Transcript Easy Electronics

Electronics
Electronics is the science and technology
of electronic phenomena. It is a branch
of physics that deals with the emission,
behaviour, and effects of electrons and
with electronic devices
Electronics, pronounced as elec.tron.ics
History of Electronics
The beginnings of electronics can be traced to
experiments with electricity. In the 1880s
Thomas Alva Edison and others observed the
flow of current between the elements in an
evacuated glass tube.
By 1920, the development of vacuum tubes
and circuits employing them had advanced to
the point where their superiority over all
other devices used in radio transmitters and
receivers was apparent.
Evolution of Electronics
In 1948 William Shockley, John Bardeen, and
Walter H. Brattain of Bell Telephone
Laboratories developed the First transistor
and during the early 1950's the technology
was developed to mass-produce transistors.
The invention of the transistor initiated a
progressive miniaturization of electronic
components . By the mid 1980s,high-density
microprocessors were developed that led to
tremendous advancement in Computer
technology.
During the 1970's and 1980's the size of the
components of integrated circuits continued
to be reduced and the number of components
that could be produced on each chip grew
rapidly.
With
increasing
miniaturization,
the
capabilities of the electronic circuits and the
speed at which they could perform their
functions greatly increased.
By 1990's, introduction of
Microelectronics led to the development
of new technologies, such as digital audio
recording; to the introduction of new
products, such as personal computers;
and to the reduction in the size of
portable telephones and many other
electronic products.
Easy Electronics
Hobby electronics combines creativity and
tinkering as part of the fun process of
creating devices that are born out of
passion, learning, dedication, curiosity and,
most importantly, play.
Before building a circuit, it is necessary to
understand some basics of electronics.
Electronics involves current and voltage.
Current
Current is the flows of electrons through a
wire. Current flows from points of high voltage
to points of low voltage.
The unit of measurement for current is the
Ampere (Amp) and is abbreviated as A
Voltage
Voltage indicates the power level of a
point and is measured in Volts.
If one point is at 5 volts and another
point is at 0 volts then when a wire is
connected between them, current will
flow from the point at 5 volts to the point
at 0 volts.
Semiconductor
Semiconductor is a substance that
releases 'free electrons' from its
outermost orbit when exposed to energy
such as heat or light.
The space from which electrons are
released
is
called
a
'hole.'
Semiconductors carry electrical current
when they release 'free electrons.'
Typical Semiconductor materials are Silicon
and Germanium. By adding impurities, it is
easy to create p-type semiconductors with
many 'holes' and n-type semiconductors
with many 'free electrons
When these two types of semiconductors
are joined, they form an element called a
diode. Transistors and IC's are formed by
combining large numbers of these diodes.
Electrons and Holes
PN Junction
When P-type and N-type silicon are placed
in contact with one another it forms a PN
junction
Biasing of PN Junction
A basic PN junction creates a diode that allows
electricity to flow in one direction but not the other
Near the PN junction the electrons diffuse into the
vacant holes in the P material causing a depletion zone.
This depletion zone acts like an insulator preventing
other free electrons in the N-type silicon and holes in
the P-type silicon from combining
Ohm’s law
There is a simple relationship between current,
voltage and resistance. This relationship is called
Ohm’s Law.
Difference in Voltage = Current x Resistance
V=Ix R
Current = Difference in Voltage / Resistance
I=V/R
Resistance = Difference in Voltage / Current
R=V/I
Ohm’s Law Triangle
Resistors
Resistors are components that have a
predetermined
resistance.
Resistance
determines how much current will flow
through a component. Resistors are used to
control voltages and currents. Resistance is
given in units of ohms
Resistor Colour code
Value of a resistor is determined using the
color coded stripes on the resistor .
Let us the a Resistor. Its colour stripes are
brown, black, orange and gold.
Value of brown is 1 and that of black is 0.
Combining these two gives 10.
The third colour is orange which means x
1,000.
The value of the resistance is found as 10 x
1000 = 10,000 ohms or 10 Kilo Ohms or 10K.
The gold stripe is the tolerance that means the
actual value of the resistor mar vary by 5%
Series Connection
When two resistors are connected in series,
their resistance will add together
For example if R1 is 500 ohms and R2 250 ohms,
then R1 + R2 = 500 + 250 = 750 ohms
Parallel Connection
When two resistors are connected in parallel,
their resistance will decrease. For example if
R1 is 500 and R2 = 250 then the resistance is
500 x 250) / (500 + 250) = (125,000) / (750) =
167 ohms.
Variable Resistors
Resistance of Variable resistor can be increased
or decreased. They have a dial or a knob that
allows you to change the resistance .In higher
resistance, less current flow and in lower
resistance ,more current will flow
Capacitor
Capacitors store current and allow AC to
pass through it. Capacitor has two
electrodes and between them there is a
dielectric material.
Electrolytic capacitors have value
printed on its body. Pins can be easily
identified. Large pin is positive. Moreover
a black / white band is printed near the
negative terminal to identify the polarity.
In Disc capacitors, only a number is printed on
its body. One or two numbers on the capacitor
represents value in PF. E.g. 8 = 8PF
Some have 3 numbers and if the third number
is zero, then the value is in P E.g. 100 = 100PF
If the capacitor has 3 numbers and the third
number is not a zero, it represents the
number of zeros after the first and second
digits E.g. 104 = 10 – 0000 PF
Disc capacitor is non polarized and can be
connected either way round
Capacitors
Variable Capacitors
Diodes
Diodes allow current to flow in only one
direction. They have a positive side leg and a
negative leg. When the voltage on the positive
leg is higher than on the negative leg then
current flows through the diode
The negative leg of a diode is the Cathode and
positive end is Anode
Types of Diodes
Light Emitting Diode
Light Emitting Diode
LEDs use a special material which emits
light when current flows through it. A
current of 0.02 Amps (20 mA) to 0.04
Amps (40 mA) is a good range for LEDs.
LED Requires a series resistor to restrict
the current through it. The resistor value
can be determined using Ohm’s law
Integrated Circuit
IC Socket
Transistors
Transistor act as a simple switch to turn a
part of circuit on and off.
The transistor has three pins namely
Collector (C) Base (B) and Emitter (E).
The Base (B) is the On/Off switch for the
transistor. If a current is flowing to the
Base, current flows from the Collector (C)
to Emitter in NPN transistor and Emitter
to Collector in PNP transistor
Transistor
Transistor coding
Transistor has codes to identify them. Usually the
code has two letters followed by the part number
First letter
A – Germanium B – Silicon C – Gallium Arsenide
D – Indium Antimide
Second letter
C – Audio frequency Amplifier D – Audio frequency
power amplifier F – Low power Radio frequency
amplifier P – High power Radio frequency amplifier
E.g. BC 548 is B – Silicon C - Audio frequency
amplifier
Transistors
Buzzer and Speaker
Switch
Switches are devices that create a short
circuit or an open circuit depending on
the position of the switch. For a switch,
ON means short circuit. When the switch
is OFF, that means there is an open
circuit
Switches
Power supply - Battery
Transformer Power supply
Printed Circuit Board
Tools
Circuit Design
Components to construct Timer
How to Identify
Soldering