Airplanes, hardware, software, jazz
Appliance: an instrument or appratus for a specific purpose. In other words, an appliance is not a general-purpose machine like a desktop computer. Another term heard occasionally is media-pc. It’s a network end-point in the living room that can play and record audio/video, and is a connection point for USB devices like webcams or memory card readers. It’s silent and has no moving parts, and is controlled primarily with an infra-red remote.
Why does anyone need a headphone amplifier? You can just plug your headphones into the jack on your iPod, can’t you? Yes, of course you can. However there are some high-end headphones that have low impedance — they need more current than the usual high-impedance phones. Often these headphones are low efficiency, meaning for the same loudness they need more input power than more efficient phones. Finally, the output amplifiers in low-power portable devices are often of indifferent quality, particularly at reasonable volume. A headphone amplifier fixes all these problems; and if you make it yourself, you can add extra features like crossover networks.
GPS is fundamentally a very accurate time-dissemination system. With an appropriate GPS receiver, the clock on a computer can be maintained to within a few milliseconds of UTC. However, consumer GPS units do not provide the “PPS” super-accurate time signal to the computer, because the USB (or serial) connection has no way of transferring it. The OEM version and a little work with a soldering iron is all that’s required. Continue reading »
The infrastructure here is DNS, NTP (stratum 1), and firewall.
A sidereal (L. “of the stars”) tracker is a camera mount that turns at exactly the speed of rotation of the earth but in the other direction, so the stars appear stationary. This allows long exposures of the stars — up to 3 hours with this one. Continue reading »
What do you get when you put a Logitech QuickCam in the hands of a geek with a bunch of Nikkor (Nikon) lenses? He is dissatisfied with the quality of the optics. Why not replace it with a Nikkor lens, he thinks. It was with me the work of a moment, and now I get excellent optics, good focussing action, aperture control for those difficult lighting conditions, and a super-fast telephoto! The Glen Park Cam no longer works, but here’s a gallery of past images. Continue reading »