Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!lll-winken!telecom-request From: 0004133373@mcimail.com (Donald E. Kimberlin) Newsgroups: comp.dcom.telecom Subject: Re: More on Frequency-Selective Ringing Message-ID: Date: 29 Mar 91 05:06:00 GMT Sender: Telecom@eecs.nwu.edu Organization: TELECOM Digest Lines: 70 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 253, Message 9 of 10 Larry Lippman, as always, brings us those bits of telephone lore that help put pieces together. In his reply he explains that Bell's way to ring more than four parties was to add coded ringing to divided ringing. (I probably misled the group by not adding to remarks about using "ground" as one side of the ringing circuit -- that the "ground" was through a cold-cathode diode vacuum tube in the protector outside the house.) As to frequency-selective ringers, I came along late in the territory of an Independent that seemed to have bought its equipment from wherever there was some that week. You could go into one house and find and Automatic Electric phone; a WECo in the next, and a Stromberg in the third ... plus assorted cats and dogs from time to time. Reminiscent of that time, when WECo built a pink Princess telephone, AT&T was so proud, they ran an double-page color ad about how modern they were in magazine. One of my neighbors remarked to their chum who worked for "the phone company" how classy that looked. A few weeks later, up rolled the chum in his yellow (remember those from the non-Bell telcos, folks?) truck with ... you guessed it ... in a box and proceeded to ask where they wanted it installed (the bedroom, of course, where else?). I don't recall it ever showed up on the bill. But then, it was a different time and a different society, wasn't it? Oh, ending the story about the pink Princess phone: The nice chum from the telco said he was sorry, but he couldn't make the ringer work. This is appropos of the pretty constant remarks about mechanical tuning of riningers. The "book" probably never told people to do it, but in that place at that time, it was done a fair amount. It was probably a result of running a dial network with all that hodgepodge of hardware. As what happens with so many of our narrow views of "the business," this kid thought it was just normal. and, yes, bells hummed and tinkled a lot in that place at that time. We all just thought it was normal. And, thanks Larry, for telling me what a "pole-changer" was for. I saw old references to them, but never in a context that explained what their function was. They must have been very archiac, for by the time this kid came along, all the offices I saw had motor generators for ringing current. I guess they were more maintenance free. I can only guess pole-changers went out before WW II. Larry mentioned "AC power line operated ringing plants" in the context of U.S. PBXs. Most of the Bell and overseas telcos I ever got into used a low frequency AC ringing current (16-2/3Hz in most, which is curiously the same .83333.... of 20 Hertz as 50 Hertz is of 60 Hertz. This always made me suspect I could guess where they got their first ringing generators from. What I found uniquely different was that in my Paris apartment, it seemed the PTT rang phones with 50 Hertz. This could easily have been a current-limited sample of the AC power line. I often thought that probably saved French-technology PTTS a few million in ringing generators over the years. Makes me wonder why the rest of us even bothered to get into 20 Hertz in the first place. But when Larry said: > Sounds like an end-cell charger to me..... and then: > remember liquid countercells? He brought up a whole tale I'll put into another nostalgia post, because this one is getting too long and wandering off its title. Anyhow, thanks and congratulations, Larry! I hope people like Al Varney have more to add to the "mysteries of ringing" and putting the two major ways into context.