# Handout 3: Superposition and Source Transform

## Superposition

- Select one of the independent sources. Set all other independent sources to zero.

- Relabel voltages and currents using suitable notation.

- Analyze the simplified circuit to find the desired currents and/or voltages.

- Repeat steps 1–3 until each independent source has been considered.

- Add the partial currents and/or voltages obtained from the separate analyses.

- Do not add power quantities (they are non-linear).

- A common goal in source transformation is to end up with either all current sources or all voltage sources in the circuit.

- Repeated source transformations can be used to simplify a circuit by allowing resistors and sources to eventually be combined.

- The resistor value does not change during a source transformation, but it is not the same resistor (i.e., currents and voltages are lost).

- If the voltage or current associated with a particular resistor is used as a controlling variable for a dependent source, it should not be included in any source transformation.

- If the voltage or current associated with a particular element is of interest, that element should not be included in any source transformation.

- In a source transformation, the head of the current source arrow corresponds to the “+” terminal of the voltage source.

- A source transformation on a current source and resistor requires that the two elements be in parallel.

- A source transformation on a voltage source and resistor requires that the two elements be in series.

Last updated:

January 6, 2018