The speed / motion of rotating / moving object is sensed by a non contact inductive type sensor. The sensor probe is installed with its sensing face in close vicinity of rotating object. The metallic pieces (flags) with specified dimensions are to be mounted on the rotating object. When these flags pass across the face of the probe, the frontally radiated electromagnetic field of the probe is damped which is converted to a corresponding output pulse. The pulse can also be generated by any other types of probes. These pulses are led to the monitoring unit via a separate interconnecting cable. The sensor probe can be mounted up to a maximum distance of 100 meters from the monitoring unit. The interconnecting cable should be of minimum 0.5sq. mm.size. These pulses are digital in nature and circuit is designed to work in electrically noisy area. An LED provided on rear side of a probe gives visual indication for sensing of the flag. In case of sensors other than inductive type, the pulses generated can be connected as specified for the individual sensor. The units are designed by using new advance micro controller based circuit. All operating features e.g. time delay, speed comparison, speed display, output relay operation are controlled precisely by the micro controller. Some parameters, related to design / operation of a speed switch, are as explained below.