We all know the problem. Your fly is open. Your zipper is undone. Always a winner at social occasions. Oh, isn't it a hoot when one of your friends says: "Paging Mr. Johnson... Paging Mr. Johnson..." our "You've got a security breach at Los Pantaloons"

I fixed this problem once and for all with the zipper alarm.

This is a double firsty! It is my first Arduino project and my first time using electronics in clothing.

Step 1: Parts

Arduino Uno,
pants with a metal zipper,
conductive sewing yarn,
normal sewing yarn,
some extra jeans fabric,
press buttons,
on/off tumble switch,
disconnecting push switch,
piezo speaker,
electric wire,
9 volt battery,
battery clip,
small nuts and bolts,
washers,
rivets,
velcro.

Tools:

soldering iron,
hot glue gun.

Step 2: Step 1: Programming and Circuit

Okay, to be honest: I only needed the Arduino to make the noise (the program is very simple). You can use another kind of circuit to do that trick but the Arduino was the easiest way out. I had a nice little metal case that fitted the Arduino perfectly.

The "circuit" is just a series of "switches", as you can see in the beautiful piece of art I named "Switches".

The fist "switch" is the zipper. When the zipper is open, the "switch area" is closed and the alarm goes off. You know there is a problem with your fly and you can avoid social humiliation.
The second "switch" is a the upper button of the pants. The first switch would set off the alarm every time you take of your pants. This might cause other embarrassing moments. With this extra switch the alarm is deactivated when you open the upper button.
The third "switch" is located on top of the casing (little red button) and is used in public toilets. When you open the zipper the alarm sets off, making the whole situation annoying. The second button doesn't solve this problem because this causes your pants to sag, exposing too much of yourself. That's why you push the third button with your free hand deactivating the alarm.

Step 3: Step 2: Sewing

The difficult part is connecting the hardware to the clothing. Because the clothing moves al lot, I made connections between the Arduino casing and the pants with little press buttons. The lager press button and the velcro is there to prevent the press buttons from disconnecting.

I've highlighted a few things in the pictures.

The upper button switch. There is conductive wire in the button hole and the button is also touching conductive wire. When the button is closed, the alarm is activated.
The zipper switch. When de zipper is open, the metal of the zipper connects two contact points on both sides of the zipper. This closes the circuit and sets off the alarm.

Step 4: Attaching the Alarm to the Pants

I made some straps that are connected to the Arduino casing with rivets and velcro. This way the arduino is accessible for changing the battery our the tone of your alarm. The alarm is attached to the pants with the press buttons and a belt through the straps.

There you have it! The Zipper Alarm. I hope you've enjoyed this instructable and if I've saved you from social humiliation: no need the thank me, just... send me a Christmas Card.

In the end part of the video you can see the alarm in action.