Using the principles of Chaos Theory, a novel scheme is presented to induce robust chaos into a perfectly running electronic circuit, a circuit whose parameters are both unknown and cannot be adjusted. To induce chaos we use a Phase Locked Loop (PLL) to inject resonant perturbations into the target system by tracking its frequency and phase. Robust chaos is achieved both by operating the PLL at the edge or just outside its lock range where it is shown to behave chaotically and also ensuring resonance. Here, by robust chaos, it is meant that the system remains in its chaotic state for a...