3/10/2015

Work done for circuit analysis

The day began with Professor Mason demonstrating a new method of circuit analysis. This new method involves solving for the voltages in a circuit that contains voltage sources rather than current sources. The method is similar to nodal analysis with current sources.

Results & Calculations

This lab required us to use the new method of nodal analysis with voltage sources in order to calculate V_1 and V_2 in the circuit diagram shown above. Using the new nodal analysis method, we calculated V_1 to be -4.424V and V_2 to be -2.424V. After building the circuit we used a multimeter to measure the voltage at thos points. The measured value for V_1 was -4.34V and for V_2 it was -2.38V. We calculated the percent error from our calculated value and measured value from V_1 to be 1.9% and for V_2 to be 1.8%. I believe this error arose from the resistors not being the exact values that were expected. We calculated V_1 and V_2 by using  6.8kΩ, 10kΩ, and 22kΩ resistance values. However, when we measured the actual resistance of the resistors implemented in our circuit the values were 6.63kΩ, 9.97kΩ, and 21.8kΩ which differed from the values used in our calculations and resulted in different voltage values for V_1 and V_2.

Circuit

Above is the circuit we built in order to measure the V_1 and V_2. We used Curtis' Analog Discovery device to supply the 5V, -5V and -3V needed in the circuit. The multimeter was used to measure the resistance values of the resistors and the voltage at V_1 and V_2.

Summary:

Today, we learned a new circuit analysis method that will simplify the number of equations needed in order to solve for the unknown voltages at different nodes. This method is different from the previous nodal analysis method because it deals with voltage sources. We also learned mesh analysis, This circuit analysis requires the circuit to be planar. It works by assigning mesh currents to the loops and using Kirchhoff's loop law. However, the loops cannot intersect other loops. For our lab, I believe in order to reduce the error for our values we should first measure the resistance values of our resistors and then use those values in our calculations.