LED stripe flickering during operation

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1

Hey there. I’m writing because I’m desperately searching for help.

I wanted to build an led controller with my esp8266 NodeMCU. I’m using a common anode 5050 LED strip and to control the strip some IRFZ44N N-Channel MOSFETs.
I connected the gate of the Mosfet with a 100-ohm resistor in series to my digital pins of the ESP.
Between Source and Drain, I soldered some 20k-ohm pulldown resistors.
The ESP shares a common GND with the Strip and the PSU. I connected the Node to the PSU via the VIN and GND pin.

So far for my setup.

My problem now is, that the strip starts to flicker randomly during operation.
If I pull the Gate of the Mosfet to GND with my ESP, I sometimes have a bit flickering and a bit of glowing on my Strip.
So far, I tried everything. I swapped the resistors with some with different values, I’ve added a LC and an RC filter to smooth out the current in front of my Node, added capacitors but everything without success.
I don’t know what to do anymore. I hope maybe some of you have an Idea which I can try.

2

The IRFZ44N has a gate trigger voltage threshold of between 2v and 4v, so even if you drive it directly (without the resistors) from an ESP8266 pin, you could find that the 3.3v provided by the ESP is insufficient to turn the MOSFET on.
I use IRLB8721 MOSFETs and these have a gate threshold of between 1.35v and 2.35v, so you can guarantee that the 3.3v from the ESP will trigger the gate.

You might find this tutorial useful…

but if you follow the code example then be aware that the ESP needs an analogWrite of 1023 to give full brightness rather than 255 with an Arduino.

Pete.

3

Thanks for your fast reply. I already suspected the Moesfets, but I was not quite sure, since someone in another forum recommended it to me. I will order a few of the IRLB8721 and will test them out if they arrive, which should be tomorrow.
Also, thanks for the hint with the analog write 1023, I looked up my code and already had that but I think this is an easy to miss step.

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Update: I tried your suggested MOSFETs. Sadly, I didn’t get the hoped success. I then tried the IRF 520 MOSFET, and they tend to work. I don’t know why, but they work.

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