I'm new and need help for my IR project

Discussion in 'The Projects Forum' started by reychirino, Aug 5, 2015.

  1. reychirino

    Thread Starter New Member

    Aug 5, 2015
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    This is my first post here and I'm new to electronics eventhough I have many ideas that I want to develop.
    Also english is not my main language so I apologize for any misundersanting that may arise.
    The idea is to setup a group of IR LEDs on a wall and direct the light in one direction creating an invisible wall
    For this project I need a "bright" IR light source that can be detected at least 10 ft away and a detector that will make a buzzer sound indicating the IR "wall" presence.
    Researching for this project brought me to this forum and I hope you don't mind me "picking up" a little your braind and save some time
    Thanks in advance
     
  2. mcgyvr

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  3. reychirino

    Thread Starter New Member

    Aug 5, 2015
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    Sorry :-( I forgot to ask!
    Thanks mcgyvr for your quick response. The instructable article is one from where I got my inspiration for this project :)

    I want the light to be like a "wall" of light not to illuminate the whole room. Let say it would illuminate 2" - 4" wide of the wall in front of the LED, from the ceiling to the floor.

    I want to build the detector by myself but for now I'm interested to know what kind of IR LED should I use as IR light source?
    How many IR LED I would need for a 8' to 10' wall?
     
  4. #12

    Expert

    Nov 30, 2010
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    Light doesn't work like that. Have you ever tried to make a cube of visible light with no side walls to contain it? IR works the same way. It radiates in every direction. If you want a column of IR light, you will have to start with a container to limit the escape of the energy towards the sides of the area. The only kind of "one direction only" light is a laser, and you will be bankrupted to coat the whole wall with IR lasers.

    Please consider your idea for requirements that can actually be accomplished.
     
  5. reychirino

    Thread Starter New Member

    Aug 5, 2015
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    Thanks #12 for your response. You are right, I wasn't clear enough in expresing my idea. sorry.

    I know light radiate in all directions but I was thinking enclosing the LED in a small 3D printed plastic container whith a vertical aperture which will direct the light in the direction that I need.
    My concern is How strong or intense this IR LED need to be to reach and illuminate a wall at 8' to 10' away with enough intensity to be detected and allow my device to do some stuff.

    Thanks again
     
  6. mcgyvr

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    Well.... a single IR diode in my remote control can easily be detected by my TV across the room..
     
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  7. #12

    Expert

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    Look to the safety beam on a garage door opener. The IR is modulated at 38KHz and the receiver looks for that frequency. It works wonders for eliminating interference in the signal. In this case, I think you would use more receivers than transmitters to detect things or people moving in the area. After all, the things detected can not stop the transmitters, but they can stop the receivers.
     
  8. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Are you trying to build a "light curtain", something that creates a sensed plane (vertical in your case), and anything that breaks the plane is detected, like walking through an invisible door frame?

    ak
     
  9. reychirino

    Thread Starter New Member

    Aug 5, 2015
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    Yes, that's exactly what I want!
     
  10. reychirino

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    Aug 5, 2015
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    And whitch IR LED would you recommend as emitters and which as sensor?

    I need to buy these little fellows but I still don't know which one I need to get?
    Can you or anyone else can help?
     
  11. ISB123

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  12. RichardO

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    I can think of ways of doing a light curtain:

    The first is to scan a narrow beam of light and detect any obstructions or reflections of the widened beam.

    Second, take a single LED or Laser and spread the light into a wide beam. this is sometimes called a line generator.

    Third, use a bunch of LED's lined up looking at a bunch of photo diodes lined up to match. An object that breaks one of the many beams is detected.
     
  13. reychirino

    Thread Starter New Member

    Aug 5, 2015
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    Thanks ISB123 for your recommendation

    Hi Richard, I find interesting your 2nd option. Can you explain more please?
     
  14. atferrari

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    Jan 6, 2004
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    Sí Rey, you still have the same story going on: once it leaves your carefully built 3D enclosure the emission will start again spreading unlimited.

    Could you show a sketch, no matter nice or rough of what you try to implement? Maybe as seen from the ceiling of that room? And showing where the sensors, or whatever, are supposed to be located.
     
  15. reychirino

    Thread Starter New Member

    Aug 5, 2015
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    Hi atferrari

    I tried to upload the manual sketch but it didn't work so I am inserting a link to the file in my dropbox. I hope it works.
    https://www.dropbox.com/s/t4tq6au0lj5o5eh/robotpath.png?dl=0

    The idea is the IR emitters are installed on the ceiling and I want them to illuminate a path of IR Light on the floor that a robot with a detector can follow.

    Maybe this is what I should have said from the very beginning. sorry!
     
  16. #12

    Expert

    Nov 30, 2010
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    A line generator is a physical structure. With a laser, it might be a lens. The goal is to turn the 360 degree radiation into a line of radiation. The line doesn't have to be clean, straight, and accurate. The goal does not depend on excellent accuracy.

    "Maybe this is what I should have said from the very beginning."
    We often play, "20 questions" but it is a waste of time. Please blurt out the truth. It's more efficient about getting good answers quickly. ;)
     
  17. reychirino

    Thread Starter New Member

    Aug 5, 2015
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    Its not about any Truth it's about plain human nature.
    I asked about the IR LEd features only because that's what I thought would solve my problem but as people asked more question in order to give me a more meaniful answer I realized I have to give more info about the whole setup.
    I wasn't hidden anything I just didn't know how much info was needed. I guess that's why those "20 questions" are important sometime.
     
  18. #12

    Expert

    Nov 30, 2010
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    That was just a, "turn of the phrase", not an impeachment of your character. I learned that phrasing by trying to communicate with my recalcitrant nephew and it kind of leaked into my everyday use. :oops:
     
  19. reychirino

    Thread Starter New Member

    Aug 5, 2015
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