Another nostalgic post about an old project that I’m purging from my closet… This time from late-1999 through mid-2000. The Kiwi was a rather ambitious built-from-scratch Linux PDA that I spent my high school years on. My original goal for this project was reminiscent of the One Laptop Per Child project. I liked typing my notes, but of course laptops were prohibitively expensive. I wanted to design a very simple PDA, with a keyboard, that... Read More

Self-contained TED receiver

My previous entry introduced a homebrew receiver for the powerline-based data protocol used by The Energy Detective. I just designed a second revision of that receiver. This one is self-contained: It gets power and modulated data from a 9V AC wall-wart transformer, and decoded data leaves via an RS-232 serial port at 9600 baud. Best of all the circuit is very simple: Just an 8-pin microcontroller and a single op-amp. Major changes in this version: DC... Read More

Interfacing with The Energy Detective

I recently bought The Energy Detective (TED), a pretty inexpensive and friendly way to keep tabs on your whole house’s electricity usage. It’s a lot like having a more featureful version of your utility company’s power meter, sitting on your kitchen counter. It can estimate your utility bill, and tell you how much electricity and money you’re using in real-time. The resolution is pretty good- 10 watts, 1 second. As a product,... Read More

Hard disk laser scanner at ILDA 4K

I should have blogged about this long ago, as I’ve been working on it off and on for about three months now, but today I reached an arbitrary milestone that compels me to post I’m still actively working on this project, so I’ll try to make updates occasionally, and if I end up putting together an actual project web page I’ll link it from here. My latest tinkery hardware and embedded systems project is a homebrew laser scanner.... Read More