An unstable nonlinear circuit
Claude M. Summers · Electrical Engineering · 1940
AN iron-core reactor in parallel with a capacitor in a series circuit with some kind of impedance will exhibit unstable characteristics under certain conditions. A change in one or more of the circuit parameters will cause the current or voltage associated with some element of the circuit to change suddenly from one stable value to another. Between these two conditions no value of current or voltage will satisfy all of the elements of the circuit simultaneously.