Boundary of Two Frequency Behaviour in a System of Three Weakly Coupled Electronic Oscillators

We review and report observations of complex dynamics associated with loss of stability of two frequency quasiperiodicity at a saddle-node bifurcation of invariant two-tori. In particular, for a system of three weakly coupled electronic oscillators we find bubbles in parameter space interrupting a curve on which there is a saddle-node bifurcation of two-tori. These are comparable to Chenciners bubbles found near a codimension two bifurcation of a planar map.