basic electronics

Basic Electronics
Eng. Mohamed Loay Ali
Eng:Mohamed Loay Ali Basic Electronics
1

Contents
Analog Electronics
• The Components of
Electricity.
• The Resistor.
• Ohm’s Law.
• The Capacitor.
• The Inductor.
• The Diode.
• The Transistor.
• Relays.
• OP-Amps.
Digital Electronics
• Introduction to Decimal, Binary and
Hexadecimal.
• Introduction to logic gates.
2

Analogue Electronics
The Components of Electricity.
• The Resistor.
• The Capacitor.
• The Inductor.
• The Diode.
• The Transistor.
• Relays.
• OP-Amps.
3

Voltage, Current, and
Resistance
Water flowing through a hose
is a good way to look at
electricity
Water is like Electrons in a wire
(flowing electrons is called
Current)
Pressure is the force pushing water
through a hose – Voltage is the
force pushing electrons
through a wire
Friction against the hole walls
slows the flow of water –
Resistance is the force that
slows the flow of electrons
4

Types of Current
• There are 2 types of current
The type is determined only by the direction the current
flows through a conductor
• Direct Current (DC)
Flows in only one direction negative toward positive pole
of source
• Alternating Current (AC)
Flows back and forth because the poles of the source
alternate between positive and negative
5

AC Current Vocabulary
6

Circuits
• A circuit is a path for current to flow
• Three basic kinds of circuits
• Open – the path is broken and interrupts current flow
• Close – the path is complete and current flows were it is
intended
• Short – the path is corrupted in some way and current does
not flow were it is intended
7

Circuits
8

Resistor
• The Resistor is an electronic device that offers
obstruction to the flow of electric current.
• Also, it can be defined as voltage per unit current through
a conductor
Resistance(R)= Volt(V)/Current(I) (Ohm’s law).
• The Symbol of the resistor
9

Resistor
• Resistor has no polarity (i.e. + and -) like a battery and
can be connected either way in a circuit.
• The parameters of the resistor:
Resistance.
Power handling capacity (wattage) .
Tolerance.
• The power handling capacity of a resistor determines the
amount of current that can be passed safely through it. It
is specified in watt (W).
• As the wattage increases the resistor's cost tend to
increase and they also get bulkier.
10

Resistor
How to identify the resistance value from color bands:
• Band no.1 signifies the 1st digit
• Band no.2 signifies the 2nd digit
• Band no.3 the multiplier.
• Band no.4 the tolerance
11

Resistor
The Following table shows how to translate the color code
of a resistor:
12

Resistor
Resistor in Series
Connection:
R(total)= R1+R2+R3
Resistor in Parallel
Connection:
1R(total)=1R1+1R2+
1R3
13

Resistor
• variable resistor whose resistance can be varied. They are
called as "Potentiometers(pots)" or "Presets".
• A potentiometer looks bigger than a preset and is used
for frequent variations.
• The Symbol of the resistor
• The terminal with the arrow(3) is the variable terminal.
• The terminals 1 & 2 are fixed.
14

Capacitor
• A device that stores energy in electric
field.
• Two conductive plates separated by
a non conductive material.
• It is charged by applying a voltage across its terminals,
and discharged by shorting the two terminals
• The voltage across the terminals of a capacitor is related
to the amount of charge stored in it by the relation:
Voltage = Charge/Capacitance
15

Capacitor
Types of Capacitor:
1. Non-electrolytic
 capacitors are non-polarized, i.e they can be connected either
way in a circuit without having to worry about + &-.
 Its value ranges between about a few pF to as high as 1 uF.
2. Electrolytic
 capacitors are polarized and they are supposed to be
connected in a specific way in the circuit.
 Its value ranges between 1 uF and upwards up to about
4700uF.
16

Capacitor
• The symbol for non-electrolytic capacitor is
• The symbol for electrolytic capacitor is
• The parameters of the resistor:
Electrolytic/non-electrolytic.
Capacitance.
max. voltage.
17

Capacitor
• Capacitor Connection:
 C(parallel)= C1+C2+C3
 1C(Series)=1C1+1C2+1C3
• The capacitor is used to: ^
 Block DC.
 Pass AC.
 Store charges.
18

Inductor
• Inductors are simply coils of wire.
• Inductance is the ability of a coil to establish (or induce) a
voltage within itself to oppose changes in current through
its windings.
• That means when varying current flows through a coil, a
voltage is induced within the coil in a direction so as to
oppose the change of current through it
• The circuit symbol of an inductor is
19

Inductor
• Inductance is measured in Henry(s).
• A Henry is a measure of the intensity of the magnetic field
that is produced.
• Typical inductor values used in electronics are in the range
of milli Henry (1/1000) and micro Henry (1/1,000,000)
20

Inductor
• Like capacitors, inductors
temporarily store energy.
• Unlike capacitors:
• Inductors store energy in a
magnetic field, not an
electric field.
• When the source of
electrons is removed, the
magnetic field collapses
immediately.
21

Inductor
• The amount of inductance
is influenced by a number
of factors:
• Number of coil turns.
• Diameter of coil.
• Spacing between turns.
• Size of the wire used.
• Type of material inside
the coil.
22

Inductor
• Applications of inductors
One of the major applications come in from "mutually
coupled" coils where the magnetic field established in one
coil, 'cuts' through the other coil and hence induces a
voltage in the other coil. This is called 'mutual inductance1.
Such coils are widely used in transformers-.
23

Inductor
• Transformers:
They are used in electronics to step-up or step-down
voltages using mutually coupled coils. When a varying
voltage(like AC) is applied to one of the coils of the
transformer(called the Primary winding), a voltage is
'induced' in the other coil due to mutual inductance. The
second coil in which the voltage is induced is called the
Secondary winding.
24

Inductor
• Transformers are specified bythe following:
Primary and secondary voltages.
Current rating.
• For example, a 230V /12-0-12V and 1A transformer
means, the primary voltage is 230V and secondary
voltages are 12V,0V,12V of the 3 tapings and can
supply a maximum of 1A (this is the root-mean-square
, rms value). If you want to 12V from the transformer,
then you can use the center tap and either of the other
2 end terminals.
25

Diode
Diode is made of:
•Silicon (Si) and Germanium (Ge) are the
two most common single elements that
are used to make Diodes. A compound
that is commonly used is Gallium
Arsenide (GaAs), especially in the case of
LEDs because of it’s large band gap.
•Silicon and Germanium are both group 4
elements, meaning they have 4 valence
electrons. Their structure allows them to
grow in a shape called the diamond
lattice.
Si
+4
Si
+4
Si
+4
Si
+4
Si
+4
Si
+4
Si
+4
Si
+4
Si
+4
26

Steady State
P n
- - - - -
- - - - -
- - - - -
- - - - -
+ + + + +
+ + + + +
+ + + + +
+ + + + +
Na Nd
Metallurgical
Junction
Space Charge
Regionionized
acceptors
ionized
donors
E-Field
++
_ _
h+ drift h+ diffusion e- diffusion e- drift= == =
When no external source
is connected to the pn
junction, diffusion and
drift balance each other
out for both the holes
and electrons
Space Charge Region: Also called the depletion region. This region
includes the net positively and negatively charged regions. The
space charge region does not have any free carriers. The width of
the space charge region is denoted by W in pn junction formula’s.
Metallurgical Junction: The interface where the p- and n-type
materials meet.
Diode
27

Diode
The Diode Characteristics Curve
•VF = Bias Voltage
•ID = Current through
Diode. ID is Negative for
Reverse Bias and Positive
for Forward Bias
•VBR = Breakdown Voltage
28

Diode
Model Circuit:
29

Forward Bias: In forward bias the depletion region shrinks slightly in width.
With this shrinking the energy required for charge carriers to cross
the depletion region decreases exponentially. Therefore, as the
applied voltage increases, current starts to flow across the
junction. The barrier potential of the diode is the voltage at which
appreciable current starts to flow through the diode. The barrier
potential varies for different materials.
Reverse Bias: Under reverse bias the depletion region widens. This causes the
electric field produced by the ions to cancel out the applied
reverse bias voltage. A small leakage current, Is (saturation
current) flows under reverse bias conditions. This saturation
current is made up of electron-hole pairs being produced in the
depletion region. Saturation current is sometimes referred to as
scale current because of it’s relationship to junction temperature.
Vapplied > 0
Vapplied < 0
Diode
30

Diode
Types of Diodes
1)Schottky Diodes:
• These diodes are designed to have a very fast switching
time which makes them a great diode for digital circuit
applications.
• They are very common in computers because of their
ability to be switched on and off so quickly.
A K
Schematic Symbol for a
Schottky Diode
31

Diode
• Light-emitting diodes are designed with a very large bandgap so
movement of carriers across their depletion region emits photons of
light energy.
• Lower band gap LEDs (Light-Emitting Diodes) emit infrared
radiation, while LEDs with higher band gap energy emit visible light.
Many stop lights are now starting to use LEDs because they are
extremely bright and last longer than regular bulbs for a relatively
low cost.
2)Lighting Emitting Diodes(LED): A
Schematic Symbol for a Light-
Emitting Diode
K
Types of Diodes
32

Diode
• While LEDs emit light, Photodiodes are sensitive to received
light. They are constructed so their pn junction can be exposed
to the outside through a clear window or lens.
• In Photoconductive mode the saturation current increases in
proportion to the intensity of the received light. This type of
diode is used in CD players.
• In Photovoltaic mode, when the pn junction is exposed to a
certain wavelength of light, the diode generates voltage and
can be used as an energy source. This type of diode is used in
the production of solar power.
Types of Diodes
3)Photo Diode: KA
Schematic Symbols for
Photodiodes
33

Diode
• Photo diode diagram:
• The Circuit:
34

Power Supply Circuit
Diode
One of the most important applications of diodes is in the
design of rectifier circuits. Used to convert an AC signal
into a DC voltage used by most electronics.
35

Rectifiers
1) Half Wave Rectifier
Diode
Note:
PIV: Peak Inverse Voltage
36

To utilize both halves of the input sinusoid use a center-tapped
transformer…
Diode
2)Full Wave Rectifier
37

3)Bridge Rectifier
Diode
Looks like a Wheatstone bridge. Does not require a enter tapped transformer.
Requires 2 additional diodes and voltage drop is double.
38

Diode
Filter
The ripple factor (r)is an indication of the effectiveness of the filter and
is defined as
39

Diode
Regulator
A voltage regulator is connected to the output of a filtered rectifier and
maintains a constant output volt-age (or current) despite changes in the input,
the load current, or the temperature
40

Diode
Power Supply Full Circuit
41

Transistor (BJT)
Structure:
42

Transistor (BJT)
Basic Operation:
1)Basing
43

Basic Operation:
2)Operation (npn)
Transistor (BJT)
44

Basic Operation:
3)Transistor Current
Transistor (BJT)
45

• DC Beta ( DC) :
The dc current gain of a transistor is the ratio of the dc
collector current (IC) to the dc base current (IB) and is
designated dc beta( beta=ICIB) range from less than 20 to
200 or higher.
• DC alpha :
The ratio of the dc collector current (IC) to the dc emitter
current (IE) (alpha=ICIE) range from 0.95 to 0.99 or
greater, always less than 1.
Important Parameters:
Transistor (BJT)
46

BJT Circuit Analysis (npn):
Transistor (BJT)
47

BJT Characteristics Curve(npn):
Transistor (BJT)
48

BJT Regions:
Transistor (BJT)
Saturations the state of a BJT in which the base current is
increased, the collector current also increases (IC=
bDC*IB).
linear region of its operation. Once the base-collector
junction is reverse-biased, IC levels off and remains
essentially constant for a given value of Ibase
Cutoff is the non conducting state of a transistor. The
amount of collector leakage current for
IB= 0.
49

The BJT as Switch:
Transistor (BJT)
50

The BJT(2N3904) as Switch Example:
Transistor (BJT)
The LED in 30 mA to emit a sufficient level of light.
Therefore,the collector current should be approximately
30 mA. For the following circuit values,determine the
amplitude of the square wave input voltage necessary to
make sure that the transistor saturates. Use double the
minimum value of base current as a safety margin to
ensure saturation. VCC 9 V, VCE(sat) 0.3 V, RC 220 Æ,
RB 3.3 kÆ, bDC =50, and VLED 1.6 =V.
51

The Photo transistor:
Transistor (BJT)
In a phototransisto rthe base current is produced when light strikes the photosensitive
semiconductor base region.
52

Application of Photo transistor:
Transistor (BJT)
53

Opto-Couplers
An optocoupleruses an LED optically coupled to a photodiode or a
phototransistor in a single package.
Optocouplers are used to isolate sections of a circuit that are
incompatible in terms of the voltage levels or currents required.
They are also used to isolate low-current control or signal circuits from noisy
power supply circuits or higher-current motor and machine circuits
54

Operational-Amplifiers
deal Op Amp: NOW ALMOST !!
▫ DC Input Offset Voltage = 0 (V+ to V-)
▫ The Gain is independent of frequency
▫ Input currents = 0 (specially in FET)
▫ Gain is INFINITE ( A = 100000 )
▫ Zin = Inf. And Zout = 0 Ohms
55

Non-ideal Op Amps
56

Practical Example
57

Practical Example
58

Practical Example
The Buffer / Unity Gain Follower
▫ High Zin and low Zout
▫ Rf is a current limitter
59

Practical Example
The Current to Voltage Converter
60

Practical Example
• The Non-Inverting Amplifier
▫ Amplification only
61

Practical Example
The Inverting Amplifier
▫ Amplification AND Attenuation
62

Practical Example
63

Practical Example
The Summing and Differential Amplifier Circuits:
64

Practical Example
The Basic Integrator and Differentiator Circuits:
65

Practical Example
Practical High-pass and Low-pass filters:
66

Single-Supply Op Amp Design Techniques
• In the previous part, all op amps were powered from dual or split
supplies, but this is not the case in today’s world of digital equipments.
• Single-supply systems do not have the convenient ground reference that
dual-supply systems have, thus biasing must be employed to ensure that the
output voltage swings between the correct voltages (0 – 5V).
• When the signal source is not referenced to ground , the reference voltage
is amplified along with the signal (Problem).
• Unless the reference voltage was inserted as a bias voltage, the reference
voltage must be stripped from the signal so that the op amp can provide
maximum dynamic range.
• An input bias voltage is used to eliminate the reference voltage when it
must not appear in the output voltage. The voltage Vref is in both input
circuits, hence it is named a common-mode voltage.
67

The non-inverting op amp circuit shown have an output of:
68

Taking an orderly path to developing a circuit that works the first time starts
here; Follow these steps until the equation of the op amp is determined.
• A linear op amp transfer function is limited to the equation of a straight line
Equation: y = ±mx ± b.
• The equation of a straight line has four possible solutions depending upon
the sign of m, the slope, and b, the intercept; thus simultaneous equations
yield solutions in four forms.
• Four circuits must be developed; one for each form of the equation of a
straight line.
• In electrical terms, the four equations, cases, or forms of a straight line are:
▫ Vout = + mVin + b
▫ Vout = + mVin – b
▫ Vout = – mVin + b
▫ Vout = – mVin – b
69

Case 1: Vout = + mVin + b
70

Example: The circuit requirements are Vout = 1 V at Vin = 0.01 V, Vout =
4.5 V at Vin = 1 V, RL = 10 k, five percent resistor tolerances, and Vcc = 5 V.
No reference voltage is available, thus Vcc is used for the reference input,
thus Vref = 5 V (space and cost savings vs noise, accuracy, and stability).
Solution
The data is substituted into simultaneous equations.
1=m(0.01)+b
4.5=m(1.0)+b
m=3.533 b=0.9646
Select RG=10K and R1=10K
Then from m and b equation calculate RF and R2.
R2=183.16K but the standard is 180k
RF=27.3k and the standard is 27k
71

The Simulation Results
72

73

Case 2: Vout = + mVin - b
74

Example:
The specifications for an example design are: Vout = 1.5 V @ VIN = 0.2 V,
Vout = 4.5 V @ VIN = 0.5 V, Vref = Vcc = 5 V, RL = 10 kΩ, and 5% resistor
tolerances.
Solution
1.5=m(0.2)+b
4.5=m(0.5)+b
m=10 b=-0.5
Select RG=20K ,R2=0.8K, RL=10K
R1=75K
RF=180k
Case 2: Vout = + mVin - b
75

Case 2: Vout = + mVin – b
76

Case 2: Vout = + mVin – b
77

Case 3: VOUT= –mVIN+ b
78

The design specifications for an example circuit are:
Vout = 1 V @ Vin = -0.1 V and Vout = 6 V @ Vin = -1 V, Vref = Vcc
= 10 V, RL= 100 Ω, and 5% resistor tolerances.
Solution
1=m(-0.1)+b
5=m(0.5)+b
m=-5.6 b=0.444
Select RG=10K ,R1=2K, RL=10K
R1=300K
RF=56k
79

Case 3: VOUT= –mVIN+ bCase 3: VOUT= –mVIN+ b
80

81

Case 4: VOUT= –mVIN –b
82

The design specifications for an example circuit are:
Vout = 1 V @ Vin = -0.1 V and Vout = 6 V @ Vin = -1 V, Vref = Vcc
= 10 V, RL= 100 Ω, and 5% resistor tolerances.
Solution
1=m(-0.1)+b
5=m(-0.3)+b
m=-20 b=-1.0
Select RG1=1K ,R1=2K, RL=10K
R1=300K
RF=20k
RG2=100K
83

84

85

• Introduction to Decimal, Binary and
Hexadecimal.
• Introduction to logic gates.
Digital Electronics
86

Introduction to Decimal, Binary
and Hexadecimal.
Decimal Numbers:
The position of each digit in a weighted number system is assigned a
weight based on the base or radix of the system. The radix of decimal
numbers is ten, because only ten symbols (0 through 9) are used to
represent any number.
(9 x 103) + (2 x 102) + (4 x 101) + (0 x 100)
or
9 x 1,000 + 2 x 100 + 4 x 10 + 0 x 1
Decimal numbers can be expressed as the sum of the products of each
digit times the column value for that digit. Thus, the number 9240 can be
expressed as
87

and Hexadecimal.
Binary Numbers:
For digital systems, the binary number system is used. Binary has a radix
of two and uses the digits 0 and 1 to represent quantities.
The column weights of binary numbers are powers of two that increase
from right to left beginning with 20 =1:
…25 24 23 22 21 20.
For fractional binary numbers, the column weights are negative powers
of two that decrease from left to right:
22 21 20. 2-1 2-2 2-3 2-4 …
88

1 A 2 F16
Express 1A2F16 in decimal.
Start by writing the column weights:
4096 256 16 1
1(4096) + 10(256) +2(16) +15(1) =
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Decimal Hexadecimal Binary
and Hexadecimal.
Hexadecimal Numbers:
Hexadecimal is a weighted number system.
The column weights are powers of 16, which
increase from right to left.
163 162 161 160
89

Introduction to logic gates
Not Gate or Inverter
90

And Gate
91

Nand Gate
92

OR Gate
93

NOR Gate
94

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