Basic Electronics

Basic Electronics

Electronics Theory the branch of physics that deals with the emission and effects of electrons and with the use of electronic devices

WHAT IS MATTER ? Scientifically we define matter as all the "material" things about us. - Occupies space - Has mass

Classes Of Matter •

Solid - Within a solid, atoms/molecules are relatively close together, or "rigid"; - of definite shape and volume; firm; neither liquid nor gaseous; "ice is water in the solid state"

•

Liquid - Liquid is a phase of matter in which the molecules are close together and can move around slowly.

•

Gas - Gas is a phase of matter in which the molecules are widely separated, move around freely, and move at high speeds

Matter Composition “A matter can be broken down into smaller pieces”

ATOMS a. Protons – positively charged particles b. Neutrons – uncharged particles c. Electrons – negatively charged particles

Atom Structure

The Law of Electromagnetic Charges • The law states: Like charges repel, and unlike charges attract

+

attraction

negative

positive Repel

+ positive No attraction occurs

Conductor and Insulator • Conductor - Materials which easily allow the flow of electrons from 1 point to another. ex. Iron, Copper, Gold

• Insulator - Materials which don't allow the flow of electrons from 1 point to another. ex . Plastic, rubber, wood

Difference Of Potential If we connect a copper wire between two oppositely charged bodies, an electron flow would result.

+

-

Difference Of Potential • Electric potential is the potential energy per unit of charge. + + PE

PE

PE

PE

• Voltage is the difference of electrical potential between two points of an electrical network, expressed in volts. Electrical Pressure WIRE

WIRE

-

+

PE

PE

CURRENT •

Electric current is by definition the flow of electric charge.

wire

•

Active wire Current is present

The unit of measure for this parameter is Ampere

Types Of Current •

Direct Current - Direct Current is the movement of an electrical charge in one direction.

•

Alternating Current - An alternating current (AC) is an electrical current where the magnitude and direction of the current varies cyclically

Measurement of Current • The magnitude of current is measured in AMPERES. A current of one ampere is said to flow when one coulomb of charge passes a point in one second. Remember, one coulomb is equal to the charge of 6.28 x 10 to the18th electrons. Example: 1 Ampere

i - current

• Frequently, the ampere is much too large a unit for measuring current. Therefore, the MILLIAMPERE (mA), one-thousandth of an ampere, or the MICROAMPERE (µA), one-millionth of an ampere, is used. The device used to measure current is called an AMMETER and will be discussed in detail in later.

Resistor • Electricity, according to Benjamin Franklin, acts like a fluid. It flows and has a measurable CURRENT . We can restrict its flow by adding electrical friction. We say that the restriction of electrical flow is called RESISTANCE and that a device which causes such RESISTANCE is called a RESISTOR . All materials, even the very best CONDUCTORS demonstrate a certain amount of RESISTANCE to electron flow.

RESISTOR IMAGE FIXED RESISTOR

VARIABLE RESISTOR

CERAMIC RESISTOR

CARBON FILM RESISTOR POTENTIOMETER This is the most general purpose, cheap resistor. Usually the tolerance of the resistance value is ±5%. Power ratings of 1/8W, 1/4W and 1/2W are frequently used. Resistors used in computers and other devices are typically much smaller, often in surface-mount packages without wire leads.

HOW TO READ THE RESISTANCE OF THE RESISTOR

RESISTOR ANALYSIS

Rough size

Rating power (W)

From the top of the photograph 1/8W 1/4W 1/2W

Thickness (mm)

Length (mm)

1/8

2

3

1/4

2

6

1/2

3

9

Resistance •

In order to compare the resistance of various materials, we need to have some standard unit of measurement. The unit of measurement for resistance is called the Ohm , and is indicated by the Greek letter Omega ( Ω ). More current

RESISTANCE TO FLOW

Less number of electrons are allowed to pass through

Resistance • Although Ohm is the basic unit, Kilo Ohm and Mega Ohm are frequently used. 1 Kilo Ohm (K Ω) is equal to 1 thousand Ω. 1 Mega Ohm (M & Omega) is equal to 1 million Ω. • Ex - 8 M Ohm = 8,000,000 Ohm = 8,000 K Ohm

Resistance There are 4 factors that determine the resistance of a material

(1) Type of Material - The resistance of various types of materials are different. For instance, gold is a better conductor of electricity than copper, and therefore has less resistance.

(2) Length - The resistance of a material is directly proportional to it's length. The longer the material is, the more resistance it has. This is because the electrons must flow through more material, and therefore meets more friction over the entire distance.

Resistance (3) Cross Sectional Area - The resistance of a material is inversely proportional to the cross sectional area of the material. This means that the thicker the substance is across, the lower the resistance. This is because the larger the cross sectional area is, the less friction there is over a given length. R=p

L A

D

A = pie (R squared) R = radius D = 2R, diameter

Area is directly proportional to diameter

Resistance •

(4) Temperature - In various types of materials, resistance can vary inversely or directly with the temperature. This is because of the chemical properties of the material. In Carbon, for instance, the resistance decreases as the temperature rises. So we say it varies inversely. In copper, however, the opposite is true, with the rise in temperature, we have a rise in the resistance.

Resistance then, is basically a form of friction which restricts the flow of an electrical current. In basic science class, you learned that by putting your hands together, and rubbing them quickly, your hands get warm. This is because friction generates heat. Electrical friction - RESISTANCE - also generates heat.

Direct Current Theory • The current leaves the battery at the negative terminal, flows through the bulb, and returns to the positive terminal of the battery. The electrons flow in one direction. This is known in electronics as DIRECT CURRENT flow because the electrons flow only in one direction.

Direct Current Theory •

•

As long as we can follow the current from the negative terminal of the battery throughout the entire circuit, and back to the positive terminal, we have a COMPLETE CIRCUIT In order to have any complete circuit, you are required to have at least 3 parts: a. The SOURCE or SUPPLY of Voltage. b. The LOAD which uses the source Voltage. c. A complete path of connecting wires.

THE BASIC ELECTRIC CIRCUIT

• LOAD - is any device through which an electrical current flows and which changes this electrical energy into a more useful form. • SWITCH - which permits control of the electrical device, interrupts the current delivered to the load. • SOURCE

.

- is the device which furnishes the electrical energy used by the load

SCHEMATIC REPRESENTATION The schematic diagram - is a "picture" of the circuit that uses symbols to represent the various circuit components; physically large or complex circuits can be shown on a relatively small diagram.

A SIMPLE SCHEMATIC DIAGRAM

Practice Reading Schematic Diagram What happens to the path for current when S1 is open as shown in the figure?

OHM'S LAW • In the early part of the 19th century, George Simon Ohm proved by experiment that a precise relationship exists between current, voltage, and resistance. This relationship is called Ohm's law and is stated as follows: •

The current in a circuit is DIRECTLY proportional to the applied voltage and INVERSELY proportional to the circuit resistance. Ohm's law may be expressed as an equation:

OHM'S LAW • As stated in Ohm's law, current is inversely proportional to resistance. This means, as the resistance in a circuit increases, the current decreases proportionately.

Capacitor Theory

Capacitor Theory • Capacitor “ENERGY STORAGE” - A capacitor basically consists of two plates with an insulator in between, although in practice the 'plates' are normally rolled up in a can to save space. It can be used in a circuit to store charge for small periods of time.

Charges will attracted to other side of the plate

Plate I

Separation called Dielectric

Plate II

Capacitor Theory • The plate on the capacitor that attaches to the negative terminal of the battery accepts electrons that the battery is producing. -

The plate on the capacitor that attaches to the positive terminal of the battery loses electrons to the battery. -

1.5 V

Once it's charged, the capacitor has the same voltage as the battery (1.5 volts on the battery means 1.5 volts on the capacitor). For a small capacitor, the capacity is small. But large capacitors can hold quite a bit of charge.

Capacitance = is the property of a capacitor, a device, or an electric circuit that defines its ability to store an electrical charge (or energy) when a given voltage is applied, measured in farads (F)

Capacitors •

Ceramic Capacitor

Electrolytic Capacitor

Tantalum capacitors

Ceramic capacitors are small in size and value, ranging from a few Pico Farads to 1 µF. Not polarized, so either end can go to ground.

Electrolytic capacitors look like small cylinders and range in value from 1 µF to several Farads. Very inaccurate and change in value as the electrolytic ages. Polarized, cathode must go to ground. Cathode is marked with a minus sign on

.

case. Value is usually written on case

Tantalum capacitors are similar in size to ceramic but can hold more charge, up to several hundred µF. Accurate and stable, but relatively expensive. Usually Polarized, anode is marked with a plus sign.

Capacitor Theory • •

The unit of capacitance is a farad. A 1-farad capacitor can store one coulomb (coo-lomb) of charge at 1 volt. A coulomb is 6.25e18 (6.25 * 10^18, or 6.25 billion billion) electrons. Applications

-

Sometimes, capacitors are used to store charge for high-speed use. That's what a flash does. Big lasers use this technique as well to get very bright, instantaneous flashes. Capacitors can also eliminate ripples. If a line carrying DC voltage has ripples or spikes in it, a big capacitor can even out the voltage by absorbing the peaks and filling in the valleys. A capacitor can block DC voltage. If you hook a small capacitor to a battery, then no current will flow between the poles of the battery once the capacitor charges

Capacitor Theory •

Capacitors in Series:

Putting capacitors in series reduces the overall capacitance: (1/C) = (1/C1) + (1/C2) + (1/C3) .....

Capacitor Theory • Capacitors in parallel: •

Putting capacitors in parallel increases the total capacitance:

Capacitors in parallel : C = C1 + C2 + C3

Capacitor Problem •

For the network shown, determine the equivalent capacitance of the network, the charge on each capacitor, and the potential difference across each.

30V 1nf 6nf

We have a capacitor network to solve. Hence the first step is to determine the equivalent capacitance of the network. C' = C1 + C2 = 1 nf + 2 nf = 3 nf 1/Ceq = 1/C' + 1/6 nf = 1/3 + 1/6 = (2 + 1)/6

or Ceq = 2 nf

2nf

Inductor Theory

Inductor Theory •

An inductor is an energy storage device. It can be as simple as a single loop of wire or consist of many turns of wire wound around a special core. Energy is stored in the form of a magnetic field in around the inductor.

Inductor Theory • The Basics In a circuit diagram, an inductor is shown like this: To understand how an inductor can work in a circuit, this figure is helpful: Most of the current should follow the low-resistance path through the loop. What happens instead is that when you close the switch, the bulb burns brightly and then gets dimmer. When you open the switch, the bulb burns very brightly and then quickly goes out.

Inductor Theory The reason for this strange behavior is the inductor. When current first starts flowing in the coil, the coil wants to build up a magnetic field. While the field is building, the coil inhibits the flow of current. Once the field is built, current can flow normally through the wire. When the switch gets opened, the Magnetic field around the coil keeps current flowing in the coil until the field collapses. This current keeps the bulb lit for a period of time even though the switch is open. In other words, an inductor can store energy in its magnetic field, and an inductor tends to resist any change in the amount of current flowing through it. Inductance = The property of an electric circuit opposes a change in current

that flow.

Series and Parallel Inductor • LT = L1 + L2

• •

L= Inductance Henry is the unit of measure for L

• Parallel Inductors (1/Ltotal) = (1/L1) + (1/L2) + (1/L3) .....

Diode Theory • Diode - diode is a component that restricts the direction of movement of charge carriers. It allows an electric current to flow in one direction, but essentially blocks it in the opposite direction.

Diode Theory • -

Rectifier. An electronic device with two wires or terminals. A rectifier allows electrical current to flow through in only one direction and is used for converting alternating current into direct current.

Zener

Diode Theory • -

Rectifier. An electronic device with two wires or terminals. A rectifier allows electrical current to flow through in only one direction and is used for converting alternating current into direct current.

Zener Diode = Voltage Regulator

Diode Theory • Biasing DIODE

Forward Bias

Diode Theory • REVERSE BIAS

ATX Power Supply

Power Supply •

A power supply (sometimes known as a power supply unit or PSU) is a device or system that supplies electrical or other types of energy to an output load or group of loads. The term is most commonly applied to electrical energy supplies.

At the motherboard

•

At the Cable

The most common computer power supply is built to conform with the ATX form factor. This enables different power supplies to be interchangeable with different components inside the computer.

A T X Connector Standard •

The ATX (for Advanced Technology Extended) form factor was created by Intel in 1995. It was the first big change in computer case and motherboard design in many years.

•

ATX overtook AT completely as the default form factor for new systems. ATX addressed many of the AT form factor's annoyances that had frustrated system builders.

AT POWER CONNECTOR

A T Standard Advanced Technology Standard

B T X Connector Standard •

In 2003, Intel announced the new BTX standard, intended as a replacement for ATX. BTX (for Balanced Technology Extended) is a form factor for PC motherboards, originally slated to be the replacement for the aging ATX motherboard form factor in late 2004 and early 2005.

At the motherboard

B T X Connector Pin Designation Pin 1 2 3 4 5 6 7 8

Signal

Description

+3.3 VDC +3.3 VDC COM Ground +5 VDC COM Ground +5 VDC COM Ground PWR_OK Power good - indicate that VDC voltages are in range. 9 +5 VSB Standby voltage 10 +12 VDC

B T X Connector Pin Designation Pin Signal Description 11 +12 VDC 12 +3.3 VDC 13 +3.3 VDC 14 -12 VDC 15 COM Ground 16 PS_ON# Active low. TTL compatible (0.1-0.8V low; 2.0 high?). When low - DC outputs are enabled. When high - power supply should not deliver DC current. 17 COM Ground 18 COM Ground 19 COM Ground 20 N/C 21 +5 VDC 22 +5 VDC 23 +5 VDC 24 COM Ground

A T X Power Connector - ATX Power Supply connector - Typical wattages range from 200 W to 500 W - There are also other, smaller connectors, most of which have four wires: two black, one red, one yellow.

“each black wire is a Ground, the red wire is +5 V, and the yellow wire is +12 V.”

ATX • • • • • • • • • • • • • •

Pin Name

Color

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Orange +3.3 VDC Orange +3.3 VDC Black Ground Red +5 VDC Black Ground Red +5 VDC Black Ground Gray Power Ok (+5V & +3.3V is ok) Purple +5 VDC Standby Voltage (max 10mA) Yellow +12 VDC Orange +3.3 VDC Blue -12 VDC Black Ground Power Supply On (active low)

3.3V 3.3V COM 5V COM 5V COM PWR_OK 5VSB 12V 3.3V -12V COM /PS_ON Green

Description

ATX • • • • • •

Pin 15 16 17 18 19 20

Name COM COM COM -5V 5V 5V

At the motherboard

Color Black Black Black White Red Red

Description Ground Ground Ground -5 VDC +5 VDC +5 VDC

At the cable

Question • Can I fit an ATX mainboard in an AT case? - Not really. An AT case and AT power supply can neither power up nor house a new ATX mainboard. ATX and AT are two different form-factors. The AT case was designed before ATX. Most of the computer cases built before late 1996 were AT form-factor. For over 10 years, from about 1985 to 1997, the AT form-factors, founded by the original IBM PC-AT, provided the standard for 90% of the PC industry. Today, the majority of new systems ATX form-factor. The ATX is also known as the Extended AT form-factor.

Choosing a Power Supply Why Weight Matters? The more appropriate question is why size matters. The weight of a power supply is directly related to the quantity, quality, and size of the material (thus cost) used to build the power supply.

Choosing a Power Supply • Conclusions This brief study clearly confirms an empirical knowledge: the quality of a power supply can be estimated by its weight.

- The very simple and easy way for ordinary PC users to estimate and compare the quality of a power supply.

Prepared by: Sir Philip

OPERATING SYSTEM - A software that provides a software platform on top of which other programs, called application programs, can run.

DOS • DOS - Disk operating system, the original system used for PCs. You type in commands instead of pointing and clicking. - A disk operating system is an operating system that resides on a disk.

An example of MS-DOS's command-line interface, this one showing that the current directory is the root of drive C.

DOS Family • PC-DOS, MS-DOS, FreeDOS, DR-DOS, Novell-DOS, OpenDOS, PTS-DOS, ROM-DOS and several others. • MS-DOS from Microsoft was the most widely used

MS-DOS Family •

MS-DOS 3.0, released in September 1984, first supported 1.2Mb floppy disks and 32Mb hard disks. MS-DOS 3.1, released November that year, first supported networking

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MS-DOS 3.2, released in April 1986, was the first retail release of MS-DOS. It added support of 720K 3.5" floppy disks. Previous versions had been sold to computer manufacturers, who pre-loaded them on their computers. This is because operating systems were considered part of a computer, not an independent product.

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MS-DOS 3.3, released in April 1987, featured logical disks. A physical disk could be divided into several partitions which are considered as independent disks by the operating system. Support was also added for 1.44Mb 3.5" floppy disks.

MS-DOS Family •

MS-DOS 4.0, released in July 1988, supported disks up to 2GB (note that typical disk sizes were typically 40-60Mb in 1988), and added a full-screen shell called DOSSHELL. Similar or better shells, like Norton Commander and PCShell, already existed in the market. This release had been considered very buggy. On November 1988, Microsoft addressed many bugs in a service release, MS-DOS 4.01.

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MS-DOS 5.0, released in April 1991, included the full-screen BASIC interpreter QBasic, which also provided a full-screen text editor (previously, MS-DOS had only line-based text editor), disk cache utility, undelete capabilities, and other improvements. It had severe problems with some disk utilities, fixed later in that year. The fixed version had been called MSDOS 5.01.

MS-DOS Family •

• •

MS-DOS 6.0 had been released, On March 1993. also featured the disk defragmenter DEFRAG, backup program MSBACKUP, memory optimization with MEMMAKER, and rudimentary virus protection via MSAV MS-DOS, 6.21 (released March 1994), appeared due to legal problems. MS-DOS 6.22 which was released in May 1994 was the last stand-alone version of MS-DOS available to the general public. MS-DOS was removed from marketing by Microsoft on November 30, 2001.

• Microsoft also released versions 6.23 to 6.25 for banks and American military organizations. These versions introduced FAT32 support. Since then, MS-DOS exists only as a part of Microsoft Windows versions based upon Windows 95 (e.g., Windows 98, Windows Me).

MS-DOS Command • Microsoft DOS (Disk Operating System) is a command line user interface. • Command line - A prompt where the user types in a command, as opposed to using the mouse to perform a command. Below is a listing of the MS-DOS commands most commonly used and that you will most likely use during a normal DOS session. - cd, - dir, - copy, - del, - format

MS-DOS Command cd - CD (Change Directory) is a command used to switch directories in MS-DOS. dir - The dir command allows you to see the available files in the current and/or parent directories. copy - Allows the user to copy one or more files to an alternate location. You can only copy files which in their extension modes del - is a command used to delete files from the computer. format

- Format is used to erase all of the information off of a computer diskette or fixed drive.

DISK PARTITION AND FORMAT

PREPARED BY: SIR PHILIP

Boot Disk •

A boot disk is a removable digital data storage medium, normally read-only, that can load (boot) an operating system or utility program.

•

Floppy disks and CD-ROMs are the most common forms of media used, but other media, such as tape drives, zip drives and more recently, USB flash drives can be used.

ZIP DRIVE

Disk Partition

- In computer engineering, hard disk drive partitioning is the creation of logical divisions upon a hard disk that allows one to apply operating system-specific logical formatting.

Purpose of Disk Partition 1.

If one partition becomes corrupt, only that partition suffers and not the whole hard drive.

2.

Often, two operating systems cannot coexist on the same partition, or use different "native" disk formats. The drive is partitioned into different logical disks for different OSes.

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Utility to create a disk partition is done by FDISK

FDisk •

Fdisk is one of the more commonly used MS-DOS commands, even today with Windows 95 and Windows 98. Fdisk allows the user to delete and/or create partitions on the hard disk drive.

•

MS-DOS 3.3x and below used fdisk.com

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MS-DOS 4.x and above uses fdisk.exe