I have designed and developed this Ringbell for our shared office in Berlin-Kreuzberg. Using Arduino and servo motors to make these big bells found on a fleahmarket ring when somebody comes to visit us.
Since there are 2 Rooms on our offices, i developed 2 modules that can be activated by 2 different buttons. The mechanism is quite simple, pressing the button makes the arduino tell the corresponding motor to pull from a small thread that makes the ring bell, it can be considered as a Digital-to-Analog artifact and the result is really natural. Way better than a cheap Buzzer!