# How many LED's can an arduino handle ??

I was making a led light display and I was wondering how many leds can 1 output port on the arduino handle if the leds are all around (2-2.5 volts each and 10-12 mA). also how many can the whole board handle of the (2-2.5 volts each and 10-12 mA) leds

Well you can usually properly power and control ONE LED wired to an output pin if you use the correct size series current limiting resistor. An Arduino however can control an almost unlimited number of LEDs is probably using various external components and power supplies.

Lefty

so if i have about 50 leds on at once with about 12v power and a speaker it wont burn out the arduino would it ??

Could you sketch out what you're on about?

HarjitNatt:
so if i have about 50 leds on at once with about 12v power and a speaker it wont burn out the arduino would it ??

Yes, it will.

Power directly sourced from an arduino is limited to 200mA. There are also limits on how much current you can get from each port or collection of eight bits. See section 28 of the data sheet for exact figures.

With external driver chips the power for the LED comes from those driver chips and the arduino just controls them with a very little current.

Thanx I also just tested it and it works I had about 25 leds on one port worked fine just a little dim thanks everyone

Very nice. Your arduino is probably gonna do this for about 1 minute.

it was running for some time and nothing happen the board runs fine I was scared but it didnt heat up at all (I kept checking the arduino). But can it happen cause Im doing a project for school and I have to decorate a roller coaster. I have a mario theme song playing and im trying to have the leds to blink with the beat.

so how many leds can I actually have running at once without burning the board

Someone said earlier 200mA is the max. A regular LED draws about 20mA .. 200 divided by 20 gives 10 LEDs.

I summarize it a bit here:

http://www.gammon.com.au/uno

200 mA for the entire board, plus a max of 100 mA for certain groups (eg. pins D5 to D13). So since that is 9 pins to draw a max of 100 from them would be 100/9 (11 mA) each.

For the cost of a \$2 or so transistor you can offload the load to that, and save your board from some mysterious failure later on.

Thanx makes more sense just learning