PSPICE for Thevenin and Norton Equivalents

In this lab we learned how to use PSpice to evaluate Norton Equivalents.

Operational Amplifier

With this lab I gained a bit more experience with a few of the uses of op-amps. The concern here was mainly with gaining some empirical information about their gain property. We played around with different values of resistance along the feedback channels and interpreted the results.

Oscilloscope 101

This lab was essentially an introduction to oscilloscopes. We found out how to measure waveforms and how to interpret the onscreen data. I also learned a little bit about function generators.

In the end, we used our new-found knowledge to measure two "mystery signals" and make sense out of them.

AC Signals #1

With this lab we measured the phase difference between AC signals that had the same frequency.

We assumed that each channel was set to 2V/div and that the horizontal time-base is set to 10 microsec/div. We measured the periood and determined the RMS value for both channels. Then we found the frequency.

Thevenin Equivalents

Motivational Analysis Problem:

Design a circuit that runs off of two regulated power sources which must supply a certain voltage across a load. Also, consider what voltage will exists at the terminals at the load if the load is removed and what the short circuit current would be there.

PSpice Thevenin and Max Power (Homework)

Here we used PSpice to answer a few homework problems.

Below is a graph made by running a simulation of the above circuit. The vertical intercept of 96.61V is the Thevenin Voltage. The slope of around 5.333 gives the Thevenin Resistance.

Below is the 2nd problem.

Once again, the intercept of 53.18V gives us our Thevenin Voltage and the slope of 50.9 gives us our Thevenin Resistance.

I created a simple representation of the circuit using the Thevenin equivalents and ran an analysis in order to determine what load resistance allows the greatest total power. A load resistance of 50.9 Ohms gives the greatest power of 13.9 W.

Nodal Analysis

Motivational Analysis Problem:

In most real-world situations, it is important to design a system so that it can take damage and still deliver the necessary results. An example of this in circuit design is building in redundant power supplies. However, it is very seldom as simple as just adding in another battery. New power sources mean that the overall system must be redesigned in order to handle variances in voltage and current while still remaining operational.

We were given the task of designing a simple circuit which consisted of two voltage supplies and a total of five resistors.

Design Parameters:

We are given that in the outer loop there is a 100 Ohm resistor followed by two 220 Ohm resistors in series. There is a 12V source connected by the positive terminal to the 100 Ohm resistor and a 9V supply connected by its positive resistor to the outside 220 Ohm resistor. The two negative negative terminals are connected to each other and ground. There are two branches connected between the ground consisting of 1000 Ohm resistors, one between the 100 Ohm resistor and the inside 220 Ohm resistor and the other between the two 220 resistors.

Setup:

Results:

We measured the voltage across the 1000 Ohm resistors along with the currents through the batteries and compared these to our predicted values.

Theoretical Value Measured % Error

Current Battery1 -17.5 mA 17.84 mA 1.94

Current Battery2 -1.8 mA 1.57 mA 12.78

Voltage1 10.25 V 10.25 V 10.35 V 1.00

Voltage2 8.6 V 8.6 V 8.76 V 1.86