Resumo:
In this work we have studied oscillating electronic circuit based on negative
differential conductivity (NDC), with possibility to present chaos. The Chua’s circuit was
chosen for the nonlinear dynamical and chaotic phenomena studies due to its simple
implementation, robustness and easy operation. Its studies have provided important
characteristics of NDC devices. Many oscillatory phenomena can be derived by controlling
quiescent points of Chua´s circuit I(V) characteristics. This is carried by changing the slope
and the position where the load line cross the I(V) characteristics. For this we have carried
out two experimental setups, by controlling two distinct parameters of the circuit, namely
the series resistance R and the D.C. series voltage with the NDC device (i.e. the Chua
diode). We have acquired time series of three circuit points and carried nonlinear dynamical
analysis of them. Our analysis considered periodic and chaotic time series depending on the
control parameter value for both considered parameters. For the experiments considering
the D.C. series voltage source we have obtained a bifurcation diagram which has given
information of the structure, sensitiveness to initial conditions and bifurcation types. Such
circuit is very stable and low noise and this has permitted us to practice nonlinear
dynamical analysis with the computational tools such as Lyapunov spectrum, mutual
information, average false nearest neighbors and dimensions like the Kaplan and Yorke,
information dimension. Poincaré sections allowed us to obtain bifurcation diagrams and to
infer what was the most confident result for the fractal dimension of chaotic attractors.
