Use logic gates (OR XOR NAND AND etc) to produce a diagram, that, once you trigger it, stays on.
So using a combination of gates it looks like.
I wish I hadn't thrown out all my BTEC Electrical/Electronics Eng. notes because I used to do this sort of stuff a lot. I wish I could remember all the stuff I learned![]()
The examiners on my A Level Technology exams loved this sort of stuff as well. I could always remember the latching circuit but never the memory ciruit....