electro-Physics: 17.3409 volts

Tim wrote: And civilian aircraft as well. When I flew from San Francisco to London in 2002, I had to make arrangements to use my CPAP machine. They were concerned because the machine is rated for 50 to 60 Hz. But it uses a switching power supply which is actually perfectly happy to run on 400 Hz, so I was able to use it. It's irritating that the manufacturer defines the rating based on what power they expect the user to have, rather than practical operational limits. Unfortuately, the mechanic assigned to wire the outlet for me (by a long extension cord and an adapter from the aviation power plug to a standard NEMA 5-15R receptacle) apparently plugged it into the "ground service bus" which is intended for non-flight use for vacuum cleaners and such, and is automatically turned off on takeoff. So I had to stay awake for the whole flight. On the return I asked them to make sure it was NOT wired to the ground service bus, and it worked fine. Speaking of annoying specifications, I was just reading the manual for an HP logic analyzer circa the mid-1990s. They make a distinction between "specifications" and "characteristics", defining the former to be something they actually test the instrument against, and the latter to be non-tested and non-guaranteed. They list the maximum clock fequency and minimum clock pulse width as specifications. But they list the number of channels and the memory depth as "characteristics", which means that if the analyzer only had 67 channels instead of the "characteristic" 68, they could still claim that it met the specifications. In practice I'm sure they wouldn't try to screw customers on that point, and couldn't get away with it anyhow because the channel count and memory depth are prominently featured in the sales literature. But after they go to all the trouble of explaining a distinction between specifications and characteristics, it seems really bizarre that they would put the channel count in the latter category since it is clear that they do actually have to test them all. Eric