Hello,
I have an 5050SMD non-addressable LED strip connected to Arduino Uno, I've built the driving circuit for red, green, and blue channels. I'm using the Arduino PWM ports to command the gates of my MOSFETS. My problem is that when I set the light to white (all channels activated) and bring the brightness down say 55,55,55 the strip seems to be slightly fading in and out. It doesn't completely go off and on, it just fads in and out very very slightly and it only does that when I switch it to white color at low brightness.
LED PS is 12V @ 2A, Arduino PS is 12V @ 1A, my LED is drawing approximately 1.2 A.
Does anyone encountered such weird thing, and if so what are the possible causes?
@UKHeliBob took me a while to remember what I did as of the circuit is hard to get rn. @Wawa I noticed that all the colors that uses blue in the mix has this pulsing effect for some reason and only appear at low brightness. Yes @runaway_pancake the mosfets are IRF540N with 22A max current.
I test it with a completely different code for testing and the problem is still there so software is not the issue. All colors that has blue in the mix has this pulsing effect and I do remember that I had to re-solder the connections to the blue mosfet as it was not conducting before I assemble everything back into the enclosure.
Only if you drive the gate with 10volt, which you don't.
The IRF540N is a poor choice for the 5-volt logic of an Uno.
You should have used logic-level fets.
As said, the blue channel is on a different PWM frequency.
Leo..
Well thats what I had laying around and the project runs perfect but the blue pulsing effect is the only issue. @Wawa so I should change them to pins 9, 10, and 11 and test it out. I will post any update regarding the issue.
Wawa has a point - your mosfets are not fully on, and likely change voltage drop depending upon the current draw, leading to varying intensity. Not just a curiosity, a valid source of effects like you are questioning.
