Thevenin's Theorem

Any combination of batteries and resistances with two terminals can be replaced by a single voltage source e and a single series resistor r. The value of e is the open circuit voltage at the terminals, and the value of r is e divided by the current with the terminals short circuited.

Thevenin voltage

Thevenin resistance

Numerical example

Norton equivalent

to AC Version

Application in Digital to Analog Converter