Ch 14 p 457
An Evolution of electronics
The beginning ...
1729 Electrical conductors &
insulators are discovered.
1745 Development of the 1st
Can store a charge
Is used to smooth out power output
1750 Benjamin Franklin sent the 1st electrical
signal over a wire.
1832 Pavel Schilling electromagnetic telegraph.
Used a coil & a magnet to make a code.
Used the binary code for the alphabet
1837 Morse Telegraph
1861 electric oven
1874 Light bulb
Better over long distances
1904 invention of diodes
Control current direction
1921 better understanding of semiconductors
1971 1ST MICROPROCESSOR AND
The first computer we owned in the
1979 handheld video games & cell
phones start to be widespread!
Pong console by “Atari”
First Super Mario
The design & development of
14.1 Electronic vs electrical devices
Made with semiconductors
Tiny & low-intensity so that
information can be
Made with conductors
(metals (copper) & alloys)
Larger & powerful circuits
14.2 Electrical Circuits
Flows from + to –
Flows from – to +
Circuit diagrams place their components (parts) to
follow the direction of conventional current!
Make a table “Circuit Symbols” with 3 columns
(how it controls current)
14.3 Power Supplies
14.3 Power Supplies
Provide the energy to cause current to move
through a circuit.
Two types of current:
DC = Direct Current
Electrons move continuously in one direction.
Can be stored.
AC = Alternating Current
Electrons move back and forth.
Easier to transport.
Eg. From power plants.
Power supply Symbols please add to table.
Alternating current AC
Direct current DC
AC electrical generators
Turns mechanical energy into electrical energy.
Makes AC current!
Using a rotating magnetic field with a stationary
I am an armature
rotating armature with a stationary magnetic
Combustion engine = Alternator (in a car)
Permanent magnets = Magneto
Steam engine (power plant) = Turbo-alternator
piezoelectric disk generates a
voltage when deformed
Symbols for power supplies
please add to table
vs many cells
How do they work?
Transforms chemical energy into electrical energy
Have to be replaced
Contain environmental hazards
Where can you find one?
Watch, mp3, remotes etc
How do they work?
AC current is sent from a power plant to the outlets
Low environmental effect (depending on source)
How do they work?
Transforms light energy into electrical energy
Depend on sunshine
Battery (chemical E Portable
(sun E electrical E)
Must be replaced
Stable source Close proximity
insulation & protection
P 464 - 468
Conduction: is the movement of current.
(light is transmitted & then converted into electricity using a
Transition metals are good
conductors of electricity and
Printed Circuits (EST/AST ONLY)
Electrical circuit printed on a
thin rigid board
1. Board = thin plastic sheet.
2. Cover with a thin copper sheet.
3. A circuit is etched in.
4. Extra copper is removed. (by leaching)
5. Electric & electronic components are then
MASS MANUFACTURING OF
CIRCUIT BOARDS VIDEO
Electronic items use circuit boards:
How are they made?
How It’s Made – Computer Circuit Boards
Function: to prevent current flow!
Allows current to stay within the wire
and reach it’s destination.
Injury to people
Ex: Ceramics & plastics
Components that stop current if there is a
short circuit or a power surge.
Regulate the current allowed to pass through a circuit.
The current can pass through the filament.
If the current intensity (amps) is too high, the filament
melts then breaks.
You must replace it.
How it works:
1. When the current intensity
gets too high….
2. The bimetallic strip heats
up & bends.
3. As it bends the connection
is broken and it snaps to
the off position.
4. You then go to your
breaker panel and reset
the switch to ON.
Fuse or Breaker
14.5 ELECTRICAL RESISTANCE
Resistors limit the current flow through a circuit.
You can add or remove resistors to meet the
needs of your component.
Refer to your Ch5 notes for reading resistors.
The “Control” function is the ability to open or
close a circuit.
Closed circuit = has electricity flowing in a loop.
Open circuit = does not have electricity flowing
(due to an opening in the wires).
Eg. switches & pushbuttons
Types of Switches
Pole = # of contact points it can open/close at
Single-pole = opens/closes one contact at a time
Double-pole = opens/closes two contacts at a time
Throw = # of paths that the electrons can flow in.
Single-throw = electrons may only follow one path
Double-throw = Electrons have a choice of two paths
Add to table please
Single-pole Single-throw switch
Single-pole Double-throw switch
Double-pole Single-throw switch
Double-pole Double-throw switch
Double double please
14.7 Energy Transformation (ST/EST/AST ONLY)
Changes one form of energy into another.
Examples of electrical components that
Turns electrical E luminous E
Current flows through a tungsten filament, as it resists
the current it heats & emits light!
Turns electrical E thermal E
Ex: ovens & kettles
Turns electrical E mechanical E
(or sound E)
Current causes the crystals to vibrate
Ex: watches & speakers
Turns electrical E magnetic E
Current flows through a coil creating a magnetic
old tape recorders
Workbook p 241 – 244
Finish for homework.
I will be checking the homework.
Detentions will be assigned if incomplete.
Reminder: Quiz on Friday.
See you soon
14.8 Components with other
functions (EST/AST ONLY)
Please Write Title
Store electrical charge.
Made of 2 metal plates separated by an
Charge builds up on one plate, when the
insulator is removed … the charge is released.
Ex: Camera flash
How the capacitor works.
The right plate builds a negative charge.
Because it is receiving electrons from the battery.
The plate on the left builds a positive charge.
Because the electrons are going to the battery leave
behind a positive charge
• Once the dielectric is
pushed out of the way
the charge jumps to
even itself out.
• High charge in a short
period of time.
Allows current to flow in one direction.
Is made of semiconductor material (silicon)
Guides the direction of current.
Protects circuits from current flowing the wrong
Someone inserted a battery backwards!
Rectifies current (changes AC to DC)
LED = light emitting diode
Visually tells you what way the current is flowing.
Emits a lot of light with low voltage.
Protect circuits, guide
current flow & rectify
AC to DC
All of the above &
Please Write onto table
Transistors (AST ONLY)
Block or amplify current
Current goes from the collector to the emitter,
through the base
The base act as a door
It is controlled by a weak current
A relay opens/closes a circuit using
an electrical signal from another
The signal can come from:
Has 2 parts:
Closing a switch
Photoelectric cell (yard light)
Receives signal & sends command Please Write
Receives command & starts 2nd circuit
High voltage circuits controlled
from a safe distance
depends on type
Turns electrical E into
Please Write onto table – others on p460