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Deimos #1 17/05/2008 - 11h51

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Registered on : 07/11/2007

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Kestrel, please update the FAQ with a few notes about LED operating conditions. I see questions about them all around the forums. Here's what i'd like to see there:

My LED's specification says it's forward current is 100mA. So that's what i should input in the LED Assembly wizard?
This value is LEDs maximum rating, meaning that it's the maximum current that won't damage the LED. Anything higher may cause permanent damage.
Here are some example recommendations for current values for IR LEDs depending on webcam:
    * camera with removed IR filter and applied visible light filter - about 25% of maximum rating
    * stock camera (with IR filter present) and visible light filter applied - about 50%-70% of maximum rating (only use the higher value if the lower isn't too bright)
    * illumination for reflective tracking (the camera has to be fully IR-modified: ni IR filter and added visible light filter) - 90%-100% of maximum value. When using such high values it's the best to mount LED in a PCB for better heat dissipation.


My LEDs are heating up. Is that normal?
Most of the LEDs can operate in temperatures up to 100 degrees Celsius without risk of taking damage. LEDs heat up when they are driven with high current (close to, or above maximum rating) which is unnecessary unless you have a good reason for it (like a reflective system). See question above for recommended current values.

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Probably there are a few more updates needed, but i don't have too much time to write anything else right now. I'll try adding some more later.

Oh, and by the way, could anyone fix the LED calculator so that it accepts both comma and period as decimal separator? Right now using values "1.5" and "1,5" for LED forward voltage yields different results.
Edited by Deimos on 17/05/2008 at 11h51.
didja #2 17/05/2008 - 13h08

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Registered on : 09/07/2007

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Many thanks Deimos ! :)

I have just updated both english and french FAQ.

Thank you for your help !!! :)

Rémy
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