There’s home made kit and then there’s HOME MADE KIT.  The ‘Secret Knock Detecting Lock’ is a complete slam dunk.  Built from an adrino board, pvc piping and a set of suction cups, the device attaches to the door and when it detects a preprogrammed knock (based on rhythm – it can be faster or slower) it activates its motor and physically turns the deadbolt.  A set of LED lights indicate when a knock is detected and flashes from red to green when the correct secret key has been entered.  To program the little doodad you simply press a red button and then knock out the key – I suggest doing this on a bathroom door away from eaves dropping ear.  Make this and I’d totally buy it.  Check the video below.

[via Techeblog]

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