The universal motor is an electric motor of small volumes, designed for use in portable or domestic appliances. An engine with these targets has its electrical scheme adapted to work with any type of available voltage. A higher power universal motor can be obtained if modifications are made to the motor design so that it performs well with direct current and alternating current. The engine thus obtained is a universal motor.

The universal motor is the only single-phase motor that has the stator coils electrically connected to the rotor by means of two sliding contacts (brushes). These two contacts, in turn, serially connect the stator and the rotor. The winding of the fixed part is called field winding. The winding of the rotating part is called the winding of the armature or induced. Some care will have to be taken in the winding. It is imperative that the field winding be run on a core formed by a packet of silicon plates. These plates have the purpose of cutting the path of the parasitic currents, that is, the electric currents that circulate in the iron, caused by the variation of the magnetic field.