Norton Equivalent Circuit Theorem

Norton's theorem for electrical networks states that any collection of voltage sources, current sources, and resistors with two terminals is electrically equivalent to an ideal current source, I, in parallel with a single resistor, R. For single-frequency AC systems the theorem can also be applied to general impedances, not just resistors. The Norton equivalent is used to represent any network of linear sources and impedances, at a given frequency. The circuit consists of an ideal current source in parallel with an ideal impedance (or resistor for non-reactive circuits). - Wikipedia

The Norton Equivalent of a circuit consists of a Norton current source in parallel with a Norton resistor and is valid for any load. In AC circuits a Norton equivalent circuit is valid for a single frequency.

The Norton current is the short-circuit current at the output - the same as what is calculated for the Thévénin short-circuit current (see Thévénin Equivalent page).

The Norton resistance is the same as the Thévénin resistance.

Original Circuit

Norton Equivalent circuit - RF Cafe

Norton Equivalent Circuit

Norton Equivalent drawing - RF Cafe