Thevenin Equivalent graph ideas

I can't thank you all enough for your help in preparing lab experiences for my students this semester. The first set of submissions will be coming in tomorrow.

Quick question... I have a Thevenin Equivalent circuit with a variable load resistor. The ultimate goal is a load line graph with I versus V and negative R as the slope of the graph. Using your Parameter techniques, I was able to create graphs of I versus R and V versus R. The only way I can see to get to the final goal of I versus V is to use the Excel spreadsheet and download the graph outside of CircuitLab. Is there something that I'm missing or another process I could use?

Thanks as usual, Carol Strong

https://www.circuitlab.com/circuit/u7p9gcxpz68c/lab-3-thevenin-equivalent-of-voltage-divider/

by strongc
September 30, 2020

Here are a couple of suggestions for drawing an I vs V graph. I replace RL with a current (or voltage) source.

The DC Sweep Sim is set up for the left hand circuit, current control. There is an alternative voltage control version on the right (you will have to change the Sweep parameters in order to graph it).

The custom values (current or voltage) are arbitrary. For simplicity I have chosen ones that fall between RL as short- and open-circuit. The graphs show a slope of 200mV per 6mA, or 33 Ohm. The slope is negative because the sim is measuring current out of Rth as +ve.

Pushing the Thevenin concept further, you could select current values outside the circuit's natural range, eg -/+2A (custom values: -2,2). In this case the graph changes 100V per 3A, or 33 Ohm.

by EF82
October 20, 2020

No Answers

No answers yet. Contribute your answer below!


Your Answer

You must log in or create an account (free!) to answer a question.

Log in Create an account


Go Ad-Free. Activate your CircuitLab membership. No more ads. Save unlimited circuits. Run unlimited simulations.

Search Questions & Answers


Ask a Question

Anyone can ask a question.

Did you already search (see above) to see if a similar question has already been answered? If you can't find the answer, you may ask a question.


About This Site

CircuitLab's Q&A site is a FREE questions and answers forum for electronics and electrical engineering students, hobbyists, and professionals.

We encourage you to use our built-in schematic & simulation software to add more detail to your questions and answers.

Acceptable Questions:

  • Concept or theory questions
  • Practical engineering questions
  • “Homework” questions
  • Software/hardware intersection
  • Best practices
  • Design choices & component selection
  • Troubleshooting

Unacceptable Questions:

  • Non-English language content
  • Non-question discussion
  • Non-electronics questions
  • Vendor-specific topics
  • Pure software questions
  • CircuitLab software support

Please respect that there are both seasoned experts and total newbies here: please be nice, be constructive, and be specific!

About CircuitLab

CircuitLab is an in-browser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital electronics systems.