Kinda reminds me of some of the old sci-fi shows.
Now all you need to finish the image is a pair of jumper cables hooked to
the tower and a lightening bolt. <:-))
Mine took a hit one morning earlier this week. I think I was setteling back
on the bed but the covers were still on the way up.
No damage to anything other than my nerves. <:-))
Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair (S# CD-2)
> At 06:42 PM 5/13/2004 +0100, Tim Makins, EI8IC wrote:
> >----- Original Message -----
> >From: "Jim Lux" <email@example.com>
> >Subject: RE: [TowerTalk] Low Inductance Ground Idea
> > >
> > > I've certainly had the unpleasant experience of having racks of
> > > where the grounding was bad, so one rack floated up to 60-70 VAC
> > > to a "good ground" just from capacitive coupling between AC line and
> > > equipment. This is not a good thing when you have low impedance
> > > attached to your head and you touch the rack.
> >OK, so you've got me all curious !! Why did you have low impedance
> >attached to your head ???
> Back in the 70s, I was doing research on brain waves, so we had high gain
> differential amplifiers hooked up, and a ground/guard electrode to reduce
> the common mode signal that the diff amp would have to reject. Typical
> electrode impedances (at 100 Hz) would be around 1K ohm, so even if the
> line was leaking through 100K, you'd feel it (threshold of sensitivity is
> around 1 mA). In this case, I think the leakage path was through some 0.1
> uF caps hooked from line to ground(and case) for "transient suppression"
> inside the equipment. The ground pin in the cord wasn't connected (or had
> failed), so the equipment case was hot, relative to the actual ground.
> In the last 20-30 years, medical equipment designers have become very
> of such paths, and patient isolation is much better. (and they have clear
> plugs so you can visually inspect the connections, too!).
> In any case, measuring microvolt signals from 1-300 Hz, and rejecting 60Hz
> interference is quite the challenge. Ground loops have real significance,
> when you're trying to get 100 dB+ CMRR.
> >73s Tim EI8IC
> >See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> >Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> >any questions and ask for Sherman, W2FLA.
> >TowerTalk mailing list
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
> TowerTalk mailing list
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
TowerTalk mailing list