Abstract: A device is disclosed having means for measuring the speed of an engine, the means including a first sensor, a second sensor offset from the first sensor by an angle .alpha., and a reference element that moves in front of the sensors. The reference element is mounted on a disc, and the disc is rigidly connected to a shaft of the engine. The speed measuring means further includes a first programmable divider down-counter whose input is connected to a clock which delivers thereto signals at a frequency fo and whose output is connected to a counter adapted to count the signals delivered by the divider. The frequency fc of said signals is equal to the frequency fo of the clock signals divided by the value of the angle .beta. equal to the difference between 360.degree. and the angle .alpha. of offset between the first and second sensors.