# Arduino UNO low output current on all pins?

Brand new user. I really love the unit so far and have had no problem with most of the projects I have tried. I just set up the IR library and could easily read my codes. When I tried to send them I can get no output from a Radio Shack IR led using any resistance more than 10k. I have tried a few leds and get the same result. The output is relatively dim looking in my camera as well but it does trigger my device from about 7 feet and less. I get the same result trying to drive it from the +5 using USB power or a 12v wall wart. Anything I am missing here? Thanks.

Measure the voltage before the resistor direct from the pin. It should never go below 4v.

resistance more than 10k.

10k is too hign. Usually leds take 20 mA, may be more in impulse mode, so base on Ohm law resistor should be: 5 V (power or digital pin) - 2 V (cross diode) / 20 mA = 150 Ohm.

Magician:

resistance more than 10k.

10k is too hign. Usually leds take 20 mA, may be more in impulse mode, so base on Ohm law resistor should be: 5 V (power or digital pin) - 2 V (cross diode) / 20 mA = 150 Ohm.

Usually LEDS run good at about half that (10ma) but yes 10K is too high. Try 1k.

Magician:

resistance more than 10k.

10k is too hign. Usually leds take 20 mA, may be more in impulse mode, so base on Ohm law resistor should be: 5 V (power or digital pin) - 2 V (cross diode) / 20 mA = 150 Ohm.

LMRAO, I just realized that I was using 220"k"Ohm resistors I thought were 220 Ohm resistors. At least my math was correct on what I needed in there, even if my implementation was just a bit off.....! On the plus side I got around 50 feet using the 10 Ohm. Glad I only had time to pulse it twice very quickly,

Thanks for the quick replies.

On the plus side I got around 50 feet using the 10 Ohm.

You can drive it with a transistor all day at that if you want.