Project Title: Secret Knock Detecting Door Lock

Project Creator: Grathio

Short Description: Much like the title suggests, this Arduino based project will recognize a specific knock based on the rhythm that you knock on the door. If the knock pattern is correct, it will unlock the deadbolt. The secret knock can also be easily changed by holding a button while knocking in a new way that includes up to 20 knocks.

Response: I think this is a really creative idea that I’d love to use at home. It’s a throwback to when my family and I would sometimes make up secret handshakes and signals in order to get past somewhere. While the creator warned that you should also carry the key, I think this would be perfect for the cases where a key is forgotten. So that it’d be exponentially more secure, it could only be used when a key is forgotten, but that wouldn’t be nearly as fun.

One change that could increase the practicality of this is having the reprogram button be from your phone too. This way if you locked yourself out of the house and didn’t remember the secret knock you could simply make a new one. This change could mean you can simply unlock it with your phone, but I think that those who love the idea and take the time to make this would actually use the secret knock.

Source: https://www.instructables.com/id/Secret-Knock-Detecting-Door-Lock/