• That's not going to work! If the gate is at 3.3V and the source is at 3.3V, then no current will flow.
    I'm not in a position to work through this issue at the moment. Obviously, the 'simple' solution is to use higher value resistors. The values I used were simply an example not taking into account of current draw. With higher value resistors you need to take into account leakage currents. Your solution of using an opto, whilst 'it works' it's not really a clean solution. The opto itself gives you no protection from spikes in the method you're using it. Note that I pulled the part bss138 off the top of my head before I saw your ascii art diagram.


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