Path: utzoo!utgpu!attcan!uunet!husc6!think!ames!amdahl!rtech!hoptoad!pozar From: pozar@hoptoad.uucp (Tim Pozar) Newsgroups: sci.electronics Subject: Re: crossing phone lines Message-ID: <5472@hoptoad.uucp> Date: 27 Sep 88 13:00:31 GMT References: <7921@cit-vax.Caltech.Edu> <2689@kitty.UUCP> <657@eplunix.UUCP> Organization: Syncstream/Widget Systems (San Francisco) Lines: 27 raoul@eplunix.UUCP (Otero) wrote: > In article <2689@kitty.UUCP>, larry@kitty.UUCP (Larry Lippman) writes: > > In the on-hook (i.e., idle) state, connecting the two lines exactly > > in parallel (tip1-to-tip2 and ring1-to-ring2) will, in general, be undetected > > by the central office apparatus since there will be no current flow. > > No such luck. Unless the voltage matching is perfect, which it never is, > a small DC current will flow from one line to the other. This will > mess up both your lines, and you will not be able to use either. Ma > Bell will also usually disconnect the lines within about a week of this > sort of nonsense, thinking there is a short somewhere (there is!). > > However, don't take any of our word for it. Just short them together > at the phone jack and see.... Try some real scientific method. Or the way I've always done it was via a transformer... t1 ----- ----- t2 )||( 600 ohms )||( 600 ohms )||( r1 ----- ----- r2 -- ...sun!hoptoad!\ Tim Pozar >fidogate!pozar Fido: 1:125/406 ...lll-winken!/ PaBell: (415) 788-3904 USNail: KKSF / 77 Maiden Lane / San Francisco CA 94108