I am controlling a simple set up, 9 leds, 3.3v and 20mA each, each connected to a 100ohm resistor and plugged into pins 3-13 (skipping a couple) and they are turning on but they are very dim. Is it because they are not receiving enough voltage?

powering multiple leds

johnwasser September 27, 2012, 4:00am 6

Perhaps this detailed LED tutorial will help you figure out what is going wrong:
http://www.ladyada.net/learn/arduino/LEDs.html

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