As I recall from the days of my youth in the Military, we had a simple system that allowed us to have three phones on two wires. Each end had a center-tapped transformer with the center tap being connected to Earth ground.
The three conversations were carried line 1 - line 2, line 1 - Ground, line 2 - ground. The two extra circuits were call Phantom circuits as there was only one (copper) line associated with that circuit. So it would be possible to get a shock if you were connected to a faulty ground connection when someone cranked a field phone connected to the other end. This is similar to circuits used many years ago, and may still, in rural areas that required many mile of copper. Just a thought. John Shinn From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John Woodgate Sent: Friday, January 19, 2007 10:25 AM To: emc-p...@ieee.org Subject: Re: On the Subject of Telephones In message <be3336be85968d49be01e66d6e365b1e01859...@sjc1amfpew01.am.sanm.corp>, dated Fri, 19 Jan 2007, "Tarver, Peter" <peter.tar...@sanmina-sci.com> writes >This has been circulating on the internet for nearly 10 years (that I'm >aware of). I recall seeing it mentioned on Snopes as an urban myth, >but that could be wrong (that site is blocked at work as >'entertainment,' so I can't confirm that at the moment). When I first >saw the story, it mentioned the UK being the poor mutt's environs. Normal UK telephones don't need a ground connection to ring. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ________________________________________________________________________ _____ Scanned by Sanmina-SCI eShield ________________________________________________________________________ _____ CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. _____________________________________________________________________________ Scanned by Sanmina-SCI eShield _______ _____________________________________________________________________ - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
