Saturday, June 11, 2005

Nothing Here, but Something Cool Elsewhere

Nothing much has happened lately at our house, robotics-wise. The kids were finishing up their last week of school and getting ready for an end-of-school party at the house. I've been trying to get the yard in shape for the summer. So I've spent the last week just dreaming of robots. The other day I saw a sidebar in Consumer Reports about single-use (disposable) digital cameras. The summary was what I always thought. What an expensive way to get digital pictures! But in my robotics frame-of-mind, it finally dawned on me: these things would be really cool to hack. Imagine, a relatively low resolution camera for $10-$20. So I looked around on the internet and found that indeed, there is a community of single-use digital camera hackers that have been doing this for at least two years. My favorite is here. I also ran across a group of amateur radio operators (hams) who used such a camera to take pictures from a weather baloon at over 32,000 feet. How cool is that?

Friday, June 03, 2005

A Non-Event

This will be a short post because of all the things that didn't happen. The modified power supply was a big success or a big disappointment, depending on your perspective. We took the newly modified power supply out onto the driveway, away from any structures in case it caught fire, and plugged it in. With a small DC motor attached, we turned it on. The event was recorded on video, in case something disasterous (but nevertheless cool) happened. Instead, the power supply worked as intended, the motor an the internal fan spun up, all the binding posts showed the correct voltage, and the load resistor does not appear to get particularly warm. So my apologies, dear reader, no video of electronics being transformed into a smoking pile of slag this week!

Wednesday, June 01, 2005

I need more power, Scotty!

School's winding down for the mermals. For Dragonfly, my high school student, this means finals. Even for Wolf Bait, my eighth grader, there are projects to finish. The only thing he's building right now is a model of Gutenberg's press for extra credit. Not content to sit idle, mermaldad had to tinker with something. Besides, if we're going to build a motor controller, we're going to need a good power supply to test the circuit with. Sure, a couple of batteries would be easier, but no one ever accused me of taking the easy route (even when it makes sense).

So let's adapt a power supply. I found a nice website at which describes turning a PC power supply into a hobby supply. I already had a PC power supply laying around, given to me by a friend. Even better, it already had a switch and cooling fan built in. So all I really needed was to connect the power feeds to some binding posts and hook in a load resistor (switching mode power supplies must have a load). I left the unused power connectors in case I ever need them to test out computer components. Here's a picture of the finished power supply:

Here's a close up of the binding posts area. The label on the power supply conveniently had the four supply voltages arranged such that I could put a binding post next to each one. The cable tie holds the load resistor against the case for heat transfer.

Hmm. I suppose it would've been smart to be sure the power supply works before doing all these modifications, wouldn't it?