Knock response automatic door opener

posted Jun 11th 2007 2:22pm by Will O'Brien
filed under: misc hacks

I’m at the beach this week – finally on vacation. Thanks to DD-WRT, I’ve got a handy wireless repeater to keep the beach house covered with network access. [sprite_tm]’s doing his best to make my vacation easier. He built this knock activated automatic door opener for a friend who wanted easy access to some locked, but empty flat (think british apartment) rooms. He used an ATTINY with some fets to drive the stepper (you can find those in old dot matrix printers for free) and a small transistor amped mic circuit to pick up the knocks. Knock the right code, and you’ll get let right in.

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Comments [16]

Reader Comments

I remember seeing a similar commercial product. Everything was mounted within a door so it could not be tampered with. the “knock code” was so long and precise it used a small battery powered key to do the knocking.

Posted at 3:44 pm on Jun 11th, 2007 by pretorious

this seems like a good candidate for using one of those piezo sensors glued to the door.

Posted at 5:02 pm on Jun 11th, 2007 by ex-parrot

This would be awesome fun to hack, if some how indicates a mistake you could keep trying, well it would be very hard but none the less fun.

Posted at 5:14 pm on Jun 11th, 2007 by wolfmankurd

Port Knocking comes full circle!

Posted at 6:21 pm on Jun 11th, 2007 by EdZ

I’m waiting for someone to make one that uses a webcam to detect shadow puppets through the peep hole as a access control method :P

Posted at 6:40 pm on Jun 11th, 2007 by _Vyper

Damn….. I just stumbled over this and thought Id submit it but it looks like I was beaten to it! oh well… it was a cool idea.

Posted at 6:53 pm on Jun 11th, 2007 by thip

I’m working on (Read: About to start, anytime now :P) a similar setup, but it takes a picture with a webcam through the peephole of whoever knocked. An answering machine, but for your door.

Posted at 7:03 pm on Jun 11th, 2007 by WaffleMatt

Cool design might leeve you a bit open to break ins tho

Posted at 5:22 am on Jun 12th, 2007 by Martin

Well, it looks unsafe, but it’s like the apartment entrydoor opener connected to your doorbell, if you won’t know it’s there, no one will brute-force knock you!
and because it’s a empty building, your neighbors won’t get tired from your knock-sequence, so they won’t give it a try someday..
nice hack!

Posted at 7:00 am on Jun 12th, 2007 by matthijs

very nice. maybe piezzo would be a bit more appropriate for mounting/gluing onto a dor.

Posted at 9:39 am on Jun 12th, 2007 by muris

I’d like to try this with a capacitance switch on a doorknob. Or weirder yet, a musical lock with a door embedded theramin.

Posted at 2:01 pm on Jun 15th, 2007 by Forrest

Another interesting idea for this would be using a few hall-effect detectors set in several spots on the inside of the door. To open the door you just put a small neodym magnet close to where you know the detectors are, then the door pops open.

Posted at 2:29 pm on Jun 15th, 2007 by Jack

Would be nice to have one where you’d have to sing a song every time you want to get the door open.
(imagine a scene where you’d have to go to the toilet)

Posted at 11:45 am on Jun 25th, 2007 by zotkop

hi
asl plz please give me idea of haking a webside now plz ok

Posted at 12:31 pm on Sep 1st, 2007 by jamshaid iqbal

http://www.hackaday.com/category/cellphones-hacks/

Posted at 8:26 am on Sep 6th, 2007 by sk

Sounds fun but I’d prefer using a key any day.

Posted at 11:33 pm on Oct 28th, 2009 by Emtek