Norton’s theorem

Other methods to simplify the circuit are Thevenin s and Norton s theorems. These two theorems can be used to replace the entire circuit by employing equivalent circuits. For example, Figure 2.34 shows a circuit separated into two parts. Circuit A is linear. Circuit B contains non-linear elements. The essence of Thevenin s and Norton s theorems is that no dependent source in circuit A can be controlled by a voltage or current associated with an element in circuit B, and vice versa. 

Similar to Thevenin s theorem, Norton s theorem states that a section of a linear circuit containing one or more sources and impedances can be replaced with an equivalent circuit model containing only one constant current source and one parallel-connected impedance, as shown in Figure 2.36. 

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