave rectifier’s output, a full-wave rectifier can be drawn to achieve the smoothening value of the Dc as output. The circuit, however, still has some ripples in the rectifier’s output. As a result, a filter circuit is built into the bridge rectifier to eliminate these waves. Receiving the output in its pure DC form becomes easier as a result of this. Capacitors can be used to decrease unwanted pulsing AC impulses. As a result, the capacitor filter has a wide range of uses. It could be able to get rid of the circuit’s waves. (Saied, 2020)
Chapter-02
Materials and Methods
- Materials and Methodology
2.1 Materials
- PCB
- Adjustable Voltage Regulator
- Potentiometer (50k)
- Resistor (220)
- Diodes
- Filter Capacitor (25v)
- Step Down Transformer(12v)
- Digital Multimetre
2.1.1 PCB
The printed “printed circuit board” is often used, although “printed wiring boards” or “printed wire cards” can also be used. We utilize soldering to attach our devices to a PCB board.A PCB (printed circuit board) uses conductive bars, pads, and other topographiesimprinted from one or more sheet coatings of copper fused ontoor between sheet coatings of a non-conductive substrate to automaticallyprovision and electrically link electrical or electricapparatuses. As illustrated in the diagram, the holes are joined in rows both horizontally and vertically. (Işıldar et al., 2016)
2.1.2 Voltage Regulator
Any electric or electrical device that retains the voltage of a power source within satisfactory limits is identified as a voltage regulator. The voltage regulator is obligatory to keep voltages within the suitable range for electric equipment that uses that voltage. This type of gadget is normallyworking in all types of automobiles to regulatethe outputvoltage of the generator to the electrical load and the battery’s charging necessities. Voltage regulators are also working in electrical devices where extreme voltage changes might be damaging. (Udayasri et al., 2016)
Figure 2.2 LM317 Voltage Regulator
2.1.3 Potentiometers
Potentiometer (also identified as a pot meter) is a three-terminal adjustable resistor that may be physicallyattuned to switch the flow of electric current. A potentiometer is a voltage divider that can be attuned.(Li et al., 2021)
Figure 2.3 Potentiometers
§ Working
A type of electronic components is a potentiometer that is not active. Potentiometers switch the location of a sliding contact across anunvarying resistance by changing its location. The full input voltage is applied over the whole length of the resistor in a potentiometer, the difference of the voltages between fixed and sliding contact is shown
below.
Figure 2.4 Working of Potentiometers
The two stations of the input source are secure to the end of the resistor in a potentiometer. The sliding contact on the output side is stimulatedend to end the resistor to vary the output voltage. (Shenet al., 2021)
§ Working Principle
This is a very elementary instrument that may be used to comparation the emf of two cells in addition toregulate ammeters, voltmeters, and watt meters. A potentiometer’s rudimentary operation is comparativelyupfront. Assume that we’ve used a galvanometer to link two batteries in parallel. As represented in the diagram below, the negative battery terminals and positive battery terminals are associated via a galvanometer.
Figure 2.5 Working Principle of Potentiometer
If the electric potential of both battery cells is exactly the same then there will be no circulating current in the, hence the galvanometer shows no deflection. This phenomenon is crucial to the action of a potentiometer. (Zhou et al., 2021)
2.1.4
Resistors
Figure 2.6 Resistors
A resistor is a passive electrical component with two terminals that opposes or limits current flow. Ohm’s law defines that “voltage put across the stations of a resistor is straightly proportionate to the current flowing over it.” Resistors work on this concept. (Chappell et al., 2016)
§ Purpose
To reduce the current flow and lower the voltage in a certain area of the circuit is the primary function of the resistors. It included of copper wires that are enfoldedround a ceramic rod and have ashielding paint covering on the exterior.
They have the SI unit ohm.
- Symbols
Figure 2.7 Symbols of Resistors
To each resistor has two stations and one connecter. We’ll look at the three different sorts of symbols used to signify a resistor. To each of the lines approaching from the scribble are the resistor’s terminuses (or rectangle). These are the wires that connect the circuit to the rest of the mechanisms. Both a resistance rate and a name are normallygot into resistor circuit cryptograms. The ohms value is clearly important for both analyzing and in factmaking the circuit.
2.1.5
Diodes
Figure 2.8 Diodes
A diode is an electricconstituent that only allows current to flow in one direction.
The most common type of diode is the p-n junction diode. One type(n) with electrons as charge transporters abuts another type(p) with holes (places exhausted of electrons that act as positively charged elements) as charge carriers in this sort of diode. A depletion area generates at their boundary, via which electrons diffuse to seal holes in the p-type. This effectively halts the flow of electrons. When this junction is forward biased (that is, a positive voltage is supplied to the p-side), electrons can readily migrate across it to seal the holes, causing current to flow over the diode. The depletion region widens when the junction is reverse biased (that is, a negative voltage is supplied to the p-type), making electrons difficult to travel across. The current remains very low until a particular or breakdown voltageis attained, the current surges intensely at that point.. (Zou et al., 2017)
Diodes are utilized in the radio and television industries for a variety of signal transmission applications.
- Diode Symbol
2.1.6 Filter Capacitor
A capacitor is anexpedient that supplieselectric energy in the form of an electric field and is made up of two conducting plates with an insulator between them. A capacitor is used in a timing circuit with a resistor to block DC signals while allowing AC signals.
Figure 2.9Filter Capacitor
The symbol for a filter capacitor is displayed below.
A basic parallel plate capacitor is what it is. Its link to the circuit, however, distinguishes it. When it comes to signal limiting, a ceramic capacitor is sometimes preferable. (Parida et al., 2017)
§ Working
The capacitive reactance principle governs the operation of this capacitor. The term capacitive reactance refers to how the impedance value of a capacitor changes as a result of the frequency signals that flow through it. Consider the resistor in the circuit as an example. The device’s resistance cannot be changed; it always provides the same resistance depending on its predetermined value. However, the capacitance of a capacitor varies. Because of the applied frequency value of the signals, the capacitance is influenced. As a result, these devices are known as reactive devices. Because of the presence of this sort of capacitor in the circuit, the impedance value changes. If the frequency signals have a high value, the resistance given by that particular capacitor will be low, and vice versa. As a result, the resistance and frequency of the signals are inversely proportional to each other.
- Filter Capacitor Circuit to Block DC and Pass Ac
As previously stated, it provides low resistance to high-frequency impulses while providing great resistance to low-frequency signals. To prevent DC, we must broadcast high-frequency signals. The constructed circuit serves as a high pass filter in this example. However, in some circumstances, a circuit requires both DC and AC signals. In this scenario, the use of a microphone is the finest illustration. To start the circuit, the initial current must be DC. At the output, the AC signals are then transferred and received. The capacitor in the circuit has a value of about 0.1 microfarads, which allows it to block DC values while allowing AC signals to pass through.
- Applications
This sort of capacitor is quite useful in a variety of circuits. The following are some of the filter capacitor’s applications:
- High pass filters, low pass filters, and other analogue filters are designed in this way.
- Line filters are included into television sets to prevent images from flickering.
- As protective circuits, where significant loads, such as air conditioners and refrigerators, are a problem.
- Generally, these are chosen in signal processing.
- As a result, the filter capacitor has several applications in a variety of industries. Let’s look at why the capacitor filter is so important in the bridge rectifier circuit.
2.1.7
Step-down Transformer
Figure 2.10Step-Down Transformer
It’s used to alter high-volt AC to the low-volt AC. The primary coil’s current is lower than the secondary coil. The primary coil has a greater number of turns than secondary coil. The applied voltage diagonally the primary coil is smaller than the induced voltage across the secondary coil, or voltage is stepped down. The wire in the secondary coil is thicker than wire in the primary coil. (Kondrateva et al., 2020)
2.1.8
Digital Multimetre
Figure 2.11Digital Multimetre
A digital Multimetre is a tool for measuring electric current (amps), voltage (volts), and resistance (ohms) (ohms). It can measure both AC and DC voltage and is ideal for debugging circuits. (Da Costa et al., 2021)
2.2 Methodology
- To begin, we connected two transformer wires to the rectifier. Because the transformer is rated at 12 volts, we can expect a 12-volt AC output.
- After passing through the rectifier, the low AC output is transformed to DC voltage.
- This DC voltage is then sent into a filter capacitor, which filters the voltage or serves as a filtering device.
- The filtered DC voltage has now entered the voltage regulator. The voltage regulator has a movable pin that is connected to a variable resistor.
- One terminal of the variable resistor is linked to the voltage regulator, while the other is grounded. As a result, the voltage between the two terminals may have been altered.
- We now connected a feedback resistor to the voltage regulator’s adjustable pin and output.
- This completes the circuit for a variable power supply. We can now charge our battery, and we can surely charge our battery if we set up our output.
- Hence by using this variable power supply circuit we can charge battery of any voltage 1.5V to 15V.
Chapter-03
Project Work
- Project Work
Step 1: We assembled all the components
- PCB
- Adjustable Voltage regulator
- Potentiometer
- Step down transformer (12v AC)
- Resistor
- Diodes
- Capacitors
- Digital Multimetre
Step 2: We connected 12v AC transformer with the bridge rectifier. This rectifier which is made by using 4 diodes gives full wave rectification. It means this rectifier corrects the output of the step-down transformer.
Figure 3.1Connecting Transformer with the Bridge Rectifier
Step 3:Next we connected a filter capacitor of 3300F to filter out the dc voltage coming from the rectifier
Figure 5‑3.2 Connecting Bridge Rectifier with Filter Capacitor
Step 4:In this step we connected LM317 voltage regulator and a resistorof 220with the terminals of capacitor and the voltage regulator.
Figure 3.3 Connecting IC LM317 with above connections
Step 5: The variable power supply circuit is ready now. We can charge any battery of voltage 3v,6v,9v and 12v by using this variable power supply system.
Figure 3.4 Final Variable Power Supply Circuit
Step 6: this power supply also giving rectification of the transformer’s output shown in figure below.
Figure 3.4:Full wave Rectification
- Working
- Project Model
- 3d Map of the Model
Chapter-04
Results and Discussions
- Results and Discussions
4.1 Results
So, at the end of the day, we have a variable dc power supply that produces variable dc volts in the series of 1.5-15volts. We can’t come to be fewer than 1.5-volts because the output voltage of the regulator can be adjusted.
- Voltage Divider Formula
Table 4.1
Output Voltage calculation
| Resistance | Variable Resistance | Output Voltage(Volts) | |
| Sr. no | R1 | R2 | Vo |
| 1 | 220 | 0.18 | 1.50 |
| 2 | 220 | 0.68 | 2.18 |
| 3 | 220 | 1.37 | 3.10 |
| 4 | 220 | 2.10 | 4.09 |
| 5 | 220 | 2.83 | 5.05 |
| 6 | 220 | 3.78 | 6.32 |
| 7 | 220 | 3.55 | 7.0 |
| 8 | 220 | 4.48 | 8.1 |
| 9 | 220 | 5.69 | 9.1 |
| 10 | 220 | 6.5 | 10.5 |
| 11 | 220 | 7.35 | 11.2 |
| 12 | 220 | 7.90 | 12.1 |
| 13 | 220 | 8.92 | 13.3 |
| 14 | 220 | 9.62 | 14.1 |
| 15 | 220 | 10.9 | 15.10 |
- Graph
4.2 Discussions:
Power supplies deliver voltage to each and every constituent in the system, letting them to function. It is the heart beat of the system, and the broughtpower functions similarly as blood in human body. Even the most influential high-end setup can be demolished in an instant if the transported electricity is faulty or may unstable. By making simple amendments, we can make this power supply really very useful at a large scale and also take the desired voltage ranges up to 15Volts. But the designed variable dc power supply is low cost and has a most important feature that we can charge batteries range from 1.5V to 15Volt that isn’t done before this research.
4.3 Conclusions:
The designed power supply is a profitablesubstitute to a more exclusive power supply. This power supply is fairly simple in plan and has only few components. It also covers a small area.
4.4 Future Scope:
In order to power smaller systems or devices, power supplies are employed in most residential and laboratory equipment. There are four segmental outputs of designed variable output power: a 5V fixed dc output, a 0-15V variable dc, and a regulated twofold rectified DC output of +12V and the –12V. Variable dc outputs ranged from 0 to 15 volts, while regulated twofold outputs generated 12 volts and the controlled dc will create 5 volts. The DC circuits were protected by a short circuit, while the AC circuit was protected by fuses. The developed power supply unit can carry out short circuit test and earthing test. The output dimensionspresented that the developed power supply was real and the measured values provided minimum disparity from the nominal. In this variable power supply LM317 has many future prospects. By using LM317 we can easily overcome the noise effect of the circuit and by changing the load resistance and voltage the noise effect can further be diminished. So that we can get a free output voltage. In other words, LM317 is highly proficient in making a circuit error free and flawless.
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