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 the previous
activity. 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:
V=12V
VR1=3.828
VR2=8.178
Rt= 690Ω
It=17.4mAmps
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:
V=12V
VR1=3.826
VR2=8.174
Rt= 690Ω
It=17mAmps
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
It=4.64
VR1=2.181
VR2=5.567
VR3=1.253
This circuit was analyzed by hand in the previous activity. 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.
The hand calculations and CDS values match up exactly
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 the previous
activity?
The measured values match with my calculated values with around a 0.5% margin of
error
It=0.249
VR1=0.67
VR2=2.479
VR3=0.819
VR4=2.033
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 the previous
activity?
The measured and hand-calculated values match with a margin of error of around 1.3%
It=5.781
IR1=1.463
IR2=1.765
IR3=2.553
© 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 calculated values in the previous
activity?
the calculated and hand calculated values are identical
It=5.372
IR1=2.222
IR2=0.6
IR3=1.818
IR4=0.732
© 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?
being able to do hand calculations can let you know if there is an error in your circuit
design because the values will differ.
2. Using the results from step (3) of the procedure, verify Kirchhoff’s Voltage Law.
0.67 + 2.479+0.819+2.033=6
3. Using the results from step (5) of the procedure, verify Kirchhoff’s Current Law.
2.222
+0.6
+1.818
+0.732
=5.372
© 2014 Project Lead The Way, Inc.
Digital Electronics Activity 1.1.5b Circuit Theory: Simulation – Page 5
© 2014 Project Lead The Way, Inc.
Digital Electronics Activity 1.1.5b Circuit Theory: Simulation – Page 6