Something Really Cool About Piezo Buzzers - Knock Controlled Door Unlocker

[Mr. Hasselhoff]

I'm sure you've all heard of piezo buzzers, the incredibly loud buzzers. When you apply a potential difference across a piezo buzzer, it will create a sound. But how? Piezo buzzers work by creating vibration, and makes them extra useful, because you can apply a vibration on them measure the pottential difference created across them.


One really cool application for this, is using piezo buzzers on doors in conjunction with motors, to create a special door opener. You can use the piezo buzzer to detect a special "knock" on the door (really the vibrations), and then using an arduino (or other micocontroller) to process the knock (once again, the vibratinos), you can open the door if a special knock has been created.

I'm going to see if I can create one of these devices in the next couple of weeks.

Edit: I've added a video and image of the basic setup without the H-bridge or the motor/servo. I recommend opening up the video in a full window.

http://hoff.zomgstuff.net//Projects/Arduino/doorKnockOpener/images/alpha.prototype.no.moter.lowres.jpg

http://www.youtube.com/watch?v=T8eAcbISkXQ

[Jason]

That's pretty cool... But if anyone hears your knock they can get in :/

[mdc4115]

you mean something like this, http://hacknmod.com/hack/secret-knock-detecting-arduino-door-lock/

[Jeroen030]

yeah, I saw that video of hacknmod, would be cool if you could make it David

[Mr. Hasselhoff]

you mean something like this, http://hacknmod.com/hack/secret-knock-detecting-arduino-door-lock/
Oh shit, I'm gonna do that! Hopefully I'll have it done by the end of thanksgiving. Maybe I'll even create kits for it.

[Mr. Hasselhoff]

Alright, here's a video of the basic prototype. I recommend opening up the video in a full window.

http://www.youtube.com/watch?v=T8eAcbISkXQ

[Mr. Hasselhoff]

Updated version.
http://www.youtube.com/watch?v=-l_DSUeFxeY

[Scruff McGruff]

if you get this to a fool proof version you should deff make kits and sell em
id buy one
hah

[Jack]

how's the vibratinos going? i heard one of them got into the mafia? sad, sad day.