...Solid State Rectifier Semiconductor technology took a giant leap forward during World War II, as radar receivers needed solid-state rectifiers to detect and convert microwave signals at frequencies higher than possible using vacuum tube diodes. Silicon and germanium emerged as the dominant semiconductor materials due to wartime R&D efforts. Millions of crystal rectifier diodes, with a metal point contacting a tiny sliver of silicon or germanium inside, were fabricated for use in Allied radar receivers. So generally rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification. Physically, rectifiers take a number of forms, including vacuum tube diodes, mercury-arc valves, copper and selenium oxide rectifiers, solid-state diodes, silicon-controlled rectifiers and other silicon-based semiconductor switches. Early radio receivers, called crystal radios, used a "cat's whisker" of fine wire pressing on a crystal of galena (lead sulphide) to serve as a point-contact rectifier or "crystal detector". Cat's Whisker Detector The cat's whisker detector is one of the most iconic components used in early radio sets. Also called the crystal detector it was an iconic component used in many early radio equipments.Today, many cat's whisker or crystal detectors sets can be seen on the antique and collectors market.In their day, the radios...
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...Highly-Efficient Battery Chargers with ParallelLoaded Resonant Converters Ying-Chun Chuang e-mail:chuang@mail.ksu.edu.tw Yu-Lung Ke e-mail:yulungke@ms25.hinet.net Shun-Yi Chang e-mail:nickelayu@hotmail.com Department of Electrical Engineering, Kun Shan University, Tainan Hsien 71003, Taiwan, R.O.C. Abstract—The well established advantages of resonant converters for battery chargers, including fast response, low switching losses, easy of the control scheme, simplicity of circuit configuration, and low electromagnetic interference (EMI), among others, have led to their increasing attraction. This work develops a highly efficient battery charger with a parallel-loaded resonant converter for battery charging applications to improve the performance of traditional switching-mode charger circuits. The charging voltage can be regulated by varying the switching frequency. The switching frequency of the parallel-loaded resonant battery charger was set at continuous conduction mode (CCM). Circuit operation modes are determined from the conduction profiles. Operating equations and operating theory are also developed. This study utilizes the fundamental wave approximation with a battery equivalent circuit to simplify the charger circuit analyses and presents an efficient, small-sized, and cost-effective switched-mode converter for battery chargers. A prototype charger with parallel-loaded resonant converter designed for a 12V-48Ah battery is built and tested to verify the analytical...
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...Name: | | Date: | | ET 1310 Final Exam 1. Electrons in the valence shell of an atom are . a. closest to the nucleus of an atom b. a completely filled shell of an atom c. a shell with more than 8 electrons d. the outermost shell of an atom 2. Intrinsic silicon _. a. has three (3) valence electrons b. has four (4) valence electrons c. has five (5) valence electrons d. is a good conductor at room temperature 3. The anode of a diode a. is the ‘N’ type material b. is the ‘P’ type material c. conducts majority carriers with a negative potential applied to it d. is represented by the long bar in the diode symbol 4. | Minorit | y current carriers are _. | | a. | electrons in the ‘P’ type material | | b.c. | electrons in the ‘N’ type materialholes in the ‘P’ type material | | d. | are located only in the depletion region | 5. A forward-biased silicon diode _. a. has negative voltage applied to the ‘P’ type material b. has approximately 0.7 V DC across the diode c. allows the full applied voltage to be measured across the diode d. blocks current from flowing in the circuit 6. When VSEC of a transformer in a half-wave rectified power supply is 12 Vp, what is the Vp of the load resistor? a. 11.0 VP b. 12 VP c. 12.4 VP d. 11.3 VP 7. Using an ohmmeter to check a diode, which of the following...
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...SECTION 2-1 REVIEW 1. At what point on the input cycle does the PIV occur? 2. For a half-wave rectifier, there is current through the load for approximately what percentage of the input cycle? 3. What is the average of a half-wave rectified voltage with a peak value of 10 V? 4. What is the peak value of the output voltage of a half-wave rectifier with a peak sine wave input of 25 V? 5. What PIV rating must a diode have to be used in a rectifier with a peak output voltage of 50V? ANSWERS:- 1. PIV across the diode occurs at the peak of the input when the diode is reversed biased. 2. There is current through the load for approximately half (50%) of the input cycle. 3. The average value is 10 V/∏ = 3 .18 V 4. The peak output voltage is 25 V - 0.7 V = 24.3 V. 5. The PIV must be at least 50 V SECTION 2-2 REVIEW 1. How does a full-wave voltage differ from a half-wave voltage? 2. What is the average value of a full-wave rectified voltage with a peak value of 60V? 3. Which type of full-wave rectifier has the greater output voltage for the same input voltage and transformer turns ratio? 4. For a peak output voltage of 45 V, in which type of rectifier would you use diodes with a PIV rating of 50 V? 5. What PIV rating is required for diodes used in the type of rectifier that was not selected in Question 4? ANSWERS:- 1. A full-wave voltage occurs on each half of the input cycle and has a frequency of twice the input frequency. A half-wave voltage occurs...
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...different dc levels. Comments. Strictly speaking, all that is really required for conversion from ac to dc is a trans- former and a rectifier (in fact, even the transformer could be eliminated if no voltage transformation is required). The filter, voltage regulator and voltage divider are mere refinements of a dc power supply though they are essential for most applications except for battery charging and running small dc motors etc. 55.4. Rectifiers We will consider the following circuits : 1. single-phase half-wave rectifier, 2. single-phase full-wave rectifier, 3. full-wave bridge circuit, 4. three-phase half-wave rectifier, 5. three-phase full-wave rectifier, 6. six-phase half-wave rectifier, 7. three-phase bridge circuit, 8. voltage multiplier circuits. Many semiconductor devices or systems (like car stereo systems) require a negative dc source or both a negative and a positive dc source. For the sake of simplicity, we will analyse only the positive dc power supplies. However, a positive dc supply can be converted into a negative one by simply reversing the two leads in the same way as we reverse the polarity of a dry cell. Quite a number of integrated circuits (ICs) require both positive and negative source with com- mon ground. In that case, the polarised components in the negative portion of the supply will have to be reversed. For example, its rectifier, filter capacitor and voltage/current regulation devices will have to be reversed as compared to the positive supply. 55.5. Single-phase...
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...Tutorial EEC, Block 2, January 2014 SILICON CONTROLLED RECTIFIERS (SCR) or THYRISTORS 1. Consider a half wave rectifier using a diode is connected to a 240 V (rms), 50 Hz supply. Neglect the voltage drop across the diode. Derive the mean load voltage for two cases: (i) when the load is a pure resistor of 10 Ω. (108 V) V mean =(240√2)/π = 339.4112/ π =108.04 (ii) when the load has a 10 Ω resistor connected in series with a 0.1 H inductance. Assume that the current continues up until ωt=30 degrees. (100.8 V) Hence calculate the mean load current for each case. (10.8 A; 3.06 A) 2. Using a single phase thyristor controlled half wave circuit with a commutating diode to supply a heavily inductive load of up to 15A from a 240 V (rms) supply, determine the mean load voltage for firing delay angles of 0 degrees, 90 degrees and 180 degrees. Specify the required voltage ratings of the thyristor and diode. Neglect the voltage drop across the thyristor and the diode. (108 V; 54 V; 0 V) (Peak-forward-voltage and peak-inverse-voltage of thyristor is 339.4 V; Peak-inverse-voltage of the diode is 339.4 V) V mean ={(120√2)/π}* (1+ cosα) Hence 2/π 240√2 cos α 76.39*1.41 cos 0 =107.71 2/π 240√2 cos α 76.39* √(2 cos 90 - =54 2/π 240√2 cos α -2 76.39*1.41 cos 180 = 0 Peak voltage across each thyristor: Vmax= 240√2 = 339.41112 3. A load of 10 Ω resistance, 0.1 H inductance, is supplied from a 7.07 V (rms), 50 Hz ac supply via...
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...proposed in this paper to achieve 1.5A and 3.8V load. This method can ensure that the output current and voltage stay within the satisfactory range. A buck converter with rectified DC voltage of 240V DC as input voltage, and output voltage of 3.8 with 1.5A output current and duty cycle of 0.016 is designed. P pice is used in designing simulation and the results of the circuit have been obtained to verify the operation and performance of the concept. The theoretical calculations are compared with the simulation results. The ripple output voltage and current obtained is relatively low as calculated of around 1%. Losses can be further controlled by adjusting the dead time and duty ratio of the circuit. Keywords— Full Wave Bridge Rectifier; Buck Converter; DCDC Converter; Smartphone Battery Charger I. INTRODUCTION Portable electronic industry has grown over the years, many different demands has increased for instance, small and cheap systems, photographing and taking video, brighter and fullcolour display and a demand for increased talk-time in cellular phones. As a result, smartphone battery is drained very rapidly with all these demands and consumer always need to charge back their device quickly. Hence, to keep up with these demands from the consumer, a more efficient system must introduce to meet these...
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...Overview My original plan for this project was to build a hybrid amplifier with a solid state preamp section and a tube power amp section. The reason for this was that I wanted the reliability and size advantage of a solid state preamp section coupled with the “fat” tube tone of a power amp section. I also felt that with a solid state preamp mounted on a PCB, I could create a preamp stage with more gain while taking up less space. For that design I would need a separate power section for the solid state preamp since it does not run on the high voltage that the tubes do. After talking with Harry Powell he suggested that I might as well go with an all tube design. That was fine with me because I wanted to know more about designing a tube preamp anyways. My design specifications were pretty simple; I wanted to design a single channel 50watt amp using 12ax7 preamp tubes, EL34 power tubes, and a baxandall tone control. The baxandall circuit attenuates or amplifies two ranges of frequencies, bass and treble. Preamp The preamp stage has two 12ax7 preamp tubes and each 12ax7 holds a pair of ECC83 triodes. 12ax7 models and information on how to create them on Pspice were obtained from duncanamps.com. The preamp basically consists of common cathode gain stages place in series, a baxandall tone circuit, and a phase splitter. The amount of gain coming from the common cathode stages was determined by the relationship between the resistor on the anode and resistor...
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...Chapter1 ------------------------------------------------- Introduction RFID is an acronym for Radio Frequency Identification. In general terms, RFID is a means of identifying a person or object using a radio frequency transmission. In other words RFID is an electronic method of exchanging data over radio frequency waves. The technology can be used to identify, track, sort or detect a wide variety of objects. In this project RFID is used for the Tracking purpose for stolen things. An embedded system is a special-purpose system in which the computer is completely encapsulated by or dedicated to the device or system it controls. Unlike a general-purpose computer, such as a personal computer, an embedded system performs one or a few predefined tasks, usually with very specific requirements. Since the system is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost of the product. Embedded systems are often mass-produced, benefiting from economies of scale. Security over the years has been a source of concern to organizations and companies. This has caused quite a significant amount of capital being budgeted for improvements on security systems, simply because it has been discovered that the access control system mechanism is an important part of an organization. One of the important security systems in building, vehicle security is door access control. The door access control is a physical security that assures the security of a building or vehicle...
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...HCKI 534F/544F - Technical Data Sheet HCKI534F/544F SPECIFICATIONS & OPTIONS WINDINGS & ELECTRICAL PERFORMANCE All generator stators are wound to 2/3 pitch. This eliminates triplen (3rd, 9th, 15th …) harmonics on the voltage waveform and is found to be the optimum design for trouble-free supply of non-linear loads. The 2/3 pitch design avoids excessive neutral currents sometimes seen with higher winding pitches, when in parallel with the mains. A fully connected damper winding reduces oscillations during paralleling. This winding, with the 2/3 pitch and carefully selected pole and tooth designs, ensures very low waveform distortion. TERMINALS & TERMINAL BOX Standard generators are 3-phase reconnectable with 12 ends brought out to the terminals, which are mounted on a cover at the non-drive end of the generator. A sheet steel terminal box contains the AVR and provides ample space for the customers' wiring and gland arrangements. It has removable panels for easy access. SHAFT & KEYS All generator rotors are dynamically balanced to better than BS6861:Part 1 Grade 2.5 for minimum vibration in operation. INSULATION/IMPREGNATION The insulation system is class 'H'. All wound components are impregnated with materials and processes designed specifically to provide the high build required for static windings and the high mechanical strength required for rotating components. QUALITY ASSURANCE Generators are manufactured using production procedures having a quality assurance level to...
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...EYE BLINK SENSOR & ACCIDENT PREVENTION Abstract: Description: The Objective of this project is to develop a system to keep the vehicle secure and protect it by the occupation of the intruders. Scope: We can’t take care of ours while in running by less conscious. If we done all the vehicles with automated security system that provides high security to driver, also gives alarm. Function: This project involves measure and controls the eye blink using IR sensor. The IR transmitter is used to transmit the infrared rays in our eye. The IR receiver is used to receive the reflected infrared rays of eye. If the eye is closed means the output of IR receiver is high otherwise the IR receiver output is low. This to know the eye is closing or opening position. This output is give to logic circuit to indicate the alarm. This project involves controlling accident due to unconscious through Eye blink. Here one eye blink sensor is fixed in vehicle where if anybody looses conscious and indicate through alarm. CONTENTS 1. Introduction ……....……………….………………………………..……6 2. System Model…….……………………………………………….…….7 2.1 Basic Model of The System …….…..……………………..…….7 2.2 Circuit Diagram …….……………………………………..……...8 2.3 Parts of The System …………………………...………..………..9 2.3.1 IR Sensing Circuit………..…….………..……………….9 2.3.2 Alarm Circuit……..………………………………………11 2.3.3...
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...TECHNICAL UNIVERSITY OF KENYA SCHOOL OF ENGINEERING SCIENCE AND TECHNOLOGY ELECTRICAL AND ELECTRONICS DEPARTMENT P.O Box 52428-00200 NAIROBI FINAL YEAR PROJECT PROJECT TITLE: PHASE-ANGLE CONTROL OF SCR USING AT89C51 BY Yamame Gerrishom Kennedy ADMISSION NO: 109/01670 SUPERVISOR: MR. BONIFACE CHOMBA ` May 20th, 2014, TABLE OF CONTENTS. DECLARATION.......................................................................................................................................i ACKNOWLEDGEMENT………………………………..….……………………………………………………………………………………ii DEDICATION………………………………..……………………………………………………………………………..………………..……iii ABSTRACT………………………………..………………………………………………………………………………………………………..iv CHAPTER ONE………………………………………………………………………………………………………………………….…………1 INTRODUCTION…………………………………………………………………………………………………………………..………1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 PROJECT BACKGROUND………………………………………………………………………..…………..1 PROBLEM STATEMENT……………………………………………………………………………………………………3 PROPOSED SOLUTION…………………………………………………………………………………………………….3 SYSTEM OBJECTIVES……………………………………………………………………………………………………….5 SCOPE OF THE PROJECT/SPECIFICATIONS……………………………………………………………………….6 BLOCK DIAGRAM……………………………………………………………………………………..…………………….6 DESCRIPTION OF THE BLOCK DIAGRAM………....………………………………………………………………7 CHAPTER TWO………………………………………………………………………………………………………………….…………………8 2.1 2.2 2.3 EXISTING SOLUTIONS……………………………………………………………………………………………………..8 LITERATURE REVIEW………………………………………………………………………………………………………9 CONCLUSION………………………………………………………………………………………………………………...
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...Siemens Connected in a meshed AC network Tunnel DC cable length: 64 km Cable Contractor: Prysmian 8 km dedicated Tunnel Commisioning date: 2014 Cost of the Project : 700M€ with 225M€ financing from EU Santa Llogaia Project update Converter Station Baixas/Santa Llogaia Modular Multilevel Converter (MMC) has become a highly attractive topology for medium and high voltage applications. It is a new type of multilevel voltage source converter (VSC). Advantages of the MMC over the classical VSC types : NPC, multilevel FC etc. - Low frequency modulation - Lower transient peak voltages on IGBT -> Less losses - Very low THD -> no need for High-pass Filters Overview of the HVDC VSC-MMC system 400/320 kV 1,000MVA Z=10% MMC-1 Rectifier 401 Levels 50mH LR 50mH LR 64 km DC Cable Wideband Model 50mH LR MMC-2 Inverter 401 Levels 320/400 kV 1,000MVA Z=10% S 400kV 50Hz Yg/∆ 1,000 MW ±320 kV S 50mH LR ∆/Yg 400kV 50Hz Control system: - PLL - Clark Transformations - P/Q Control (Outer control) - Inner Control - NLC modulation - Capacitor Balancing Control Control system: - PLL - Clark Transformations - Vdc/Q Control (Outer Control) - Inner Control - NLC modulation - Capacitor Balancing Control Overview of the MMC topology Id iua SM-1 arm At normal operation, S1 and S2 are complementary The sub-module consist of two...
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...EXPERIMENT 4 AMPLITUDE DEMODULATION OBJECTIVE: * To Study AM detection using an envelope detector * To build an AM envelop detector. Theory and Background: Diode detector is simplest and most effective types of detector. The output of this circuit is almost linear and therefore harmonic outputs are limited. The abrupt non linearity occurs for the negative half cycle. The modulated carrier is introduced into the tuned circuit made up of LC1. Since the diode only conducts only during the half cycles and gives the result. Although the average input voltage is zero, the average output voltage across R always varies above zero. The low pass filter, made up of capacitor C2 and resistor R, removes the RF (carrier frequency) which so as far as the rest of the receiver is concerned serves no useful purpose. Capacitor C2 charges rapidly to the peak voltage through the small resistance of the conducting diode, but discharges slowly through the high resistance R. the sizes of R and C2 normally form a rather short time constant at the intelligence frequency and a very long time constant at the radio frequencies. The resultant output with C2 in the circuit is a varying voltage that follows the peak variation of the modulated carrier. It is so far this reason often termed an envelope detector circuit. Diagonal clipping: Careful selection of component part is necessary for obtaining optimum efficiency in diode detector circuits. One very important fact to consider is the value of...
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...Accenture Previous Interview Questions: Candidate: May I come in mam. Interviewer: Yes Me: Good evening Mam Interviewer: Are you Tensed? Candidate: A little bit mam. Interviewer: Ya, Introduce yourself Candidate: while i was introducing myself she asked something related to it. Interviewer: What are all your hobbies? Candidate: Singing songs but the problem is my friends get irritated when i start to sing. Interviewer: Laugh Louder Candidate: Continued about Traveling because i have mentioned it as one of my hobby Interviewer: Where are you from? Candidate: Told and explained the specialty of my city. Interviewer: OK do you have any jobs in hand? thestudentdaily.com Candidate: No mam Interviewer: Will you Relocate? Candidate: Yes Mam. Even if you throw me in anypart of India I will work Interviewer: It's too over that's Irritating Candidate: Sorry mam Interviewer: I am just joking, tell me what do you know about Accenture Candidate: Told Interviewer: About Your Family Background Candidate: Told Interviewer: Do you have any questions for us? Candidate: What’s the right shift symbol in accenture indicates mam? Interviewer: That means we are moving forwards. Ok do well in your technical interview i just give my feedback to merittrac member. Candidate: I confident that i will be selected as i thought i moved through next round Here 46/60 was short listed for Technical Round. The Next Round was Technical Round. Candidate: May i come in Sir? Interviewer::...
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