We are going to create a circuit using sensor that when you are passing to enter in the sensor the 7 segment will count increment and when you passing back the sensor will be decrement....
What kind of sensor and Components am i going to use???
Just use an infrared beam (from an infrared led) and a photo-diode, when somebody walks by, the infrared beam will be blocked and the photodiode sensor will send a pulse to a BCD counter. Then send the BCD (binary coded decimal) to a 7 segment led driver chip. If connected properly, it will count up when you walk by. It might be more complicated to make it count down though when you walk the other way. You would need some logic chips, and two sensors!!
Just use an infrared beam (from an infrared led) and a photo-diode, when somebody walks by, the infrared beam will be blocked and the photodiode sensor will send a pulse to a BCD counter. Then send the BCD (binary coded decimal) to a 7 segment led driver chip. If connected properly, it will count up when you walk by. It might be more complicated to make it count down though when you walk the other way. You would need some logic chips, and two sensors!!
You will need a HEF4518 BCD counter and a 7 segment display driver such as a CD4511 shown in the circuit. For the sensor, you could use a LM339 voltage compartor to "compare" the signal that the photo diode is putting out to a pre-set signal from a potentiometer .The potentiometer can adjust the sensitivity. How much knowledge in electronics do you have?
Eric's post contains a very good circuit for a two sensor up/down counter. You would replace the up push button with possibly an NPN photo diode and the same for the down counter. That circuit is exactly what you are seeking. Look at the circuit and study the data sheets for the chips used. Understand how it works.