With a $40 pay-as-you-go cell phone, stun gun, and some basic electronic components, you can teach bike thieves a lesson and, hopefully, foster a small social change through individual action:)
Shameless self-promotion: I've got this and my other stuff for sale here
Updated: here's me demoing this at Dorkbot Austin last month. And yes, I shock myself:)
Here's the original video of me explaining details on building this:
Step 1: Ingredients
For a basic system that shocks and tracks, here's what you'll need:
-stun gun; I used the basic, ~50,000 volt one I found at a local sporting goods store. ~$20. You could also mod an instant camera or build one from scratch...
-Phone capable of talking to some tracking system. I went with mologogo, but feel free to play around with others. For the boost mobile motorola i425t, I paid ~$40. Unlimited internet service is like 35 cents a day. I haven't tried, but I've heard reports of being able to use mologogo without buying the net service...
-a diode to connect in paralel with the stun gun, because we're obviously concerned about safety...
-assorted thin-gauge interconnecting wires and non conductive electrical tapes
-circuit protobyping board
-a basic npn transistor, with datasheet. i used the 2n5088.
-a resistor sized based on your transistor. i used a 1.5-ohm one
To choose the right transistor and resistor, read this guide and look at these circuits. If you're using this same design as I did, the load you're trying to control is the 9v battery connection to the stun gun at 9volts 2.8 amps. If you go off the vibrating motor, you're controlling this via something like ~5volts .5 amps...
Useful tools were:
-screwdriver for the weird screws in the back of the cell phone. it was like ultra-tiny torx or something; your best bet is to get the phone, try your existing collection of weird screwdrivers, and get a specific new one if you need to
-multimeter (with ammeter)
-soldering iron, solder
-'helping hands' alligator clip + magnifying glass thing