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 wider range of system parameters. This has a big advantage over the traditional schemes in the sense that even if the system parameters are varied real-time, this method still successfully induces chaos. Practical applications of chaos require the chaotic orbit to be robust. The advantages of using this technique to jam circuits and make them inoperable is that it consumes minimal power and the entire process is reversible. This makes the method viable for real life practical applications as a portable device especially in the military where it can be put to use as a jamming device.