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Lecture 13: Basic Circuit Theory I

Lecture 13: Basic Circuit Theory I. EEN 112: Introduction to Electrical and Computer Engineering. Professor Eric Rozier, 4/1/ 13. QUIZ GRADES AND RESULTS. Quiz III Grade Distribution. Grade Distribution. REVIEW. Identify the Architecture. Program Memory Data Memory. CPU. Bus.

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Lecture 13: Basic Circuit Theory I

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  1. Lecture 13: Basic Circuit Theory I EEN 112: Introduction to Electrical and Computer Engineering Professor Eric Rozier, 4/1/13

  2. QUIZ GRADES AND RESULTS

  3. Quiz III Grade Distribution

  4. Grade Distribution

  5. REVIEW

  6. Identify the Architecture ProgramMemory Data Memory CPU Bus

  7. Identify the Architecture ProgramMemory CPU Bus Data Memory Bus

  8. Memory • Nonvolatile memory? • Volatile memory?

  9. Memory • Nonvolatile memory? • Retains stored information even when unpowered • Long-term or persistent storage • Volatile memory? • Requires constant power for storage • Information is lost when the power supply is off or interrupted • Temporary memory

  10. What is a Microprocessor?

  11. What is a Microprocessor? • Single chip that contains the whole CPU • Fetches, decodes, and executes instructions stored in memory • Can access memory, I/O, and peripherals

  12. What is a Microcontroller?

  13. What is a Microcontroller? • Microprocessor + on-chip memories and I/O devices • “Computer-on-a-chip” • Contains the CPU • Memory • Some I/O and peripherals

  14. What is an Embedded System?

  15. What is an Embedded System? • Special purpose computer system, usually completely inside a device it is designed to control • Works to help solve specific problems, and perform pre-defined tasks • Usually contains inputs (sensors), a microcontroller, and outputs (actuators and indicators)

  16. MIDTERM II

  17. Midterm II • Midterm II, this Wednesday! • Covered topics • Signal Processing (Quiz II, and lectures online) • Microprocessors/Microcontrollers (Quiz III, and lectures online) • PBASIC Programming (last lecture, online)

  18. BASIC CIRCUIT THEORY

  19. Atoms

  20. Atoms • Smallest part of an element. • Nucleus surrounded by “orbiting” electrons • Protons – positive charge • Neutrons – no charge • Electrons – negative charge

  21. Electron Configurations • Electrons move independently in an orbital, an average field wave function

  22. Electron Configurations • Arranged in electron shells • Shells contain fixed numbers of electrons • 1st shell – 2 electrons • 2nd shell – 8 electrons • 3rd shell – 18 electrons • 4th shell – 32 electrons • etc

  23. Electron Configurations • 14 protons, 14 neutrons, 14 electrons • 1st shell – 2/2 electrons • 2nd shell – 8/8 electrons • 3rd shell – 2/18 electrons

  24. Electron Configurations • Electrons in the outermost shell are known as valence electrons • When valence electrons gain sufficient energy, they can break away and become free electrons. • Free electrons can drift from one atom to another • Free electrons make electrical current possible

  25. Free Electrons • The number of free electrons in a material allow it to be classified • Conductors • allow current to flow easily • large numbers of free electrons • Examples: silver, copper, gold

  26. Free Electrons • The number of free electrons in a material allow it to be classified • Conductors • Semiconductors • less free electrons • unique characteristics, basis for modern electronics • Examples: silicon, germanium

  27. Free Electrons • The number of free electrons in a material allow it to be classified • Conductors • Semiconductors • Insulators • very small number of free electrons • poor conductors • Examples: ceramics, rubber, air, dry paper

  28. Electric Charge (Q) • Two types of charges, positive and negative • Q – the electrical charge • Units in Coulombs (C) • One electron has a charge of 1.6*10^(-19) C • In 1 Coluomb there are 6.25*10^18 electrons

  29. Current • Rate of flow of electrons through a circuit • Symbol is I, measured in Amperes (or Amps) • The flow of on coulomb/second is one Amp

  30. Voltage • Related to potential energy • Measured between two points • One of those points is “ground”, a reference level to which all voltages are compared • If a pin is at 5V, it is measured at 5V with respect to ground

  31. Resistance • Voltage and current related by resistance • When voltage is applied to an electrical system, current begins to flow • Level of current is determined by resistance of the system

  32. Types of Resistors

  33. Resistors • Resistance value in an electrical circuit is given in Ohms, and represented by R

  34. Resistors

  35. Ohm’s Law • Ohm’s Law – The amountof current (I) that will flow isproportional to the voltage(V) applied, and inverselyproportional to theresistance (R) of the circuit • I = V/R As resistance increases, current decreases

  36. Hydraulic Analogy • Consider the diagram, when the valve is released, what will happen?

  37. Hydraulic Analogy • Flow rate (I) dependent on: • (V) pressure of thetanks • Restriction (R) offlow from the valve

  38. Batteries • Batteries feature surplus electrons on one side, and a deficiency of electrons on the other side (holes)

  39. Flow of electrons

  40. Power (P) • Power measures the rate of energy conversion • For a simple direct current (DC) system, it measures the rate at which electrical energy is converted into heat by power-dissipating resistive elements

  41. Power (P) • Lightbulbs convert electrical energy into heat and light • Unit for electrical power is familiar in this context • The Watt • P = V I • Using Ohm’s law and the power equation… • P = V I = V^2/R = I^2 R

  42. WRAP UP

  43. Wrap Up • Exam next class • Quiz III corrections due next Monday

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