IR Diode to Car system diagram?

Discussion in 'The Projects Forum' started by ripcord, Sep 20, 2010.

  1. ripcord

    Thread Starter New Member

    Sep 20, 2010
    2
    0
    Hi
    I am a novice at heart so not too cluey on setting up a circuit correctly.

    This is basically what im doing

    Im setting up a bunch of IR diodes to a car system (12VDC)

    i just need to know what/how many resistors i need and how to setup the circuit. Im pretty sure ill be doin it in series too

    the specs of the IR diodes

    size: 5mm.
    Voltage: 1.5V-1.6V.
    Wavelength: 850nm.
    Current: 60mA-120mA.
    View Angle: 15-30 degree.
    Lens Colour: Water Clear.
    Emitted: Infrared light LED

    Any help would be appreciated, thanks!
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    That is rather vague - like how many might constitute a "bunch"? 850 nm is a bit hard to see - what is the point?
     
  3. ripcord

    Thread Starter New Member

    Sep 20, 2010
    2
    0
    there will be 20
    i need it to go around the border of a sign.
    I wasnt sure if 850nm or 940nm would be brighter, in the day picked up on camera.
     
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Remember that a car's charging circuit can result in your "12V" as being anywhere from 11.8V - about 13.8V maximum.

    Considering the current specs they're fairly forgiving, you can put 8 or 9 in series directly to a 12V supply and they should hold up fine.

    Individually you'd want to use somewhere between 120 - 240 ohms in series with each LED.
     
  5. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Depends on the peak wavelength response point of the camera.

    If you can go with 24 that would be three strings of 8 with no resistors, if not then set it up as 8, 8 and use around 68 - 75 ohms in series with the last series set of 4.
     
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