This paper studies superstable phenomena in a simple circuit consisting of two capacitors, two signum voltage-controlled current sources and one time-controlled impulsive switch. The circuit equation defines piecewise constant vector field, the trajectory is piecewise linear, and the embedded return map is piecewise linear: it is well suited for precise analysis. In some parameter range the map has infinite extrema and one flat segment. In this case the circuit exhibits extremely complicated periodic orbits characterized by superstability for initial value, very fast transient and sensitivity for parameters