- Feb 25, 2020
Resistance increases with load, if I remember well. That's why for higher loads you'll see more than one MOSFET on the circuit, in parallel I suppose.I am trying to PWM dim about 8A of light strips running off 24vdc nominal so about 29vdc max. I figured design it for 10A for some buffer. I think part of my problem is I was trying to just upgrade the MOSFET on a burned dimmer I have running off a 555 timer. I was able to read the full 28vdc on the gate which seams problematic and I don't know the switching frequency or gate charge capacity and was reading a significantly higher ohm resistance across the MOSFET when on.
I found a nice paper with the formulas to calculate dissipated heat VS Rds (on), a good reason to choose MOSFETs with a low resistance; IRFZ44N has a lower resistance of IRF540 (I have these two models on my desk)
What about ESP8266 (for e.g. Node MCU V3 or Wemos D1), costs less and has less pins. I also bought some ESP12, even smaller and less available pins, but needs some wiring (and resistors) to be programmed.Now after some more learning about MOSFETS I am thinking it is time to build my own circuit to run of an ESP32 so I can add remote control. Of course that becomes a big project and I need to decide what I want to use all the extra pins on the ESP32 for