The introduction covers the issues of measuring small torques in the range of up to several dozen mN·m, characteristic of precision drive systems with DC micromotors or micro stepping motors. Torque measurements in such systems can be performed, among others, using rotary torque meters. In these experiments, rotary torque meters enable, for example, determining the static and dynamic characteristics of micromotors and entire drive systems, or testing the efficiency of power transmission systems. The meters are then included in the kinematic chain of the tested system. Next, a subclass of rotary torque meters is characterized - phase-differential torque meters adapted to the presented requirements. The concept of building such a small range meter is presented, with Hall sensors generating periodic signals as a result of the magnetic field of miniature permanent magnets. A mathematical model of the described torque meter is developed and the stages of its identification and the results of numerical experiments optimizing the measurement system are presented. The design of the technology demonstrator is described and the results of its research are presented, as well as examples of the use of the device in micromotor research.