Equipment:
List the equipment that you will use for this experiment.

Components:

• R1 - 300 Ohm Resistor
• R2 - 470 Ohm Resistor
• R3 - 560 Ohm Resistor
• R4 - 680 Ohm Resistor
• R5 - 750 Ohm Resistor
• R6 - 910 Ohm Resistor
• R7 - 4.7 KOhm Resistor
• R8 - 1 KOhm Potentiometer

• Analyze and reduce three dc circuits to their Thevenin equivalents
• Create all of the necessary diagrams and data tables to support the analysis

                                                Figure #2
 
 

                                                Figure #3
 
 

1. - (PreLab H/W) DC Thevenin Analysis
Based on the class notes, you should be familiar with the concept DC Thevenin.  In this section you are asked to analyze circuits given to find their Thevenin voltage(Vth), Thevenin resistance(Rth) and short circuit current(Isc) between terminals A and B.  You will first derive the general formula and then use ORCAD simulator to find the values of the Vth, Rth and Isc.
 

1A. For the circuit of Figure #1:
With respect to terminals A and B of the circuit in Figure #1 and leaving the resistors in their reference designator symbol, DERIVEa general formula to find:

1. Thevenin Voltage (Vth).
2. Thevenin Resistance (Rth).
3. Short circuit current (Isc).
4. Using nominal values of resistors given in the component section of this report and V1=6V, use the ORCAD software to simulate the circuit and find the nominal values for Vth, Rth and Isc.  Put these information in Data Table 1A.
5. Draw the Thevenin equivalent circuits for Figure #1.  Label the circuit "Figure 1A- Thevenin Equivalent of Figure 1A"

1. Thevenin Voltage (Vth).
2. Thevenin Resistance (Rth).
3. Short circuit current (Isc).
4. Using nominal values of resistors given in the component section of this report and V1=6V, V2=9V and V3=12V, use the ORCAD software to simulate the circuit and find the nominal values for Vth, Rth and Isc.  Put these information in Data Table 1B.

Draw the Thevenin equivalent circuits for Figure #2.  Label the circuit "Figure 1B- Thevenin Equivalent of Figure 1B"

1. Thevenin Voltage (Vth).
2. Thevenin Resistance (Rth).
3. Short circuit current (Isc).
4. Using nominal values of resistors given in the component section of this report and V1=6V, V2=9V and V3=12V, use the ORCAD software to simulate the circuit and find the nominal values for Vth, Rth and Isc.  Put these information in Data Table 1C.

Draw the Thevenin equivalent circuits for Figure #3.  Label the circuit "Figure 1C- Thevenin Equivalent of Figure 1C"

In this section you will construct the circuits of Figure #1, Figure #2 and Figure #3.  You will then do some detailed measurements to find voltages, current and thevenin resistances using DMM.

2A. For the circuit of Figure #1:

1. Construct the circuit of Figure #1.  DO NOT connect the voltage source (V1) to the circuit yet.  In the place of V1 install an electrical short using wire.  Use DMM to measure the Thevenin resistance (Rth) between terminal A and B. Create and put this information in Data Table 2A.
2. Remove the electrical short and connect the voltage source (V1) to the circuit.  Use DMM to measure the voltage drop across each resistor in the circuit.  Put these information in Data Table 2A.
3. Measure VAB with R7 connected and disconnected across terminal A and B.  Put this information in Data Table 2A.
4. Measure IR7  (current across R7) and put the result in the Data Table 2A.
5. Build the thevenin circuit of Figure 1A.  Set R8 (the 1 K Ohm potentiometer)  to the value of Rth you calculated in part 1.  Measure VAB with R7 connected and disconnected across terminal A and B.  Find also IR7 (current across R7).  Place these information in the Data Table 2A.
6. Compare the value of VAB obtained from part (4) and (6).

2B. For the circuit of Figure #2:

1. Construct the circuit of Figure #2.  DO NOT connect the voltage sources (V1,V2 and V3) to the circuit yet.  In the place of voltage sources install an electrical short using wire.  Use DMM to measure the Thevenin resistance (Rth) between terminal A and B. Create and put this information in Data Table 2B.
2. Remove the electrical short and connect the voltage sources (V1,V2 and V3) to the circuit.  Use DMM to measure the voltage drop across each resistor in the circuit.  Put these information in Data Table 2B.
3. Measure VAB with R7 connected and disconnected across terminal A and B.  Put this information in Data Table 2B.
4. Measure IR7  (current across R7) and put the result in the Data Table 2B.
5. Build the thevenin circuit of Figure 1B.  Set R8 (the 1 K Ohm potentiometer)  to the value of Rth you calculated in part 1.  Measure VAB with R7 connected and disconnected across terminal A and B.  Find also IR7 (current across R7).  Place these information in the Data Table 2B.

Compare the value of VAB obtained from part (4) and (6).

1. Construct the circuit of Figure #3.  DO NOT connect the voltage sources (V1,V2 and V3) to the circuit yet.  In the place of voltage sources install an electrical short using wire.  Use DMM to measure the Thevenin resistance (Rth) between terminal A and B. Create and put this information in Data Table 2C.
2. Remove the electrical short and connect the voltage sources (V1,V2 and V3) to the circuit.  Use DMM to measure the voltage drop across each resistor in the circuit.  Put these information in Data Table 2C.
3. Measure VAB with R7 connected and disconnected across terminal A and B.  Put this information in Data Table 2C.
4. Measure IR7  (current across R7) and put the result in the Data Table 2C.
5. Build the thevenin circuit of Figure 1C.  Set R8 (the 1 K Ohm potentiometer)  to the value of Rth you calculated in part 1.  Measure VAB with R7 connected and disconnected across terminal A and B.  Find also IR7 (current across R7).  Place these information in the Data Table 2C.

Compare the value of VAB obtained from part (4) and (6).

1. Determine the accuracy of your measurement data compare to your calculation data.  What are the percentage of errors?