WEST VIRGINIA UNIVERSITY COLLEGE OF ENGINEERING
COMPUTER SCIENCE AND ELECTRICAL ENGINEERING DEPARTMENT
EE 252
DIGITAL ELECTRONICS LABORATORY
Summer 2012
Lab # 1
Introduction to PSpice
Introduction
In this lab exercise we will learn how to simulate circuits using PSpice circuit simulation software.
PSpice is installed on each computer in the lab and on some computers in the ESB 2 nd floor
computer lab. It is a good idea to install a copy of PSpice on your PC because we will be using it
heavily throughout the semester. Please note that the student version is no longer available from
the Cadence/OrCad website. However, you may obtain a copy of the student evaluation version 9.1
at: http://www.engr.uky.edu/~cathey/pspice061301.html
In this experiment we will simulate a voltage divider, a half wave rectifier and a full wave bridge
rectifier.
Procedure
Important commands in Pspice
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From the Start Menu, select Programs → PSPICE Student→ Schematics
To get components Draw → Get new parts or Ctrl + G
o Resistor
r
o DC Voltage source
VDC
o Sinusoidal voltage source
VSIN
o Diode
D1N4002
o Earth ground
GND_EARTH
To rotate components
Ctrl + R
CTRL+W
To connect (wire)
Double click on components to change parameters and labels
Voltage Divider
Construct the voltage divider circuit in PSpice. Before running the simulation you need to setup the
simulation by entering the analysis setup. You can do this by clicking the “Setup Analysis” button on the
upper toolbar. Make sure that you read the output across R2. Initially you should use values of 5V for the
DC source and 1Kohm for the resistors. After the initial simulation change the value of R2 to 5Kohm,
2.5Kohm, 500ohms, and 250ohms. Run the simulation for each of these values and record the output across
R2.
Half Wave Rectifier
Next construct the half-wave rectifier shown below. You can pick your own values for the amplitude and
frequency but 5V and 100Hz will work very well. After setting up the voltage source wire the circuit and
connect the ground. Your circuit should look like the circuit below.
You must place the voltage markers on the circuit before running the simulation. You can get the voltage
markers in the upper right hand corner of the schematic editor. Next you need to enter the simulation setup.
Uncheck the box next to bias point detail and check the box next to transient. Click on the transient button to
setup the transient analysis. If you chose to use 100Hz as the frequency of the voltage source you should set
the final time field to 0.1 second so you can see several oscillations in the printout screen. Your transient
setup screen should look similar to the figure above on the right.
Finally, run the simulation and look at the graphical output of the input and output voltage. Be sure to
include these graphs in your report. You might want to show the output and input on separate graphs.
Full Wave Bridge Rectifier
By this point you should be familiar with the PSpice simulation software. You should construct the
following circuit and analyze the output using the transient simulation.
Note how the output waveform of this circuit differs from the output of the half wave rectifier. Next put a
50uF capacitor in parallel with the load resistor. Note how the output waveform has changed. Finally,
change the value of the 50uF capacitor to 100uF and note how the output waveform has changed.
Questions to be answered on your report
1. Explain why diodes are useful for rectification.
2. What does PSpice stand for?
3. How do the outputs of the half wave rectifier and the full wave rectifier differ? Is one circuit
more efficient? If so explain why.
4. Why is it important to perform simulations before actually building a circuit?
5. How does adding the capacitor in parallel with the load resistor change the output of the full
wave rectifier circuit? Does the value of the parallel capacitor change the output of the full
wave rectifier circuit? If so explain why.
6. What is a non-linear circuit element? Name one non-linear circuit element.