LAB 3

PSpice Introduction

Purpose

To learn how SPICE is used to design, draw, and simulate real circuits.

Prelab

Download the PSpice software from available here. Note: Windows Only.
- The download process does take some time to ensure that this is done prior to attending the lab.
- If you like but not required before the lab:
  - Run the installer with the default options.
  - Start "CIS Capture Lite" and ensure that it runs, retry the install if you run into an error.
Bring your laptop to the lab session, one per group is sufficient but we recommend everyone have the software eventually.

Theory

Pspice is part of the SPICE software family. SPICE stands for Simulation Program w/ Integrated Circuit Emphasis. There are many different spice softwares with various feature sets, but much like other CAD software families, the utility is very similar from program to program. SPICE software began as a programming language not unlike how MAPLE is used in class, and the "behind-the-scenes" behavior maintains that original design. The modern graphical interface makes the software much easier to use and adds the ability to draw, save, and print circuit designs.

PSpice is a circuit simulation tool used in real industry to verify circuit behavior before committing time, money, and resources before a final design is settled upon. PSpice also acts a convenient way to draw circuits, keep track of part counts, and create a bill of materials for a project.

In the lab to follow we will touch on the basics of PSpice, but the software has capabilities way beyond the scope of Circuits I. PSpice includes temperature, EMF field, and vibration profiles for many parts, and can simulate real world conditions for designs that will face harsh climates or unusual circumstances. PSpice can also model digital circuit behavior and circuits with transient responses. PSpice also allows the user to create their own parts with prescribed behavior to be used in designs.

We will use PSpice to solve circuits exactly as you would by hand in class. We can easily find many parameters for common electronic components in circuit including: voltage, current, and power. We can also show the time varying behavior of circuits with transient response. This makes PSpice very useful outside of the lab as a way to check your homework answers, gain some additional insight into difficult problems, and as a way to make up your own problems to check understanding.

PSpice includes an enormous library of parts, but we will only look at the sources, resistors, capacitors, inductors, and op-amps in this course.

It is recommended that you keep PSpice for use in Design II if your project will involve electronic components.

Circuit Diagrams

Circuit 3.1

Resistors:

R1 100Ω
R2 12Ω
R3 10Ω
R4 100Ω
R5 120Ω
R6 120Ω
R7 12Ω

Procedure

Run the installed file titled : CIS Capture Lite, and select New Project.
In the menu that comes up, set a project name.
- Ensure that PSPice Analog or Mixed A/D is selected.
Press OK.
Select "Create a Blank Project" in the next menu.
Draw Circuit 3.1 (The same as Circuit 2.1 from last week's lab on Kirchhoff's Laws) using the appropriate values and components.
- All of the components can be found under "Place" and then "PSpice Component".
- Pressing the "R" key on the keyboard will rotate a part before you place it.
- Pressing the "esc" key will cancel the placement of a part.
- Highlighting a part and pressing "Delete" will remove it from the schematic.
- Clicking on the value of a component will open a menu in which you can specify the desired value.
- You can click and drag component names and values to neaten your design if desired, or if they overlap.
- The magnifying tools may be helpful for small or large circuits that do not fit in the window.
- Be sure that proper pin connections are made, and that no accidental connections are made while building.
Add the 5V source as was done in Lab 2.
The PSpice software requires that you add a GND to your circuit
- Often it is connected to the "-" side of the Voltage source, but you connect it as desired to set the "0V" basis of your circuit.
- The GND symbol can be found in the "Place" menu, or in the right hand side bar.
Save the file.
Press the button labelled "New Simulation Profile".
Name your simulation "Circuit 3-1 Simulation" or something similar.
Click the Green Play button to the right of "New Simulation Profile".
Click the green V, I & W buttons to show/hide those parameters.
You can drag and drop the displayed values to neaten the display.
Save a screenshot of the circuit showing both current and voltage.
- Don't include the full Windows display, use the snipping tool or crop out the circuit portion.
Change the value of the source to 12V and run the simulation again.
Save a screenshot of the circuit showing both current and voltage.

Results

Compare the values given by PSpice to those obtained in the Prelab calculations from Lab #2, and those obtained during the session in the case of 3.1.
- Use the table below to show all of the currents and voltages measured in Lab 2 and those reported by PSpice for the 5V circuit.
Include the screenshots in your report.

Questions

Run your 3.1 simulation again, this time show only the "W" for power, what is the sum of the powers consumed and dissipated ?
Show or circle the power simulation result that would indicate which resistor failed in Lab #2.
PSpice shows node voltages, how can you find the voltage across a component from this information ?
- Give an example from your data.

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