resistors on my 5mm & 3mm led lights

I am using an Arduino UNO in conjunction with Vmix to make my own tally light system for my church video ministry.

I have uploaded the firmata standard firm ware on the Arduino and opened the vMix software. I have the 5mm leds on the breadboard and everything works on the breadboard nicely just like it should when I switch camera's the different lights come on, just like I need them to.

You might be wondering what my question is at this point! Here is my question, everything I read about using the 5 & 3 mm led lights says I should use a resister with them to keep the LED's from frying. However every time I put the resister between the signal and the led nothing works. I have tried the resister on the short pin after the led as well but still nothing.

I don't want to be soldering new leds on my tally lights so do I need the resisters or Not? The resistors I have are blue with 5 bands, (brown,red,black,purple,yellow) Sorry I tried to find my order to see what the resisters were rated at but couldn't find it.

Thanks in Advance

Seems like a 47k resistor.
That won't light up a LED.

Yes, you HAVE to use a current limiting resistor with LEDs. Otherwise you could fry things.
Try a 220ohm resistor.

thank you so much. I will put an order in for those today.

Without a resistor you are operating both the LED and Arduino beyond their design limits and you could fry the LED or the Arduino, or both. Or, you might have an occasional crash or reset, or you might just shorten the life of the Arduino and/or LED.

It's a little like revving the engine in your car over the redline, or like driving it around everywhere in 1st gear with your foot to the floor. The engine might quit after a couple of minutes or it might survive for a few weeks.

....with 5 bands, (brown,red,black,purple,yellow) Sorry I tried to find my order to see what the resisters were rated at but couldn't find it.

[u]Wikipedia - Resistor Color Code[/u]. :wink:

In ancient times (before surface mount) almost all resistors used the color code and it was one of things you'd learn in a beginning electronics class.

On surface mount resistors you'll usually see a code like "103". That means 10 followed by 3 zeros (10K). And if you read it upside down it says "EOI". So, don't read 'em upside down! :smiley:

If you have a link to the LEDs you're using, we might be able to find a datasheet for it and figure out the optimal resistor value. Different colors of LEDs will require different resistor values to drive the LEDs at a specific current.

It would be good to know the current limit of the LED and it would be good to know if you want the LEDs to be at their maximum brightness.

220 ohm resistors will probably work fine but they might not be the optimal value. With a datasheet and information about how bright you want them to be, we could help figure out the optimal resistor value.