Lec 1 electronics, application & components
- 1. By: Engr. Sundas Islam Page 1 of 5 Lec-1: Basic Electronics. By: Engr. Sundas Islam 1.1 What is Engineering? Engineering itself is a process to carry out sub-processes of designing, operating, controlling & optimizing. 1.2 Fields of Engineering that deals with flow of Electrons Electrical Engineering is the father of Electronic Engineering. Electronic engineering can be differentiated from Electrical engineering in following aspects. Attribute Electrical Engineering Electronic Engineering Definition Electrical engineering deals with generation, transmission & distribution of electrical power & its utilization. Electrical engineering is defined as anything relating to or concerned with electricity. Electronic engineering is a science & technology that is concerned with the development & applications of electronic devices which deal with current conduction through a vacuum, gas or semiconductor. Behaviour Electrical devices mainly change current into other form of energy such as heat or light. Electronic devices manipulate current in such a way that it can do a particular task. Relation It is related to producing or being operated by electricity. It is concerned with the applications of electronic devices involving flow of current. Data Manipulation Electrical devices do not manipulate data. Electronic devices manipulate data to assign meaning to it. Current Electrical devices use alternating current (AC). Electronic devices use direct current (DC). Voltage Electrical devices work on high voltages. Electronic devices work on low voltages. 1.3 Direct Current and Alternating Current 1. Alternating Current (ac) periodically reverses in direction as the voltage source (applied voltage) periodically reverses in polarity. OR the current that changes its direction as the applied voltage changes its polarity.
- 2. By: Engr. Sundas Islam Page 2 of 5 When voltage having different polarities is applied to an electronic circuitry then its outcome would be an alternating current flowing across the circuitry. 1. Direct Current (dc) a current flow that has just one direction because the voltage source (applied voltage) has fixed polarities. When voltage having fixed polarity is applied to an electronic circuitry then its outcome would be either steady voltage and current across the circuitry OR it would be pulsating DC voltage and current across the circuitry. 1.4 Application of Electronics 1. Rectification: The conversion of a.c. into d.c. is called rectification. Electronic devices can convert a.c. power into d.c. power with very high efficiency. For example, Diode, DC supply which can be used for charging batteries, or can be used for supplying DC voltage to electronic circuitry. 2. Amplification: The process of raising the strength of a weak signal is known as amplification. Electronic devices that perform amplification are amplifiers. For example, Amplifier are used in radio sets where the weak signals are amplified so that it can be heard loudly. Similarly, amplifiers are used in public address system, television etc.
- 3. By: Engr. Sundas Islam Page 3 of 5 3. Control: Electronic devices find wide applications in automatic control. For example, speed of a motor, voltage across a refrigerator etc. can be automatically controlled with the help of such devices. 4. Generation/Oscillation: Electronic devices are capable of converting d.c. power into a.c. power of any frequency. For Example, Electronic device performing this function is known as oscillators. The oscillators are used in a wide variety of ways. 5. Conversion of light into electricity: Electronic devices can convert light into electricity. This conversion of light into electricity is known as photo-electricity. For Example, Photo-electric devices are used in Burglar alarms, sound recording on motion pictures etc. 6. Conversion of electricity intolight: Electronic devices can convert electricity into light. For Example, This valuable property is utilized in television and radar. 1.5 Most Commonly used Electronic Components Electronic components are categorized as being active or passive. Both are generally used together to form complete circuits in all types of electronic equipment. 1. Passive components can control energy, but they cannot modify it. E.g: Resistors, Capacitors and inductors. a. Resistors: Resistors are perhaps the most common component in electronic circuit. The main function is to limit the flow of current or reduce voltage in a circuit. Resistance is the measure of the degree to which a conductor opposes an electric current passing through it. It is measured in ohms Ω Type of Resistors Schematic Symbol Notes Fixed Resistor provides fixed amount of resistance. Some fixed resistors are color coded to indicate their resistance value, while others have their resistance values printed on the body. Variable Resistor whose resistance keeps on changing. Potentiometer - Has three end points / terminals. - Varies Voltage. Rheostat - Has two end points / terminals.
- 4. By: Engr. Sundas Islam Page 4 of 5 - Varies Current. b. Capacitors: • A capacitor is a component that is able to hold or store an electric charge. • It consists of 2 metal plates separated by an insulator or free space. • It blocks direct current and passes alternating current. • Capacitance is the ability of a body to store an electrical charge. A material with a large capacitance holds more electric charge at a given voltage, than one with low capacitance. The basic unit of capacitance is farad (F). Type Schematic Symbol Notes Fixed provides fixed amount of capacitance. Stores electric charge. Blocks dc, passes ac. Electrolytic Either one of the metal plates is oxidized to make it polar or both the metal plates are oxidized to make it non-polar (bipolar). - Has large capacitance - May be polar, non- polar(bipolar) - Fixed values only Variable whose capacitance keeps on changing. Used for tuning radios, TVs, and other electronic communications equipment. c. Inductors: • Its physical construction is simply a coil of wire. And often called coils. • They are opposite of capacitors in that they are able to pass a dc current and blocks ac current. • Inductance is the property of an electrical conductor by which a change in current flowing through it induces an electromotive force in both the conductor itself and in any nearby conductors. It is measured in Henry (H). Type Schematic Symbol Notes Air has air in between the coils - Induce voltage when current changes. - Passes dc and limits ac. Iron Core has iron in between the windings. - Use for low frequency.
- 5. By: Engr. Sundas Islam Page 5 of 5 Variable whose inductance keeps on changing. - Used for tuning radios, TVs and other electronic communication equipment. 2. Active components are capable of changing energy from one form to another form. Such components perform process of rectification / amplification. E.g: diodes and transistors. a. Diode: A diode is an electronic component which allows current to flow through it in one direction. It changes ac voltage to pulsating dc. b. Transistors: An electronic component that can be used to amplify small ac signals or switch to dc voltage. Bipolar Junction Transistor(BJT) is used for amplification. Field Effect Transistor FET is used for switching purpose commonly used in ICs (Integrated Circuit).