So - i started a project at my civil-service. I want to fill a old snack-machine with things we need in the ambulance (bandages, cool-packs, etc.)
In order to get the current amount of everything without counting everything all these things should be stored in the snack-machine. The Arduino should be attached to the signal wires of the machine. If a signal is firing (when a button is pressed) the microcontroller should decrease the current amount of the item in the connected database.. so it is easy to see if some product is running low.
The machine itself works with AC. now the problem: I'm not that professional with microcontrollers/hardware and this is my first big project.
If the Arduino is connected between the motherboard of the machine and the buttons the Arduino won't interrupt when something is pressed. I attached a picture of the circuit. (The only thing what's not on the picture are resistors between arduino and the buttons). The voltage on the wires is about 7.5-8 Volts alternative current.