[HH] music operated lock

[Tom Metro]

RadioShack tweeted:
> Straight out of RPGs, here's a lock that opens only when you play the
> correct tune. What would your lock tune be? http://t.co/PiCW7ueg

That links to a YouTube video. It shows what looks like a jewelry box
with some electronics on one end of it and a visible motorized lock
mechanism. The person demonstrating it first played the correct 6-note
tune on an electronic piano, and the lock opened. Then again with a
slightly incorrect tune, and it does not.

A more interesting application of this concept would be to stick a DTMF
decoder wired to a mic and preamp, with its decoded data fed to a micro,
which then controls a lock (electromagnetic striker). The other half
would be an app to run on your cell phone, which could rapidly spew out
a long sequence of tones, making it practical to have something like a
20 or 30-digit pass code.

This would be pretty cheap and simple to build, and would work with most
phones. If you give up on the long code idea, and had fairly relaxed
timings, you could even support "feature" phones, many of which are
capable of generating DTMF tones over their speaker.

No need to carry keys, dongle (like for a car), or require special
hardware on the phone (Bluetooth or NFC). And no need to have a visible
keypad on the door, which raises the bar slightly for someone attempting
a non-brute-force break-in.

There was something similar to this in the news a few months back,
except they had some idea of playing the tones or using the phones
vibration motor to play a pattern while you held the phone, and the
detector not only looked for the tone pattern, but the unique
distortions introduced by the sound conducting through your bones. Here
it is:
http://www.forbes.com/sites/alexknapp/2012/06/05/att-will-transfer-data-through-your-bones/

The bone conduction thing seems like more trouble than it is worth, but
I like the idea of using a guitar pickup as the receiver. That way you
could embed it inside the lock, shielded from weather, and further
reduce stray pickup from ambient noise. You'd touch your phone to the
door handle, press the app's unlock button, and magically it would unlock.

 -Tom