I. OBJECTIVES

1. To troubleshoot a complex circuit and determine various currents and voltages using mesh analysis.

2. To simulate the complex circuit in MultiSim and record the required quantities.

3. To determine the various currents and voltages after wiring the circuit.

II. PARTS LIST

Equipment:

DC Power Supply

DMM (Digital Multimeter)

Parts:  

1-Resistors

2- Breadboard and Hook-Up Wires

Software: MultiSim

III. PROCEDURE:

Part III - A

For the circuit in Figure 4-1 below, predict circuit characteristics using themesh analysis theorem.

1. Mesh Analysis Using Branch Currents

Figure 4.1a: DC Circuit with Two Voltage Sources (Branch Currents)

Where V_S1= 12 V, V_S2= 5 V,R1 = 180 ?, R2 = 390?, R3 = 220 ?, andR4 = 470 ?.

To use themesh analysis method, select the branch current direction, I1 and I2, as indicated below. Write down the two simplified mesh equations  needed.

To use themesh analysis method, select the loop current direction, I1 and I2, as indicated below. Write down the two simplified mesh equations  needed.

3. Solve the above equations and calculate the loop current, I1 and I2, then use the information to complete the rest of the table. 

Table 4-1

4. Verify KVL using your calculated voltages from the table above for each loop.

KVL for Loop 1:

KVL for Loop 2:

5. Verify KCL for Node C.

KCL for Node C:

Part III - B

Simulated Circuit Calculations UsingMultiSim

For the circuit in Figure 4-2 below, simulate using MultiSim. In this exercise, you need to verify all of the values calculated in Step 2 of Part III - A.

1. Build the Basic Circuit in MultiSim as follows in Figure 4-2. Place your meters in their appropriate location and record the values in the table below. 

Figure 4-2 - MultiSim Circuit

Part III - C

Construction of the Circuit and Measurement of Circuit Characteristics

1. Select the resistor components. Measure and record their values.

R1 = ________ (?)      R2 = ________ (?)        R3 = ________ (?)       R4 = ________ (?)

2. Is each resistor within the acceptable tolerance range? _______ (YES or NO)

3. Construct the circuit in Figure 3.1. Do not connect the power supply yet.

4. Set one power supply voltage to 12 VDC. Set the second power supply voltage to 5 VDC.

5. Record the voltage reading of the first supply. _______

Adjust the power supply, making sure you read close to 12 VDC.

6. Record the voltage reading of the second supply. _______

Adjust the power supply, making sure you read close to 5 VDC.

7. Switch OFF the power supplies. Connect the voltage source to the proto board.

8. Set DMM to measure each ofthe branch currents I_R1, I_R2, I_R3,and I_R4.(Be sure to switch OFF the voltage source while making the DMM connections for the branch current measurement. Then, switchON the DC power to the proto board to obtain the measurement reading.) Record the current reading. The process is repeated for each current measurement.     

I_R1 =_____________ (A)        I_R2 =_____________ (A)       

I_R3 =_____________ (A)        I_R4 =_____________ (A)

9. Turn OFF the power switch.Reconnect the DMM to measure the indicated resistor voltages. Turn ON the power switch. Measure the voltages across each resistor.

D. Results Analysis of a Series-Parallel Circuit

1.      Complete the table containing the theoretical results and experimental results obtained for R1, R2, R3, R4, V_S1 (supply voltage), V_S2 (supply voltage), I₁(current thru R1), I₂(current thru R2), I₃(current thru R3), and I₄(current thru R4). Calculate the power sourced by both supply 1 and supply 2.

2. Calculate the percentage of error for each result recorded in Step D1.

Percent of error = (experimental - theoretical)/Theoretical * 100%

3. Provide your thoughts on the results regarding the percentage of errors obtained between the experimental and theoretical results.

Part III - D

Troubleshooting & Testing

IV. TROUBLESHOOTING

Describe any problems encountered and how those problems were solved.

IV. Questions

1. I₁ was measured to be 27.54 mA, and the voltage across R₃ is 2.058 V. Both supply voltages were tested to be with the correct value. What is the fault in the circuit? (Hint: Use MultiSim).

2. If V_R2 was measured to be 12 V, then what is the fault in the circuit?

3. What is the relationship between the branch currents, loop currents, and resistor currents?