Carbon nanotube (CNT) oscillators based on a single-walled CNT bundle were investigated using classical molecular dynamics simulations. We present the schematics of a CNT bundle oscillator that could be initiated by an electrostatic capacitive force. While the capacitive force acting on a CNT oscillator extruded it, the force exerted on the CNT oscillator by the excess van der Waals energy sucked it into the bundle. Therefore, the CNT oscillator could be oscillated by both Coulomb and the van der Waals interactions. The operation frequency of a CNT bundle oscillator could be controlled by both the size and the length of the bundle. Our molecular dynamics simulation results showed unique features of the CNT bundle oscillators such as chaotic signature and high damping rate. CNT oscillation in the bundle showed the coupled motion to be dependent on other CNTs rather than a collective motion of the bundle. As the number of CNTs in the bundle oscillator increased, the chaotic signature of the CNT bundle oscillator increased with the increasing of coupled CNTs.