Abstract: A motion producing device using permanent magnets as the source of energy including one or more permanent magnets at least one having a coil mounted on it, and an electric circuit for connecting the coil to a source of electric energy whereby application of the energy to the coil changes or modifies the magnetic characteristics of the permanent magnet on which it is mounted in such a manner that when another permanent magnet is in the field of the controlled permanent magnet, the interaction between the permanent magnets will be modified so as to change the coupling force therebetween. The present device can be used to produce rotational motion, linear motion, oscillating motion, and combinations of these.