Build Your Own Musical Lockbox [Instructables How-To]

Locks are a symbol of trust. Not necessarily the low level of trust you feel in your fellow man when it comes to swiping your stuff, but a far more fundamental trust—the trust you feel in yourself. Your locked door means you trust yourself to have your keys on you, to hang on to them throughout the day, and be able to locate them quickly when you get to your door and play that game where you think, “Oh my god, if someone was chasing me how fast would I be able to get into my house.”

The bottom line is, you trust yourself too much. Sure, you’re a responsible person who manages to keep yourself alive from day to day, but do you really believe you can accomplish all of the above without ever screwing it up? If you’re reading this on your phone while sitting on your front steps waiting for your housemate to get home, you will find this little invention very useful.

A music lock is a mechanism that opens up when it hears the right tune. That’s right, you should trust yourself more to remember the melody from that awful Dave Matthews Band song than you would to remember your keys. This how-to from Instructables user basil.shikin takes you through the construction and programming of a music lock so that you can come home and “Da da deeeeeee, dee dee dee doo doooooo” your way in. Let’s get started.

For this project, you’ll need a few items. For an exhaustive list with detailed explanations of each, check out Instructables. For the briefer, easier to digest version, read on. You’ll need an electret microphone, a servo, a switch, a regulator, and a battery charger. Interestingly, all those items are also the names of Warren G songs. Go ahead, look it up… Ohhh snap, you looked it up didn’t you!? You were like, no way, and then you saw “Regulator” and thought, hmm maybe, I’ll look that up. Sorry, couldn’t help myself.

Let’s get to it.

The microphone detects pitch through frequency, meaning that it can differentiate between notes because each one oscillates at a unique rate. Using a Fourier transform and a couple of handy algorithms, you can set the microphone up to react only to certain notes. However, sing to it off-key, and it won’t react at all, much as human beings don’t every time it’s your turn at karaoke.

As far as the circuitry, you’re basically going for a “this bone connected to the… that bone” chain of bon—I mean, electrical components. As you can see in the graphic below, this one goes hip, thigh, knee, shin, foot, thigh again, neck, head, knee, head, knee.

Now it’s time to make the box. If you’d like the box to fit your components exactly, there are several companies that do custom jobs. But if you really want to save money, go out and get yourself a well-built small pet coffin. Parrot is sufficient, but you can go bunny if you really feel like you’ll need the extra room.

Now it’s time to do some programming, which we usually equate to yelling at the circuitry, having the IT guy do it, or yelling at the IT guy while he’s tinkering with the circuitry. We tried yelling at the circuitry while the IT guy was tinkering with it one time but it got weird fast and everyone in the room felt a sort of sympathy for the pile of wires that now seems wildly unnatural.

So now you’ve got a musically locked wooden box. Close that bad boy up, let’s see if we can get it to open. Go ahead, play that song. The song you use as your key to this thing. What do you mean, “how does it go,” it’s your lock. Didn’t you just set this up? How do you not remember what song it is? That was literally five minutes ago. OK, well, what was in the box? Your keys? Good grief.

[via Instructables]

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