Activity 1.1.5b Circuit Theory: Simulation
Introduction
As much fun as it is to analyze circuits by hand, the process becomes tedious as circuits grow in
size and complexity. This is where Circuit Design Software (CDS) comes to the rescue. As the
name implies, the CDS is a software tool that can be used to enter and simulate analog and
digital circuit designs.
As with most computer applications, the CDS handles the mundane and repetitive tasks
associated with analyzing circuits, allowing the designer (you) to concentrate on producing
quality and creative designs.
In this activity you will gain experience using the Circuit Design Software to analyze simple
analog circuits. In future activities we will use the CDS to analyze digital circuits as well. The
circuits analyzed are some of the same circuits that were analyzed by hand in Activity 1.2.2.
Thus, the theoretical and simulation results can be compared.
Series Circuit
Parallel Circuit
Equipment


Calculator
Circuit Design Software (CDS)
© 2014 Project Lead The Way, Inc.
Digital Electronics Activity 1.1.5b Circuit Theory: Simulation – Page 1
Procedure
1. Shown below is the schematic for a simple series circuit. Analyze this circuit to determine
its total current and the voltage across each of the two resistors. To make these
measurements, add an ammeter and two voltmeters. The second schematic shown is the
original circuit with the added meters.
Calculated Values: VR1=3.74V
VR2=7.99V IT=17mV
Using the CDS, enter and simulate this circuit. Measure and record the circuit’s total
current and the voltage across each of the resistors.
Measured Values:
2. Using the CDS, analyze the circuit shown below to determine IT, VR1, VR2, & VR3.
Add the appropriate ammeters and voltmeters. Be sure to put your answer in proper
engineering notation and use the correct units.
© 2014 Project Lead The Way, Inc.
Digital Electronics Activity 1.1.5b Circuit Theory: Simulation – Page 2
This circuit was analyzed by hand in Activity 1.2.2. How do these measured values
compare to the previously calculated values? If they do not match, review your circuit,
your calculations, and make any necessary corrections.
They Match Perfectly.
3. Using the CDS, analyze the circuit shown below to determine IT, VR1, VR2, VR3, & VR4.
Do the measured values compare to your previously calculated values in Activity 1.2.2?
The Values Where very close.
4. Using the CDS, analyze the circuit shown below to determine IT, IR1, IR2, & IR3.
Do the measured values compare to your previously calculated values in Activity 1.2.2?
The Values Where very close.
© 2014 Project Lead The Way, Inc.
Digital Electronics Activity 1.1.5b Circuit Theory: Simulation – Page 3
5. Using the CDS, analyze the circuit shown below to determine IT, IR1, IR2, IR3, & IR4.
Do the measured values compare to your previously calculate values in Activity 1.2.2?
The Values Where very close.
© 2014 Project Lead The Way, Inc.
Digital Electronics Activity 1.1.5b Circuit Theory: Simulation – Page 4
Conclusion
1. It should be obvious that using a CDS to analyze circuits is far easier than performing
the calculations by hand. Yet, being able to perform these calculations by hand is still
an important skill for a circuit designer. Why?
The Computer will not always be there for you to use and knowing them by hand helps you
calculate anything you want even without a computer.
2. Using the results from step (3) of the procedure, verify Kirchhoff’s Voltage Law.
Series
VT= V1+V2+V3….
3. Using the results from step (5) of the procedure, verify Kirchhoff’s Current Law.
Parallel
VT=V1=V2=V3=….
© 2014 Project Lead The Way, Inc.
Digital Electronics Activity 1.1.5b Circuit Theory: Simulation – Page 5