The purpose of the invention is the realization of a motor assembly formed from a stepping motor and its control circuit capable of operating at a maximum speed substantially greater than that obtainable with comparable existing assemblies. This is effected by substituting for the single coil or for each coil of a known motor two or more windings and adopting a control circuit which connects the windings in series or parallel according to whether motor drive pulses of low or high frequency are applied thereto. The total number of winding turns and the sum of the resistances of the windings are preferably chosen to be equal respectively to the number of turns and the resistance of the coil which they replace in order to avoid basic modification of the characteristics and performances of the motor when operating at low speed. When the windings are connected in parallel their resistance and equivalent self-inductance are less than that of a single coil. The energy transfer from the voltage source to the rotor of the motor is increased and facilitated and the maximum speed of the motor is considerably increased.
