  We study entropy of chaotic oscillation of electrical currents in the Chua's
circuit controlled by triggering a pulse that brings the orbit that goes onto
an unstable branch back to a stable branch. A numerical simulation of the
voltage of the two capacitors and the current that flows on an inductor of the
Chua's circuit reveals various oscillation patterns as the conductance that is
connected between the two capacitors and directly connected to an inductor is
varied. At small conductance, the Lissajous graph of the voltage of the two
capacitors shows a spiral, while at high conductance a double scroll pattern
appears. The entropy of the current that flows on the inductor is alocal
minimum in the spiral state which is in the steady state, while it is maximum
in the stable double scroll state. The stable double scroll samples are
analyzed by using the Hidden Markov Model (HMM) and the eigenvectors of the
transition matrix of long time series are found to be strictly positive but
those of unstable short time series have negative components. We thus confirm
maximum entropy production in the double scroll of the longest time series
around the right fixed point, while the local minimum entropy production occurs
in the spiral around the left fixed point.
