ECE 220 PreLab

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ECE 220 Pre-Lab

• Lecture 5

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When and Where?

• Turn in to the Stockroom
• Due by 400 PM on Friday

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Changes to Lab 5!!

• Page 1, Part 1b
  C1 0.05 uF changes to C1 0.1 uF
• Page 4, Part 4, All Frequencies
• 125 Hz changes to 100 Hz

4
Outline

• Purpose of the lab
• What to turn in
• Results you should expect
• Questions

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Purpose?

• To introduce the analysis and design of RL and RC
  circuits
• To introduce the integrating op-amp circuit
• To introduce new PSpice skills
• Labeled nodes
• Initial conditions of Cs and Ls
• Switches
• New voltage sources

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Part 1 Something like this
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What to turn in?

• General expressions for V(t), IC(t), IR(t) in
  terms of I1, R, C, Vo, and to
• If necessary, give separate expressions for t lt
  to- and t gt to
• Printed schematic
• Plots for V(t), IC(t), and IR(t)
• Mark the values at t 0.3 ms
• Hand calculations using general expressions to
  solve for V, IC, and IR at t 0.3 ms, and
  comparison to PSpice
• Brief explanation of the form of V(t), IC(t), and
  IR(t) in terms of the capacitor characteristic at
  t to and t infinity

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What to expect?
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Approach

• Use information on page 7 of the prelab to derive
  your general expressions
• When explaining the form of the plots, remember
• Capacitor acts like a short circuit before
  charging
• Capacitor acts like an open circuit when fully
  charged

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Part 2 Something like this
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What to turn in?

• Printed schematic and plot
• The of the final value Vout reached at t 6 ms
• Printout of plot with VPWL changed
• The of the final value Vout reached after 5
  time constants

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Results?
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Results for 5 time constants?
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Part 3 Something like this
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What to turn in?

• General expressions for IR(t), VL(t), and VR(t)
  in terms of V1, R, L, and to
• If necessary, give separate expressions for t lt
  to- and t gt to
• Printed schematic
• Plots of IR(t), VL(t), and VR(t)
• Mark values at t 0.3 ms
• Hand calculations using general expressions to
  solve for I, VL, and VR at t 0.3 ms and
  comparison to PSpice
• Brief explanation of the form of IR(t), VL(t),
  and VR(t) in terms of the inductor characteristic
  at t to and t infinity

16
Results?
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Approach

• Use information on page 7 of the prelab to derive
  your general expressions
• When explaining the form of the plots, remember
• Inductor acts like an open circuit before
  charging
• Inductor acts like a short circuit when fully
  charged

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Part 4 Something like this
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What to turn in?

• Calculations for your design
• R1 must be a combination of standard resistor
  values, with total resistance in the range 5k to
  330k
• C must be a single capacitor of standard value in
  the range 0.01 uF to 1 uF
• Printout of schematic with designed values
• Plots of input and output waveforms for
  approximately 20 cycles
• Value of R2 that stabilizes Vout and observations
• Plot of Vout with new R2

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Results?
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Approach

• Everything you need to solve this problem is on
  page 8 of the prelab
• To get the value of R2, you must iterate
  different values for R2 until you get a stable
  output with exactly the correct peak to peak
  voltage
• When you get it right, it will look similar to
  the plot on the next slide

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Results after R2 set correctly?
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Questions?

• The only stupid question is the one you didnt
  ask!!!!

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The End

• Good luck and see you next time!!