This is more secondary circuit related than directly to the Arduino itself.
Anyway, I have an controller that outputs an unknown PMW and I have to interface it with a Fan that can take as much as 30A (peak).
After taking some measurements, the PWM logic seems to be inverted. Measuring directly (no filter!) with a digital voltmeter from its output, it delivers 3.8V with the knob set on minimun and 0.8V when on maximum.
I was thinking in a low pass filter, connected to a opamp voltage-follower, maybe an inverting amplifier and then a MOSFET, but I don't have enough knowledge to do so.
By the way, it's all going to be operated from a 12V battery.
All help is greatly appreciated.
Thanks in advance!