Scientific paper ID 880 : 2013/3

Duffing oscillator is a non-autonomous dynamical system with sinusoidal entrance effects. Mathematical model of these oscillators is a nonlinear differential equation of second order with a cubic nonlinear function, known in the literature as an equation of Duffing. These equations modeling events in different fields: physics, biology, economics, etc.

The Equation of Duffing might be mathematical model in a number of nonlinear circuits, which a nonlinear element is described by a function of the third order. The coefficients of the equation depend on the parameters of the circuit, so that the type of equation’s solution also determined by them. Depending on the parameters of the elements can be prepared periodical, pseudoperiodical or chaotic solutions.

In the current paper is tested a electrical circuit, witch is described with a system of two non-linear differential equations of first order. She is equivalent to the Duffing equation. The chain contains a circle to feedback relation, which is consisting of a resistor and two diodes. By circle to feedback relation introducing a non-linear function of the equation. For testing of the circuit is set up the simulation model in PsPice. Through this model are simulated processes in the chain and are examined how their character is amended according to the parameters of the chain. Its are received different phase portraits and have been conclusions under what parameters are obtained a dual chaotic attractor.