ELECTRIC CIRCUITS ECSE2010 Spring 2003 Class 13

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ELECTRIC CIRCUITSECSE-2010Spring 2003Class 13

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ASSIGNMENTS DUE

• Today (Tuesday/Wednesday)
• Will do Experiment 5 in Class (EP-5)
• Activity 13-1 (In Class)
• Thursday
• Experiment 4 Report Due
• Will do Experiment 6 in Class (EP-6)
• Activity 14-1 (In Class)
• Next Monday
• No Classes Presidents Day
• Next Tuesday
• Mondays Class All Sections Meet Tuesday

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EXAM I

• Expect to have Exam I graded and returned in
  class next week Tuesday

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REVIEW

• Circuits with C L
• iC C dvC/dt vL L diL/dt
• DC Steady State d/dt 0 gt iCSS 0 vLSS 0
• DC Steady State C gt Open Circuit
  L gt Open Circuit
• vC and iL cannot change instantaneously
• Electrical energy is stored in C and L
• C and L can interchange electrical energy with
  the circuit
• Circuits become far more interesting

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CAPACITANCE
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INDUCTANCE
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SWITCHED CIRCUITS

• Circuits that Contain Switches
• Switches Open or Close at t t0
• to Switching Time
• Often choose to 0
• Want to Find is and vs in Circuit Before and
  After Switching Occurs
• i(to-), v(t0-) i(to), v(t0)
• Initial Conditions of Circuit

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INITIAL CONDITIONS

• Cs and Ls Store Electrical Energy
• vC Cannot Change Instantaneously
• iL Cannot Change Instantaneously
• In DC Steady State C gt Open Circuit
• In DC Steady State L gt Short Circuit
• Use to Find i(to-), v(t0-) i(to), v(t0)
• Lets do an Example

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EXAMPLE
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EXAMPLE
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EXAMPLE
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EXAMPLE
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1ST ORDER SWITCHED DC CIRCUITS
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ACTIVITY 13-1
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ACTIVITY 13-1

• Charge a 20 nF Capacitor to 100 V thru a
  Variable Resistor, Rvar
• Lets Use a Switch that Closes at t 0
• Rvar 250k, 500k, 1 M
• Circuit File Has Been Run
• C/Files/Desktop/CE-Studio/Circuits/act_5-2.dat
• But Lets Practice Using Schematics and Take a
  Quick Look

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PSPICE WITH C AND L

• To Describe C and L in Schematics
• Capacitor Use Part Named c
• Inductor Use Part Named L
• Doubleclick on C or L
• Set Value
• Set Initial Conditions in Volts and Amps
• vC(0) and iL(0)

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ACTIVITY 13-1
Circuit File v 1 0 dc 100 R 1 2 R C 2
0 20n ic0 .param R250k .step param R list
250k 500k 1meg .tran .1 .1 uic .probe .end
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ACTIVITY 13-1
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PSPICE TRANSIENTS

• Transient Analysis Schematics
• Click on Setup Analysis
• Choose Transient
• Doubleclick on Transient
• Choose Print Step .1
• Choose Final Time .1
• Save
• Click Simulate

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VARIABLE RESISTOR

• Schematics
• Choose Part Rvar
• Place in Circuit
• Doubleclick on Rvar
• Set Value Rvar
• Change SET to 1.0
• Choose Part Param
• Doubleclick on Param
• Set Name1 Rvar, Value1 250k

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VARIABLE RESISTOR

• Click on Setup Analysis
• Select Parametric
• Select Global Parameter
• Select List
• Set Variable Name Rvar
• Set List of Values 250k 500k 1meg

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PSPICE WITH C AND L

• To Describe C and L in Circuit File
• C2 4 5 1n IC3
• L4 4 5 3m IC4u
• Capacitor Named C2 (Must Start Name with C)
• Inductor Named L4 (Must Start Name with L)
• Positive Terminal Node 4
• Negative Terminal Node 5
• Value of C 1 nanoFarad
• Value of L 3 milliHenries
• vC(0) 3 Volts iL(0) 4 microAmps

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PSPICE TRANSIENTS

• Transient Analysis Circuit File
• .tran Statement
• General Form .tran tp tf uic
• Start time for Analysis is always t 0
• Print Step Size tp End time tf
• Usually Choose tp tf
• uic use initial conditions
• Must Specify Initial Conditions when describe C
  and L

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VARIABLE RESISTOR

• Circuit File
• R 1 2 R
• Need a .param Statement
• .param R 250k
• Need a .step Statement
• .step param R list 250k 500k 1meg

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OP AMPS WITH Rs AND Cs

• Can Make Very Useful Circuits by using Capacitors
  in Op Amp Circuits
• Replace RF with C in an Inverting Voltage
  Amplifier
• Replace R1 with C in an Inverting Voltage
  Amplifier

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OP AMP INTEGRATOR
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OP AMP DIFFERENTIATOR
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OP AMPS WITH Rs AND Cs

• Replace RF with C in an Inverting Voltage
  Amplifier
• i1 vin / R1 ic
• vout 0 - vc - vc
• Interchange R and C

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EXPERIMENT 5

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EXPERIMENT 5

• Use Cu in Plastic Box Unknown C
• Use Function Generator for vin
• Measure vin with Scope, not FG
• Reading of FG is seldom correct
• Use 741 Op Amp
• Must supply 5 V and - 5 V for Op Amp
• Set voltages independently
• Handle wires carefully

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EXPERIMENT 5

• Op Amp Differentiator
• Input Voltage Sinusoid

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EXPERIMENT 5
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741 PIN LAYOUT
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OP AMP PIN LAYOUT
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MOUNTING OP AMPS