With this project we can display 0-9 digits on the 7 segment and we can count the no of persons entering in the room. Here a counter IC 7490 is used along with BCD to 7 segment decoder IC 7447. The function of 7490 is to provide the counting value and decoder IC is decoding that value to 7 segment output. Every time when you will push the switch

the clock of IC7490 will be triggered and as a result count will increase by 1. Hence with this simple project we can display numbers 0 to 9 on seven segment display just by pressing switch. It`s a very easy circuit and you can easily implement it on a general purpose PCB. So instead of using switch we will use LDR here, we will place LDR at the entry door in such a manner that the shadow of the entering person should fall directly on LDR, when shadow will fall on LDR clock of IC 7490 will be triggered and as a result the count will increase by one. Circuit wilh some small changes is as shown. Variable resistor is used to adjust the resistance to synchronize the light intensity for better results.

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