This paper considers the development of a smooth "starter" for a DC motor based on a switch controlled DC-to-DC power converter of the "buck" type. The dynamic feedback controller is based on a suitable combination of passivity based control, flatness and a /spl Sigma/ - /spl Delta/ modulator implementation of the average designed controller. The scheme proposes an indirect regulation of the motor shaft speed by means of input current regulation on the "buck" converter circuit. As a consequence, the proposed feedback controller does not require the use of an electromechanical velocity sensor for measuring the angular velocity. The effectiveness of the proposed controller was verified by computer simulations using the P-Spice circuit simulation program.