Do anyone here know where i can find cheap rgb leds and how to control them with the minimum outputs of my arduino?
do i need shift registers ?
Can you explain further what you said about SIPO because im not very familiar electronics yet?
I talked about shift registers because outputs of arduino is an issue for me and that why in the project i want to do
i will use many many leds but i want to control as many as separate .
And i want to use high power rgb leds.
If you are unfamiliar with electronics, then perhaps you should start more simply. Blinking a single LED is the classic place to start.
There's plenty of information out on the Internet on shift registers, SIPO, etc. I only mentioned them because you stated you thought you might need shift registers. I've never had an occation to use shift registers with LEDs, but it is certainly possible.
There are a few posts on this site, and many on the Internet, about building LED cubes, which might provide you with some guidance. I don't think they are using shift registers.
It all comes down to what you are trying to do. What exactly is it that you are trying to accomplish? I am not going to provide you with an overview of how shift registers work. If you think you need them for your project, do some reseach and then come back with specific questions.
Correction: It looks like the LED cubes do use shift registers, along with a concept called persistence of vision to provide control over each LED.
You might adapt this approach to your Christmas decoration idea. There are step-by-step instructions on building an LED cube on the Internet. Try Instructables.com.
Well i have passed this level ,i mean i know how to light a led with my arduino,but i dont know how to control many of them .
I want to make something for christmas.Im actually thinking of making a wooden christmas tree with many rgb leds that i will control with arduino and get them working in different patterns with a pot or something.(and hoping to control it though internet)
To make you understand what im saying here is what i want to make but for more rgb leds
Check the current ratings for the LEDs. Typical LEDs light fine at 20mA or a little less, but there are high brightness ones that need more current. Make sure you use appropriate current limiting resistor. OddBot has a great post about how to make your LEDs glow not blow, which you may want to read if you are not familiar with using LEDs.
If you only need 20mA per LED (for each color in each LED), then you should be able to control each LED color with one Arduino output. If you need/want to control more than one LED with one Arduino output, but you don't need individual control, you can do something like Kelpy did here.
Using shift registers is something you might want to do if you want to reduce you output pin usage on the Arduino, but it will require more external hardware. You could use a Serial In-Parallel Out (SIPO) shift register arrangement to feed in a serial signal from the Arduino that will result in an interesting combination to light your LEDs on the parallel output.
The cheapest LEDs are on ebay :)