thyristor-controlled rectifier and the chopper is that in the former the motor current always flows through the supply‚ whereas in the latter‚ the motor current only flows from the supply terminals for part of each cycle. A single-switch chopper using a transistor‚ MOSFET or IGBT can only supply positive voltage and current to a d.c. motor‚ and is therefore restricted to quadrant 1 motoring operation. When regenerative and/or rapid speed reversal is called for‚ more complex circuitry is required‚ involving
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Chapter 1. Introduction to Computer Organization and Computer Evolution I. Computer Organization and Computer Architecture In describing computers‚ a distinction is often made between computer architecture and computer organization. Although it is difficult to give precise definitions for these terms‚ a consensus exists about the general areas covered by each. Computer Architecture refers to those attributes of a system visible to a programmer or‚ put another way‚ those attributes that have a
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PLDs • MPGAs – Wide fan-in‚ 2-level SOP‚ optional flip-flops on output – Best known: 22V10 with 22 inputs‚ 10 outputs‚ from AMD – Programmed by users – Fusible links – Also called gate arrays – More dense than PLDs – Predesigned transistors with customized wiring – Wiring done during
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required It was difficult to programmed‚ because they used only machine language Non-portable Limited commercial use 2 .Second generations of computers (1956-1963) The transistor technology was used in second-generation computers. The electronic component transistor was invented in 1948 at Bell Laboratories The transistor is smaller in size and more reliable than vacuum tube. Therefore‚
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Graphene replaced with copper Graphene nanoribbons have a current-carrying capacity two orders of magnitude higher than copper Recent research into the properties of graphene nanoribbons provides two new reasons for using the material for interconnects in future computer chips. In widths as narrow as 16 nm‚ graphene has a current-carrying capacity approximately a thousand times greater than copper while providing improved thermal conductivity. The current-carrying and heat-transfer measurements
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sensor for 1000 ppm of LPG concentration in the air with load resistance of about 10-47 kilo-ohms. Pre-set VR1 is used to adjust the sensitivity of the sensor to a particular gas concentration. Output from the sensor is connected to the base of transistor T1‚ which acts as a switch to trigger the alarm gene rat or built around
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First Edition‚ last update January 18‚ 2010 2 Lessons In Electric Circuits‚ Volume VI – Experiments By Tony R. Kuphaldt First Edition‚ last update January 18‚ 2010 i c 2002-2011‚ Tony R. Kuphaldt This book is published under the terms and conditions of the Design Science License. These terms and conditions allow for free copying‚ distribution‚ and/or modification of this document by the general public. The full Design Science License text is included in the last chapter. As an open
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Outline of the Course • Fundamentals of Control Systems • Introduction to Microprocessor-Based Control • Operational Amplifiers & Signal Conditioning • Switches‚ Relays & Power-Control Semiconductors • Mechanical Systems • Sensors • Electrical Machines • Electric‚ Hydraulic & Pneumatic • Feedback Control Principles • Relay Logic‚ PLCs & Motion Controllers • Basics of Modern Control Theories Dr. Kadir ERKAN Introduction to Control Systems 3 First Lecture : Fundamentals of Control Systems
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“INNOVATION is what America has always been about‚” President Obama remarked in his recent State of the Union address. It’s hard to disagree‚ isn’t it? We live in a world dominated by innovative American companies like Apple‚ Microsoft‚ Google and Facebook. And even in the face of a recession‚ Silicon Valley’s relentless entrepreneurs have continued to churn out start-up companies with outsize‚ world-changing ambitions. Multimedia Graphic Bell Labs: A Hive of Invention But we idealize America’s
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into two major stages The Q1 stage consisting the oscillator‚ the audio amplifier and the modulator The Q2 stage which is made up majorly of the RF amplifier and the antenna 3.2 Q1 STAGE One transistor is used as the audio frequency (AF) amplifier. The Colpitt’s oscillator is used. It consist a transistor which amplifiers the AF and the tank circuit for the generation of the carrier wave. The model of the oscillator used is shown in FIG. 3.1. + R1 L
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