Introduction: Theft Prevention Device for Less Than 10$

By Bilal Ghalib
About: Bilal Ghalib is interested in doing things that surprise him and inspire others. Let's create a future we want to live in together.
Some bum just stole my bike seat. This instructable is the first in a series where I'll try to add electroprotection to my stuff.

Theft is a huge problem and a major irritant. Insurance is a good option when you purchase something you really value but revenge is much much sweeter than a new Ipod. So let's try to create a anti theft device which will electroshock the attempted crook, you know, give him a bit of a jolt. If someone tries to nab a few things that gave him some lightning, maybe it'll make them think twice before grabbing valuables off a park bench.

Basic idea for this iteration:
1) Take the guts from a electroshock pen and amplify the input voltage
2) Replace the Activator Switch with a tilt activated switch, this is brought to you by: Instructables User frank26080115
Frank's Tilt Activated Switch
3) Using conductive tape, continue the connections to the nabbers most likely handholds

That's it, it's simple and all the parts you can pick up locally and will probably cost you in the range of 3-10 dollars.

-BG
Here's a video of it in action:

Here's a video of a robot in pain:

Step 1: Gather Materials and Tools

Get your stuff:
1) Acrylic sheet from the window isle at your hardware store (only necessary if you want a box)
2) Short screws with bolts
3) Washer
4) Aluminum tape from the ducting section of your hardware store
5) Electric Pen you may also find it at your local gag shop
6) Acrylic glue

Tools:
1) Drill and bits
2) Soldering Iron
3) Hot glue gun

Step 2: Make Tilt Sensor

You'll need Frank's Tilt Activated Switch. Frank has some nice animations and fairly easy instructions on how to make one with some plastic acrylic and a few drill bits.

After building one I realize that it is very important to sand down the inside of the washers as well as the lower base of the screws in order to ensure proper contacts. In picture 2 you can see I just used a dremel to do this, careful the washers and screws get quite hot!

Step 3: Take Apart the Pen

The pen unscrews at both the top and the bottom. Remove the battery and the bottom half is not needed. The top half is composed of a tube glued into the outer shell, you'll need to break this. Grab the inner tube with a pair of pliers, pull at one side till it cracks and then proceed to pull on the opposite side. It should crack again and slide right out.

The coils on the transformer are very thin, keep them safe, don't remove the tape that comes over them.

The coils work like a transformer with the high voltage coming out from the middle tab you see that would normally connect to the metal sleeve of the pen. The nub coming off the top of the transformer goes to the + of the battery and the thick wire goes to the - of the battery.

The idea is that the - side of the transformer will only be activated if the tilt sensor connects the central screw and one of the side bolts which would act as one continuous wire to the negative terminal of the battery.

Step 4: Put It Together:

Solder the + terminal of the battery with the +LV of the transformer [see first picture]

Then solder the -LV of the transformer to the middle bolt's hole. To complete the path the washer must connect one of two places, the bottom screw and the middle screw which will complete the -LV side. Or the top screw and the -LV side. So solder that now by connecting the - terminal of the battery with two wires one going to the top screw and one going to the bottom screw. [see third picture]

If you wanted to can make a nifty little case out of acrylic. Just cut out these dimensions:
2 x 1" x 2.5"
2 x 1" x 3.75"
2 x 2.5" x 3.75"

These measurements worked on my model, be sure to take your own (twice!) before you cut. once you have your pieces lay it out and attach "extension" bits of tape to the HV + and the batteries - terminals [see picture 2]. Remember that the aluminum part of the tape MUST touch the terminal in order for it to count as a connection.

Step 5: Finishing Touches:

Once your box is glued you should take the tabs and fold them over till they're nearly flush with the body. Then next step requires you to fold them over into two broad strips. You want the the aluminum part of the tape to touch the extensions aluminum also. So to do this I trifolded the tape and stuck it to the body of the device with the middle strip. You can check the pictures for step by step directions:

Now that the device is done you can go extend the foil tabs out to the most likely hand holds of an object you'd like to protect. Or you could just toss the entire thing to an unsuspecting victim.

Step 6: Future Iterations:

Here's my idea about a second iteration....

Can you use an amplified darlington array touch sensor to trip the shock device rather than the tilt sensor?
(I tried this and it didn't work at first... I overloaded the triplet with current and they died.)

Now some questions:

Is there a better touch sensor we can use that doesn't share a terminal?

Can we make this much smaller?

What's a better shock element?

Maybe with your help, I can make my dream of electroprotecting my bike a reality!
-bg