Knock detecting lock

posted Nov 4th 2009 8:00am by Caleb Kraft
filed under: arduino hacks, security hacks

[Steve] shows us his version of the knock detecting lock system. The idea is pretty simple, knock in a certain pattern and the door unlocks. We’ve seen it before several times. This solution is somewhat cleaner than the others, not only in physical design, but also in how you reprogram it. Simply push the reprogram button and enter your new knock. We’re a bit surprised that the suction cups actually hold it on the door. Maybe it’s just us, but we can never seem to get those things to hold very well. There are lots of great pictures as well as the source code available on his site.

[via HacknMod]

Comments [15]

tagged: arduino, knock, lock

Reader Comments

“Knock, Knock……click……..helllloooooo”

Love it.

Posted at 8:10 am on Nov 4th, 2009 by Cabe

If only I had that for my club house as a kid!

Posted at 8:24 am on Nov 4th, 2009 by ham sandwich

Thats cool… a litle insecure, but cool :)

Posted at 8:26 am on Nov 4th, 2009 by chicosoft

how do you turn the knob when you want to leave if it’s attached?

Posted at 8:42 am on Nov 4th, 2009 by robomonkey

robomonkey: It would be fun if you just pressed the program button quickly to open/lock the door, and held it down to program.

It may be one of those doors whose deadbolt unlocks when you turn the door handle from the inside.

Posted at 8:46 am on Nov 4th, 2009 by Shadyman

“We’re a bit surprised that the suction cups actually hold it on the door. Maybe it’s just us, but we can never seem to get those things to hold very well.”

Get some dishwashing soap. Clean the surface you wanna put it on and clean the cups. let it dry and don’t touch on the surface. Take your tongue (or much better: a damp sponge) and wipe over the cup. Press it down – et voila.
Most people don’t care about really cleaning the surfaces, so it doesn’t hold well. Same people that say Second adhesive never works for them… clean (and i really mean: get rid of all fat sitting on your surfaces) and glue and you will never get it apart again…

Posted at 10:22 am on Nov 4th, 2009 by Roland

And of course, the surface has to be very flat and smooth.

A light coat of mineral oil on the suction cup will also help it hold.

Posted at 12:32 pm on Nov 4th, 2009 by Matt

Nice, and nice presentation in that video.
I know the suction-cups are not going to last, but you can affix it how you want of course, this is more for portable presentation I guess so I for one look past that.

Posted at 1:15 pm on Nov 4th, 2009 by Wwhat

If I or another normal person used this the knock would be pretty simple but there are some guys I used to know for whom this could actually be secure. They loved to freestyle (rap) and would pound out beats on the desk for each other. Some of them were pretty complex. Even so, I wouldn’t use it for anything I really wanted to keep secure.

Posted at 2:23 pm on Nov 4th, 2009 by K

good post Caleb don’t let people give you schit

Posted at 2:44 pm on Nov 4th, 2009 by rooftop ridicule

Interesting device, if he uses three sensors, he could also require you to knock on a certain spot on the door.

Posted at 2:44 pm on Nov 4th, 2009 by Jack Sprat

I like…the bit about the suction cups is not important as someone already mentioned, because I finally version would be fixed.

I think that I would rather have something digital broadcasting using a key fox, but something secure and encrypted, but I’ve only started playing with the arduino so I don’t know how it would cope with encryption.

Posted at 4:19 pm on Nov 4th, 2009 by tehgringe

so anyone who hears the knock can then enter without breaking anything ? That includes neighbors, people you let in and people with a directional microphone…

It is a bit like a digicode where you would be shouting the code each time you want to enter

Posted at 2:31 am on Nov 5th, 2009 by Iv

Pretty cool. I also don’t know how those suction cups are holding that up, but I like the device.

Posted at 8:38 am on Nov 5th, 2009 by Philadelphia personal injury attorney/lawyer

Ow… very cool! This is very creative lock circuit.
Great!

Posted at 10:31 am on Nov 5th, 2009 by Tercio