4.5 Thevenin’s Theorem (1)
It states that a linear two-terminal
circuit (Fig. a) can be replaced by an
equivalent circuit (Fig. b) consisting
of a voltage source VTH in series with
a resistor RTH,
where
VTH is the open-circuit voltage at the
terminals.
RTH is the input or equivalent resistance at
the terminals when the independent
sources are turned off.