On Sat, Feb 21, 2009 at 03:49:39AM +0000, pete shorthose wrote: > It may not be ideal to have the path to ground traveling though > several devices but in this instance it works. Well done. > nb: Someone measured the voltage coming off the case of a later model > dell at around 100v. Nice huh. Good job the current is low. Yes, roughly 100V is what I've measured, and we have 240V domestic power in Australia. The insulation ensures the current is low, but it also acts as a capacitor and so the AC can cross it. The low voltage side of the power supply ends up floating at about half the total input voltage, and the low current means that even measuring it brings it down. There's another potential cause of a significant voltage on the low voltage side, and that is a domestic neutral that is not well terminated to the building ground ... but it depends on your local electrical safety regulations, not every regulator does this. If you have that problem you're in for even more interesting effects. > Apples have had problems too or so I've read. I've a MacBook here, hang on ... yes, you're right, between electrical outlet earth and the USB connector shell is 74V AC, which drops to 20V AC if I touch both ground and the shell, and drops to zero if I turn off the adaptor. -- James Cameron mailto:quozl@xxxxxxxxxxxxx http://quozl.netrek.org/ _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
