Connecting RGB Leds in parallel to Arduino

I have ten of these https://www.sparkpcb.com/components/embedded/led-lighting/5mm-4-pin-rgb-led.html

I need to connect them in parallel. I need to connect - to GND , Red - Pin 13, Blue - Pin 12, Green - Pin 11. Is there any easy tricks to do it ?

And I forgot a thing, I need to use it 24X7X365. I mean all time on. So I like to avoid resistors. And also the circuit should not get (very) hot. Thanks in advance.

You cannot drive them parallel directly.
U'll need resistors (many) or combo resistor/transistor or LED.driver ICs

The Arduino outputs can only source or sink 40 mA Absolute Maximum (that means any more and you are likely to cause the chip to fail). If you want to drive 10 LEDS in parallel directly from a single pin you will have to limit the current to about 3 mA per LED. That will be very dim because LEDs typically run on 10 to 20 mA. And it will require resistors.

If the LEDs are on all the time, why use an Arduino?!?

johnwasser:
If the LEDs are on all the time, why use an Arduino?!?

To control the color and wavelength of LEDs and other things...

You can't control the wavelength of an LED... They are fixed. You can mix the colors of the RGB to get the color you want.

But no, you cannot just put them in parallel. Use a resistor per color per led. So 30 resistors (calculate them per color).

And indeed, a Arduino pin can only source 40mA. So use a transistor or MOSFET (PNP or p-channel because of the common cathode) per color. Google it to see how to connect it :slight_smile:

septillion:
You can't control the wavelength of an LED... They are fixed. You can mix the colors of the RGB to get the color you want.

If the color change wavelength also changes, Isn't it ? Or am I wrong ?

Check this Wavelength to Colour Relationship | Academo.org - Free, interactive, education.

The wavelength does not change. But a mix of different wavelengths appear to our eyes as color which is between the wavelengths of the individual colors. But it you would put it though a prism you will just see three bands of color (red, green and blue).