It looks like Siemens Energy and Automation has a has made their Seimens Technical Education Program (STEP!) courseware available (PDFs). Topic range from basic electronics, to motor control, to power distribution. What really caught my eye was the abundance of easily understandable safety information in the power distribution course section. The surge protection section is easy to understand and seems to contain enough information on properly wiring a residence to avoid certain catastrophes. Basically, this place seems like a good place to start for those who would like to do some minor work on their home’s power system but don’t have the required training. (This is not to say that STEP has all of the required training either!)
On a side note, I am in the middle of writing a document up to overview the Yagi antenna. I am more than half of the way done, however, I am going to the Neural Interfaces Conference next week. Consequently, the full version should be up next Thursday. If anyone else is there and has a desire to meet up then send an email.
As some of you may have known, I am a bit of a FreeBSD enthusiast and have been using it regularly since around the time of the Linux fragmentation/teardrop vulnerability. I have always kept a FreeBSD system running at home so that I could perform various network tasks and automate things. In an effort to conserve power and reduce noise, I have been using my trusty Sony z505sx (pictured above). Recently, I switched to a Jetway MINI-ITX board and have been quite happy. The board runs a 1.2GHz Via C7 Eden processor, is fanless and consumes only a few watts of power while operating. It is loaded with 1GB of ram and a 750GB SATA (also low power) drive to provide ample storage. Since the system has RCA/S-Video out, I added a 5″ LCD screen on the top. So far, the machine performs well running as media/web/ftp/ssh server and is barely audible with no fan attached.
I am manufacturing a custom case for this machine and will post a full writeup once I have a cover that I like, for now, you will have to enjoy the single image below. As far as the z505sx is concerned, I decided to put it on eBay in a preemptive spring cleaning effort and to avoid clutter.
If anyone has had their computer crash due to very brief power flicker, you can sleep better knowing that there Information Technology Industry Council is working hard to keep you on-line. I started reading a book on power delivery and quality and have found this figure above, the CBEMA/ITIC curve. The idea is that power supplies and systems in “information technology” are designed to comply with certain voltage tolerances, or rather tolerate certain deviations from the normal 120Vac@60Hz (in the U.S.A.) for specified amounts of time. For example, this type of equipment is supposed to tolerate a total loss of power for one half of a cycle without interruption. Conversely, the same equipment is supposed to tolerate a voltage surge of 500% of the nominal value for 1% of a total cycle period.
After looking deeper, I also located a SEMI F47 power standard which applies to manufacturers of equipment and subsystems destined for semiconductor manufacturing. This standard is not as rigorous as the one above and is only specified for voltage sags. It can be seen that this type of equipment must be tolerant of a reduction of line voltage to 50% of nominal value for up to 0.2 seconds on a single phase system or on one phase to neutral for a three-phase system. A presentation covering updates to the SEMI F47 standard is available here.
( voltage_tolerance.pdf )
( semi_standards.pdf )
( 4overviewofsemif47-0706.pdf )
( iticurv.pdf )