IR led light source

Discussion in 'The Projects Forum' started by das7771, Jan 26, 2009.

  1. das7771

    Thread Starter New Member

    Jan 26, 2009
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    I am looking to build an IR light source to use with my Sony video camera. I purchased a cheap IR flashlight that has 25 IR led lights on it, but I want some thing that would put out a wider beam of light.

    I purchased 50 of these -Infrared LED 1.1-1.6V 20mA 850nM- and wish to build a light source out of this. This is going to be my first build of any thing like this and I don't really no where to start.

    If any one could point me in the right direction, I would greatly appreciate it.

    Thanks in advance.
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    I would check voltage drop @ 20mA of all led's and put them in piles of = V drop. Just for discution assume a matrix 7X7. Select values[ on paper first ] to give about a 9.45 V for 7 led's,assuming a 12V supply,adjust 9.45V up or down to give greatest number of strings of = V. Figure value of current limiting resistor: 12V- 9.45 = 2.55V/ .02 = 127 or std value of 130Ω. Leftover strings might have 6 to 8 led's,just figure them seperatly.

    To give desired beam spread, use a segment a plastic bowl [ approx. hemispherical ]. For narrowest beam , use 7 mm centers , for wider beam spread centers as desired. Make a paper patern .marking centers then led lead holes. Dampen paper and form over bowl, tape in place when dry. Remember holes for resistors, 1/4 W. Drill lead holes as snug as possible. Insert leds, bend leads to over lap and solder
     
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    I goofed on thumbnail.
     
  4. das7771

    Thread Starter New Member

    Jan 26, 2009
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    Thanks, this definitely helps. I still have not received the LED's but now I know where to start. Thanks again.
     
  5. Greg G

    New Member

    Jan 25, 2009
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    How far away is the object? If it's more than about 15 feet away you might want to consider switching to a larger LED, like a 1 watt, and an orange peel reflector. There are companies that sell an LED mounted to a star/heatsink, and it comes with a reflector. It's a P60 type, and will swap right into many lights, such as a Surefire 6P. You could always build an array of them if you need a lot of lumens. www.dealextreme.com has the P60 drop-ins as well as the individual LED's.

    What were you planning on using for a battery pack and driver?

    Here is a star:

    http://www.dealextreme.com/details.dx/sku.13961
     
    Last edited: Jan 31, 2009
  6. das7771

    Thread Starter New Member

    Jan 26, 2009
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    Bernard,

    excuse me for asking this question, but like I said I am new to this so I just need a little clarification.

    On the diagram you posted, you are showing the (+) side of the power supply going into the resistor. then the led's connected with the (-) being at the end. This would mean that the power would flow through the (-) side first, then through the lights, then into the resistor. The whole conventional vs. electron flow notation has me a little confused. I thought since the power actually flows from (-) to (+) that the resistor should be connected on the negative side first before leading up to the lights. So that way the power is then regulated to the voltage I need to power the 7 led's.

    Or is your diagram actually using conventional flow notation and when I do connect every thing I actually do it according to the electron flow notation and connect the resistor to the (-) side of the power supply first, before leading up to the led's?
     
  7. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    The order of placement of the parts makes no difference, just be sure cathodes of LED's go to the most - side of circuit.
     
  8. das7771

    Thread Starter New Member

    Jan 26, 2009
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    Okay, thank you
     
  9. Wendy

    Moderator

    Mar 24, 2008
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  10. das7771

    Thread Starter New Member

    Jan 26, 2009
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    I just want to say thanks for the help. I put together a set of led's that was 7x7. I now have a nice IR light for my camera with 49 led's that works well. This is a very informative site with some good people to get advice from. Now I just gotta decide what I want to make next.
     
  11. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    It's refreshing when a Threaded gives a final report, come back again sometime.
     
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