Let’s say that we want to simplify the circuit below to an equivalent voltage source and resistor that captures the circuit behavior at the terminals (Thevenin-equivalent circuit).
Since we only care about the terminal behaviour, any of the other circuit details may be simplified. We can apply source transforms in two places:
- Norton to Thevenin source transform circled in red. This results in voltage sources and resistors all in series, which can be added.
- Thevenin to Norton transform in green. This results in a parallel-series-parallel configuration, which cannot be early simplified.
- Therefore, only the red Norton-to-Thevenin transform is applied.
Now, the resulting circuit has 3 resistors and 2 voltage sources in series, which can be added together since we don’t care about the internal details of the circuit.
Finally, a Thevenin to Norton transform places the resulting resistor in parallel with the circuit’s remaining resistor:
The resistors can be combined and a final source transform rearranges the circuit into the final Thevenin equivalent form:
