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infrared problem..
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infrared problem..

by grandemahatma on Wed Jan 30, 2008 1:45 pm

hallo!
I'm following the arduino tutorial in ladyada.net, lesson 3: "Breadboard and LEDs".
Now I'm using a Boarduino, 2.2K resistor and a 5mm white LED.
It blinks perfectly, but when I use a infrared LED instead of the white one, nothing happens: the tiny red led on the Boarduino stops blinking, and thus (I suspect) the IR let is not blinking either..
Why is it so?
I'm using a infrared led, 5mm, type: LD 271.

Thanks to everyone that could help..
Ale
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by adafruit on Wed Jan 30, 2008 1:46 pm

you can use a camera to tell if the IR led is blinking or not

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mh..

by grandemahatma on Wed Jan 30, 2008 1:50 pm

sure, but since the onboard red led is not blinking (while it IS blinking when I use a white LED) I suspect something is not working..
:(
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by Entropy on Wed Jan 30, 2008 3:46 pm

The Vf of an IR LED is MUCH lower (1.2-1.4V) than for a white LED (around 3.6V). This means that with an identical resistor, current consumption will be much higher.

That said, if you are indeed using a 2.2k resistor it shouldn't matter...
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..

by grandemahatma on Wed Jan 30, 2008 4:32 pm

ok, so?
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by Entropy on Thu Jan 31, 2008 8:41 am

I have no clue - there shouldn't be a significant difference if it's a 2.2k resistor.

You sure it's not 220? Then the difference in current resulting from the different Vfs could possibly be overloading the output port and making the AVR unhappy.
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mh..

by grandemahatma on Thu Jan 31, 2008 4:29 pm

indeed is a 2.2k.. mumble mumble.. and I tried with several IRleds..
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.

by grandemahatma on Thu Jan 31, 2008 4:53 pm

done.. a 330ohm and it works fine. Still the onboard red LED is not blinking, but I don't mind..
thanks a lot
ale
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Re: .

by problah on Thu Apr 24, 2008 4:20 pm

grandemahatma wrote:done.. a 330ohm and it works fine. Still the onboard red LED is not blinking, but I don't mind..
thanks a lot
ale


I was just doing something similar to this last night with an IR, and a blue UB. When I plugged in the IR, the IR would turn on, and blink, but the blue (And the onboard, as this was pin 13) would stay on. I believe my IR was a 5v hog, and "took" the power over. I verified the IR was lighting up with my cameraphone (Never understood why cameras were on phones until now!).

I'm not sure if this helps, as I'm n00bish, but It didn't seem to make the Arduino Angry, it just wouldn't share the pin.

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Please be positive and constructive with your questions and comments.