pat@AdamAtSea @Sophistifunk yeah, those I have definitely use opto-couplers for galvanic insulation and they seem to have some sort of transistors too. But I can't find a datasheet that would be of much use. They'll tell ya they want 3 to 6 V logic, but that's about it. Nothing about the current. And yeah, I do need at least 4 GPIOs extra.
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