Download Find the Thévenin Equivalent circuit between terminals AB for the

LAB 6 – Combining Superposition &
Thévenin’s Theorems
In this Lab you will apply a combination of the Superposition
Theorem and Thévenin’s Theorem to the circuit in FIG. 1 to arrive
at the Thévenin Equivalent of that circuit as shown in FIG. 2.
The Superposition Theorem is necessary here because the initial
circuit in FIG. 1 contains TWO voltage sources that cannot be
combined into one.
You will explore the usefulness of the Superposition Theorem in
predicting the influence that a change in one particular source
voltage applied to one part of circuit has in the voltage developed
in another part of the same circuit.
V2
3V
Thévenin
Equivalent
R2
1K2
R1
1K2
V1
5V
R3
5K6
RTh
R4
1K2
A
VTh
R5
10K
B
B
FIG. 1
A
FIG. 2
The circuit in FIG. 1 is similar to the one analyzed in class, with
different resistor and voltage values. The voltages have been
reduced to make it possible to implement with the lab power
supply, and the resistor values have been reduce to get
reasonable voltage values across all components.
PROCEDURE
1.
In this step you will calculate the resistance RAB seen between
the terminals AB of the circuit in FIG. 1 which will be the value of the
resistance RTh in the Thévenin Equivalent of FIG. 2.
2.
Use the partial circuit in FIG. 3 to mark the changes required in
the circuit of FIG. 1 to calculate the Thévenin resistance.
3.
Use the space provided below to calculate and record RAB.
FIG. 3
R2
1K2
R1
1K2
R3
5K6
R4
1K2
A
R5
10K
B
RAB = ________ 
CALCULATED VALUE
4.
Implement the circuit in FIG. 3 and use
an OHMETER to measure the resistance
between terminals AB. Record your
measurement in the box to the right. Compare
this value with the calculated one.
Troubleshoot your circuit if they differ by more
than 5%.
RAB = ________ 
MEASURED VALUE
5.
Use the partial circuit in FIG. 4 to mark the changes required in
the circuit of FIG. 1 to calculate the voltage VAB(1) that will appear
between terminals AB due ONLY to the voltage source V1.
6.
Use the space provided below to calculate and record VAB(1).
FIG. 4
R2
1K2
R1
1K2
R3
5K6
R4
1K2
A
R5
10K
B
VAB(1) = ______ V
CALCULATED VALUE
7.
Implement the circuit in FIG. 4 and use a
VOLTMETER to measure the voltage VAB(1)
between terminals AB. Record your
measurement in the box to the right. Compare
this value with the calculated one. Troubleshoot
your circuit if they differ by more than 5%.
VAB(1) = ______ V
MEASURED VALUE
8.
Use the partial circuit in FIG. 5 to mark the changes required in
the circuit of FIG. 1 to calculate the voltage VAB(2) that will appear
between terminals AB due ONLY to the voltage source V2.
9.
Use the space provided below to calculate and record VAB(2).
FIG. 5
R2
1K2
R1
1K2
R3
5K6
R4
1K2
A
R5
10K
B
VAB(2) = ______ V
CALCULATED VALUE
10.
Implement the circuit in FIG. 5 and
use a VOLTMETER to measure the voltage
VAB(2) between terminals AB. Record your
measurement in the box to the right.
Compare this value with the calculated one.
Troubleshoot your circuit if they differ by
more than 5%.
VAB(2) = ______ V
MEASURED VALUE
11.
Use the Superposition Theorem to calculate the voltage VAB
that will appear between the terminals AB when BOTH voltage
sources are present as in the circuit of FIG. 6. To do this simply
ADD algebraically the voltages VAB(1) and VAB(2) you obtained
before by having each voltage source act upon the circuit
independently. Record your result in the box below.
V2
3V
FIG. 6
R2
1K2
R1
1K2
V1
5V
R3
5K6
R4
1K2
A
R5
10K
B
VAB = VAB(1) + VAB(2) = ______ V
CALCULATED VALUE
12.
Implement the circuit in FIG. 6 and
use a VOLTMETER to measure the voltage
VAB between terminals AB. Record your
measurement in the box to the right.
Compare this value with the calculated one.
Troubleshoot your circuit if they differ by
more than 5%.
VAB = ______ V
MEASURED VALUE
Question 1
13.
With reference to the circuit in FIG.
4, what would have been the voltage
VAB(1) if the polarity of the source V1 had
been flipped?
Enter your answer in the box to the right.
VAB(1) = ______ V
14.
Reconnect the circuit of FIG. 4 and
actually flip the polarity of V1 Measure the
voltage VAB(1) and record your result in the
box to the right. Compare this value with
the calculated one. Troubleshoot your circuit
if they differ by more than 5%.
VAB(1) = ______ V
CALCULATED VALUE
MEASURED VALUE
Question 2
15.
With reference to the circuit in FIG.
5, what would have been the voltage
VAB(2) if the polarity of the source V2 had
been flipped?
Enter your answer in the box to the right.
VAB(2) = ______ V
16.
Reconnect the circuit of FIG. 5 and
actually flip the polarity of V1 Measure the
voltage VAB(2) and record your result in the
box to the right. Compare this value with
the calculated one. Troubleshoot your circuit
if they differ by more than 5%.
VAB(2) = ______ V
CALCULATED VALUE
MEASURED VALUE
Question 3
17.
With reference to the circuit in FIG.
6, what is the voltage VAB if the polarity of
the source V2 is flipped?
Enter your answer in the box to the right.
VAB = ______ V
18.
Reconnect the circuit of FIG. 6 and
actually flip the polarity of V2. Measure the
voltage VAB and record your result in the box
to the right. Compare this value with the
calculated one. Troubleshoot your circuit if
they differ by more than 5%.
VAB = ______ V
CALCULATED VALUE
MEASURED VALUE
Question 4
19.
Use the analyses covered up to this point to predict what
change in VAB would be observed in the circuit of FIG. 1 if V1
increases by 16%. Prove your calculation by measuring the
change in VAB when increasing V1 by 16%.
VAB = ______ V
CALCULATED VALUE
VAB = ______ V
MEASURED VALUE
Question 5
20.
Implement the Thévenin Equivalent of the circuit in FIG.
1 and demonstrate that both the original circuit (FIG. 1) and its
Thévenin Equivalent (FIG. 2) behave the same (i.e. have the same
voltage and current between terminals AB) when the loads RL
listed in TABLE 1 are connected across their respective AB
terminals. Record your measurements in TABLE 1.
TABLE 1
Original Circuit
FIG. 1
RL
OPEN
SHORT
1K
2K2
10K
Thévenin Equivalent
FIG.2
VAB
IAB
VAB
IAB
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured
Measured