A Lock That Detects Secret Door Knocks

Never be locked out again.

A microphone (okay, really a speaker) presses against the door and listens for knocks. If it hears the right number of knocks in the right cadence it triggers the motor to turn the deadbolt and unlock the door. If the sequence isn't recognized, the system resets and listens for knocks again.

Click the image to read about how you can make one.



Thanks To Keith at BagOfNothing