Abstract: A power supply includes a housing receiving an electric motor, first and second fans, a generator, and a power device. The generator is concentrically mounted around the electric motor. When the electric motor is supplied with electricity from the power device and operates, a shaft of the electric motor drives the first fan to rotate, generating wind power close to the second fan. The second fan is rotated by the wind power in the housing and drives the second rotor and the second rotor seat to rotate. The first and second magnets create repulsive and attractive forces to provide inertia driving the second rotor seat, making the generator continuously supply electricity to the power device and the electric motor, thereby keeping the electric motor running to generate the wind power while the first fan continuously using the wind power to drive the second fan and the generator to generate electricity.