wb8foz@mthvax.cs.miami.edu (David Lesher) (03/24/91)
Donald E. Kimberlin suggested that changing the capacitor in tuned ringer phone will change its response to other frequencies. I hate to object to his statement when the rest of his submission was full of great telco history, but, according a friend of mine, who did extensive magnetic (i.e. ferroresonant transformers) design work AND also collected telephone equipment: The cap does NOT set the response of a mechanical ringer; rather it's done in the armature/coil design. I can only add a story of my own. One day, the Big_Boss brought in this old piece_of_junk 500 set, and complained it would no longer ring. Well, I hooked it up to my Subcycle, and sure enough, it hmmmed a little, but no ring. Ah_ha, I thought, bad cap in the 425K network. So I got the cap off of an old E1, and put it across A & K. Same thing. Well I asked the Big_Boss WHEN it stopped ringing, and got an evasive answer. Turns out it was his mother's, and I guess he was catching hell for not being able to fix it. So then I took a stab in the dark, and said, "She used to have a party line, before she moved. Correct?" He, at last, admitted such. I told him to find another ringer, and I'd install it. He did, I did, and his 90 year old grandmother was happy with him. Me? I kept the tuned ringer, and gave it to friends for their telephone museum. When you looked at the ringer, the magnetic shunt was cut. sssssssss s s cccccc s cccccc s cccccc sx cccccc x cccccc sx cccccc s cccccc s cccccc s s s sssssssss where c is the coil, s the shunt, and x a piece of much thinner material spot-welded around the gap. By the way, there is another Ohio name to add to the saga. C. P. Stocker designed the first magnetic 60-20 hz converter, called it the Sub-Cycle, and founded Lorain Products Inc. just west of Cleveland. They also made no end of telco power equipment. I recall hearing about a 5000 amp, 9 volt supply. Think how many Walkmans THAT would run.
0004133373@mcimail.com (Donald E. Kimberlin) (03/25/91)
In a post (Digest v11,iss232) David Lesher writes: > I hate to object ... but, according a friend of mine, who did > extensive magnetic (i.e. ferroresonant transformers) design work AND > also collected telephone equipment: > The cap does NOT set the response of a mechanical ringer; > rather it's done in the armature/coil design. Unfortunately and confusingly, David, *both* ferroresonant and L-C tuning were used to set the frequency of ringers. My remarks were perhaps hasty, in that I thought of the many Automatic Electric phones used by GTE companies from the fifties onwards. It is in fact, probably more likely that ferroresonant ringers were used in the earlier era. And, it's very likely that Bell Labs got the max value it could from ferroresonance in its 20 Hertz-only ringers, being as they had Western Electric make millions of them for the monopoly-era Bell System. But, the next anecdote is curious: > ... the Big_Boss brought in this old piece_of_junk 500 set... and sure > enough, it hmmmed a little, but no ring. Ah_ha, I thought, bad cap in > the 425K network. So I got the cap off of an old E1, and put it across > A & K. Same thing. > Well I asked the Big_Boss WHEN it stopped ringing, and got an evasive > answer. Turns out it was his mother's, and I guess he was catching > hell for not being able to fix it. > So then I took a stab in the dark, and said, "She used to have a party > line, before she moved. Correct?" He, at last, admitted such. I told > him to find another ringer, and I'd install it. He did, I did, and his > 90 year old grandmother was happy with him. Me? I kept the tuned > ringer, and gave it to friends for their telephone museum. Watch out you didn't fool yourself a bit there. Did you look at the frequency of your Sub-Cycle? *Most* of them put out 30 Hertz, not 20, and a nice, sharply-resonant 20 Hertz straight-line ringer won't work on a PBX Sub-Cycle for that reason, be it ferroresonant or a tuned circuit. Later description in the post about cutting the magnetic shunt of the ringer core probably has some bearing on the matter, but it goes beyond my knowledge of what WECo did in fact do. The remark that it was a 500 set, taken at face value of that set being of WECo origin, indicates that maybe Bell Labs did go heavily into ferroresonant techniques. However, the point I'd like to make very strong is that Bell did *not* use frequency-selective ringing ofr its party-line service offerings (at least in general). Bell people were usually quite puzzled when it came to Harmonic, Decimonic, Synchromonic, or the other various forms of party-line ringing. Bell instead, used 20 Hertz exclusively, and a system of ringing tip-to-ground or ring-to- ground for two-party, adding polarized (negative or positive) polarity to the tip- or ring-to-ground connection for four-party. That's really what the yellow wire inside the phone was for, when you find those strange cords with only three wires ... red, green and yellow in the jacket. One side of the ringer would be connected to the yellow wire and then connected to a ground wire brought inside to the the 42A block. That also explains the several forms of three-conductor station wire found in old buildings. You may have heard the common Bell jargon, "tip party" and "ring party," alluding to which side of the line their ringer was connected to. Bell called its party line ringing system, "divided ringing," and telephone sets made for divided ringing usually had the suffic letter "D" (for example, 500D). In the manual days, the code letters M,J,R or W added to a phone number alluded to the four possible combinations of line side and ringing polarity. Meantime, non-Bell companies could ring a half-dozen or more parties straight-line with different frequencies, and when they got really clever and added divided ringig to it, they could ring a dozen or more on a line. I personally suffered one in the 1950's that had *thirteen* parties on one pair. Needless to say, we had a rotten grade of service! Also, needless to say, I changed a *lot* of ringer capacitors in that network ... which was *not* Bell-style!) David's post concludes with: > By the way, there is another Ohio name to add to the saga. C. P. > Stocker designed the first magnetic 60-20 hz converter, called it the > Sub-Cycle, and founded Lorain Products Inc. just west of Cleveland. > They also made no end of telco power equipment. In fact, when my first post got to the point of North Electric and then W.W.Dean's frequency-selective ringer, I thought of mentioning Mr. Stocker's Sub-Cycle, but its date was 1935 and we were getting too far from Chicago and very early suppliers, so I left it out. The book I mentioned does give Mr. Stocker due credit for yet another non-Bell innovation in telephony. Lorain Electric is, of course, still in business, providing many a Sub-Cycle to this very day. If one wants to brag on the *many* innovations of non-Bell sources, Ohio certainly ranks up there with Illinois. The book I referred to credits the Lorain (Ohio) Telephone Company with the first ship-to-shore radio- telephone service, which survives to this very day on the Great Lakes and the Mississippi-Ohio river valleys, as the Lorain Radio Company. Herein lies a perfect example of one of the major problems with trying to develop a balanced sense of telecommunications history. Bell history also accurately claims rdaiotelephone service to ships, but at sea, and beginning in 1929, in a service well-documented to the U.S.S. Leviathan sailing the Atlantic. But, the non-Bell domestic operators on the Great Lakes didn't know of it; thus they inaccurately claim primacy in that technique. David ends with yet a third topic: > I recall hearing about a 5000 amp, 9 volt supply. Think how many > Walkmans THAT would run. No question about that, but I don't know what anyone use that large a 9 Volt supply for. Voltages of 24, 48 or 52 Volts at 2,000 or 5,000 or even 10,000 Amps weren't (and still aren't unusual to provide talk battery for a whole telephone exchange. They consist simply of an AC-powered set of rectifiers charging ("floating") a large string of lead-acid batteries, just like the one in your car, to power the phones and for that matter the switching and transmission equipment as well. What's fun is to happen to be near the cells when the AC fails. The current draw is such you can see the plates in the glass cell tanks bend and flake under the stress. The whole notion of rectifier-floated batteries went so far as to have a 252 Volt battery string for the plate voltage in microwave atations. It consisted of *forty-two* 6 Volt automobile batteries connected in series, floated across a rectifier. THAT not only could shock you; it could do a nice burn at the same time. Needless to say, one works *very* carefully in such plant!