Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site chronon.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!whuxl!whuxlm!akgua!akguc!codas!peora!pesnta!pyramid!chronon!eric From: eric@chronon.UUCP (Eric Black) Newsgroups: net.consumers Subject: Re: RS phone cords Message-ID: <173@chronon.UUCP> Date: Fri, 7-Mar-86 13:05:26 EST Article-I.D.: chronon.173 Posted: Fri Mar 7 13:05:26 1986 Date-Received: Sun, 9-Mar-86 08:46:03 EST References: <4907@alice.UUCP> <44000039@uiucdcs> <714@bonnie.UUCP> <237@micropro.UUCP>, <584@mmm.UUCP> Organization: Chronon Computer Corp., Mtn. View, CA Lines: 70 In article <584@mmm.UUCP> mrgofor@mmm.UUCP (MKR) writes: >In article <237@micropro.UUCP> edg@micropro.UUCP (Ed Greenberg) writes: >>In article <714@bonnie.UUCP> dnc@bonnie.UUCP (Don Corey) writes: >>>I needed to buy some coiled line cords a few months ago. While all of the cords >>>I looked at had four connector jacks on them, some of them only had two wires >>>in the cord. Radio Shacks cord had four wires. A telephone only uses two wires, >>>but I needed four wires for my application. Just as an aside, one of the three >>>cords I bought from Radio Shack was defective. >>>Don Corey >>>AT&T Bell Laboratories >> >>My telephone, (A Western Electric 2500 set with the ubiquitous >>"BELL SYSTEM PROPERTY -- NOT FOR SALE" stampted in the baseplate, has >>four wires running from the modular connector in the handset to the four >>connection points (two each for mouthpiece and earpiece.) >> >>Most every telephone I know of had the same connection. Most standard >>sets have one wire each from the earpiece and mouthpiece connected to >>the same screw on the network box (I forget which one.) Thus, a set >>could actually be wired with a 3 conducter cord and a jumper in the >>earpiece. I have never seen a telephone set with two wires for the >>handset. (I've never even seen one with 3.) >> >>Taco Bell: Part of the nationwide Bell System! >>-- > > Every time I've moved, I've wired up the new phones in my new house, >and I've done it for friends, too - and I have never had to use more than two >wires for any phone - even in a two-line house. > >-- > --MKR A phone line (and therefore the connection of the phone to it) requires two wires for talk current. The power to ring the bell has to come from somewhere as well. Non-party-lines bridge the 80-130 VAC for the ringer over the same two wires as carry the DC talk power. A capacitor in the network (the encapsulated circuit contained in that box with all the screw terminals on it) handles passing the AC ring current to the bell and blocking the DC. Party lines provide the ring current slightly differently. Instead of using the same two wires, the ring current uses ONE of the talk wires, and uses earth ground for its return. This is why (up until just recently) phones had three wires, red, green, & yellow, for connection to the phone line. The red and green are the talk wires, just as now. The ringer, however, is connected between the yellow wire and either the green or the red wire (the red wire as usually shipped). To install the phone on a normal line, the yellow wire is connected together with the green, and *poof* it's a 2-wire connection with the ring current coming over the talk wires. To install on a party line, the yellow wire is connected to local earth ground, and the other end of the ringer is connected to the red or green as appropriate. Note that the phone co. can selectively ring one phone or the other by imposing the ring current on either of the two talk wires and ground. For party lines with two parties this means nobody gets a ring meant for the other party. If there are more than two parties on the line, the long-short-count-'em codes for rings must be used. Party lines are no longer being installed, and existing ones are being converted to private single-party lines. Therefore there is no real need for three wires in the connecting cord for new phones, and they are disappearing. Extra features such as an illuminated dial require extra conductors, however, as pointed out above. -- Eric Black "Garbage In, Gospel Out" UUCP: {sun,pyramid,hplabs,amdcad}!chronon!eric VOICE: (415) 941-0403 US SNAIL: Chronon Computer Corp. 2570 El Camino Real W. Suite 206 Mountain View, CA 94040