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Lectures 1 and 2: Welcome to IEE A practical introduction to Electrical, Computer and Systems, and Electric Power Engineering Concepts Beginning with Voltage, Current, Resistance, Power, & Diodes 17 July 2015 Introduction to Engineering Electronics K. A. Connor 1 Prof. K. A. Connor • • • • • • http://www.rpi.edu/~connor [email protected] Office: JEC 6010 Phone: 8552 Secretary: Audrey Hayner in JEC 6003 Info on WebCT – Go to http://webct.rpi.edu 17 July 2015 Introduction to Engineering Electronics K. A. Connor 2 Course Organization • Lectures each Monday on a range of topics involving the use of electronics and other fundamental concepts in engineering, particularly in Electrical, Computer and Systems, and Electric Power Engineering • 10-11 Labs • Homework (Not very much) • All work must be completed in a timely manner to pass. (S/U grade) 17 July 2015 Introduction to Engineering Electronics K. A. Connor 3 Requirements • All lectures are mandatory Attendance is taken through a variety of activities Up to 2 unexcused absences are permitted • All labs are mandatory Make up time is provided should a lab be missed Missed labs must be completed promptly. You cannot be more than one lab behind at any time. • Signed rules statement is required Please read syllabus (online) for policy details 17 July 2015 Introduction to Engineering Electronics K. A. Connor 4 Voltage, Current, Power and Resistance • Fundamental concepts Voltage Current Power Resistance V I W R volt amp watt ohm R1 50 I V1 R2 V 50 0 17 July 2015 Introduction to Engineering Electronics K. A. Connor 5 Voltage • Voltage is defined as the amount of work done or the energy required (in joules) in moving a unit of positive charge (1 coulomb) from a lower potential to a higher potential. Voltage is also called potential difference (PD). When you measure voltage you must have two points to compare, one of them being the reference point. When measuring the voltage drop for a circuit component it is sometimes called measuring the potential across that component. 1 volt = 1 joule/coulomb 17 July 2015 Introduction to Engineering Electronics K. A. Connor 6 Voltage • Voltage is analogous to pressure. A battery in an electrical circuit plays the same role as a pump in a water system. 17 July 2015 Introduction to Engineering Electronics K. A. Connor 7 Current • Current is the amount of electric charge (coulombs) flowing past a specific point in a conductor over an interval of one second. 1 ampere = 1 coulomb/second • Electron flow is from a lower potential (voltage) to a higher potential (voltage). + e e e e - Wire 17 July 2015 Introduction to Engineering Electronics K. A. Connor 8 Current • For historical reasons, current is conventionally thought to flow from the positive to the negative potential in a circuit. 17 July 2015 Introduction to Engineering Electronics K. A. Connor 9 Power • Power is the rate at which energy is generated or dissipated in an electrical element. 1 watt = 1 joule/sec Generated Dissipated 17 July 2015 Introduction to Engineering Electronics K. A. Connor 10 Resistance • Charges passing through any conducting medium collide with the material at an extremely high rate and, thus, experience friction. R l A • The rate at which energy is lost depends on the wire thickness (area), length and physical parameters like density and temperature as reflected through the resistivity 17 July 2015 Introduction to Engineering Electronics K. A. Connor 11 Circuit Diagram e Res istor BA TT ERY Heat Exchanger Pump e e e e Current Water • Water flow analogy is helpful, if not totally accurate 17 July 2015 Introduction to Engineering Electronics K. A. Connor 12 Basic Electrical Laws • Ohm’s Law V IR • Kirchoff’s Voltage Law V 0 • Kirchoff’s Current Law I 0 17 July 2015 Introduction to Engineering Electronics K. A. Connor 13 Ohm’s Law Georg Ohm • There is a simple linear relationship between voltage, current and resistance. V IR 17 July 2015 Introduction to Engineering Electronics K. A. Connor 14 Kirchoff’s Voltage Law (KVL) Gustav Kirchoff • The sum of the voltage differences around a circuit is equal to zero. V 0 17 July 2015 Introduction to Engineering Electronics K. A. Connor 15 Kirchoff’s Current Law (KCL) Applying conservation of current. • The sum of all the currents entering or exiting a node is equal to zero. I 0 17 July 2015 Introduction to Engineering Electronics K. A. Connor 16 Conservation Laws • Both the KVL and KCL are based on conservation laws. KVL conserves voltage KCL conserves current • Other conservation laws we know about Conservation of energy Conservation of momentum • A key to understanding any system is identifying the relevant conservation laws 17 July 2015 Introduction to Engineering Electronics K. A. Connor 17 Series Combination of Resistors A + Ia Vr1 + - V + Vr2 Ib R1 R2 + V + Req Vreq - - - B • Resistors add in series REQ R1 R2 ... RN 17 July 2015 Introduction to Engineering Electronics K. A. Connor 18 Series Combination of Resistors R1 10Vdc 30ohms V1 R2 10ohms 0 • The effect of resistors in series is additive. There is a corresponding voltage drop across each resistor. REQ R1 R2 ... RN 17 July 2015 Introduction to Engineering Electronics K. A. Connor 19 Parallel Combination of Resistors A I1 I2 V Ib Vr1 + + R1 - I3 + + + R2 - Vr2 V Req Vreq - - I4 B • The reciprocal or inverse of resistors add in parallel. 1 1 1 1 ... REQ R1 R2 RN 17 July 2015 Introduction to Engineering Electronics K. A. Connor 20 Parallel Combination of Resistors 10Vdc V1 R1 R2 30ohms 10ohms 0 • For resistors in parallel, the same voltage occurs across each resistor and more than one path exists for the current, which lowers the net resistance. 1 1 1 1 ... REQ R1 R2 RN 17 July 2015 Introduction to Engineering Electronics K. A. Connor 21 Series Combination of Resistors A V Vr1 Vr 2 • KVL: + Ia Vr1 + R1 - V • Ohm’s Law: V I a R1 I a R2 + Vr2 R2 - • Solve for Ia: B Ib + V + Req Vreq - 17 July 2015 V V Ia Ib R1 R2 REQ • In General REQ R1 R2 ... RN - Introduction to Engineering Electronics K. A. Connor 22 Parallel Combination of Resistors • KCL: A I1 Vr1 + I2 V + R1 I3 - I4 B R2 Vr2 • Ohm’s Law: V V V I1 R1 R2 REQ • In General: Ib + V + - - I1 I 2 I3 + Req Vreq - 17 July 2015 - 1 1 1 1 ... REQ R1 R2 RN Introduction to Engineering Electronics K. A. Connor 23 Combination of Resistors • Series REQ R1 R2 ... RN • Parallel 1 1 1 1 ... REQ R1 R2 RN • For two resistors, the second expression can be written as REQ 17 July 2015 R1 R2 R1 R2 Introduction to Engineering Electronics K. A. Connor 24 Combination of Resistors • Adding resistors in series always results in a larger resistance than any of the individual resistors • Adding resistors in parallel always results in a smaller resistance than any of the individual resistors 17 July 2015 Introduction to Engineering Electronics K. A. Connor 25 Diodes D1 ANODE CATHODE DIODE • A diode can be considered to be an electrical one-way valve. • They are made from a large variety of materials including silicon, germanium, gallium arsenide, silicon carbide … 17 July 2015 Introduction to Engineering Electronics K. A. Connor 26 Diodes • In effect, diodes act like a flapper valve Note: this is the simplest possible model of a diode 17 July 2015 Introduction to Engineering Electronics K. A. Connor 27 Diodes • For the flapper valve, a small positive pressure is required to open. • Likewise, for a diode, a small positive voltage is required to turn it on. This voltage is like the voltage required to power some electrical device. It is used up turning the device on so the voltages at the two ends of the diode will differ. The voltage required to turn on a diode is typically around 0.6-0.8 volt for a standard silicon diode and a few volts for a light emitting diode (LED) 17 July 2015 Introduction to Engineering Electronics K. A. Connor 28 Diodes D1 D1N4002 V AMP L = 10V V1 R1 F RE Q = 1k 1k • 10 volt sinusoidal voltage source 0 • Connect to a resistive load through a diode This combination is called a half-wave rectifier 17 July 2015 Introduction to Engineering Electronics K. A. Connor 29 Diodes V AMP L = 10V • Sinusoidal Voltage V1 F RE Q = 1k 10V 5V 0V -5V -10V 0s 0.5ms 1.0ms 1.5ms 2.0ms 2.5ms 3.0ms V(D1:1) Time 17 July 2015 Introduction to Engineering Electronics K. A. Connor 30 Diodes D1 VAMPL = 10V V1 V D1N4002 V R1 FREQ = 1k 1k • Half-wave rectifier 0 10V 5V 0V -5V -10V 0s 0.5ms V(D1:1) 1.0ms 1.5ms 2.0ms 2.5ms 3.0ms V(D1:2) Time 17 July 2015 Introduction to Engineering Electronics K. A. Connor 31 17 July 2015 Introduction to Engineering Electronics K. A. Connor 32 17 July 2015 Introduction to Engineering Electronics K. A. Connor 33 At the junction, free electrons from the N-type material fill holes from the Ptype material. This creates an insulating layer in the middle of the diode called the depletion zone. 17 July 2015 Introduction to Engineering Electronics K. A. Connor 34 17 July 2015 Introduction to Engineering Electronics K. A. Connor 35 17 July 2015 Introduction to Engineering Electronics K. A. Connor 36 Diode V-I Characteristic • For ideal diode, current flows only one way • Real diode is close to ideal Ideal Diode 17 July 2015 Introduction to Engineering Electronics K. A. Connor 37 17 July 2015 Introduction to Engineering Electronics K. A. Connor 38 Where Will You See These Concepts Again? • In later labs in this course • V, I, R, Kirchoff’s Laws, Combining Resistors: ECSE-2010 Electric Circuits • Diode and Transistor Theory and Electronic Design: ECSE-2050 Analog Electronics, ECSE-2060 Digital Electronics and ECSE-2210 Microelectronics Technology 17 July 2015 Introduction to Engineering Electronics K. A. Connor 39