IT Lecture 05 - Information Technology ESD103-2 PDF

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Information Technology
ESD103-2...

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Information Technology ESD103-2

Ms. Yanusha Mehendran

ELECTRICITY AND THE PC

Electricity flows through a circuit in much the same manner as water flows through a pipe or hose. When water is flowing through a pipe, it is pushed along by a measurable rate of pressure. Electricity also flows through a circuit with a measurable pressure. This pressure is measured in units called volts.

While the water is flowing through a pipe or hose, it experiences some loss of pressure through friction. The same thing happens to electricity as it flows through a circuit.

There is friction that causes a loss in pressure. This friction is called resistance and is measured in units called ohms.

The amount of water that flows through a pipe for a specified length of time, such as the gallons-per-minute, is called the volume of the water flow. For an electrical current, volume, or the rate of flow, is measured in amps.

AC POWER AND DC POWER An electrical current is the flow of electric charge.

There are currents:

two

types

•Alternating Current (AC) •Direct Current (DC)

of

electrical

ALTERNATING CURRENT (AC) Alternating current (AC) changes the direction of the electrical flow at a rate of about 60 times per second. What is special about AC electricity is that the voltage can be readily changed, thus making it more suitable for long-distance transmission

DIRECT CURRENT (DC) The electrical flow in a direct current (DC) keeps a constant pace and flows in the same direction all the time.

What power do you have at your standard household electrical outlets? AC or DC What power should the computer must have to operate properly?

A conflict ???????

WHAT HAPPENS IS…… Inside your PC is a module called the power supply, which converts the electricity in your household circuit (HC) from AC power into the DC power that the computer needs. The typical voltages supplied are: 3.3 volts 5 volts 12 volts

POWER SUPPLY PROBLEMS The PC power supply is probably the most failure-prone item in a personal computer. A stalled cooling fan is a predictor of a power supply failure due to subsequent overheated components. A typical failure of a PC power supply is often noticed as a burning smell just before the computer shuts down

Another problem could be the failure of the vital cooling fan, which allows components in the power supply to overheat. Failure symptoms include random rebooting or failure in Windows for no apparent reason. REMEMBER: All devices in a PC receive their DC power via the power supply.

EXTERNAL POWER ISSUES

Electrical power can be a very unstable. It can damage the PC. As the electrical power tends to fluctuate in its voltage, its normal operating range can vary. Sometimes the current spikes above or drops below its normal range and causes damage to a PC that is unprotected from sudden changes in the current.

HOW TO PREVENT THIS? The best way to protect your PC is with a surge suppressor or an Uninterruptible Power Supply (UPS).

A UPS generally protects a computer against four different power problems: •Voltage surges and spikes •Voltage sags •Total power failure •Frequency differences

ELECTROSTATIC DISCHARGE (ESD) It is an electric charge built up on persons or objects through friction. One of the most insidious destroyers of PC circuits is electrostatic discharge (ESD), which can occur when you touch the fragile electronic components of the PC.

HOW TO PROTECT YOUR COMPUTER FROM ESD? Use an Antistatic Wrist Strap

HOW TO PROTECT YOUR COMPUTER FROM ESD? Be aware of the temperature Use anti-static bags:

•Keep components and expansion cards inside their anti-static bags until you are ready to use them.

HOW TO PROTECT YOUR COMPUTER FROM ESD… Consider the floor Think of your attire

Don’t wear accessories

CONDUCTORS, INSULATORS, AND SEMICONDUCTORS A conductor is an object or type of material which permits the flow of electric charges in one or more directions. Example:

A wire is an electrical conductor that can carry electricity along its length.

TYPES OF CONDUCTORS • Pure elemental silver

• Brass

• Copper

• Saturated saltwater solution

• Steel • Gold • Aluminum

• Mercury

INSULATORS

Electrical insulators, are materials that can withstand the flow of electrical current. In other words, they are non-conducting materials. They are the opposite of electrical conductors which allow electricity to flow through a material. These protective materials help prevent electrical shock or sparks.

GOOD INSULATORS OF ELECTRICITY • Porcelain

• Dry air

• Mica

• Glass

• Plastic

• Styrofoam

• DRY wood

• Paper

• Rubber • Cloth

SEMICONDUCTORS

Many of the electronic components inside the computer are neither conductors nor insulators. These materials, which can be made chemically and electronically to be either conductive or insulating, are called semiconductors. Depending on the type and purpose of a circuit, a semiconductor can be set to provide the right action.

SEMICONDUCTORS… Computer chips, both for CPU and memory, are composed of semiconductor materials. Silicon and Germanium are the most common semiconducting materials

THE ELECTRONIC BUILDING BLOCKS OF THE PC Four primary electronic components are used on virtually every electronic circuit inside the computer. •Resistors •Capacitors •Diodes •Transistors.

A resistor slows down the flow of electrical current in a circuit. A capacitor is used to store electrical charges. Most of the computer’s capacitors are small, but there are some large capacitors in the computer that hold enough charge to kill you, such as those in the monitor and power supply. A diode forces the electricity to flow in one way only. Transistor, a device composed of semiconductor material that amplifies a signal or opens or closes a circuit

Resistors

Capacitors

Diode

Transistors...