s3.amazonaws.comcramster-resource4913_n_16855.ppt by yurtgc548

VIEWS: 0 PAGES: 44

									ELECTRIC CIRCUITS
    ECSE-2010
    Spring 2003
     Class 4
        ASSIGNMENTS DUE
•       Today (Tuesday/Wednesday):
    •    HW #1 Due
    •    Activities 4-1, 4-2, 4-3 (In Class)
    •    4-2 in NOT in your Supplement
•       Thursday:
    •    Activities 5-1, 5-2, 5-3 (In Class)
•       Next Monday:
    •    HW #2 Due
    •    Experiment #1 Report Due
    •    Activities 6-1, 6-2, 6-3, 6-4 (In Class)
               WEBSITE
• Main Website: http://www.ecse.rpi.edu
  • Academics
  • Course Homepages
  • Spring 2003 – ECSE 2010
• Backup Site :
 http://128.113.60.136/ECSE-
  2010/index.html
              TA’S
• Section 1:
    • Tong Zhang (zhant@rpi.edu)
• Section 2:
    • Amit Kekare (kekara@rpi.edu)
    • Rahul Kalaskar (kalasr@rpi.edu)
•   Section 3:
    • Sunil Rao (raos@rpi.edu)
    • Shahab Uddin (uddins@rpi.edu)
GRADING ASSIGNMENTS
 • Activities:
   • Amit Kekare – Sections 1&3
   • Rahul Kalaskar – Section 2
 • Experiments:
   • Sunil Rao
 • Homework:
   • Shahab Uddin
 • Computer Projects:
   • Tong Zhang
               REVIEW
• PSpice:
  • Download a copy and start practicing
  • http://www.cadencepcb.com/products/down
    loads/PSpicestudent/default.asp
  • Practice with Activities, Homework, etc.
  • Get comfortable with “rules” for Circuit
    Files and Learn to use Schematics
  • We will slowly build our list of commands
 MORE CIRCUIT ELEMENTS
• Potentiomenter:
  • Variable Resistor with 3 terminals
  • Resistance varies as shaft is turned
  • Will Use Digital Pots in our Experiments
• Controlled or Dependent Sources:
  • Source whose Voltage or Current Output Depends
    on a Voltage or Current Somewhere Else in the
    Circuit
POTENTIOMETER
   CONTROLLED SOURCES
• 2 Types of Sources for Circuit Models:
  • Independent Voltage and Current Sources
     • Usually Model with Ideal Sources
  • Controlled Voltage and Current Sources
     • Also called Dependent Sources

• Controlled/Dependent Source:
  • Voltage or current source whose value depends
    on the v or i at some other point in the circuit
  • Cannot buy a controlled source!
  • Used to model the behavior of electronic devices
• Controlled Sources Make Ckt Analysis
  Much, Much Harder!
  CONTROLLED SOURCES
• Controlled Source cannot be the only
  source of Energy in a complete circuit
  • Need an Independent Source to create the
    controlling current or voltage
• All circuit models for Transistors and
  other Electronic Devices involve
  Controlled Sources
  • Whole field of analog electronics is based on
    controlled sources
CONTROLLED SOURCES
  CONTROLLED SOURCES

• See Example:
  • Special Symbol for Controlled Sources
  • Diamond
• 4 Types of Controlled Sources
  •   Voltage Controlled Voltage Source (VCVS)
  •   Voltage Controlled Current Source (VCCS)
  •   Current Controlled Voltage Source (CCVS)
  •   Current Controlled Current Source (CCCS)
• See Examples:
CONTROLLED SOURCES
CONTROLLED SOURCES
CONTROLLED SOURCES
CONTROLLED SOURCES
CONTROLLED SOURCES
 USING SCHEMATICS
ACTIVITY 4-1
                ACTIVITY 4-1
• KVL:
  • v - i R + 6 i = 0 => v = i (R - 6)
• i = v / (R - 6)
  • Note: Singularity at R = 6!; Current “blows up”
  • Interesting things can happen with controlled
    sources
• vc = 6 i = 6 v / (R - 6)
  • Controlled source tries to put out infinite voltage
    when R ~ 6 ohms
  • What really happens is that circuit model fails
             ACTIVITY 4-1
• Equivalent Resistance “Seen” by
  Source:
  • Req = v / i
• Req => 0 as R => 6 ohms
• Controlled sources allow much more
  interesting things to happen, but make
  circuit analysis much harder
        ACTIVITY 4-1
• v = 20 Volts
    APPLICATION OF
 CONTROLLED SOURCES
• Controlled Sources are used to Model
  the Behavior of Electronic Devices
  • Single devices such as Transistors
  • Complete circuits such as Amplifiers
• A good Example is given in Section
  4.1 of your Text – Design Challenge
  • Uses a Potentiometer and an Amplifier
  • Models Audio Control on Stereo
  • Let’s take a quick look at this – Activity 4-2
POTENTIOMETER
VOLTAGE AMPLIFIER
ACTIVITY 4-2
ACTIVITY 4-2
ACTIVITY 4-2
ACTIVITY 4-2
ACTIVITY 4-2
EQUIVALENT RESISTANCE
 EQUIVALENT RESISTANCE
• LOAD Network:
  • Any Circuit with R’s and Controlled Sources
  • No Independent Sources
• See Example:
  • Define v, i using Passive Convention
• Req = v / i
  • Can Replace Any Load Network with its Req
  • Powerful Ckt Analysis Technique
  • See Example
EQUIVALENT RESISTANCE
Req With Controlled Sources
• “Connect” Test Voltage, vt:
   • Independent Source (Active Element)
   • Define it using Active Convention
• Use Ckt Analysis to find it in terms of vt:
   • Linear equation relating it to vt
   • 1 Equation; 2 Unknowns
• Req = vt / it:
   • See Example
Req with Controlled Sources
Req with Controlled Sources
Req with Controlled Sources
            ACTIVITY 4-3
• Electronic devices allow for “amplification”
  of a current or voltage:
  • Make it bigger or smaller
  • Will examine in more detail soon
  • Model electronic devices with controlled sources
• Models will use controlled sources with
  “Variable Gain”:
  • Variable depends on characteristics of the
    particular electronic device being used
  • Usually want to solve general circuit - then put in
    characteristics of particular device - from spec’s
ACTIVITY 4-3
          ACTIVITY 4-3
• Part a): KVL

•

• Part b): “Supernode” around

•
ACTIVITY 4-3
      ACTIVITY 4-3
• Part c):
           ACTIVITY 4-3
• Part d):
• .2 A source in parallel with 10 ohms
• Model Amplifier with Rin
ACTIVITY 4-3
ACTIVITY 4-3

								
To top