I have designed, developed and built this little ringbell system for our shared office in Berlin-Kreuzberg. Using Arduino and servo motors to make these brass bells found on a fleahmarket  ring when somebody comes to visit us.

Since there are 2 Rooms on our office, i developed 2 modules that can be activated by 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!