IR Sensor

[ismith1984]

working on a project i came across somewhat of a problem. i am thinking of a design with two ir sensors (sensor A and sensor B) respectively. when sensor a is broken and then sensor b is broken i want the output to give a 1. then when sensor Bis again broken and then sensor A i want the output to be a 0. I magine the final out will be a flip-flop of some sort but i was thinking of any way that the first infrared input will remain on until the second is activated so that the output cold be activated.

 

[MikeMl]

This is crying out for a state transition diagram. Do you know how to make one?

 

[ismith1984]

I have no idea how to go about constructing one. Do have an idea as to what it is exactly I wanna acheive.

 

[MikeMl]

Ok, I think this does what you want: It takes four states, therefore two state variables: X,Y. Two inputs, A,B. The output can be taken from either Y, or X~ (Xnot).

I implemented it using Set-Reset FlipFlops constructed out of Nand gates. It works with either overlapping and non-overlapping A and B.

 

[ismith1984]

hey mike i took a look at the circiuit and i decided i was gonna try to implement it. i have two questions for you. the first is what points on the schematic do i take the inputs and outputs from on the actual schematic. and another question is do i need the pulse voltage or did you use it just to simulate the state of the inputs.

 

[Reloadron]

Some time back, maybe a few weeks ago someone was looking at a people counter. It would up or down count when a photo diode (or any sensor) was tripped. The attached was part of the diguital logic. With minor modification it may be what you are looking for.

Ron

 

[ismith1984]

hello ron,

thanks you very much for the schematic diagram. i have two question about the circit. where you i power the circuit and what are the values of the resistors that are not labelled.

 

[ismith1984]

IRED cIRCUIT

ok so guys i tried constructing a circuit for the infrared part of thee circuit and i ran into a few problems and was wondering if any of you guys could help me out here. in the attached circuit switches J4 and J3 and used to simulate the infrared switches. so if j3 come on before j4 then someone is entering the room and the reverse if someone is leaving . my problem is with j2. j2 has to go to the on position and then back to the off position for the counter to go up or go down and this has to be done once that state of the output of the IRED ( connector I03) has changed. more or less i need it to be done without the switch. any help on this would be greatly appreciated.

 

[ismith1984]

Sorry that was only the subcircuit here is the circuit.

 

[Reloadron]

OK, the resistors that are unlabeled will depend on the photosensors used. The existing drawing simply shows a few photo diodes but a variety of sensors could be used like photo transistors, or whatever. Typically between 100K and 10 Meg depending. The photo sensors toggle the 7400s inputs at TTL levels.

Additionally the way this works is if the first photo sensor is triggered and then the second is triggered while the first is still triggered the count will increment up one. If the second is triggered and then the first while the second is still triggered then the count will increment down one count.

I added the VCC and common pins for the chips also in a note.

 

[ismith1984]

Ok guys i figured out how to use the circuit you gave me to accomplish what i was the count up and down. form the output of the counter i used the DCD hex display output as inputs to another part of my circuit to turn on and off my lights. my problem is that i am using PIR sensors and i am not getting any kind of response from it . i am using a sensor which is located at the link below i and it is used in the configuration below. any ideas as to the approach would be greatly appreciated guys.



https://www.futurlec.com/PIR_Sensors.shtml

 

[Reloadron]

I am missing something here. Your link shows a family of PIR devices including PIR modules. All of these devices, including modules are 3 pin devices. Your drawing shows a two pin input to your circuit as I see it?

Ron

 

[Dvinchy]

working on a project i came across somewhat of a problem. i am thinking of a design with two ir sensors (sensor A and sensor B) respectively. when sensor a is broken and then sensor b is broken i want the output to give a 1. then when sensor Bis again broken and then sensor A i want the output to be a 0. I magine the final out will be a flip-flop of some sort but i was thinking of any way that the first infrared input will remain on until the second is activated so that the output cold be activated.

You can accomplish a task with the help of these components:
http://www.datasheetcatalog.org/datasheet/toshiba/97.pdf
http://www.datasheetcatalog.org/datasheet/stmicroelectronics/2183.pdf

 

[ismith1984]

i think i didnt give enough information when i previously asked the question. here is part of the datasheet which shows how the diagram connects. i also posted the link so you could have taken a look at the datasheet if there was a need to . i took the liberty of posting the direct link to the datasheet.

Infrared Radial Sensor

 

[Reloadron]

If you are working to the drawing I provided all you need to do is remove R1 & D1 that feed pins 1 & 2 of U2 (U2A). Your PIR Pin 1 goes to VDD (+5 V), Pin 2 (Output) goes to Pins 1 & 2 of the U2A and Pin 3 (G) goes to common (GND) then you repeat the process for U2C.

Your PIR is self contained with power (+5 V) on pin 1, Signal Out on Pin 2 and common (GND.) on pin 3.

Ron

 

[ismith1984]

hey ron my problem is not really to connect the sensors but i was just asking whether someone had any idea how to get these sensors to work. these sensors apparently do not work when i connect them as the is not difference in voltage when the output is measured. the voltage just stays around .6V and does not deviate too much from that value. any help with its connection would be greatly appreciated.

 

[Reloadron]

I don't get it. It should be doing something. Pin 1 is 5 volts and pin 3 is ground and pin 2 is the output. You are sure you have the pins correct? You don't have 1 & 3 reversed as .6 volt has an eerie ring to it. Assuming a good unit there isn't much to this.

I have a few Parallex modular versions around here somewhere and there was nothing to making them work as I recall.

Ron

 

[ismith1984]

Well do you have the model number of the one you used maybe I can use that one. Since you already know that it works.

 

[Reloadron]

The PIR sensors I have lying here (I dug them out) are this type sensor and are actually configured to be motion detectors. They are not what you want.

What you want, looking back to the first post is a sensor that will trigger an up count and another that will trigger a down count on a counter if I read all this right. I think what you are after is something more along these lines. That or even a simple photo cell (CDS) using a visible light beam. Just something to get started that will work.

I don't know your location but there was a time when Radio Shack sold IR emitter / detector pairs for literally a few bucks.

Ron

 

[ismith1984]

No rob I don't think they do anymore. I think I will just use the link you sent me though and are how this works for me. Any other suggestions will be greatly appreciated