Analog RGB stripe is flickering. Any idea why or how to fix this?

Hi,

I'm using a 12V analog RGB LED stripe that I'm controlling with an Arduino. My setup is like the one shown here: Usage | RGB LED Strips | Adafruit Learning System

There seems to be some issue with my setup as the lights seem to pulse or flicker. The more dimmed the lights are, the more noticeable are the random flickers.

It doesn't seem to be a software problem, I tried with a simple analogWrite sketch on setup that set all the LEDs to 50, and the flicker was still there. The same was happening when I was simulating the analogWrite by using digitalWrite(HIGH);delay(20);digitalWrite(LOW); in a loop. It had still the flicker.

I added the resistors to the PWMs just in case it was caused by that, but the stripe doesn't seem to be working any different with or without them.

I tried two different power supplies. The original one from the LED RGB stripe (12v 600mA), and an other one (12v 2A). But with both the stripe still has that noticeable flicker.

I'm completely out of ideas by now, and I'm not sure how to tackle this problem anymore. Could it be the Arduino? The NPN? Some kind of electrical induction on my breadboard? Or something else?

Greetings and thanks for any reply.

P.D: I've attached a picture of my setup.

Top View:

General Overview:

LED Connection:

Are all the connections on the breadboard tight?

What are you using for the MOS FET?

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