Beginner Long range IR Transmitter

Discussion in 'The Projects Forum' started by smashdk, Jul 22, 2010.

  1. smashdk

    Thread Starter New Member

    Jul 22, 2010
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    Hello all,
    I need some guidence on an IR transmitter for up to 200 ft. I have just started building circuits and I have completed a small scale Transmitter reciever and it seems only good up to 12 inches. So I am looking for some advice as to a list and a schematic to transmit further. No data transmitting, this is simply for a beam break detection.

    I perferr this to be on a 9v or 12v. Any help would be great.

    Thanks,
    DK
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    That's going to be tough.

    I'd use an LED laser instead. You could use a laser pointer, and modulate the output. Use a phototransistor or photodiode at the other end.
     
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    200 ft range will require some refinement. I suggest you read some of the datasheets and ap notes from a reliable manufacturer, such as Vishay. You will need to use a modulated beam. Simple on/off detection will not have the sensitivity and immunity from false signals that you will need.

    Here is an example of a detector:
    http://www.vishay.com/docs/82090/tsop48xx.pdf

    Here is a general reference for Vishay:
    http://www.vishay.com/ir-emitting-diodes/

    Here is a high intensity, low dispersion emitter:
    http://www.vishay.com/docs/81007/81007.pdf

    Are you considering using a microcontroller? That woud be the easiest way to go for the transmitter. If not, it can be done with a pair of LM555's or similar. Various circuits have been discussed here many times.

    John
     
  4. BMorse

    Senior Member

    Sep 26, 2009
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    Optics would also play a great deal in the sensitivity and the range required...

    B. Morse
     
  5. smashdk

    Thread Starter New Member

    Jul 22, 2010
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    Yes it will be with a microcontroller.

    I have considered the 2 options:

    1 IR led with optics. Question here which optics and which emitter? What receiver is best over this distance?

    2: IR laser. My question here is what are the safety issues here? There will be animals around, what are potential harmful issues? or is there any? I have been reading on these and cannot find one that makes me comfortable. But would love to be able to use one that would show a full line all the way across without cutting things in half.. :D

    This is my only issue in dealing with this break beam at variable distances up to 200ft that a user can line up.
     
  6. smashdk

    Thread Starter New Member

    Jul 22, 2010
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    Also can someone point me to a specific IR LED? I am not good with the LED specs and how they make them perform over distances / Power usage.

    Also can someone point me to a good site with optics?

    Will I need to combined multiple IR LEDs?
     
  7. hgmjr

    Moderator

    Jan 28, 2005
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    You will probably need to resort to using an array of IR leds to achieve the distance you require.

    hgmjr
     
  8. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    You left out microwave. That is apparently used in a number of animal hazard warning systems:

    http://www.oregon.gov/ODOT/TD/TP_RES/docs/Reports/AnimalVehicle.pdf?ga=t

    Why do you not want to use a visible laser?

    Do you have any experience with infrared optics?

    What are you really trying to do? I ask that, because it is not infrequent that someone comes to this site with specifications that are more in the world of dreams than reality. Once their real goal is established, the problem frequently becomes much easier.

    John
     
  9. smashdk

    Thread Starter New Member

    Jul 22, 2010
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    Zero experience in IR optics. Good time to learn.

    What I am trying to do. My GF is a barrell racer. We are trying to put a barrier system in our Practice pasture. But I do not want it in the fence at all there will always be someone walking the edges and horse, etc, could knock it over so forth. so it needs to beable to go the 200ft. horse passes through then the barrier is broke, computer picks it up. Its that simple. I can do it on a smaller scale, I am just lost to what steps to take it to the 200ft.

    Thanks,
    DK
     
  10. Papabravo

    Expert

    Feb 24, 2006
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    If you read the datasheets very carefully you will note that there are specifications for continuous duty where you turn the the IR source on and leave it on at some current. There is also the pulsed application where you can use much higher currents at a very low duty cycle. This allows more illuminance from the source and reduces the heating involved in having that amount of current on continuously.

    It is not uncommon to use small resistors in this mode to allow a higher maximum current.
     
  11. bertus

    Administrator

    Apr 5, 2008
    15,638
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    Hello,

    200 ft is not really a beginners project.
    An advanced project can be found at the pages of the "ronja project":
    http://ronja.twibright.com/
    They are communicating with IR over a distance of over 1 km.

    Bertus
     
  12. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I think a simple red laser as suggested by SgtWookie (post#2) is the way to go. Commercial emitters have fairly narrow dispersion, and if you need optics, they can be made of glass. You may need to modulate it,* but that is not certain. Putting the detector at the end of a tube increases selectivity considerably.

    John

    *Modulation helps distinguish signal from background. Background will not be modulated, so it is like separating AC (modulated) from DC.
     
  13. smashdk

    Thread Starter New Member

    Jul 22, 2010
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    Okay thanks for the help. I guess this is something that I will just test until I get it right. I just figured that there would have to be something out there already that was close.

    DK
     
  14. BMorse

    Senior Member

    Sep 26, 2009
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  15. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    You might consider a garage door safety sensor. They are about $25 from all the major suppliers. The problem is range.

    A typical 2-car garage is about 24ft wide, but the products generally do not give a specific range. I found one product with a stated range of 32 feet, which is still far less than the 200 ft that you need.

    John
     
  16. smashdk

    Thread Starter New Member

    Jul 22, 2010
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    So this looks like to reach what I want then an Infrared Laser is going to be the trick.

    Does anyone have a recomendation for one? One that they have had pretty good success with?
     
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