Variable Dc Power Supply Project Report 2h3m36

HITEC UNIVERSITY TAXILA CANTT Electrical department

BASIC ELECTRONIC PROJECT REPORT VARIABLE DC POWER SUPPLY

SUBMITTED TO: ➢ ➢

LECTURER:. Sir .OBAID SABIR LAB ENGINEER: SIR.

TABLE OF CONTENTS: HITEC UNIVERSITY TAXILLA CANTT

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Group . Introduction. Background. Abstract Method of procedure. 1. Circuit diagram. 2. List of components. 3. Pre-assembling on breadboard. 4. PCB making and soldering components. 5. Working. 6. Output voltage formula 7. Results.

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Conclusion. Refrencess

variable

Dc power supply

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GROUP : ZEESHAN KHAN (EE-151).(team leader) ZEESHAN MOHSIN (EE-150).

INTRODUCTION:

It is a simple variable dc power supply which gives 5 to 12 dc volts as an output.here we use a simple full wave rectifier along with a voltage regulator which give a constant output and its output can be increased by using a pair of voltage divider resistor in which one resistance is variable to get variable output.

BACKGROUND:

Our respectable teacher Eng obaid sabir give us a project to make a variable dc power supply We got the idea of this project while reading the full wave rectifier and almost every group use the full wave rectifier with little bit changing in their circuit.

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ABSTRACT: Here we make a variable

dc power supply and the main working principle of this project is full wave rectification which is done by bridge configuration in which we are using 4 diodes which rectifies the output of the step-down transformer which stepdown the 220 AC v to 9 AC volts .here we are using a voltage regulator which give constant voltage ,here we are using 7805 which give 5 volts . Now the main task is to get variable output for this we use the pair of voltage divider resistors to increase the output of the regulator and in which of resistance is variable so when we increase or decrease the value of that resistor the output voltage of the regulator will also change and we get a range of 5 to 12 v , here we can’t get less than 5 volts because of this is the output of the regulator In this circuit we use three capacitor , c1 and c2 are use to get constant input to the regulator moreover it also help to reduce the sharp peaks in the output . connect the 0.27 uF capictor to close to the input of the regulator and the 10 uf capacitor to the output because these capacitor reduse the noise and also help to reduse the ripples produce by the regulator so that regulated output has less ripples.

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METHOD OF PROCEDURE: This section include all the steps and the action we do for the making of our project and it also cover the method we adopt during the complication of our project.

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CIRCUIT DIAGRAM: The circuit we use for this project is given below.

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➢LIST OF COMPONENTS:

These are components that are required for our project

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Stepdown transformer 9v/ 1A Diode 1N2007 (4) C1 2200uF (25v). C2 0.27uF (25V) C3 10 uF (25v) IC 7805 Voltage regulater 500 ohm variablr resistor. R1 470 ohm resisrtor. R3 3.3K ohm resistor. Led 1 A fuse 9 v dc supply Voltage regulator 7805 PCB Soldering iron and soldering wire Ic holders wiroboard

➢PRE-ASSEMBLING ON BREADBOARD :

Before making the circuit on the pcb or on wiro-board make it on the breadboard and we also make it in LAB and our lab assistants had also checked it .

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PCB MAKING COMPONENTS :

AND

SOLDERING

IF your circuit work on the breadboard .Then the next step is to make the circuit on the pcb or on wiroboard . Here I make the keypad on the pcb while the other circuit is made on the wiroboard. For pcb making recall all the steps involved in pcb deg and make ,first mount the circuit image on the pcb and do the etching after this solder the components on pcb and also the components on the wiroboard.

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WORKING :

The main working principle of this project is full wave rectification which is done by bridge configuration in which we are using 4 diodes which rectifies the output of the step-down transformer which step- down the 220 AC v to 9 AC volts .here we are using a voltage regulator which give constant voltage ,here we are using 7805 which give 5 volts .these regulators are available in various outputs like 6v,9v,12v and 15 v.

Fig 1: pin configuration of 7805 Now the main task is to get variable output for this we use the pair of voltage divider resistors to increase the output of the regulator and in which of resistance is variable so when we increase or decrease the value of that resistor the output voltage of the regulator will also change and we get a range of 5 to 12 v , here we can’t get less than 5 volts because of this is the output of the regulator here the given below fig shows the increasing output voltage.

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Fig 2: increasing output voltage of regulator In this circuit we use three capacitor , c1 and c2 are use to get constant input to the regulator moreover it also help to reduce the sharp peaks in the output . connect the 0.27 uF capictor to close to the input of the regulator and the 10 uf capacitor to the output because these capacitor reduse the noise and also help to reduse the ripples produce by the regulator so that regulated output has less ripples. ➢

OUTPUT VOLTAGE FORMULA :

Here if we want to check the output voltage theoretically we knows by the ohms law V=IR As we output voltage contain the fixed voltage and the voltage across the R2 by using the voltage divider formula. Vout=Vfixed + Vr2 =Vfixed + IR2 =Vfixed +R2(Ir1+ Is) Vout =Vfixed+ R2(Vfixed/r1 + Is) Here the Is is the standby current of the of the regulator which is 2.5m A

➢RESULTS AND OBERVATIONS :

SO at the end our variable dc power supply is completed which give variable dc volts and it ranges from 5 to 12 v here we can’t get less then 5 v because it is the output voltage of the regulator which can be increased .

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REFRENCESS : ➢ ➢ ➢ ➢

I collected the data from the mention below sites our teachers and our text book also helps a lot. www.youtube.com www.pcbheaven.com www.circuittoday.com www.Wikipedia.com

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