A knock to unlock puzzle box is a locked box that is opened by knocking on it with a particular sequence of knocks, for example “knock-pause-knock-knock-pause-knock-knock-knock” There are several versions of these boxes on the internet. For my version, I wanted to make a box that has nothing mounted on the outside – no lights, no switches, no wires going through the box, and no outside latch. I have photos of it, a parts list, a wiring list of the connections of the various parts, and Arduino code on my WordPress site. Here’s a link to my write-up of it: Knock to unlock box
That’s a really nice simple writeup and a cool project. Thanks for sharing it here.