A couple computer/electronics projects for fun

This page lists a couple past projects I did at home in my spare time for fun.  

Available in Polish

Gun Turret
The purpose of this project was to enforce the rule of "no dog in the kitchen" while I was not at home. The end result was a squirt gun and web cam mounted on a turret, controlled by the computer with a VB program. I could access the VB program over the web from my work computer and see the image in the web cam, and then if the dog was going in the kitchen I could track and squirt him. The turret was operated with stepper motors (allowed fixed positions to be memorized- mostly for fun), which were controlled by a circuit board I designed and implemented to interface my computer's parallel port and control the stepper motors and solenoid (for firing the squirt gun). There was also a pen laser mounted on the turret which you could turn on and off for "targeting" purposes.  I used no micro-controller for this project, instead implementing with a couple logic chips, transistors, and a relay or two. This was quite a bit cheaper for the simple functionality required. Obviously, I didn't have time to watch the web cam every few minutes while working, so I began developing a version with image processing to have the computer decide when the dog was in the kitchen and fire automatically. I got to the point where the computer would take a snapshot when it thought the dog was in the kitchen and play a sound- but didn't actually hook it up to the gun since it might do bad things if it malfunctioned and was allowed to fire the gun on its own.

Solar Tracker
The purpose of this project was to have a solar panel array track the sun to increase performance. Tracking the sun can increase performance 30-40% from fixed position performance. Based on the cost of solar panels (they're not cheap), 30-40% performance improvement on a set of panels adds up to hundreds of dollars in savings on panels you don't have to buy. I did it using a circuit that looked at the relative resistance of two photocells (electronic eyes which generate a resistance based on light level). With a little hysterysis in the circuit, it tracked the sun nicely without moving every second (saving power), or being fooled and moving around when clouds passed over. This was operational until the photocells died from exposure to the sun- the next version will have "sunglasses" or maybe not use photocells at all.