johnwasser:
Perhaps you calculated the resistance incorrectly?What is the voltage drop across the LED?
What is the current requirement of the LED?
If you have the 276-0143 "High-Output 5mm Infrared LED" the answers are 1.2V and 100mA. That would be a problem because the Arduino output can't source 100 mA (40 mA MAX). You would typically use a transistor to switch the high current. Perhaps you could tie three output pins together and draw 33.3 mA from each.
5v - 1.2v = 3.8v
3.8v / 0.0333 A = 114+ Ohms (Use 120 ohms)So:
Arduino pin2---- 120 Ohm ---
Arduino pin3---- 120 Ohm --- |
Arduino pin4---- 120 Ohm ----+--- (+) IR LED (-) ----- GND on Arduino..Turn all three on and you should get close to 100 mA through the LED.
Thanks all
Yes, exactly!! I'm using 276-143 from radio shack, 1.28v 100mA
I will follow your information.
Please let me know if you have any other option 