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.
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