Sprite Mods sent in a fantastic Knock to Open Door hack that they have just come up with. It is a door that will unlock when the correct knock pattern is performed. Funny thing is I had a similar idea a few years ago except my idea was to use the door bell as an input device and use bi-color LEDs mounted inside the door bell as indicators to allow the user to enter in a code.
Video after the jump.
“After some brainstorming, we came up with a James Bond-worthy concept: knock on the door in a certain fashion, and the door’ll open automatically. The idea was perfect: no need to drill holes, sneaky enough so the landlord wouldn’t accidentally trigger it, easy enough to remember.
The complete device gets its power from a laptop PSU. The power-supply is riddled with capacitors: we’re switching coils here, so there will be lots of EMF introduced on the power-supply-lines and we don’t want that messing with our CPU. In the middle, the brains of the thing: an ATTiny2313. The ATTiny drives four BUZ11 MOSFETs, who in turn switch the bipolar stepper motor which turns the knob. While not drawn, the BUZ11s have integrated ESD-protection diodes to protect form EMF backlash by the motors coils.
To convince the device to turn its motor, two ways are provided: first of all, a set of buttons for testing purposes. Secondly, there’s the analogue stuff right from the microcontroller, which basically is an elektret microphone plus a really crude and hacked pre-amp. It took some fiddling to get the resistor values right, but when I drew the schematic of what I had built, that turned out to be no surprise: as you can see in the schematic, T2 is upside-down, with its collector and emitter switched. ”
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I might add this to my list of locks to get through for a big safe…..
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cool i likey, just hope nobody whos watching has a tape recorder………
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If i ever own a bank, this will be the first door to the vault
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what will be the second??
not bad!!
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Great hack
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Great hack, and I’m all for DIY, but in case you don’t have the skillz or need it NOW, there’s this.
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Whoops, no HTML? Here’s the link:
http://www.nokey.com/knocknoctoac.html
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Hi Ed T,
Great find, who would ever think there would be knock to open system available for purchase! It seems to be harder and harder to create anything that is unique anymore…
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Alan,
Well, as Barbara Grizzuti Harrison once said, “There are no original ideas, only original people”. 🙂 Besides, as an engineer the challenge is always not to invent a brand new thing, but to execute an existing idea in as an efficient manner as possible or to retask an existing idea for a new purpose.
BTW, love the blog – one of the few that stay in my RSS stream.
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I hope it can handle more complicated knocks than that. Similar to passwords; longer is better.
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well said Ed. T
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This is really cool… A secret knock