Having just purchased a half decent bicycle, and living in a city with a bike theft rate almost as high as New York, I wanted to have some peace of mind that if a thief with an angle grinder were to cut through my U-lock I could still catch them.
My main design constraints were as follows:
- The device has to be Arduino based so that if I run into trouble I can easily search the forums for help
- Whatever I make has to be able to fit into a small bag that goes under my seat
- The battery must last for a very long time, at least a few weeks. I don't want to have to plan my bike rides around my lock being charged or not.
This project is pretty cheap, especially if you compare it to the cost of replacing your stolen bike! I've outlined the cost of all the components used in my design below. I was able to use some old parts I had lying around and hopefully you will too. If I had bought everything needed brand new this would have cost about $225.
- Arduino Uno ($24.95) https://www.sparkfun.com/products/11021
- Arduino GSM Sheild ($99.95) http://www.amazon.com/Arduino-GSM-Shield-Integrate...
- Adafruit Ultimate GPS Breakout ($39.95) http://www.adafruit.com/product/746
- Arduino Prototyping Shield http://www.adafruit.com/products/51
- >1.5A PNP Transistor, I used the TIP127 just because it's what our local electronics store had. I'll go over precautions for using different transistors later. ($1.00) http://ca.mouser.com/ProductDetail/STMicroelectron...
- 2.7K Resistor ($1.00/pack)
- 7.4V 2S Li-Po Battery Pack ($10) http://www.hobbyking.com/hobbyking/store/__37346__...
- Retractable Cable Lock ($12.42) http://www.amazon.com/Master-Lock-4605D-3-Foot-Ret...
- GSM SIM Card ($10 + 30cents/sms) This is the rate on Rogers in Canada. Just make sure you are on a GSM carrier.
- Under Seat Bag ($14) for vancouverites MEC has a great one that fits everything snugly. I suggest you try fitting everything in the bag before you take the tags off. http://www.mec.ca/product/5024-801/mec-shell-seat-...
- 5 Minute Fast Set Epoxy ($5)
- Zap Straps ($2)
- 2S Li-Po Battery Charger
- Soldering Iron
- Wire Strippers
- Philips Head Screwdriver
- Flat head screwdriver (or some other good prying tool)
- Digital Multimeter