I want to echo this advice yet again. Unfortunately, the hobbyist site which was linked here suggested doing this in a non-isolated way (with the caveat that you have to know what you are doing). I think that is UTTERLY FOOLISH. Normal power supplies usually have rather large leakage currents from the AC line to the output. Several milliamps is common. This could be very dangerous if routed directly across your chest with a good connection. DO NOT connect anything to your body unless it is isolated in some way from the AC power lines. Sean On Tue, Jan 25, 2011 at 9:52 AM, RussellMc wrote: > This is IMMENSELY GOOD ADVICE from Olin. > Ignore it and die, or kill somebody, possibly. > > Real world devices go to the utmost care to avoid killing people. > >> You definitely don't want to have a direct connection between your body = and >> your computer, or anything else ultimately tied to the power line. =A0It= 's not >> the magic smoke of the electronic parts you should be worried about, but >> releasing the magic smoke from your heart. =A0Stuff happens. =A0The prob= ability >> may be low, but when the electrodes are tightly coupled to your heart mu= scle >> the consequences can be severe. =A0Remember that the main difference bet= ween a >> EKG and a electric chair is what the wires are tied to. > >> I would run the gizmo off a few batteries, and opto-couple the output to= a >> serial line on your computer. =A0Having the gizmo in your pocket also he= lps >> with the common mode rejection, since it will be subjected to much of th= e >> same common mode signals your body is, and they will therefore cancel >> without active electronics having to do it. > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .