ELECTRICAL ENGINEERING

History

Chapter 14

1745: 1ST Electrical Capacitor

1837:1st Electric Telegraph

1861: 1st Electric Oven

WOOD

COMBINATION

ELECTRIC

1874:1st Electric Light Bulb

1887: 1ST Alternating Current Network

1904 :1st Diode

1929: 1ST Theory of Semi-Conductors

1943:1st Programmable Electronic Computer

1947:1st Transistor a semiconductor device is used to:

amplify switch electronic signals switch electrical power

1971 : 1ST Micro-Processor & 1st Micro-Computer

1975: Pong console

1977: Atari 2600 Console

1978: Electronic QB banned from high schools

1980: 1st Handheld Video Games and Commercial Cell Phones

1980s: 1st Personal Computer

1980s: The Walkman

1998:1st Hard Drive MP3 Player

Electrical Engineering relates both electronics and electrcity

Electronic vs Electrical Electronic Made with

semiconductor material Usually silicon Examples

Capacitors Diodes Transistors Relays

Electrical Made with

conductor material Metals and alloys Examples

Wires Switches Fuses

Alloy A homogeneous mixture made by

fusing two or more metals, or a metal and a nonmetal.

To obtain desirable qualities such as hardness, lightness, and strength.

Brass: Copper & Zinc Bronze:Copper & Tin

Electrical Current Electron flow current

occurs from the negative terminal (where there is an excess of negative electrons) to the positive terminal (where there is a lack of electrons)

Conventional current

Direct Current Electrons move continuously in the one

direction

AlternatingCurrent Electrons vibrate back and forth in a regular

pattern 60 Cycles per second or 60 Hz

Electrical function: the role that a component plays in the

control or transformation of electric current

Power Supply Provides the energy that causes

the current to flow through the circuit

AdvantagesPortable/CompactReplaceableRechargeableCheap

AdvantagesContinuous equal flowRecharges othersGood for big items

AdvantagesRenewableEnvironment friendlyGood for remote places

DisadvantagesDrains fastLimited PowerPolluting

DisadvantagesStationaryFire

DisadvantagesExpensiveFragileGood only when sunny

Conduction Energy transfer from one material to

another by direct contact. Conductors are materials that allow transfer

to happen. E.g. copper, aluminum, silver and optical

fibres. A printed circuit is an electrical circuit

printed on a solid support called a circuit board.

Insulation The electrical function performed

by a component to prevent the flow of an electric current

Prevent injury and short circuits E.g. Ceramic and plastic

Protection Protection is a component that

stops the flow of current in the event of a power surge

E.g. Fuses and circuit breakers

Control The function performed by a

component that can open or close a circuit

switches and pushbuttons are examples of controls

Switches Rocker Toggle Push button Magnetic contact

Switches Single pole switches open/close 1

contact at a time Double pole switches open/close 2

contacts Single throw switches allow

electrons to follow 1 path. Double throw switches allow

electrons to follow 1 of 2 paths

Energy Transformation Change of one form of energy (electricity)

to another form of energy Light energy Thermal (heat) energy Mechanical Sound Magnetic Induction

Components with other Functions

Capacitors Diodes Transistors Relays

Capacitors Can store electrical charge Composed of two electrical surfaces

separated by an insulator Charge builds up on one plate,

when the insulator is removed,

the charge is released

E.g. Camera flash

Diode Allows electric current to flow in one

direction Made of semi-conductors Protects electronic parts from

having electrons flow in the wrong direction

Used to convert AC to DC LEDs are Light Emitting Diodes

Transistors Block or amplify an

electric current Base acts like a valve that

controls current

Relays A relay opens or closes

a circuit using an electrical signal from another circuit

Used in lighting in a theatre, high voltage appliances

Resistors Resistors limit the flow of electrons through an

electrical circuit E.g. A 10 Ω resistor has less conductance than

a 100 Ω resistor.

Coding on 4 band resistors: the 1st two bands tell you the first two digits

of resistance (e.g. red=2; blue=6) the next band tells you what to multiply those

numbers by (e.g. red=100) the last band is tolerance factor

(e.g. gold= ±5%) Therefore a resistor with red, blue, red, gold

would have resistance of 2600 ohms ±5%

Activity Page 479, Q. 1-15