From owner-freebsd-hackers Fri Mar 6 19:58:02 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id TAA17813 for freebsd-hackers-outgoing; Fri, 6 Mar 1998 19:58:02 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from sendero.simon-shapiro.org (sendero-fddi.Simon-Shapiro.ORG [206.190.148.2]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id TAA17785 for ; Fri, 6 Mar 1998 19:57:55 -0800 (PST) (envelope-from shimon@sendero-fxp0.simon-shapiro.org) Received: (qmail 23123 invoked by uid 1000); 7 Mar 1998 04:06:14 -0000 Message-ID: X-Mailer: XFMail 1.3-alpha-021598 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <19980306213559.63726@mcs.net> Date: Fri, 06 Mar 1998 20:06:14 -0800 (PST) Reply-To: shimon@simon-shapiro.org Organization: The Simon Shapiro Foundation From: Simon Shapiro To: Karl Denninger Subject: Re: SCSI Bus redundancy... Cc: lada@ws2301.gud.siemens.at, hackers@FreeBSD.ORG, julian@whistle.com, wilko@yedi.iaf.nl, dmlb@ragnet.demon.co.uk, Terry Lambert , Chuck Robey Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG 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