I would like to make a switch which will be able to switch on/off 12-60V low current devices using nRF52840, optocoupler and mosfet. I found this schematic and my idea was just to adjust R1 because voltage of GPIO of nRF52840 is 3.3v. I realized that source current of GPIO might not be enough to run optocoupler so I decided to look for low input current optocoupler. I found VO618A and my questions is would it be fine if I just switch PS2801 with VO618A and adjust R1? (I don’t have many experience with electrical engineering experience so any guidance/help is welcomed)
There's a couple of problems with your circuit - the mosfet won't like much over 20V on it's gate and your circuit doesn't limit it. The 100nF cap is of little use across the led of the opto - why did you place it there?
The opto coupler is really a waste of time - it adds very little. You'd be better off to chose a mosfet that has a logic level gate.