RPM counters are used to measure Speed of Motors (AC/DC) or any Rotating Object. They measures and indicates current Rotating Speed of Motor. They are very essential in applications like Speed Control of Motors and close Loop Control System. Such industrial RPM counters are very accurate made up of microcontroller or microprocessor. 

CD4017 is a 16 pin CMOS decade counter/ Divider.  It takes clock signal from the clock input and turns on the 10 output in sequence, each time when it receives [[wysiwyg_imageupload::]]clock input pulses. A popular IC, CD4017 is extremely useful in various projects like Light Chaser, Matrix Die. It is also useful in many applications like Binary counter/decoder, frequency division, divide by N counting, Alarm system etc. In order to understand the working of IC CD4017, one must know about its individual pins. It has 3 input pin and 10 output pin and one is ground pin and another is used for power supply and one is Carry out pin.

The circuit developed here will count the number of visitor entering or exiting from door of auditorium or hall or any other place. Depending on the interrupt from the sensors, the system identifies the entry and exit of the visitor. On the successful implementation of the procedure, it displays the number of visitor present in the room. Therefore it can be economically implemented in all the places where the visitors have to be counted and controlled. This circuit is good enough for only one person entering at a time. It will also give you visual indication of circuit with the help of LED. It is operated at wide range of temperature from 5V to 20V. The big advantage of the 4026B counter IC is that it can drive a 7-segment display without needing a decoder driver IC. It will count the number of visitor up to 99 which can be increased by cascading more 4026 IC.