This paper proposes a tunable pendulum energy harvesting system incorporating a Cone Continuous Variable Transmission (Cone CVT) design. The goal is to build upon the resonance state observed in previous adaptive-tuned vibration absorber research by integrating a converter to transform mechanical energy into electrical energy. The system dynamically tunes itself in response to varying excitation frequencies. In this design, a Cone CVT is installed between the pendulum stem and the dynamo. Additionally, a conventional PID controller is employed to adjust the wheel position. A mathematical model is developed to predict system response and performance for different design parameters. MATLAB ODE45 and ODE23 solvers are utilized for simulation, generating data for dynamic system analysis. The analytical model is validated by tuning the frequency within the range of 1 to 5.24 rad/s. The outcomes demonstrate that, following the tuning algorithm, the pendulum enters a resonance state, leading to a significant increase in output voltage, approximately 10 times compared to the initial value.