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Introduction to Electronics

Introduction to Electronics. Contents. Evolution of Electronics, Impact of Electronics in industry and in society. Resistors- types, specifications. Standard values, marking, colour coding. Capacitors: types, specifications. Standard values, marking, colour coding.

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Introduction to Electronics

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  1. Introduction to Electronics www.infonics.co.nr/electronics

  2. Contents • Evolution of Electronics, Impact of Electronics in industry and in society. • Resistors- types, specifications. Standard values, marking, colour coding. • Capacitors: types, specifications. Standard values, marking, colour coding. • Inductors- types, specifications, Principle of working. • Transformers: types, specifications, Principle of working. • Electro mechanical components: relays and contactors. www.infonics.co.nr/electronics

  3. Electronics ??? • Branch of science that deals with • study of flow & control of electrons • study of their behavior & effects in vacuums, gases, and semiconductors, and with devices using such electrons. www.infonics.co.nr/electronics

  4. Evolution of Electronics • 1752-Ben Franklin – Lightning • 1784- Charles Augustin Coulomb – Electrical Charge • 1791-Luigi Galvani – Bio electricity • 1799- Alessandro Volta –Voltage www.infonics.co.nr/electronics

  5. Evolution of Electronics • 1820- Hans Christian oersted – Electromagnetism • 1827- George Simon Ohm- Resistance • 1831- Michael Faraday - Electromagnetic induction • 1864- James Clerk Maxwell - Maxwell’s equation www.infonics.co.nr/electronics

  6. Evolution of Electronics • 1876- Alexander Graham Bell-Telephone • 1879- Thomas Alva Edison – Electric Bulb • 1888- Heinrich Hertz – Radio Waves • 1895- Marconi-Radio www.infonics.co.nr/electronics

  7. Evolution of Electronics • 1904- Ambrose Fleming – Vacuum Tube • 1906- Lee De Forest-Triode • 1925- John Logie Baird – Television • 1939- Russell Ohl – PN Junction Diode www.infonics.co.nr/electronics

  8. Evolution of Electronics • 1948- William Schockley, John Bardeen and Watter Brattain- Transistor • 1958- Jack Kilby – Integrated Circuit www.infonics.co.nr/electronics

  9. Evolution of Electronics • 1971- Robert Noyce and Gordon Moore-Microprocessor www.infonics.co.nr/electronics

  10. Impact of Electronics in industry and in society www.infonics.co.nr/electronics

  11. Impact of Electronics in industry and in society • Besides electronic devices (radio & TV receivers, audio & video players, calculators, mobile phones, etc.,) electronics has offered its services in different walks of life. • Computer: major achievement www.infonics.co.nr/electronics

  12. Impact of Electronics in industry and in society • All techniques and devices make use of electronics - reliability & precision are key factors • industrial operations, • medical diagnostics and surgery, and • in laboratory practice. • development of communication facilities • wireless communication • Aircraft uses radio communication-weather & terminal traffic information • Satellite communication • space voyages to moon or mars • in defence • Radar • electronic warfare www.infonics.co.nr/electronics

  13. Applications of electronics in various fields • Home Appliances: Washing machines, microwave appliances, security systems, dishwashers, DVD, HV and AC systems, etc. • Automobile: Airbag systems, GPS, anti-locking brake system, fuel injection controller devices, etc. • Security: Building security system, face recognition, airport security system, eye recognition system, alarm system, finger recognition systems, etc. • Aerospace: Flight attitude controllers, space robotics, automatic landing systems, navigational systems, space explorer, etc. • Medical: Medical diagnostic devices: ECG, EMG, MRI, EEG, CT scanner, BP Monitor, Glucose monitor. • Banking and Finance: Share market, cash register, smart vendor machine, ATM. • Defense: Radar system, explosive detection system, metal detector, surveillance systems. www.infonics.co.nr/electronics

  14. Introduction to Electronic Components www.infonics.co.nr/electronics

  15. Electronic Components-Classification • Passive components • Not capable of processing an electrical signal such as amplification, oscillation, modulation etc. • Aid the active components in functioning. • Store or maintain Energy in the form of Voltage or Current. • The behavior of passive components is linear. • Examples: resistor, capacitor, inductor etc. • Active components • Capable of processing an electrical signal such as amplification, oscillation, modulation etc. • Produces energy in the form of Voltage or Current. • The behavior of active components is nonlinear. • Examples: transistors and diodes. www.infonics.co.nr/electronics

  16. Introduction to Passive ComponentsResistors www.infonics.co.nr

  17. Resistors • Device which provides a force opposing the charge-flow (or current) in a circuit. This opposing force is called resistance (R). • measured in ohms (symbol is Ω). • power ratings. • It is the maximum power that can be dissipated without raising the temperature too high. • Common standard power ratings are ¼ W, ½ W, 1 W and • 2 W. www.infonics.co.nr

  18. Resistors-Types • Two basic types of resistors. • Linear Resistors • Non Linear Resistors • Linear Resistors • values change with the applied voltage and temperature • which current value is directly proportional to the applied voltage • Two types of linear resistors:a) Fixed Resistors b) Variable Resistors. • Fixed Resistors • specific value and we can’t change the value. • Types of Fixed resistors. • Carbon Composition Resistors • Wire Wound Resistors • Thin Film Resistors • Thick Film Resistors www.infonics.co.nr

  19. Carbon Composition Resistors • Construction • made of carbon clay composition covered with a plastic case. The lead of the resistor is made of tinned copper. • Available in wide range of values. • available in as low as 1 Ω value and as high as 22 MΩ value. • Tolerance range is of ± 5 to ± 20 %. • Advantage • easily available in local market in very low cost and they are very durable too. • Disadvantage • very much temperature sensitive. • Tendency of electric noise due to passage of electrical current from one carbon particle to other www.infonics.co.nr

  20. Wire Wound Resistor • Construction • Formed by wrapping a resistive wire around a non-conducting rod. The rod was usually made of some form of ceramic that had the desired heat properties since the wires could become quite hot during use. End caps with leads attached were then placed over the ends of the rod making contact to the resistive wire, usually a nickel chromium alloy. • available for wide range of ratings. • values varies from 1 Ω to 1 MΩ. • Tolerance limit varies from 0.01 % to 1 %. • Advantages • Different sizes and ratings can easily be achieved by using different lengths and diameters of the wire. • They can be used for high power applications of 5 to 200 W dissipation ratings. • Disadvantages • The cost is much higher than carbon resistor. www.infonics.co.nr

  21. Thin Film Resistors • Construction • A very thin conducting material layer overlaid on insulating rod, plate or tube which is made from high quality ceramic material or glass. • Types of thin film resistors. • Metal Film Resistor. • Carbon Film Resistor. www.infonics.co.nr

  22. Metal Film and Carbon Film Resistor • Construction • constructed by means of film deposition technique; deposition a thin film of resistible material such as pure carbon or metal on to an insulating core. • Metallic contact cap is fitted at both ends of the resistor. The caps must be in contact with resistible film. The lead wires are welded to these end caps. • Advantages • can be made up to a value of 10,000 MΩ • size of this type of resistor is much smaller than wire wound resistor. www.infonics.co.nr

  23. Thick Film Resistors • Construction • same like thin film resistors, but the difference is that there is a thick film instead of a thin film or layer of resistive material around. • Two types of thick film resistors. • Metal Oxide Resistors • Cermet Oxide Resistors • Fusible Resistors www.infonics.co.nr

  24. Fusible Resistors • Construction • Same like a wire wound resistor. • When a circuit power rating increased than the specified value, then this resistor is fused, i.e. it breaks or open the circuit. That’s why it is called Fusible resistors. Fusible resistors perform double jobs means they limit the current as well as it can be used as a fuse. • They used widely in TV Sets, Amplifiers, and other expensive electronic circuits. Generally, the ohmic value of fusible resistors is less than 10 Ohms. www.infonics.co.nr

  25. Variable Resistors • value can be adjusted. Construction • Resistive material is deposited on a non-conducting base. stationary contacts are connected to each end of the resistive material. Finally, a moving contact or wiper is constructed to move along the resistive material and tap off the desired resistance. www.infonics.co.nr

  26. Non Linear Resistors • current flowing through it does not change according to Ohm’s Law but, changes with change in temperature or applied voltage. •  flowing current through a resistor changes with change in body temperature-Thermisters. • flowing current through a resistor change with the applied voltages-Varistors or VDR (Voltage Dependent Resistors). • Flowing current through a resistor change with the light falling on it-Photo Resistor • Different types of Non Linear Resistors. 1.Thermisters 2.Varisters(VDR) 3. Photo Resistor or Photo Conductive Cell or LDR www.infonics.co.nr

  27. Thermistors • Thermally sensitive resistors whose prime function is to exhibit change in electrical resistance when subjected to a corresponding change in body temperature. • made from the cobalt, Nickel, Strontium and the metal oxides of Manganese. • Negative Temperature Coefficient (NTC) thermistors exhibit a decrease in electrical resistance when subjected to an increase in body temperature • Positive Temperature Coefficient (PTC) thermistors exhibit an increase in electrical resistance when subjected to an increase in body temperature. www.infonics.co.nr

  28. Varistors • flowing current through a resistor change with the applied voltages-Varistors or VDR (Voltage Dependent Resistors). • used to protect circuits from destructive voltage spikes.  www.infonics.co.nr

  29. Photo Resistor or Photo Conductive Cell or LDR (Light Dependent Resistors) • Resistance value changes with light intensity. • The material which is used to make these kinds of resistors is called photo conductors, e.g. cadmium sulfide, lead sulfide etc. •  When light falls on the photoconductive cells (LDR or Photo resistor), then there is an increase in the free carriers (electron hole pairs) due to light energy, which reduce the resistance of semiconductor material (i.e. the quantity of light energy is inversely proportional to the semiconductor material). It means photo resistors have a negative temperature coefficient. www.infonics.co.nr

  30. LDR-Structure and Symbol www.infonics.co.nr

  31. Resistor Marking • 4-band resistors • First two bands identify the first and second digits of the resistance value, and the third band indicates the number of zeroes. The fourth determines the tolerance. • 5-band resistors • First three bands provide the first three digits of the resistor value. The third band is only used when the tolerance of the resistor is less than 2%. The fourth gives the multiplier.The fifth indicates the tolerance of the resistor. • 6-band resistors • First five bands have the same meaning as the 5-band resistors. The sixth band is a temperature coefficient that indicates the change in electrical conductivity with temperature. www.infonics.co.nr

  32. Colour Code Chart • Black • Brown • Red • Orange • Yellow • Green • Blue • Violet • Grey • White • 0 • 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 Tolerance: Gold = ±5% Silver = ±10 % No colour means 20 % Colours Value www.infonics.co.nr

  33. Four Band Resistor www.infonics.co.nr

  34. Capacitors www.infonics.co.nr

  35. Capacitor • simple passive element that is used to ‘store electricity’. • a component which has the ability or ‘capacity’ to store energy in the form of an electrical charge producing a potential difference across its plates, much like a small rechargeable battery. www.infonics.co.nr

  36. Capacitor-Structure • consists of two or more parallel conductive plates which are not connected or touching each other, but are electrically separated either by air or by some form of a good insulating material such as waxed paper, mica, ceramic, plastic or some form of a liquid gel as used in electrolytic capacitors. The insulating layer between capacitor plates is commonly called the Dielectric. www.infonics.co.nr

  37. Capacitor structure www.infonics.co.nr

  38. Capacitance • property of a capacitor to store charge on its plates in the form of an electrostatic field is called the Capacitance of the capacitor. • Capacitance, C = ε0εr A / d • where A is the area of plates, • d is the plates separation, • ε0 is the permittivity of free space ( 8.84 x 10-12 F/m ) • εr is the relative permittivity of the material being used as the dielectric  . • unit of capacitance being the Farad (abbreviated to F) named after the British physicist Michael Faraday. www.infonics.co.nr

  39. Symbols and Classification • Three main classes of capacitors: • (i) Non electrolytic or normal capacitors • (ii) electrolytic capacitors • (iii) variable capacitors. www.infonics.co.nr

  40. Non electrolytic capacitors • Non electrolytic capacitors are mostly of parallel plate type and can have mica, paper, ceramic or polymer as dielectric. • Mica Capacitors • Ceramic Capacitors • Paper Capacitors www.infonics.co.nr

  41. Mica Capacitors • made from plates of Aluminium foil separated by sheets of mica. The plates are connected to two electrodes. The mica capacitors have excellent characteristics under stress of temperature variations and high voltage applications (~500 V). Available capacitances range from 5 to 10,000 pF. www.infonics.co.nr

  42. Ceramic Capacitors • A ceramic disc is coated on two sides with a metal, such as copper or silver. These coatings act as two plates. After attaching tinned-wire leads, the entire unit is coated with plastic . • Their working voltage ranges from 3 V up to 6000 V. The capacitance value ranges from 3 pF to about 3 mF. www.infonics.co.nr

  43. Paper Capacitors • consists of two metal foils separated by strips of paper. This paper is impregnated with a dielectric material such as wax, plastic or oil. • have capacitances ranging from 0.0005 mF to several mF, and are rated from about 100 V to several thousand volts. www.infonics.co.nr

  44. Electrolytic Capacitors • Construction • Consists of an aluminium-foil electrode which has an aluminium-oxide film covering on one side. The aluminium plate serves as the positive plate and the oxide as the dielectric. The oxide is in contact with a paper or gauze saturated with an electrolyte. The electrolyte forms the second plate (negative) of the capacitor. Another layer of aluminium without the oxide coating is also provided for making electrical contact between one of the terminals and the electrolyte. In most cases, the negative plate is directly connected to the metallic container of the capacitor. The container then serves as the negative terminal for external connections. www.infonics.co.nr

  45. Constructional Diagram • Disadvantage • Relatively low voltage rating and due to the polarization of electrolytic capacitors. • They must not be used on AC supplies. • Two basic forms; Aluminium Electrolytic Capacitors and Tantalum Electrolytic Capacitors. www.infonics.co.nr

  46. Variable Capacitors • Capacitance may be intentionally and repeatedly changed mechanically. Variable capacitors are often used in L/C circuits to set the resonance frequency, or as a variable reactance for impedance matching in antenna tuners. • The most common variable capacitor is the air-gang capacitor. The dielectric for this capacitor is air. By rotating the shaft at one end, we can change the common area between the movable and fixed set of plates. The greater the common area, the larger the capacitance. www.infonics.co.nr

  47. Variable Capacitor • In some applications, the need for variation in the capacitance is not frequent. One setting is sufficient for all normal operations. In such situations, we use a variable capacitor called a trimmer (sometimes called padder). Both mica and ceramic are used as the dielectric for trimmer capacitors. www.infonics.co.nr

  48. Colour and Number code of capacitors • Electrolytic Capacitors • There are two designs of electrolytic capacitors: (i) Axial where the leads are attached to each end (220µF in picture) and (ii) Radial where both leads are at the same end (10µF in picture). www.infonics.co.nr

  49. Colour and Number code of capacitors • Non-polarised capacitors ( < 1µF) • Small value capacitors have their values printed but without a multiplier. For example 0.1 means 0.1µF. Sometimes the unit is placed in between 2 digits indicating a decimal point. For example:   4n7 means 4.7nF. www.infonics.co.nr

  50. Numerical Coding • If the number written on the capacitor is greater than one, the value will be in pF. Otherwise, it will be in μF. For example, 10 means 10 pF and 0.1 means 0.1 μF. • If there are three digits in the number, the third number indicates the number of zeros to be put after first two digits and the value will be in pF.104 means 10,0000 pF or 0.1 μF • If the letter k follows the digits, the value will be in kpF (kilo picofarad). 10 k means 10 kpF or 0.01 μF. • If the letter is ‘n’ or ’M’ the value will be that much nano farads or micro farads respectively. 47n means 47 nF and 47M means 47 μF. • If the letter n, M or k is between two numerals, the value of the capacitor can be obtained by putting a decimal in place of the letter and multiplying by the factor nF, μF or kpF respectively.4k7 means 4.7 kpF and 2M2 means 2.2 μF. • If the letters k or M follows the three digit number, it implies the tolerance value 10% and 20% respectively. www.infonics.co.nr

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