FIELD: automation and control, in particular, devices for regulation of rotation frequency and active power of electric power plants. SUBSTANCE: device has second photodetector which is located in opposite to track of mechanical modulator. Optical axes of photodetectors are located in parallel in single plane. Their outputs are connected to inputs of logical unit which is designed as X1 prohibition, or X2 prohibition or X1 and X2 prohibition unit. Another claim of invention describes device design in which photodetectors are located in same position and logical unit is designed as logical one source and two D flip-flops. EFFECT: constant duration of output pulses for constant rotation frequency and possibility to keep precision of conversion using modulators which have increased tolerance range. 2 cl, 14 dwg
