I’ve created a thread in the Arduino forum but I thought I’d post here as well.
I have a wall switch that toggles an AC power socket. I want to send a trigger as a GPIO input when the wall switch is toggled on/off. I’ve used a phone charger and some resistors to bring the 5V down to 3.6V and the “on” is very responsive, but because the 5V converter has capacitors inside, the GPIO stays HIGH for a few seconds after I switch the socket “off”. I’m trying to come up with a way for "on"and “off” to be nearly instantaneous.