I'm new in the topic of microcontrollers etc.. I only have plenty experience in programming.
I want to build this: http://www.instructables.com/id/30-channel-LED-RGB-Ambilight-Clone/?ALLSTEPS
Today I've connected a little piece of the RGB LED strip with an external power supply and the Arduino. I did it like in the image at step 2 in the link: +12 V Power Supply --> +12 V LED Strip GND Power Supply --> GND Arduino
To control the LEDs I've connected the 3 colours from the strip to PINs 9 (red), 10 (green) and 11 (blue).
My main problem at the moment is that all LEDs are shimmering even if I set the PINs to HIGH/255. Green and red are much more brighter than blue and therefore if the strip should be off there is a greenish yellow.
I have the same problem if I want only one of the base colours, it's not possible because the other two LEDs are shimmering and that's for mixed colours also a problem.
How can I fix this? I tried to use different resistors but the only difference is the overall brightness of the LEDs.