1. Will this be used on an interior or exterior doorway?
Interior
2. Is the width of the doorway in the diagram (10ft) accurate or can it be smaller?
4ft -10ft ; can manage with 4 ft
3. How much traffic will be going through the doorway? Basically, will people be walking through the doorway so often that there will be no space in between them?
Moderate, i mean about 4 persons in a minute(that maximum)
4. What is the maximum number of people the system will have to count before it is allowed to rollover?
I just want to show the concept this time; so 10 counts will do.
5. How do you want the count to be displayed? LCD? Computer? 7-segment LED? Interpretive dance?
7 segment LED
6. Will the system have to count children or short people too?
Not required, But what changes should i make for it?[I think Just lowering the sensors will do.]
7. Does the system have to account for more than one person walking through the doorway at once?
No, but just tell me how can it be done if required.
8. Can the 1 ft minimum as shown in the diagram be changed(larger or smaller)?
Surely.
9. What are you doing this project for? Work? School? Fun?
Student Project + Fun
10. What is your favorite color?
Color? Why?
1. Will this be used on an interior or exterior doorway?
Interior
Since the doorway to be monitored will be interior, there is less concern for ambient light to affect the system than there would be if it was on an exterior doorway exposed to sunlight. You can probably get away with something like
this for your transmitter and reciever pair. That's what I would try first anyway.
2. Is the width of the doorway in the diagram (10ft) accurate or can it be smaller?
4ft -10ft ; can manage with 4 ft
I asked the question about door width because if the door width is narrow enough, you could get away with using an IR distance sensors instead of a transmitter/reciever pair with each one mounted on an opposite side of the doorway. 4 ft would be narrow enough for this to work. The system would interpret someone passing through the doorway as a shortening of measured distance. This could be fed into a logic circuit to produce the desired output. This would probably be the more difficult approach though since you aren't going to use a microcontroller
3. How much traffic will be going through the doorway? Basically, will people be walking through the doorway so often that there will be no space in between them?
Moderate, i mean about 4 persons in a minute(that maximum)
This is good becasue that will give time in between people for the IR beam to "reconnect". All this circuit is doing is counting the number of times the line of sight between the IR LED and the phototransistor is broken. If people were to walk through such that their "shadows" overlapped, it would trick the system into thinking only one person had passed through.
4. What is the maximum number of people the system will have to count before it is allowed to rollover?
I just want to show the concept this time; so 10 counts will do.
If all you're doing is showing the concept, than a single 7 segment display 0 - 9 should be fine. It will simplify your circuit some.
5. How do you want the count to be displayed? LCD? Computer? 7-segment LED? Interpretive dance?
7 segment LED
Personally, I would have gone with interpretive dance but if you're not up to the challenge, I guess a 7 segment would be fine.
6. Will the system have to count children or short people too?
Not required, But what changes should i make for it?[I think Just lowering the sensors will do.]
If you are going to count short people or children, you will have to mount the sensors low enough so that they couldn't walk underneath them. This is great until a person of normal height walks through the door. If they are swinging their arms alot, it could produce false counts. It will be more reliable if you design it for only normal size people.
7. Does the system have to account for more than one person walking through the doorway at once?
No, but just tell me how can it be done if required.
If you want to account for people walking in the door side by side you would have to mount the sensors over head and have multiple pairs of sensors. This could become complicated so I would not make it a requirement.
8. Can the 1 ft minimum as shown in the diagram be changed(larger or smaller)?
Surely.
If you can adjust the distance that the recievers are away from one another, you might be able to get away with one transmitter (i.e. IR LED). With a single transmitter, the line of sight to each reciever (i.e. phototransistor) will be slightly different and they won't get broken at the same time. This might be doable with some tweaking but if you're not up for optimizations and just want to get the project done then the two LED two phototransistor setup will work fine.
9. What are you doing this project for? Work? School? Fun?
Student Project + Fun
What are you studying? What projects have you done so far?
10. What is your favorite color?
Color? Why?
Because I was going to buy you a car in your favorite color. Dude...it was a joke.
So this is how I would take a first hack at this project.
I would set up the two IR LEDs side by side. Maybe sepearted by 3" - 4". Wire them so they are on continuosly. I would mount the LEDs at the bottom of a long tube or maybe even a drinking straw. The reason is that I want the beam that comes out of the LED to be really narrow. I don't the adjacent LEDs to affect the adjacent phototransistors.
Next, I would mount the phototransistors on the other side of the door. You will have to be very careful to make sure the LEDs line up with the phototransistors for proper operation.
The phototransistors will be on when they can see the IR LED. Take the output from the phototransistor and feed them into a logic circuit. More on this logic circuit soon.
I would then feed the logic signals into a 4510 counter, connect the output of the 4510 to a 4511 and then ultimately into a common cathode 7 segment display. A tutorial for using the 4510, 4511, and 7 segment can be found
**broken link removed**.
Now for the logic circuit. The 4510 has an input referred to as UP/DN. This input determines whether or not the low to high transition of the clock input increments or decrements the count. The logic signal to this input should change depending on which IR LED gets blocked first (i.e. if a preson is entering or leaving the room). According to the data sheet of the 4510, the UP/DN input pin should only be changed while the clock input is high. So this is what your logic circuit would have to do.
Depending on which LED gets blocked first the logic circuit would have to change the state of the UP/DN count or not. It should work like this:
No LEDs blocked:
UP/DN - high
CLOCK - high
LED1 gets blocked first (person enters):
Inhibit LED2
UP/DN - high
CLOCK - pulse low and then back to high
Re-enable LED 2
LED2 gets blocked first (person exits):
Inhibit LED1
UP/DN - transition to low
CLOCK - pulse low and then back to high
UP/DN - transition back to high
Enable LED1
There are several ways this logic circuit can be made and there may be easier methods but this is what I'd try first.