Electronics uses electricity to control other devices and circuits. It operates at three levels: components, circuits, and devices. Components like resistors, capacitors, diodes, and transistors are the basic building blocks. Circuits are groups of connected components that perform control functions. Devices encase multiple circuits in a shell with inputs and outputs to interact with users. Electronic devices control things like automatic doors, lighting, and air conditioning using internal circuits made of electronic components connected by circuit boards.

1. Lesson 7: Electronics
Technology 3 ESO bilingual

2. Index




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Definitons. Concepts
Electricity and electronics: Differences
Levels in electronics
Components
Resistors: Fixed and variable value resistors
Condensators
Semiconductors: Diodes, transistors
Electronic circuits
Electronic devices

3. What is electronics?

Electronics is the part
of engineering aiming
to use electricity with
the purpose of
controlling other
devices or circuits
Index

4. Electricity and electronics
Circuit
Purpose
Electric
Electronic
Transporting
and
transforming
electricity
Controlling other
devices
Intensity
and power
to
Resistance
value
to
Index

5. Levels in electronics



Components: elements
within a circuit which play a
certain role over the signals
Circuits: A group of
components which form a
circuit and performs
controlling operations
Devices: A circuit/group of
circuits encased in a shell,
which include a screen and
buttons to interact with a
user
Index

6. Components
 Fixed
value resistors
 Variable Value resistors
 Condensators
 Semiconductors


Diodes
Transistors

7. Fixed value resistors


Fixed value resistors
are used to limit the
current passing through
an electronic circuit.
A bar code is used to
indicate the value and
the tolerance of a
resistance

8. Why do we use resistors?

9. Variable value resistors: LDR


LDR: ligth dependent
resistance. Based on
photovoltaic effect,
those resistances value
diminish when ligth hits
them,
Their values vary
between MΩ and
hundreds of Ω(intense
ligth)

10. Variable value resistors:
thermistor


Thermistors
are
resistances which vary
with temperature (PTC
and NTC)
Their values raise (ptc)
or fall (ntc) when
temperature increases

11. Variable value resistors:
Potenciometer

A Potenciometer is a
variable resistance
which value can be
fixed by a user. To do
so, a bar or a wheel is
moved. It displaces a
movable contact of a
resistance along a
resistive material.
Remember that R=pL/s2
Index

12. Condensators



Condensators are
capable of
accumulating (a very
small amount of)
electric energy
The amount of energy
that they can store is
called Capacity. C=Q/V
Condensators are
placed in parallel to
other components
Index

13. Semiconductors



Semiconductors are metals which have a variable conductivity,
which can be modified by inserting other atoms. There are two types
of semiconductors: P and N
The electric properties of semiconductors are extremely important
for electronics.
There are two main electronic components based on
semiconductors: Diodes and Transistors

14. Diodes
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A diode is an electronic component
formed by two semiconductors, one
is N and other is P, joined together.
Depending of the electric current
sense, the diode can be directly or
inversely polarized
If the diode is directly polarised it
acts as a closed switch. Current
flows
If the diode is inversely polarised it
acts as an opened switch. Current
stops.
There is an special type of diode
called LED, which emit ligth when
currents flow trough them.
There are many uses for diodes.
One example is the conversion of
AC to DC in power sources of
electronic appliances
Index

15. Transistors

A transistor is formed by three
semiconductors. They can be
2 of type n and one of type p:
npn or vivecersa pnp. Each
semiconductor acts as an
electrode. One is called
colector, other base and other
emisor. The base is between
the other two and is used to
control the flow. Current flows
from the collector to the emisor
when the current coming from
the base exceeds a thresold
value

16. States of a transistor
Ib
Cut
Corte
Conduction
Saturation
Vce
Vcc
<IT
Ice
0
~0.001mA
IT<IB<IBS
IB>IBS
I BS
V − 0.2
= CC
β RC
Vcc –
VBE(0.2)Rc·βIB
0
ß·IB
I BS =
VCC − 0.2
RC
Index

17. Electronic circuits

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An electronic circuit
formed by one or more
electronic components
connected.
Electronic circuits perform
a control action using
electricity, such as
controlling automatic
doors, a ligthmimg circuit,
air conditioning
Normally, electronic
circuits are built over
cupper film boards
(integrated circuits)
Index

18. Electronic devices


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An electronic device consists
of one or several electronic
circuits joined together and
encased in a protective shell
The operation of an electronic
device is the group of tasks
that its inner circuits can
perform together
Electronic devices normally
include buttons so that the
user can interact with them
To provide outputs of their
tasks, electronic devices often
include LEDs, an screen or
sound components
Index