ELECTRONICS ENGINEERING
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Transcript of ELECTRONICS ENGINEERING
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ELECTRONICS ENGINEERING
Unit I: Semiconductor Diodes and Applications
Before we start with Electronics Let us
review the Basics of Electricity
Q. What are the two main quantities in electricity ?• CURRENT
• VOLTAGE
Unit I: Semiconductor Diodes and Applications
What is Current?
Unit I: Semiconductor Diodes and Applications
What is Voltage?
Unit I: Semiconductor Diodes and Applications
What is a Voltage Source ? A device that produces voltage output continuously.
DC Voltage Source and AC Voltage SourceTYPES:-
Unit I: Semiconductor Diodes and Applications
What is a Current Source ? A voltage source that has a very high internal
impedance as compared with external load impedance is a Constant Current Source.
• Example: A dc battery of 1000 V with internal resistance 950kΩ and load resistance varying from 50 KΩ to 150 KΩ.
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Series and Parallel Connections Two 12 V batteries in
series Two 12 V batteries in
parallel What will be the output
voltage if a 24 V battery is connected in parallel with a 12 V battery?
• The branch of engineering which deals with current conduction through a vacuum, or gas or semiconductor is known as electronics.
Applications:-•Rectification•Amplification•Control•Generation•Conversion of Light into Current•Conversion of Current into Light
Unit I: Semiconductor Diodes and Applications
Classification of Solids Insulators:
(e.g. wood, glass)
Conductors:
(e.g. copper, aluminum)
Semiconductors:
(e.g. germanium, silcon)
Conductors, Insulators and
Semiconductors
Unit I: Semiconductor Diodes and Applications
Semiconductors A semiconductor is a substance which
has conductivity (2 to 2000/ ohm-meter) in between conductors and insulators e.g. germanium, silicon, carbon etc.
A semiconductor is a substance which has almost filled valence band and nearly empty conduction band with a very small forbidden energy gap i.e. 1.1eV for silicon and 0.7eV for germanium.
Unit I: Semiconductor Diodes and Applications
Intrinsic & Extrinsic semiconductors A semiconductor in an extremely pure
form is known as an intrinsic semiconductor.
The intrinsic semiconductor has little current conduction capability at room temperature.
To be used in electronic devices, the conducting properties of intrinsic semiconductor are significantly increased by adding a small amount of suitable impurity, it is then called extrinsic semiconductor.
The process of adding impurities to a pure semiconductor is known as doping.
Man adding water to milk
12Unit I: Semiconductor Diodes and Applications
P-N Junction• If a semiconductor is doped with p-type impurities
at one end and n-type impurities at the other end, a p-n Junction is formed
13Unit I: Semiconductor Diodes and Applications
Diode It is a one way valve. It allows current to flow in one direction
only. It is commonly used (as a switch) in making
Power supply to convert ac voltage into dc voltage.
Unit I: Semiconductor Diodes and Applications
Half-wave Rectifiers
Half-wave rectifier – A diode placed in series between a transformer (or ac line input) and its load.
Unit I: Semiconductor Diodes and Applications
Positive Half-wave Rectifiers
This circuit converts an ac input to a series of positive pulses.
Unit I: Semiconductor Diodes and Applications
Negative Half-wave Rectifiers This circuit converts
an ac input to a series of negative pulses.
Unit I: Semiconductor Diodes and Applications
Full-wave Rectifier
Unit I: Semiconductor Diodes and Applications
Negative Full-wave Rectifiers
The negative full-wave rectifier converts an ac input to a series of negative pulses.
Unit I: Semiconductor Diodes and Applications
Full-Wave Bridge Rectifiers The most commonly used because:
It does not require the use of a center-tapped transformer.
It can be coupled directly to the ac power line. It produces a higher dc output than a comparable
full-wave center-tapped rectifier.
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Transistors
21Unit I: Semiconductor Diodes and Applications
Digital Circuits Digital circuits are prepared using analog
components like transistor as a switch. The binary numbers 1 and 0 are
represented by +5Volts and 0Volts.
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