Can Thevenin/Norton equivalents be used for circuits with dependent sources? If so, what must be preserved?

• A. Yes; keep dependent sources active and include their controlling relationships.
• B. No; dependent sources must be removed.
• C. Yes; but only if all independent sources are zero.
• D. Yes; but you must replace dependent sources with their equivalents.

Answer: (A)

Dependent sources rely on voltages or currents elsewhere in the circuit, so they cannot be turned off when forming an equivalent. The Thevenin/Norton view of the network must reproduce how the port voltage and current respond, and that response depends on those dependencies. Therefore, you keep the dependent sources active and preserve their controlling relationships so the external terminals see the same I–V behavior as the original network. When determining the equivalent, compute open-circuit voltage and short-circuit current with the dependencies intact; if you need the equivalent resistance, apply a test source with the dependent sources active, since their output depends on the circuit variables. In short, yes—Thevenin/Norton equivalents can be used with circuits that include dependent sources, and you must preserve the dependent sources and how they depend on the circuit signals.