Control LED strip with microcontroller using n-channel MOSFETs

Question

I am struggling to set up the wiring for controlling a LED Strip using MOSFETs.

I have seen a lot of different tutorials. According to this tutorial for example, source and gate are connected with a 10 kΩ resistor, which was working only partially for me. It seemed to create an inversed logic with a simple LED (+ resistor to diminish the 12 V current). When I then used the LED-strip (without resistor) it turned on and off but wasn't bright enough.

This one didn't use any resistors. I even tried reproducing it with an additional 10 kΩ resistor from gate to ground.

^{simulate this circuit – Schematic created using CircuitLab}

Provided the ESP32 GPIO is turned on, everything seems right. The problem is that turning off the GPIO, or even unplugging it, doesn't change anything; the red LED stays turned on.

Answer 1

You are correct the logic will be reversed. That is simple to correct in software. I see some potential problems. You do not have enough voltage to drive that obsolete MOSFET fully on. You need to control the MOSFET when you are in reset mode and do not have control of the GPIO. To solve this problem place a resistor from the GPIO pin to ground, 10K would work. This can be a bit tricky as some of the GPIO pins need to be floating so you need to check the data sheet for the part you are using. You will need to either add a driver to use the existing MOSFET or pick one that will be on at less than 3V worse case. I generally define On and Off as High and Low but that depends on what I am driving. For inverted define on as low and off as high. You can use whatever you like.