ELECTRONIC COMPONENTS
AND CIRCUITS
TIJ1O1
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Recap: What is an electric
current?
An electric current is a flow of microscopic particles
called electrons flowing through wires and
components.
+
-
In which direction does the current flow?
from the Negative terminal to the Positive terminal of a
battery.
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simple circuits
Here is a simple electric circuit. It has a battery, a
lamp and a switch.
battery
wires
switch
lamp
To make the circuit, these components are connected
together with metal connecting wires.
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simple circuits
When the switch is closed, the lamp lights up. This is
because there is a continuous path of metal conductor
for the electric current to flow around.
If there were any breaks in the circuit, the current
could not flow.
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circuit diagram
Engineers usually draw electric circuits using symbols;
Battery
lamp
switch
wires
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circuit components
In circuit diagrams—also called schematic diagrams- components are represented by the following
symbols-here are some examples…
capacitor
LED
battery
switch
lamp
voltmeter transistor resistor
diode
variable
resistor
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circuit components
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circuit components
WIRE:
is a CONDUCTOR which is a material that permits
electrons to flow freely from atom to atom and
molecule to molecule. Wire is commonly made of the
metal copper which carries (conducts) electrical
current well.
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circuit components
The wire is covered in plastic called insulation. An
INSULATOR is a type of material the impedes or
stops the free flow of electrons. Insulators isolate
conducting materials from each other. Examples:
plastics, paper, rubber, glass and dry air.
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circuit components
WIRE GAUGE:
It’s the thickness or diameter of a wire.
The greater the gauge, the more electric current
it can safely carry.
Wire gauge is measured in AWG units. AWG stands for
American Wire Gauge. The higher the number, the
thinner the wire.
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circuit components
DC VOLTAGE SUPPLY:
It can take the form of a battery or an electronic
power supply (PSU) like used in computers. PSU’s
convert AC (Alternating Current) into low voltage DC
(Direct Current) more useful for electronics.
You will be using a 9 Volt battery for your project. A
battery
is a chemical-based power storage device that
produces Direct Current—current that flows in
one direction only.
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circuit components
BATTERY SNAP:
It connects to the POSITIVE and NEGATIVE
terminals of the 9 Volt battery to be used in your
Flashing LED Project.
You must be certain that the polarity of the
battery snap and battery match—the connectors
on the snap only fit one way. Remember, BLACK
wires connect to the NEGATIVE (-) terminal and
RED wires connect to the POSITIVE (+) terminal.
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circuit components
RESISTOR:
A resistor is a component that develops a voltage
drop when supplied with a current—it resists or
impedes the flow of electrons. The amount of
resistance is measured in OHMs Ω. Remember
Ohm’s Law: R=V/I
Resistors do not have polarity. You can orient
them in either direction.
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Resistor
Colour
Code
BLACK
BROWN
RED
ORANGE
YELLOW
GREEN
BLUE
VIOLET
GRAY
WHITE
GOLD
SILVER
0
1
2
3
4
5
6
7
8
9
+/- 5%
+/- 10%
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circuit components
CAPACITOR:
A capacitor is a storage container for an electric charge.
While the capacitor is charging up, current flows. The
current will stop flowing when the capacitor has fully
charged. Capacitance is measured in units called
Farads.
Capacitors DO have polarity. The longer lead is
Positive and the shorter lead is Negative.
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circuit components
A SEMICONDUCTOR is a material in-between
conductors and insulators in their ability to allow
the free flow of electrons. SEMICONDUCTORS
are the foundation of modern electronics, including
radios, TV’s, computers, smart phones, etc.
Some examples of electronic components that are
made from semiconductor material, usually silicon,
are transistors, diodes, LED’s (Light Emitting Diode)
and photovoltaic (solar) cells.
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circuit components
TRANSISTOR:
A transistor is used either for amplifying, or as a
switch. You will be using it as a switch. Computer
CPU’s have millions of microscopic transistors
embedded in them to perform logic calculations.
Transistors have three leads: Emitter, Base and
Collector, and must be connected correctly for
the circuit to function.
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circuit components
LED (Light Emitting Diode):
An LED is a semiconductor light source. They are
illuminated by the movement of electrons in
a semiconductor material and last much longer than
incandescent light bulbs and use much less energy.
They also produce very little heat.
LED’s have polarity: The longer lead
is the positive and is called the
Anode. The Shorter lead is the
negative and is called the cathode
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circuit components
The Asus P4T motherboard uses many of the same kind
of electronic components that you will be using in your
LED Flasher Circuit Project
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circuit components
The LED Flasher Project uses: battery (1), switch (1),
wires, resistors (4), Capacitors (2), transistors (2), LED’s (2)
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Circuit Schematic Diagram –
LED Flasher
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