  We show that oscillations are excited in a complex system under the influence
of the external force, if the parameters of the system experience rapid change
due to the changes in its internal structure. This excitation is collision-like
and does not require any phase coherence or periodicity. The change of the
internal structure may be achieved by other means which may require much lower
energy expenses. The mechanism suggests control over switching oscillations on
and off and may be of practical use.
