In this paper, first, we have presented a simple circuit design method for obtaining non-autonomous chaotic oscillator circuit from any given second-order sinusoidal oscillator with two capacitors. The proposed method relies on applying a periodic pulse train as the excitation source and an addition of a signum-type nonlinear self-feedback to the given sinusoidal oscillator. The existence of chaos in the resulting system has been shown using Poincare-Birkhoff Theorem. Experimental results verifying theoretical analysis for two novel chaotic oscillators are given. Secondly, we have introduced a new non-autonomous system which generates butterfly attractor similar to the one of the classical Lorenz system.