Electronic Equipments Theory Vocational Education HIGHER SECONDARY - SECOND YEAR A Publication under Government of Tamilnadu Distribution of Free Textbook Programme (Not For Sale) Untouchability is a sin Untouchability is a crime Untouchability is inhuman TAMILNADU TEXTBOOK CORPORATION College Road, Chennai - 600 006. C Government of Tamilnadu First Edition - 2011 CHAIR PERSON Dr.R.S.D. Wahida Banu Professor and Head, Department of Electronics & Communication Engineering, Government College of Engineering, Salem - 636 011. AUTHORS Dr. M. Chandrasekar Miss. S. Salma Mehajaben Associate Professor, Lecturer, Department of Electronics & Department of Electronics & Communication Engineering, Communication Engineering, Government College of Engineering, Government College of Engineering, Salem - 636 011. Salem - 636 011. Mr. C.Amirdalingam Mrs. G.Umamaheswari Vocational Teacher, Vocational Teacher, Govt.Hr.Sec.School, Govt.Hr.Sec.School, Yethapur- 636 117 Mettupatty- 636 111 Salem District. Salem District. This book has been prepared by the Directorate of School Education on behalf of the Government of Tamilnadu This Book has been printed on 60 GSM Paper Printed by web offset at : HIGHER SECONDARY – VOCATIONAL ELECTRONIC EQUIPMENTS 12th Std Syllabus Unit 1 : Digital Circuits 1.1.Introduction – Multivibrators – Astable – Monostable – Bistable (IC 555) 1.2. Basic gates – NOR – NAND – EX – NOR – Construction – Verification of Truthtable 1.3. Half adder – Full adder – Full subtractor 1.4. Flipflop – Registers 1.5. Counters – Encoder – Decoder – Multiplexer Unit 2 : Network Antenna and Propagation 2.1. Introduction – Modulation – Demodulation – MODEM 2.2. Pulse Modulation techniques – PAM – PTM – FWM – PPM 2.3. Pulse Digital Modulation – Pulse Code modulation 2.4. Microwave transmission 2.5. Antenna Introduction – Transmitting antenna – types 2.6. Receiving antenna – λ - Yagi – Dish antenna – LNB – Satellite receiver Unit 3 : Radio Transmission and Reception 3.1. Introduction – Transmission Principle – Types – AM Transmitter – FM transmitter 3.2. Receivers – Principle – TRF receiver 3.3. Superhetrodyne Principle – AM, FM receivers – communication receiver 3.4. Construction of AM receiver – Construction of FM receiver 3.5. Alignment, Faults and Rectification techniques Unit 4 : TV Transmission and Reception 4.1. Introduction – TV transmission principle 4.2. Camera tube – types 4.3. B/W TV Principle – Colour TV principle 4.4. TV tuner – types 4.5. Video stages 4.6. Sync stages and deflection unit 4.7. Power supply – types 4.8. Audio stage 4.9. Alignment, Faults and Rectification techniques Unit 5 : Audio and Video Equipments 5.1. Introduction – Gramaphone – Recording techniques 5.2. Magnetic tape – Tape recorder – Mono – Stereo – Spool type 5.3. Compact Disc – VCD, MP3, DVD, MP4, Blue Ray 5.4. Memory Card USB 5.5. Home Theatre – Dolpy – DTS Unit 6 : Tranceivers 6.1. Introduction – Cell Phone – PCS, GSM, CDMA, TDMA Transmission 6.2. Infra red – Blue tooth, GPRS, Camera, VGA, Pixel type 6.3. Half Duplex – Full duplex – Channel range – Cell phone frequency – Radio frequency – Radio Telephony 6.4. WLL – Satellite Phone Unit 7 : Digital Computer 7.1. Introduction – Analog – Digital – Evaluation of DC 7.2. Fundamentals of DC – Generations of Computer – Generations of Language – Major Division of CPU – I/P and O/P Devices – Compilers and Interpretor Unit 8 : Telecommunication 8.1. Introduction – OFC 8.2. Microwave Transmission and Reception 8.3. Types of Satellite – Application 8.4. RADAR – SONAR Unit 9 : Medical Electronic Equipments 9.1. Introduction – Electronic blood testing equipment 9.2. ECG 9.3. CT Scan and ultrasound 9.4. Electronic BP apparatus 9.5. Digital Thermometers 9.6. EEG 9.7. Digital X-Ray 9.8. Nano technology and its applications iv HIGHER SECONDARY – VOCATIONAL ELECTRONIC EQUIPMENTS INDEX Page No. Unit 1 : Digital Circuits 1 - 15 Unit 2 : Network Antenna and Propagation 16 - 30 Unit 3 : Radio Transmission and Reception 31 - 60 Unit 4 : TV Transmission and Reception 61 - 126 Unit 5 : Audio and Video Equipments 127 - 139 Unit 6 : Tranceivers 140 - 156 Unit 7 : Digital Computer 157 - 170 Unit 8 : Telecommunication 171 - 179 Unit 9 : Medical Electronic Equipments 180 - 191 v 1. DIGITAL CIRCUITS 1.1 INTRODUCTION In a digital system, a more precise representation of a signal can be obtained by using more binary digits to represent it. While this requires more digital circuits to process the signals, each digit is handled by the same kind of hardware. In an analog system, additional resolution requires fundamental improvements in the linearity and noise characteristics of each step of the signal chain. Computer-controlled digital systems can be controlled by software, allowing new functions to be added without changing hardware. Often this can be done outside of the factory by updating the product’s software. So, the product’s design errors can be corrected after the product is in a customer’s hands. Information storage can be easier in digital systems than in analog ones. The noise-immunity of digital systems permits data to be stored and retrieved without degradation. In an analog system, noise from aging and wear degrade the information stored. In a digital system, as long as the total noise is below a certain level, the information can be recovered perfectly. Digital circuits are made from analog components. The design must assure that the analog nature of the components doesn’t dominate the desired digital behavior. Digital systems must manage noise and timing margins, parasitic inductances and capacitances, and Tool flows for large logic systems such as microprocessors can be thousands of commands long, and combine the work of hundreds of engineers. power connections. MULTIVIBRATOR A multivibrator is an electronic circuit used to implement a variety of simple two-state systems such as oscillators, timers and flip-flops. It is characterized by two amplifying devices (transistors, electron tubes or other devices) cross-coupled by resistors and capacitors. There are three types of multivibrator circuit: • Astable, in which the circuit is not stable in either state it continuously oscillates from one state to the other. Due to this, it does not require a input (Clock pulse or other). • Monostable, in which one of the states is stable, but the other is not the circuit will flip into the unstable state for a determined period, but will eventually return to the stable state. This circuit is also known as a one shot. • Bistable, in which the circuit will remain in either state indefinitely. The circuit can be flipped from one state to the other. This circuit is also known as a latch or a flip-flop. MONOSTABLE MODE Vcc The relationships of the trigger signal, the voltage on R 4 8 RESET V C and the pulse width in monostable mode In the monostable 7 cc DIST mode, the 555 timer acts as a “one-shot” pulse generator. 6 3 C THR OUT OUT The pulse begins when the 555 timer receives a signal at the 2 TRIG trigger input that falls below a third of the voltage supply. Trigger GND CTRL 15 The width of the pulse is determined by the time constant of 10nF an RC network, which consists of a capacitor (C) and a GND resistor (R). The pulse ends when the charge on the C equals Figure.1.1 IC 555 in monostable mode 1 2/3 of the supply voltage. The pulse width can be lengthened or shortened to the need of the specific application by adjusting the values of R and C. The pulse Trigger Signal width of time t, which is the time it takes to charge C to 2/ 3 of the supply voltage. Volts Capacitor Voltage The pulse width of time t, which is the time it takes to charge C to 2/3 of the supply voltage, is given by Output Pulse t = RC ln (3) ≈ 1.1RC where t is in seconds, R is in ohms and C is in farads. See Time Figure.1.2 RC circuit for an explanation of this effect. BISTABLE MODE In bistable mode, the 555 timer acts as a basic flip-flop. The trigger and reset inputs (pins 2 and 4 respectively on a 555) are held high via pull-up resistors while the threshold input (pin 6) is simply grounded. Thus configured, pulling the trigger momentarily to ground acts as a ‘set’ and transitions the output pin (pin 3) to Vcc (high state). Pulling the reset input to ground acts as a ‘reset’ and transitions the output pin to ground (low state). No capacitors are required in a bistable configuration. Pins 5 and 7 (control and discharge) are left floating. ASTABLE MODE In astable mode, the ‘555 timer ‘ puts out a continuous stream of rectangular pulses having a specified frequency. Resistor R1 is connected between VCC and the discharge pin (pin 7) and another resistor (R2) is connected between the discharge pin (pin 7), and the trigger (pin 2) and threshold (pin 6) pins that share a common node. Hence the capacitor is charged through R1 and R2, and discharged only through R2, since pin 7 has low impedance to ground during output low intervals of the cycle, therefore discharging the capacitor. In the astable mode, the frequency of the pulse stream depends on the values of R1, R2 and C: Vcc 1 f = R 4 8 In(2) . C . (R1 + 2R2) 1 RESET Vcc 7 The high time from each pulse is given by DIST 6 3 high = In(2) . (R + 2R ) .C THR OUT 1 2 R 2 OUT 2 TRIG and the low time from each pulse is given by GND CTRL low = In(2) . 2R .C 1 5 2 C 10nF where R1 and R2 are the values of the resistors in GND ohms and C is the value of the capacitor in farads. Figure.1.3 Standard 555 Astable Circuit 1.2 DEVELOPED LOGIC GATES Logic gates process signals which represent true or false.