i modified my door bell with a NodeMCU which is now capable of triggering the door opener using a relay. Now I want to add a door bell detection to this system. I figured out two contacts which supply a DC of ~5V for a second while the bell rings. How can I connect this to the NodeMCU since it has only 3.3v GPIOs as far as I know. Do I need a resistor and if so - how much ohm? Or a step down converter? And what's about the amperage?
Sorry I'm really new to electrical engineering and might need some noob explanations :)