Electronic Circuits and Projects Forum

Originally Posted by Reloadron

Yes, a 4013 would work. Configure as a /2 where first pulse toggles it on and second pulse toggles it off.

Ron

Dear Ron, there is another problem. The sensor must distinguish between a person entering and a person leaving, otherwise when the first person walks into the room the light will switch on, but when a second person walks in, the light will toggle again which result light will turn off, which not desired. So, do you have any idea to fix this problem?

Originally Posted by Reloadron

This is a homework assignment on the old people counter problem. I suggest you look at the attached and work from there. Everything you need to know and understand is in the attached.

Ron

Ron, first I pay thanks to you for the help.

This technique is useful when there are two passages for in and out. In this situation only one door to enter in the room, so, If i replace photodiode with occupancy sensor, being a wide coverage area, both of them trigger simultaneously, which is not required so please help me if you have another idea.

Originally Posted by Reloadron

If you look close at the circuit I posted and make sure the sensors are spaced about a 6 inches apart then both sensors do not trigger at the same time. Look at the logic. If a person enters the room one triggers before the other and if a person exits, the other sensor triggers first. So while yes, both will trigger, one will always trigger before the other. This allows a counter for example to count up (person enters) or count down (person leaves). Think about it.

Ron

Ron, I think you will agree with me that to make project simple and reliable, putting a shutter placed in front of occupancy sensor will fix the problem. Because the shutter will open for every 1 minute and then closed, so it will detect presence or absence of someone and the circuit will trigger accordingly. Please give your expert opinion.