Date: Fri, 06 Mar 1998 20:06:14 -0800 (PST) From: Simon Shapiro <shimon@simon-shapiro.org> To: Karl Denninger <karl@mcs.net> Cc: lada@ws2301.gud.siemens.at, hackers@FreeBSD.ORG, julian@whistle.com, wilko@yedi.iaf.nl, dmlb@ragnet.demon.co.uk, Terry Lambert <tlambert@primenet.com>, Chuck Robey <chuckr@glue.umd.edu> Subject: Re: SCSI Bus redundancy... Message-ID: <XFMail.980306200614.shimon@simon-shapiro.org> In-Reply-To: <19980306213559.63726@mcs.net>
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On 07-Mar-98 Karl Denninger wrote: ... > I'm not talking about getting buzzed. I'm talking about bridging it with > something near-zero resistance (say, a metallic object). Like I said, that scredriver incident was as loud as a handgranade. The scredriver dropping fellow came out unharmed, except for the courtmarshal sentence to some 35 days in the brigg for violating more safety rules than anyone could count. > People discount lower-voltage circuits because they *think* they're > safer. > They're not really if there is what amounts to a near-infinite current > source behind them. >From R/C car racing, a sub-c NiCd battery will put out 60 AMp for about 3.5 minutes. > 110V is perfectly safe if you provide no path to ground through yourself > and never bridge hot and neutral (or ground). 48V is perfectly safe > under > the same conditions. Violate those conditions and you find out how > unsafe either can be. A telephone man older than I am (yes, there is such a thing), claimed that Union rules had as much to do with telephony voltages as pure engineering. The DC thing dates back to the days that DC/AC converters used mechanical vibrators and were less than efficient or reliable (yes, I used these on FM two-way radios) These old days were NOT good. Simon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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