Canard is a new phenomenon of slow-fast systems, which was found by the numerical computations. Our primary purpose of this paper is to study the canard from the experimental viewpoint. The following results are obtained by the experimental observation of a nonlinear circuit: (1) Canard really appears in the actual circuit. But canard's life in the circuit is extremely short. (2) When a canard vanished, an irregular oscillations or a cycle with period two is still there, which usually does not occur in the two dimensional autonomous systems.

A new phenomenon of a slow-fast system, canard, is studied. Some interesting propeties and the existence of canards are shown by using non-standard analysis and singular perturbations. There results explain the strange behavior of a nonlinear circuit with a small parameter.