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13 Presented by:- NAME : Sanjay Kumar Pani BRANCH : Electrical & Electronics GROUP : ‘B1’ ROLL NO. : E/04/14

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15 CONTENTS 1. Introduction 2. A Typical linear Power Supply. 3. Working Of SMPS. 4. Capacity Of Power Supply. 5. Power Supply PC. 6. The Computer Supply’s Duties. 7. Power Supply Improvement.

16 INTRODUCTION:- INTRODUCTION:-  A Power supply is the heart of computer system. The power supply converts alternating current (AC) line from your direct current (DC) needed by the personal computer.  A computer needs a well regulated 5 volt and 12 volt DC power supply for the proper functioning of its various parts. Without a good and proper power supply the computer can not do work.

17  AS shown fig-1, a power supply is used in between the computer and mains to convert the 240v AC current to a well regulated 12 volt and 5 volt DC current.  Usually, the electronic components and circuits in the system (Motherboards, Adapter cards and Disk drive logic boards etc.) use the 5 volt & Motors in the disk drive and the hard disk use 12 volt respectively

18  The main specification of power supply is in watts. A watt is the product of volts and current in amperes.  Today we turn on the power with a little push button &turn off machine with menu option. A Typical Linear Power Supply:- The basic components of a typical linear power supply are shown in fig-2. The basic components of a typical linear power supply are shown in fig-2.

19  This power supply contains a transformer, rectifier, capacitor, and regulator. Disadvantages: The main disadvantages of linear power supply are its large and poor efficiency. Because, the computer system use a completely different type of power supply, which is called as SMPS or Switch Mode Power Supply. Because, the computer system use a completely different type of power supply, which is called as SMPS or Switch Mode Power Supply. Advantages: The main advantages of SMPS as the power supply is it reduced size, less cost, high efficiency.  The main difference between the linear power supply & switch mode power supply is the way the output voltage is generated and regulated.

110 Working of SMPS:-  In a SMPS, the mains AC supply is first send to a rectifier/filter unit, which converts the Ac supply into very high value, DC voltage.  The high voltage DC supply is given to switching transistor circuit. The switching transistor circuit switches the given high voltage DC on & off at the same frequency. The voltage at secondary winding is then rectified and filtered to produce the rectified output.

111 Disadvantages: The disadvantages of SMPS are, The disadvantages of SMPS are,  It heats and cool each time it is used and receives the first in-rush of AC current when the personal computer switched.  A typical failure of PC power supply is often burning smell just before the computers shutdown.

112 Capacity of Power Supply:-  The capacity of a power supply is measured in watt or kilo watt. Watt is the unit of amount of the work done by the electricity. So that all the parts of the computer such as: RAM, Motherboard, Drives etc. Power Supply of PC:-  A PC contains many electronic components such as: a lot of memory, adapter cards, hard disk etc. it requires high quality power.  Modern SMPS power supplies used in computers are small and efficient and also equipped with a fan for cooling purpose.

113 The back of the power supply contains four things. They are  The computer’s power connector.  The monitor’s power connector  The fan exhaust port  A power switch

114 The computer power supply’s duties: The power supply has 3 main duties. They are The power supply has 3 main duties. They are It supplies PC with power. It supplies PC with power. It cools the system. It cools the system. It protects the internal components. It protects the internal components. Power Supply Improvement:- Some new computers, particularly those designed for use as servers, provide redundant power supplies. This means there are two or more power supplies in this system, with one providing power and other acting backup. Some new computers, particularly those designed for use as servers, provide redundant power supplies. This means there are two or more power supplies in this system, with one providing power and other acting backup.

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