phototransistor to detect if someone walk in the door how to ?

Hi I hope someone can help me with this

I am tray to make phototransistor to detect if someone walk in and out the door
to connect to up/down counter


I will start with the phototransistor the counter I will thing about later

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I have up/down counter but I need to replace the button with phototransistor but the only problem with the counter is
I need to press button to change if I want to count up or down
so when I walk in the door the phototransistor press the button to count up or down and the he press the button to count
so best if I can find how to make up/down counter I don't need to press button to select if I want to count up or down
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I hope someone have sample of phototransistor Schematic Please it need to be in the door

Regards
Sigster

I just replay to my self

I did find the up/down counter and phototransistor


I vas thinking it work to have 2 phototransistor one in and on out in the same door
if the same person count when he/she walk in the first sensor and then count out when he/she cross over the second sensor so the center will still be zero

Infrared sensitive phototransistor
**broken link removed**

Up/Down counter
**broken link removed**