An electromechanical tool including a casing, a shaft driving a tip in rotation and a rotary transformer. The rotating shaft integrates an electronic circuit configured to measure a physical parameter of the shaft, and the rotary transformer includes a stator fixedly attached to the casing and a rotor affixed to the rotating shaft. The stator integrates a first coil and a first support of this first coil, and the rotor integrates a second coil and a second support of this second coil. The supports are made out of plasto-ferrite material.