Hi everyone i just recently purchased the Arduino Duemilanove, and i know the out put is 5v from the i/o's and i was looking to hook these up to some kind of relay so i could hook up roughly 40-50 10mm leds to each channel and have them stobe in quad flashes like police car i have a 12v 7.2 amp hours source to power the leds...any help would be much appreciated.
In this case motors and LEDs are the same sort of load:-
http://www.thebox.myzen.co.uk/Workshop/Motors_1.html
Don't directly connect the relay to the pin, you need some sort of buffering.
okay looked at that tutorial and could only read bits and pieces as the pic for some reason were covering info...and also what kind of buffering? and i seen i could use a transistor?
Yes a transistor, or something like a ULN2803A which is like 8 transistors in one package.
and could only read bits and pieces
Sorry you must have an old browser.
Try this:-
http://www.kpsec.freeuk.com/trancirc.htm
you prob dont need the relay, just the transistors should be enough. just make sure the ones you get are rated for the current and voltage you want.