Door key of B flat major
Another irresistible hack: here’s a deadbolt that opens if you knock the correct pre-programmed tune onto the door. Speed doesn’t matter, so if you set up, say, the Pachebel Canon, the bolt will respond to either the proper stately tempo or something a bit speeded up. Could be a great home entry strategy for people with fine motor dexterity disabilities.
Engadget: ‘Secret Knock’ Door Lock defends home from rhythmically-impaired perps (video)