ir distance needed

Discussion in 'General Electronics Chat' started by vallka, Jan 10, 2014.

  1. vallka

    Thread Starter New Member

    Jan 10, 2014
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    0
    Ok I am new to this stuff.
    I had ordered some Ir stuff from ebay, both red and white diodes, I got them to work, but not past a distance of 5".
    I am using them for a timing system for a slot car race timer.
    I have 3mm red and 5mm white (clear) running on a 5v cell phone charges with 30 amp resistors. I just cant get the distance I need between them, I did get a wide viewing angle for the white one but not sure about the red ones (wish I new the terms for the names of them!!)
    Is there something I should look that tells me the distance expected from them? Or a link to some on ebay or some other seller?
    Hey Thank for all the help with this,
    Troy
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,090
    3,027
    I'm confused - you mentioned IR, white and red LEDs. Which is it? If your detector is looking for IR, the red should work a bit better but IR would be better still.

    A common trick for getting more distance (used in remote controls) is to pulse the LED at, for example, 80kHz, and then at the receiver filter out anything not arriving on that frequency. MUCH higher signal to noise and thus distance. But you need only 1 foot or so?
     
  3. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,645
    759
    I find that inconsistent.

    Resistors are usually specified in Ohms.

    30 amp (amperes?) and a cell phone?

    Verify your data whatever it is.
     
  4. vallka

    Thread Starter New Member

    Jan 10, 2014
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  5. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    You may need optics or filters.

    Have you tried putting them in tubes? Like a ball point pen tube? May have to cover with foil for ir.

    Generally, beam is modulated and the frequency selectivly detected.

    I would think you could get more than a few inches though.

    See if it works better in the dark. That may be a clue.
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,090
    3,027
    What are you using for the detection circuit?
     
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