I built a robotic vehicle with unusual components:
- Two drive motors are cheap electric drills from K-mart at each
- Swivel for castoring rear wheel is from old hard drive, very smooth
- Body of car is an old plastic toy wagon, very strong
- Tire for castoring rear wheel is model airplane tire
- Two tires for drives are plastic timing gears, the cogs dig into carpet nicely
I modified an old TV cart and use it as a computer station. Looks odd, but works well.
The drive coil and the magnet from an old hard drive make a great vibration sensor. I hung it from the basement ceiling and attached a one yard bar to it with a weight attached. Tremors in the basement beams generate a signal in the drive coil. Would it make a good seismic detector if it was magnetically damped, the correct pendulum length and weight attached, and proper signal conditioning added?