As seen here, Ty Palowski had a very first world problem. If someone comes to the door to present him with food from Uber Eats or treasures he’s ordered from Amazon he has to take off his headphones in anticipation in order to hear them knocking. While that seems like a small sacrifice, if you’re paying for the service, one can understand how that would get annoying.
Rather than accept this situation, Palowski of course turned to electronics, including a trio of Arduino Nanos. The idea here is that when someone arrives at his door, they push a button on a keypad outside. The rig then transmits a signal using a 433 MHz RF module to a receiver and Arduino situated at his desk. From there, the desk-Arduino turns on a motor using a relay, which spins and taps on his desk over and over with a weight, with an angle bracket and hose clamp providing a bit of spring force to allow it to move after contact.
The setup reportedly works quite well, and this type of device could perhaps even be helpful for those with limited or nonexistent hearing abilities. The other trick here is that since he lives with a roommate, a second button on the keypad signals an Arduino for his room, which he can mount as he chooses. There’s also a third and fourth button which as yet to be used. Palowski is open to suggestions, so feel free to chime in via the video below’s comments.