Cir cuit s 212 Lab
Lab #2
Linear Network Theorems
A circuit that contains only voltage sources, current sources, resistors, capacitors, or
inductors is a linear circuit. There are several useful theorems that can be applied to
linear circuits that ease the analysis. For instance, if you are only interested in the
voltage or current at a particular point and are not concerned with the rest of the
network, you might try replacing the rest of the circuit with an equivalent circuit. When
confronted with a complicated circuit, you might consider breaking the circuit into two
simpler problems that can be superimposed to give the answer to the more complicated
problem. In this lab you will simulate, analyze, and test various circuits using and with
the help of linear network theorems (superposition, source transformation, Thevenin's
theorem, and Norton's theorem).
Labs will be performed in groups of two. Each person will turn in his or her own copy of
the required work for the lab. The lab report is due one week after the completion of the
experiment.
For this lab, one person from your group will need to check out the following from the
EECS Shop.
• A probe kit (metal toolbox)
• A breadboard
Parts List
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1 - 51 Ω Resistor (Use this resistor as a 50 Ω Resistor)
1 - 100 Ω Resistor
3 - 240 Ω Resistor
1 – 330 Ω Resistor
4 – 1K Ω Resistor
2 – 2K Ω Resistor
2 – 3K Ω Resistor
2 – 3.9K Ω Resistor
1 – 5.1K Ω Resistor
Notation
For this lab, V_Load and VL represent the voltage across the load resistor R_Load. And
I_Load and IL represent the current through the load resistor R_Load.
Experiment 1. Superposition (Day One)
Build the circuit in figure 1. You will need an extra voltage supply to do this experiment.
The voltage supply in the lab requires that all its voltage sources (+6V, +20V, and -20V)
have the same ground). As you can see in the figure, the two voltage sources do not
have the same ground; therefore two voltage supplies with separate grounds are
needed. Once you've built the circuit, measure the VL and IL. Now set V1 to 0 (replace
with a short) and measure VL and IL. Set V1 back to 12V and set V2 to 0 and measure VL
and IL. Add these results together
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Do you end up with the original measurement? Explain why or why not.
Do these values correspond with what you expected? If they do not, try to give an
explanation why.
Simulate this circuit using PSpice (DC Bias Point Only). Do your simulated values
match your measured values?
Figure 1
Experiment 2. Source Transformation (Day One)
Build the circuits in figure 2. Measure VL and IL in each circuit. You will need to use
source transformation on the first circuit to find the current source I1 and resistance Ri in
the second circuit.
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Do the circuits give the same VL and IL? Explain why they do or do not.
Do these values correspond with what you expected? If they do not, try to give an
explanation why.
Simulate this circuit using PSpice (DC Bias Point Only). Do your simulated values
match your measured values?
Figure 2
Experiment 3. Thevenin’s and Norton’s Equivalent (Day Two)
Build the circuit in figure 3. Measure VL and IL. Build this circuit’s Thevenin equivalent.
Measure VL and IL.
• Are the results equal? Explain why or why not.
• Do these values correspond with what you expected? If they do not, try to give an
explanation why.
• Simulate this circuit using PSpice (DC Bias Point Only). Do your simulated values
match your measured values?
Figure 3
Experiment 4. Maximum Power Transfer (Day Two)
Build the circuit in figure 4. To achieve a 30V potential difference, you will need to use
the +15V as the positive terminal and -15V as the negative terminal (+15V - -15V = 30V).
Feel the temperature of each of the resistors (the 1K resistors, the 240 Ω Resistors and
R_Load). Do this for R_Load = 50, Rth, and 2K. You should end up with three sets of
data (one set of data for each value of R_Load).
Be careful, the resistors in some cases will be very hot
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Explain why each resistor is the temperature it is. Calculate the power dissipated in
each resistor. Do these results correspond with how hot the resistors were?
which value of R_Load represents maximum power transfer? Was this load the
hottest? Explain why or why not.
Figure 4