It's been years since I worked day to day with electronics and I am slowly coming back to the hobby. This is a question related to an intersection of my hobbies though: arcade stick modding and electronics.
I have a stick with 4 buttons for "functions" like "Select", "Start" and etc. The problem is I forgot 2 functions, so I am short 2 buttons.
I can solve that with a "shift" like function. So 1 button will be 'shift', 3 buttons with functions + 3 shift+button = 6 buttons.
Arcade stick PCBs w/ common ground simply close the ground with a pin on the PCB to register the button activation, so if I can simulate a NC/NO relay using smaller pieces I can make it work (the shift button will just close contacts to a different pin). The thing is, I don't want to use 4 huge relays to do that. I think that means that I have to pull low on the PCB pins, I measured and have 3.3v between GND and the PCB pin, so I actually have to find a way to generate 'low pulls' from something.
I have a 5v VCC line that I can use to probably flip some transistors around, but I can't figure out if/how I can make it work with GND being the 'signal' to pass.
This would be what I would do using a relay (of course that's for a single set of buttons, not all of them, I would need 3 relays for that and I am trying to design something quick and simple).
So I bow to youse people that are way smarter and savvier on electronics to help me with that.