What is a Thevenin Equivalent Circuit?

A Thevenin equivalent circuit is a simplified model of any linear electrical network consisting of a single voltage source (Vth) in series with a single resistor (Rth). This powerful concept, developed by French engineer Léon Charles Thévenin in 1883, allows complex circuits with multiple sources and resistors to be reduced to a simple equivalent circuit from the perspective of a specific load.

The Thevenin equivalent is particularly useful for:

• Simplifying circuit analysis by replacing complex networks with a simple equivalent
• Analyzing how circuits respond to different loads
• Troubleshooting and designing electrical circuits
• Understanding maximum power transfer to a load

The Thevenin theorem states that any linear electrical network containing voltage sources and resistors can be replaced by an equivalent circuit consisting of a voltage source Vth in series with a resistance Rth, where Vth is the open-circuit voltage at the terminals, and Rth is the equivalent resistance looking back into the circuit with all sources replaced by their internal resistances.

How to Use the Thevenin Equivalent Circuit Calculator

Step 1: Select the appropriate circuit type from the dropdown menu. The calculator supports three common circuit configurations: Voltage Divider, Multiple Sources, and Wheatstone Bridge.

Step 2: Enter the circuit parameters in the input fields. For a voltage divider, input the source voltage and resistor values. For multiple sources, provide the voltage values and resistances. For a Wheatstone bridge, enter the source voltage and all four resistor values.

Step 3: Input the load resistance value if you want to calculate the current through and voltage across a specific load.

Step 4: Click the “Calculate Thevenin Equivalent” button to process your inputs. The calculator will instantly determine the Thevenin voltage (Vth), Thevenin resistance (Rth), load current, and load voltage.

Step 5: Review the detailed calculation explanation and circuit diagrams provided below the results. These explanations show the formulas used and step-by-step calculations, helping you understand how the Thevenin equivalent values were derived.