From: <so...@pk...> - 2007-12-31 20:55:55
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> What happens if you connect EEG gnd and PC gnd? > > I thought PC gnd was tied to earth gnd. Probably nothing. A PC's ground may or may not be connected to earth ground. It shouldn't be connected to earth ground. You'd have to have the schematics to see. The first time I fired up my system I had GND connected to the RS232 GND on my IBM laptop. I don't think I died. But to be safe it is much more prudent to isolate the system. I now run off batteries and have an optoisolated RS232 interface. I wanted my system to be as simple as possible. Batteries eliminates the need for a DC-DC converter. The DC-DC converter is actually a second level of isolation. The transformer in the DC supply also isolates you from the mains. But if your RS232 is not isolated, then you defeat the function. > thanks, > > -Oscar Scott O |