We’re starting off the new year with some terrific applications. Some of the best projects we feature aren’t based on original ideas; they’re often recreations of products that are already available commercially. The lessons learned from the experiences are useful, of course. But the fun part is seeing how the new designs compare to off-the-shelf versions and what improvements were made. We have some interesting comparisons in this issue.

TiVo fans will be interested in Miguel Sanchez’s digital personal video recorder (page 16). He decided to build his own because commercial PVRs aren’t sold in his native Spain. Miguel used Linux, a Hauppauge DVB-S digital satellite receiver card, and a Proxim ORiNOCO Wi-Fi card to design his own PVR. He warns that the do-it-yourself route is undoubtedly more expensive than simply buying a PVR, but we agree with him that it’s definitely more fun.

From home electronics to bar electronics, we also have an article about building your own karaoke machine (page 36). Brad Stewart won Second Prize in the Zilog 2003 Flash for Cash Z8 Encore! International Design Contest with this project. (For more information about the design contest, visit www.circuitcellar.com/magazine/contests.htm.) He designed a programmable, low-cost audio signal processor around a Z8 Encore! evaluation board. One of Brad’s notable achievements is the quality of the processor’s pitch shifting capability, which enables him to create harmony with only one voice.

Back in June 2001, David Smith wrote about an AVR-based submersible data logger he built to upload data to a PC (“Under the Sea: A Scuba Dive Monitor,” 131, June 2001). He’s back this month with another 8-bit AVR-based project designed for scuba divers (page 20). When deep diving, breathing Nitrox instead of regular air enables scuba divers to stay at extremely high depths for longer periods. Because Nitrox is enriched with more oxygen than regular air, it’s critical to monitor the ratio of oxygen to nitrogen. An imbalance of too much oxygen can lead to serious health problems or death. David designed an innovative AT90S4433-based analyzer that uses a Teledyne sensor to measure the percentage of oxygen in a Nitrox tank. The analyzer boasts accuracy that rivals commercial units.

In addition to these projects, this issue also features a number of other exciting applications, including a couple from the college and university contingent. Turn to page 44 to learn how a team from Mesa State College, Colorado, reverse engineered an RC transmitter, modified it for PC-control, and wrote software to design their own PC-controlled RC car. A group from the Jerusalem College of Technology–Machon Lev has made signal processing with DSPs easier (page 52). This group demonstrates how to eliminate the need to add external peripherals by using a peripheral-rich Analog Devices ADuC812 to design and implement digital filters.

We enjoyed reading about all of the projects featured this month. We hope you find them as interesting and useful as we did. 

jennifer.huber@circuitcellar.com