brainwagon

Breaking news: Silicon Valley pioneer Steve Jobs has stepped down as CEO of Apple, and Tim Cook will be stepping up from his previous role as chief operating officer to become CEO. This post talks a bit about my employer, Pixar Animation Studios, but in no way should be construed as anything but my own […]

This is awesome! MIT has created an interesting course as part of the their Open Course Ware project: it describes how radar can work, and as a final project, students were expected to build an test a simple radar system. Their description: Are you interested in building and testing your own imaging radar system? MIT […]

A couple of months ago, Collin’s Lab featured a story about making your own piezoelectric crystals from Rochelle salt. Collin stopped short of making an actual microphone though: he just demonstrated that the salt crystal would generate a series of voltage spikes when whacked with the handle of a screwdriver. Leafcutter John followed pretty much […]

At various times, I’ve wanted to set up a little webcam server, but hadn’t really found a program which combines ease of use with versatility. But today, I found a mention for the program “Yawcam”, a Windows only webcam software written in Java, and decided to give it a try. Bingo! It works pretty well! […]

While researching some information on the old CP/M operating system (don’t ask) I found Herb Johnson’s excellent retrotechnology.{com,net} website. It’s chock full of good information on old Apple Macintosh systems, S-100 systems, and cool virtual exhibit on the PDP-11. Bookmarked for later consumption: tons of good information. http://www.retrotechnology.com, .net/. Addendum: It’s amazing how often I […]

NASA astronaut Ron Garan snapped this awesome picture of a Perseid meteor from his vantage point on the ISS: Astronaut Photographs Perseid Meteor… From Space : Discovery News No additional commentary: it speaks for itself.

I didn’t get a chance to record any more ARISSAT-1 data this weekend, but I did catch up on some reading. Apparently, it’s batteries are giving out quicker than expected: the voltage is dropping low enough to cause a reset when the satellite goes into eclipse each orbit. If you were thinking of grabbing some […]

A couple of weeks ago, I programmed an Arduino to take digitized sound stored in its rom, and send it out via PWM of an LED. A couple days after that, I used the same code to send voice using a small 5mw laser module. Ever since then, I thought it would be good to […]

I haven’t had the chance to do any ARISSAT-1 SSTV lately, but I thought I’d snoop over to their gallery to have a peek. Some good pictures are being received, but it appears that some earlier pictures are simply being removed: two pictures that I submitted to them earlier are no longer available. Their comment: […]

Scott Harden had a very cool idea: sending Hellschreiber, an old fax-like teleprinter code invented by Rudolf Hell, using just an Atmel ATMega48 and a canned oscillator. The idea is pretty simple: the canned oscillator will produce a square wave with the same amplitude as the input voltage. So, you simply power the oscillator with […]

I hadn’t worked through the biasing calculations for collector feedback common emitter amplifiers before, so I thought I’d do that for the simple one transistor NPN preamp that Dino built as his weeklyhack. But even before I got to it, I was confused by something. Check out the schematic (cribbed from Dino’s post): I was […]

I was looking for some amplifier references to brush up on amplifier design. I found this one to be pretty good: Amplifier Tutorial.

I’ve always had an interest in forensics in general, and fingerprints in specific. Previously, I had blogged about the FBI publication The Science of Fingerprints. Today, I noticed that another major work on the subject had been released by Project Gutenberg: Francis Galton’s Finger Prints. Francis Galton was a prolific scientist in a number of […]

A few weeks ago I did an experiment that stored an 8 bit PCM file in the flash memory of an Arduino, and then used PWM to flash a laser at a high rate so I could transmit that audio over a long distance to a solar cell based receiver. A few days ago, I […]

Success! I managed to record the pass of ARISSAT-1 from my front yard this morning. I woke up around 7:00AM, and tried quickly to get ready. I pulled on some clothes, then I dug out my handy Arrow antenna (a hand held dual band Yagi antenna for 2m and 70cm) and my tiny Yaesu VX-3 […]